Super Chevy and DSE Test

[Steve Chryssos]

Maybe this belongs in the suspension topic. I think it belongs here since it speaks to the philosophical concept of Pro-Touring performance as a whole.

All too often, the "1g" lateral acceleration number is tossed around like it is somehow easily attained (Alcino's short wheelbase, lightweight, killer Mustang II excluded). At the same time there is a constant clamoring for real world before/after product and system testing.

Well, the May 06 issue of Super Chevy is in my dirty paws, and the numbers are in! So the big question is: Are You Happy?

They tested a 1969 Camaro with complete front and rear DSE suspension, Fikse wheels and high performance rubber. The car represents the top of the bell curve for pro-touring enthusiasts where comfort and ride quality are important factors. Build cost for their test vehicle is also within reason since the car is powered by a crate 383. The only anomaly is the choice of "pricey" Fikse wheels. Obviously they could have tweaked the tuning or chosen a "stiff" car with a cage or dropped a ton of weight to exaggerate the numbers. But instead they chose to test the car in real world trim where ride quality and amenities are paramount.

BEFORE
A stock, full weight F-body with high performance radials is good for about .75g (I can't imagine what these cars did in 1969 on rubber of that era.)

AFTER
The DSE test car--with full front and rear suspension upgrades--generated .84g's of grip. That's a healthy gain, but it's nowhere near the lofty expectations of the message board myopics. So now you know. I'm willing to sacrifice ride, comfort and amenities for performance, so I am quite comfortable with the results.

Are you?

[EFI69Cam]

What were the before and after slalom speeds?

I'm not a suspension guru, but it seems to me that driving the car in a circle to find the tires breaking point is not the same as a slalom speeds.

Seems to me that the lateral g number is like the RWHP horsepower from a chassis dyno and the slalom speed is like the 1/4 time. Or how well can the car use its traction.

[Rick Dorion]

I guess, assuming original leafs, I would like to have seen an upgrade with their leaf springs, then the quadra-link.

[DLinson]

I don't think the lateral G measurement is a good gage either. I've discussed this with Kyle before and he said that he uses the slolum testing to gage the vehicle performance.

Isn't .84 G on line with some of today's sportier cars like the Mustang and the 4th gen Camaros? I guess that's a big part of Pro-touring, making an old muscle car drive and handle like a late model. It's not going to win on track day but that's not the point for a lot of pro-touring cars. If it were, we would probably call this "Pro-tracking" instead?

Take the test car in the magazine, through on different springs and shocks and you may bump the numbers up into the .9 range and closer to 1g with some autocross tires. It probably won't make for a comfortable driver but it's a different goal for the car.

Dennis

[MarkM66]

Haven't seen the newest issue yet.

What size and brand of tires are on it?

[Steve1968LS2]

It's VERY uncommon for a musclecar to attain better than (or even close to) .90g on non-R-Compound tires.

The cones is more than a measure of traction, it's also a test of the suspension and how it reacts to constant changes in direction.

[Steve1968LS2]

Isn't .84 G on line with some of today's sportier cars like the Mustang and the 4th gen Camaros?

Yes, .84 is a great number for a new car to get.. I don't think Johnny's ''05 Mustang was better than that (corvettes excluded :) )

[Steve Chryssos]

What were the before and after slalom speeds?
I'm not a suspension guru, but it seems to me that driving the car in a circle to find the tires breaking point is not the same as a slalom speeds.
Seems to me that the lateral g number is like the RWHP horsepower from a chassis dyno and the slalom speed is like the 1/4 time. Or how well can the car use its traction.


I'm with you. I'm just trying to avoid confusing the issue with too much info. Since lateral acceleration is the buzzword, I started there.
**Baseline numbers: About 41-42 mph on a 420 foot course.
DSE front and rear upgrades: 58.39 mph avg.

**I pulled the baseline numbers from another article in the same issue since the "front upgrades only" test (April issue) does not include factory stock numbers.

Rick, The leaf spring numbers were posted in the April issue and also serve as the before numbers in the may issue. 55.55mph avg and .81g. That's front suspension upgrades and wheels/tires only.

[baz67]

I think that is awsome for DSE to have the balls to do that. How many venders are willing to let everyone know how thier products perform in real number tests in such a public venue?

[EFI69Cam]

I'm with you. I'm just trying to avoid confusing the issue with too much info. Since lateral acceleration is the buzzword, I started there.
**Baseline numbers: About 41-42 mph on a 420 foot course.
DSE front and rear upgrades: 58.39 mph avg.

**I pulled the baseline numbers from another article in the same issue since the "front upgrades only" test (April issue) does not include factory stock numbers.

Rick, The leaf spring numbers were posted in the April issue and also serve as the before numbers in the may issue. 55.55mph avg and .81g. That's front suspension upgrades and wheels/tires only.
I don't know for sure but 16+mph improvement seems huge. If that is over and above what the car did with tire upgrade, this is even more amazing to me.

[Rick Dorion]

Yes, I know. I just don't know if the leafs are true originals or upgraded. If original, then it seems there would be a benefit in adding that one upgrade in between for incremental improvement. All in all, I do applaud the testing and data availability.

[MuscleRodz]

Not having the issue in hand, it sounds like this was done with a leaf rear. I wonder what differences there would be with a Quadra-link rear? Kudos to DSE for standing behind their products with real world numbers.

Mike

[Steve Chryssos]

The May issue is Full DSE front with Quadra-Link. I assume that the previous month was with DSE 175 lb leafs. So the May issue shows apples to apples gains for the Quadra-Link--or at least it shows the quantitative gains: .81g to .84g. Gains in ride quality are difficult to measure.

And perhaps they should have used a sidebar to satisfy the benchracers with numbers based on hardcore tuning (springs/sway bars, shock valving, etc) where ride quality might be sacrificed in the name of numbers. Doing so might have added perspective to the real world numbers.

[DJW32]

Not having the issue in hand, it sounds like this was done with a leaf rear. I wonder what differences there would be with a Quadra-link rear?

Mike

Mike,
This was with the Quadra-link.

The article was a great read

edit*Steve and I posted at the same time...damn computer is slow

[MuscleRodz]

Ride quality is purely subjective. I have a '97 Chevy One ton crew and it has as nice of a ride as my '94 1/2 ton Chevy did, although neither one is as nice as my parents Lexus and don't expect them to be. If the ride quality of my '68 Camaro is comparable to my 1 ton, I will be happy. To others, they may hope it is as good as their BMW or Mercedes daily drivers.

Mike

[Steve Chryssos]

The quarter mile stuff is hard to peg as well. Too many variables. No such thing as a 383 in 68. But the Leaf Spring to Quadra-Link data is apples to apples:

All other things equal:
Leaf Springs: 15.16 @ 98.62 mph
Quadra-Link: 14.28 @ 101.22 mph

Lemme see.......That's damn near a second with no engine changes.

[DJW32]

Steve,
Was the car equipped with dse 3" springs first? I don't have the article in front of me

[harshman]

**Baseline numbers: About 41-42 mph on a 420 foot course.
DSE front and rear upgrades: 58.39 mph avg.

55.55mph avg and .81g. That's front suspension upgrades and wheels/tires only.
:jawdrop: Holy Hell!!!
If you guys have ever seen a test in person those numbers are flat out hauling ass!! 58.39 - that isn't a typo?

[Rick Dorion]

It was never specified, if I'm remembering correctly. I thought the rear leafs were only referred to as original.

[Steve Chryssos]

:jawdrop: Holy Hell!!!
If you guys have ever seen a test in person those numbers are flat out hauling ass!! 58.39 - that isn't a typo?

That's right!! Your car was tested, wasn't it? No, I checked, no typo. Can you post numbers for your car? I don't know if your course was comparable.
The slalom in this test was 420 feet 70 feet apart. The Skidpad was only 125 feet in diameter. I don't see enough data in the article to fill in the blanks.

[harshman]

here it is (http://popularhotrodding.com/features/0408phr_harshman/)


I'm swapping to an ls1/r compound/air bar/hydroboost/more stiffer/more times my faster....you get the idea. all in hopes to get a new shoot - Johnny's camaro pissed me off - stock '96 z28 w/nitto's and it riped my car a new one.

If you couldn't tell, I've got the bug badly.:seizure:

[Steve1968LS2]

That's right!! Your car was tested, wasn't it? No, I checked, no typo. Can you post numbers for your car? I don't know if your course was comparable.
The slalom in this test was 420 feet 70 feet apart. The Skidpad was only 125 feet in diameter. I don't see enough data in the article to fill in the blanks.

I need to check into this.. that seem impossibly fast for the nomal cone setup we use.. for reference Alcino's car ran 48mph I think and at the time that was the fastest car ever tested..

I will check on monday what it was. Also, we generally use a 200ft skidpat.. 125 feet is pretty damn small..

[Nutsy]

I need to check into this.. that seem impossibly fast for the nomal cone setup we use.. for reference Alcino's car ran 48mph I think and at the time that was the fastest car ever tested..

I will check on monday what it was. Also, we generally use a 200ft skidpat.. 125 feet is pretty damn small..

Any updates on this Steve?

[woody80z28]

Didn't the G/28 only hit like .91g and 46mph on the Nitto R-compounds?

[Steve1968LS2]

Didn't the G/28 only hit like .91g and 46mph on the Nitto R-compounds?

I do believe g/28 did .94 in the 200ft skidpad and 46.48 in the cones..

[Steve1968LS2]

**Baseline numbers: About 41-42 mph on a 420 foot course.
DSE front and rear upgrades: 58.39 mph avg.

**I pulled the baseline numbers from another article in the same issue since the "front upgrades only" test (April issue) does not include factory stock numbers.

Rick, The leaf spring numbers were posted in the April issue and also serve as the before numbers in the may issue. 55.55mph avg and .81g. That's front suspension upgrades and wheels/tires only.

Uh.. the car did not run the cones at 58.39 mph.. no car ever has come close to that..

I don't know how the writer came up with those numbers, but they are not possible. The car was not tested by us so I don't have the tech sheet. More than likely they ran the test and screwed up the formula. If I knew the time through the cones I could calculate the correct MPH. The writer is not a Super Chevy staff writer, freelancer?

Alcino's car ran the cones at 48.1 and I know that car didn't beat it by 10mph.. a new C6 vette couldn't do 58mph

[Steve1968LS2]

That's right!! Your car was tested, wasn't it? No, I checked, no typo. Can you post numbers for your car? I don't know if your course was comparable.
The slalom in this test was 420 feet 70 feet apart. The Skidpad was only 125 feet in diameter. I don't see enough data in the article to fill in the blanks.

Yep, typo.. I haven't seen the Super Chevy story but if it says 58.xx then it's a typo.. I though you just made the typo.. lol.. am I in trouble now????

For comparison (420ft cones)

g/28 = 46.48 mph
Alcino Mustang II = 48.1 mph
red '69 Camaro tested in the same issue as the DSE car = 48.5 (another one of our higher scoring cars.. actually the highest musclecar)

All three of these cars were running super sticky tires.. See a pattern?

I've never seen a 125ft skidpad, i guess it's possible but it seems like it would hurt your number.. we use 200 feet and that feels pretty tight. Still, .84 g seems like a reasonable number on the tires listed in the story (pilot sports).

Formulas:

420ft Slalom Equivilants

420/time = ft per sec x 3600 / 5280 = mph
------
200-ft Skidpad

g= 1.225 x radius (in feet) / time sq.

[nickdoe6]

Steve is correct. We tested a shifter kart that did a best of 58 MPH in the 420' slalom, so there is no possible way the numbers for that Camaro are correct.


Nick L

[96Z28SS]

What did the Art Morrison 55 chevy do for numbers? Did it have street tires on it?

I would've liked to see the Camaro beat the bigger 55 Chevy, but I can't remember what the number was it was above .9

[alcino]

It pulled a .94 skid and did the slalom in 5.92sec, from what Katz told me.

That computes to 48.37mph slalom!

and from what I recall it did not use R compound tire. Correct me if I'm wrong. Now thats amazing for such a huge car.

[Steve Chryssos]

.. lol.. am I in trouble now????

It's not your fault. Just call DSE and corroborate.

[TA219]

The quarter mile stuff is hard to peg as well. Too many variables. No such thing as a 383 in 68. But the Leaf Spring to Quadra-Link data is apples to apples:

All other things equal:
Leaf Springs: 15.16 @ 98.62 mph
Quadra-Link: 14.28 @ 101.22 mph

Lemme see.......That's damn near a second with no engine changes.
:jawdrop: That leaf spring set up must have been expierencing alot of axle wrap. I wonder what the 60" was.

[Steve1968LS2]

It pulled a .94 skid and did the slalom in 5.92sec, from what Katz told me.

That computes to 48.37mph slalom!

and from what I recall it did not use R compound tire. Correct me if I'm wrong. Now thats amazing for such a huge car.

Yes, the Art Morrison car did very well.. I do not think any car has managed to hit 49mph..

[Steve1968LS2]

It's not your fault. Just call DSE and corroborate.

I will... but it's a fact that those cone numbers are very different from ours.. It's like posting that someone ran the mile in 1 minute.. lol

The main question would be how did they time everything. lights? Stopwatch?

I have a feeling that whatever they did it was the same for both tests (before and after). So the fact that there was a huge gain is not in dispute. a 3mph gain is huge.

To be honest I really shouldn't be involved since it's not my magazine. I only need to make sure this is clear since is screws up all of our testing results. After all, if we talk up a car that did 48.x as super great, the people who read the DSE SC story would be like.. "that's a terrible number" since they would think 58mph is actually possible. make sense?

[69rs]

Go Columbo! Let us know what you find out!

[Rick Dorion]

To be honest I really shouldn't be involved since it's not my magazine. I only need to make sure this is clear since is screws up all of our testing results. After all, if we talk up a car that did 48.x as super great, the people who read the DSE SC story would be like.. "that's a terrible number" since they would think 58mph is actually possible. make sense?

Perhaps speak with your counterpart rather than get in the middle with DSE?

[Steve1968LS2]

Ok.. I had a nice long talk with Kyle at DSE.. here is the jist of it..

DSE did test through a 420 foot set of cones and they were 70 ft apart (like us out west). I sounds like they tried to replicate conditions as closely as possible, even going through the expense of getting new tires for the second test so the comparo would be fair (had new tires in the first test).

The only realy difference is in how we both optain our data. DSE used a VBOX data logging system that employs GPS and lateral accelerometers to determine speed. This is the same sort of system used by companies like GM and I think maybe even Motor Trend. They used the EXACT same spot to test with the cones in the exact same spots.

We use a set of timing lights. A car trips the first light going in and the second set going out. the distance between the lights is 420 feet and there are cones 70 ft apart. This system is widely used in racing and in events like autocross. We test in the exact same spot and we have spray painted marks so the cones and lights are in the exact same spot.

So what does this mean? Hell if I know, but I do belive that DSE was honest in reporting what they came up with and Kyle was very adamant that he stands by his number and would run the car again for any doubters. I've know DSE longer than I've worked here and have zero reason to doubt thier integrity.

Even if there was some flaw with thier equipment the testing would still be consistant and show an almost 3mph gain in the cones. That is a huge gain for such a short distance. When we tested the air ride stuff we got a .4 mph gain and we were happy. A 3mph gain is huge.

I think we just have to chalk up the differences to how the data was obtained (scientific methodology)..

Their skidpad numbers seem dead on given the tires they were running and I confirmed that a 125ft skidpad is quite possible although they most likely could have done bigger with a larger radius. They ran 125 ft since that's all the room they had a Maxton (it's a converted airport)

So, no drama.. just a difference in testing methods. I was very satisfied with Kyles explanation and I know that if he wasn't 2400 miles away he would be happy to run his car through our testing equipment and that shows a LOT.

[Steve1968LS2]

Perhaps speak with your counterpart rather than get in the middle with DSE?

Terry Cole (editor of Super Chevy) is no longer working here.. and there is no "in the middle with DSE".. they want to get the facts out there as much as anyone. Kyles explanation made sense and I feel they carried out thier tests with integrity and the proper use of science. I don't know enough about the VBOX to discuss how it may vary from timing lights.

I think we should also give DSE credit for putting thier stuff to the test unlike many mfgs who just sell promises.

[alcino]

Oh I get it now. It’s like Einstein relative math. In the car(data acquisition) you are wiggling through cones at 58mph(more distance than 420'/time), but an observer watching from the side (entrance and exit lights) sees a car passing by at 48mph(420'/time). The only thing the same is the time elapsed from the entrance to the exit. Without it, it’s like comparing apples to oranges.

[Mkelcy]

Ok.. I had a nice long talk with Kyle at DSE.. here is the jist of it..

DSE did test through a 420 foot set of cones and they were 70 ft apart (like us out west). I sounds like they tried to replicate conditions as closely as possible, even going through the expense of getting new tires for the second test so the comparo would be fair (had new tires in the first test).

The only realy difference is in how we both optain our data. DSE used a VBOX data logging system that employs GPS and lateral accelerometers to determine speed. This is the same sort of system used by companies like GM and I think maybe even Motor Trend. They used the EXACT same spot to test with the cones in the exact same spots.

We use a set of timing lights. A car trips the first light going in and the second set going out. the distance between the lights is 420 feet and there are cones 70 ft apart. This system is widely used in racing and in events like autocross. We test in the exact same spot and we have spray painted marks so the cones and lights are in the exact same spot.

So what does this mean? Hell if I know, but I do belive that DSE was honest in reporting what they came up with and Kyle was very adamant that he stands by his number and would run the car again for any doubters. I've know DSE longer than I've worked here and have zero reason to doubt thier integrity.

Steve: We appreciate your work in trying to understand the very different results between the PHR methodology and that used in the DSE tests. I don't understand why different methods of measuring the same test would result in a 20% or greater difference in test results UNLESS one of the two methodologies introduces error in the measurement.

Understanding why the DSE methodolgy gets markedly faster results than the PHR methodolgy is important, because depending on where and how the measurement variables are introduced, the repeatablity of one of the two methologies may be suspect.

LET ME BE VERY CLEAR, I'm not in any way suggesting DSE rigged the tests.

I'm not familiar with Vbox technology, but I wonder how the data acquisition is triggered (manually, in or out of the car; taken from a longer data set and edited down to the slalom run; externally triggered; other). If manually triggered an error of 0.10 seconds on entry and exit could account for 1.8 MPH of the difference. In addition, differential GPS technology is supposed to be accurate to within 1 to 3 meters. I don't know whether the error is consistent - that is whether the GPS receiver is always wrong by the same amount. If it is, this is not likely a source of error. If it's not, then this could also contribute one to two MPH of the difference. Finally I wonder if there was any run-in and run-out on the DSE slalom course. A brief burst of acceleration could also contribute a bit of speed.

If DSE were willing to do so, a back-to-back test using the Vbox technology and your fixed, autiomatically triggered timing lights might be a very interesting article.

[Steve1968LS2]

Understanding why the DSE methodolgy gets markedly faster results than the PHR methodolgy is important, because depending on where and how the measurement variables are introduced, the repeatablity of one of the two methologies may be suspect..

To be clear.. this is not "PHR methodology" it's PRIMEDIA methodology.. same as used with Super Chevy, Chevy High, PHR, Street Rodder, etc...

A set of timing lights is a pretty basic and time tested (pardon the pun) testing method.. lol

[Steve1968LS2]

If DSE were willing to do so, a back-to-back test using the Vbox technology and your fixed, autiomatically triggered timing lights might be a very interesting article.

Yes it would be and Kyle stands by the performance of his system. Maybe we could ship out our lights or they could ship us thier VBOX.

In any case the gain they experienced is still a valid scientificly derived result.. and that's the important part.

[Mkelcy]

Yes it would be and Kyle stands by the performance of his system. Maybe we could ship out our lights or they could ship us thier VBOX.

In any case the gain they experienced is still a valid scientificly derived result.. and that's the important part.

I agree the methodology used by PriMedia is pretty much foolproof. However, unless and until we understand why the DSE methodolgy gets results that are roughly 20% greater than the results the PriMedia methodolgy measures, we can't speak to the validity of the gain measured by DSE.

As for exchanging technologies and running the slalom using both methodologies simultaneously, I'm all for it.

[Damn True]

Oh I get it now. It’s like Einstein relative math. In the car(data acquisition) you are wiggling through cones at 58mph(more distance than 420'/time), but an observer watching from the side (entrance and exit lights) sees a car passing by at 48mph(420'/time). The only thing the same is the time elapsed from the entrance to the exit. Without it, it’s like comparing apples to oranges.


Ding ding ding! Winner. I figured you'd be the first to figure this out.

PHR test - elapsed time from entrance to exit extrapolated into speed
DSE test - speed in MPH while between entrance and exit w/o consideration of time/distance

There is no attempt at funny business or a right or wrong. Just a different way of collecting data. The bummer is that you can't accurately compare the two, because you don't know how far the DSE car deviated from the course centerline, so you can't measure the entire distance covered.

The salient point though is that they picked up 3mph with the modifications. That is HUGE. It by no means though discredits Alcino's time in the PHR test.

[wendell]

not to be a downer but a 3mph increase in 1/4 trap speed would indicate that an 8th spark plug was added in addition to the quadra link rear suspension. While the lower ET may have been a result of the rear suspension, trap speed is a function of horse power and 3mph is a big deal.

[Mkelcy]

Ding ding ding! Winner. I figured you'd be the first to figure this out.

PHR test - elapsed time from entrance to exit extrapolated into speed
DSE test - speed in MPH while between entrance and exit w/o consideration of time/distance

There is no attempt at funny business or a right or wrong. Just a different way of collecting data. The bummer is that you can't accurately compare the two, because you don't know how far the DSE car deviated from the course centerline, so you can't measure the entire distance covered.

The salient point though is that they picked up 3mph with the modifications. That is HUGE. It by no means though discredits Alcino's time in the PHR test.
Assuming you're being serious, no. You are attemtping to measure the average speed at which the car goes through the slalom. In every case, that's a measure of how long (time) the car took to complete the course (distance). How you measure the two variables should NOT affect the result.

[Damn True]

Assuming you're being serious, no. You are attemtping to measure the average speed at which the car goes through the slalom. In every case, that's a measure of how long (time) the car took to complete the course (distance). How you measure the two variables should NOT affect the result.

Except that is not what was done.
PHR uses timing lights. They are capturing the elapsed time from when the car enters the course to when it exits. That time x course distance = speed over the 420' not speed within the course.

DSE used some form of in-car data logger that measured the speed of the car within the course not the speed over the 420'

One is a meausure of speed from a to b, the other is a measure of speed while traveling between a and b. Very different.

[Mkelcy]

Except that is not what was done.
PHR uses timing lights. They are capturing the elapsed time from when the car enters the course to when it exits. That time x course distance = speed over the 420' not speed within the course.

DSE used some form of in-car data logger that measured the speed of the car within the course not the speed over the 420'

One is a meausure of speed from a to b, the other is a measure of speed while traveling between a and b. Very different.
Sorry, the "measure of speed from a to b" and the "measure of speed while traveling between a and b" are both simply time and distance. There is something in the DSE methodology that is giving them very different results from those obtained by the PriMedia methodology. This is not an application of the Heisenberg Uncertainty Principle.

[Damn True]

Sorry, the "measure of speed from a to b" and the "measure of speed while traveling between a and b" are both simply time and distance. There is something in the DSE methodology that is giving them very different results from those obtained by the PriMedia methodology. This is not an application of the Heisenberg Uncertainty Principle.

No, no they are not.
What you are suggesting would only be true if they were capturing the data the same way. They are not.
Think about it.

In the PHR test the actual distance traveled is greater than 420' because of deviation from course centerline. They could, and probably are going just as fast, but the additional distance brings their speed over the 420' course down.

In DSE's test they are measureing the speed within the course irrespective of distance travelled or actual course length.

[wendell]

This whole site just stepped it up a level with a reference to Heisenberg's uncertanty principle. We know how much the camaro weights. We know how fast it was going. If only we could figure out where it is...

[Damn True]

For those who don't know what that is: http://en.wikipedia.org/wiki/Uncertainty_principle

[Mkelcy]

No, no they are not.
What you are suggesting would only be true if they were capturing the data the same way. They are not.
Think about it.

In the PHR test the actual distance traveled is greater than 420' because of deviation from course centerline. They could, and probably are going just as fast, but the additional distance brings their speed over the 420' course down.

In DSE's test they are measureing the speed within the course irrespective of distance travelled or actual course length.
I think you're correct. DSE is apparently using the average speed over a course that is, in effect, substantially longer than 420 feet, while Primedia is assuming a distance of 420 feet regardless how far the car actually travels going between the cones. They're measuring two different things and the results are, as we've seen, very different. Unfortunately, we can't compare the two results because we don't know how far the car in either method actually travelled.

Too bad.

[alcino]

Hallelujah!!! Agreement

[Damn True]

I think you're correct. DSE is apparently using the average speed over a course that is, in effect, substantially longer than 420 feet, while Primedia is assuming a distance of 420 feet regardless how far the car actually travels going between the cones. They're measuring two different things and the results are, as we've seen, very different. Unfortunately, we can't compare the two results because we don't know how far the car in either method actually travelled.

Too bad.

Cool. I thought I was going nuts there for a second.

Irrespective of the difference in data collection the fact that DSE picked up and average of 3mph between their test "A" & "B" is bloody impressive.

[Damn True]

Hallelujah!!! Agreement

More importantly, your record is secure.

[silver69camaro]

What did the Art Morrison 55 chevy do for numbers? Did it have street tires on it?

I would've liked to see the Camaro beat the bigger 55 Chevy, but I can't remember what the number was it was above .9

Art's '55 managed a .94 average and damn close to 49MPH in the cones. This was done on 245/45 and 275/40 BFG KDs. Same tires used to drive from Washington to CA.

I'm pretty excited about the Corvette project with a C5 front and a slightly modified triangulated 4-bar used in the '55. It will be about 800lbs lighter than the '55, with larger tires.

I just wish it would use my 3-link. Either way, I'm sure it will pull some good numbers.

[alcino]

I hate to say record cause I know there are better times out there, for one the morrison gt55 5.92s to my 5.95s slalom. Mine is just currently the best at PHR, and a few other mags. Hope someone beats it on PHR. Maybe then they will let me do some mods and tunning and try to defend my title.(just a ploy to get me in mag again :look:)

[Steve1968LS2]

Ding ding ding! Winner. I figured you'd be the first to figure this out.

PHR test - elapsed time from entrance to exit extrapolated into speed
DSE test - speed in MPH while between entrance and exit w/o consideration of time/distance

There is no attempt at funny business or a right or wrong. Just a different way of collecting data. The bummer is that you can't accurately compare the two, because you don't know how far the DSE car deviated from the course centerline, so you can't measure the entire distance covered.

The salient point though is that they picked up 3mph with the modifications. That is HUGE. It by no means though discredits Alcino's time in the PHR test.

Give this man a cupie doll! :)

We can't compare the data between the DSE test and say Alcino's car, but we can compare the before and after tests on the DSE car since they were done using the same scientific method.

Case Solved..

[Streetking]

All I can say is, never doubt anything Kyle has to say. He has no reason to b.s. anyone.

For anyone that doesn't believe the numbers, I know they are taking the car to Road Atlanta for more testing, I'm sure he wouldn't mind giving a few rides.:razz:

SW

[Damn True]

All I can say is, never doubt anything Kyle has to say. He has no reason to b.s. anyone.

For anyone that doesn't believe the numbers, I know they are taking the car to Road Atlanta for more testing, I'm sure he wouldn't mind giving a few rides.:razz:

SW

Nobody is doubting Kyles integrity, the validity of the numbers or the efficacy of the modifications. We are saying that the way he did his test was different, and therefore the results netted a higher speed in both the before and after. The bummer is that because he conducted the test differently we cannot compare those numbers against tests done in a similar fashion to the PHR/Motor Trend test protocol.

[Bill Howell]

All I can say is, never doubt anything Kyle has to say. He has no reason to b.s. anyone.

For anyone that doesn't believe the numbers, I know they are taking the car to Road Atlanta for more testing, I'm sure he wouldn't mind giving a few rides.:razz:

SW

Hey SW, long time.
You coming to the Year One event this month?

[Mkelcy]

The bummer is that because he conducted the test differently we cannot compare those numbers against tests done in a similar fashion to the PHR/Motor Trend test protocol.
And that's unfortunate. DSE could make the tests comparable by telling us how many seconds it took to complete the 420 foot course, or how far the car travelled weaving between the cones. Until that's done however, all we know is that the 4 link car peformed better than the leaf spring car (which, based on the quarter mile results, appears to have had issues); we can't compare the 4 link car to any of the cars ever tested by the PriMedia folks.

[Steve1968LS2]

And that's unfortunate. DSE could make the tests comparable by telling us how many seconds it took to complete the 420 foot course, or how far the car travelled weaving between the cones. Until that's done however, all we know is that the 4 link car peformed better than the leaf spring car (which, based on the quarter mile results, appears to have had issues); we can't compare the 4 link car to any of the cars ever tested by the PriMedia folks.

It's no big deal..

Even if DSE had that data it still would not be comparable since it was obtained a different way. We break beams so the measurement is the time to go through the two beams regarless of how far you drive. The VBOX comes up with it's calculations an entirely different way.

And you are right. Thier tests DO show that the car picked up signifigant performance in the before and after tests.

We might try and borrow thier VBOX eventually to do a comparo to the timing lights (run it in the car at the same time we run through the cones). Or maybe we can send Kyle our timing light system. It would be more for curiosity more than anything. For instance to run the VBOX in Alcinos car or something to that effect.

Nobody should doubt the honesty of Kyle or DSE though. I dealt with them enough and know enough people that have dealt with them to know it's a stand-up company.

[Mkelcy]

It's no big deal..

Even if DSE had that data it still would not be comparable since it was obtained a different way. We break beams so the measurement is the time to go through the two beams regarless of how far you drive. The VBOX comes up with it's calculations an entirely different way.

Nobody should doubt the honesty of Kyle or DSE though. I dealt with them enough and know enough people that have dealt with them to know it's a stand-up company.
First, I'm not doubting the honesty of Kyle or DSE. I have no reason to do so. However, whenever someone decides to use a different way of expressing the results of a standard kind of test, I ask myself why. In this case, we can't compare how the 4 link car did compared to any car ever tested by any PriMedia magazine in the slalom. If I'm marketing a new rear suspension for first generation Camaro's that inability to compare results might be useful. It might also be the unintended result of the test method used and the data collected.

However, in order to determine the average speed through the slalom, doesn't the Vbox have to be told when to start and when to stop so it knows what to average? If so, the time through the slalom is known and the DSE test could easily be restated in traditional PriMedia terms. If not, how do they know they measured the car's average speed over a 420 foot slalom and not one that was 400 or 440 feet?

None of this is intended to question honesty, it's more simply a request for more details about the testing procedure and a curiosity why (if its the case) the data needed to convert the DSE results to tratidional PriMedia results aren't available.

By the way, I've been very careful to use PriMedia and not PHR. I hope you appreciate my diligence.

[Steve Chryssos]

.....None of this is intended to question honesty, it's more simply a request for more details about the testing procedure and a curiosity why (if its the case) the data needed to convert the DSE results to tratidional PriMedia results aren't available.

Vbox is gps based. No start and stop. Big brother is watching.

http://www.racelogic.co.uk/?show=VBOX

[Streetking]

Hey SW, long time.
You coming to the Year One event this month?

When is it? Sorry I haven't been around, been real busy with work and other car "stuff"!!

SW

[Bill Howell]

April 21-23 or there about, whatever that weekend is. There is a thread on it in the racing events section. Drop mama off in Al. and come on.

[Mkelcy]

Vbox is gps based. No start and stop. Big brother is watching.

How does the "box" know what speed to record?

[Steve Chryssos]

Beats me. Pushbutton, Yaw sensor. Doesn't matter. There is no comparable 2 point measuring system. The ground based start/finish optical beams have been replaced by doppler data sampling. Two points might be replaced by thousands. The two points you seek are lost in the sample. Optical - Doppler; 2 points- many points

The Heisenberg Uncertainty Principle was waaaaay over my head, so I based my response on the google principle. It would appear that all of Motor Trend's three competitors--Automobile, Car & Driver and Road & Track--are down with the Vbox. Good stuff.

http://www.caranddriver.com/features/2509/how-we-test-cars.html

http://automobilemag.com/test_data//index3.html

http://www.roadandtrack.com/article.asp?section_id=12&article_id=2973

[Steve Chryssos]

"The VBOX communicates with the U.S. government's global positioning system, a constellation of 24 satellites that orbit the earth 10,600 miles overhead. At least four of the satellites are above the horizon at all times, and each sends a carrier signal that is picked up by the VBOX's antenna (a small magnetic unit that you affix to a test vehicle's roof). As a vehicle travels, it draws nearer to some satellites and farther from others. As this happens, the frequency of the carrier signal shifts minutely. The VBOX senses this frequency shift, which is also known as the Doppler effect, and calculates the velocity, acceleration, and distance traveled."

[DLinson]

Kyle and Stacy were both GM engineers before starting DSE and they were both involved with suspension testing. I would assume he gets his methods of testing from what he did at GM. I would tend to believe that it would be a more sophisticated means of testing.

A point was made that the gain in speed may just be due to horsepower. If you were just going straight, I'd believe it but they are going through a slolum. If you can still accelerate while flinging the car through the cones, the suspension is working better.

I believe Kyle is using exit speed for his testing. It seems like that would be the best tell for handling. It doesn't factor in entry speed like the timing lights would. If you go in too fast then you would have to slow down through the corse to acheive the fastest time the suspension could handle. If you go in slower, you could only accelerate as much as the suspension could handle. I think you would end up with the same exit speed either way because it is dependent on the suspension's capabilities. That's the way I see it. It may be ass backwards but it makes sense to me to use exit speed and not elapsed time vs. distance.

Dennis

[Mkelcy]

Maybe I'm just not a member of the club.

I don't have a copy of the SuperChevy article so all I can go by is what I've found on the Net. SuperChevy in describing the tests to be conducted said:
"In the before tests, the car will use Fikse wheels with Michelin Pilot Sport 245/40 ZR18 tires on the front and 275/40s on the rear. Modifications will then be made with the installation of the Quadra-Link system, DSE deep tubs, and 335/30 ZR18 Goodrich tires on the rear, followed by post modification testing."
So assuming the tests were done as SuperChevy claimed, all we can say about the DSE test is that a 4 link car with 335/30 18's (of unknown composition and tread design) was faster in the slalom and the 1/4 mile than a leaf spring car with Michelin Pilot Sport 275/40's. That result, frankly, doesn't surprise me, and could be largely (if not entirely) attributable to the tires used. So far as I'm aware, we don't know the complete suspension setup for the leaf spring car and, given the nature of the results published, we can't compare the 4 link car to any other car that's ever been tested by PriMedia magazines.

So I guess I have the same questions I'd ask about a new company publishing these same results: please give us a full description of the front and rear suspension setups for both cars, how much of the difference is the result of wider and stiffer rear tires on the 4 link car and how much is attributable to the 4 link (in other words, why not use the same size tires for both suspension setups) and why not use a standard way of stating the results so they could be compared to a database full of comparable tests?

As I say, I guess I'm pretty much alone out here in not being willing to go on blind faith even though I respect what DSE does and has done for our hobby.

[Steve1968LS2]

Kyle and Stacy were both GM engineers before starting DSE and they were both involved with suspension testing. I would assume he gets his methods of testing from what he did at GM. I would tend to believe that it would be a more sophisticated means of testing.

A point was made that the gain in speed may just be due to horsepower. If you were just going straight, I'd believe it but they are going through a slolum. If you can still accelerate while flinging the car through the cones, the suspension is working better.

I believe Kyle is using exit speed for his testing. It seems like that would be the best tell for handling. It doesn't factor in entry speed like the timing lights would. If you go in too fast then you would have to slow down through the corse to acheive the fastest time the suspension could handle. If you go in slower, you could only accelerate as much as the suspension could handle. I think you would end up with the same exit speed either way because it is dependent on the suspension's capabilities. That's the way I see it. It may be ass backwards but it makes sense to me to use exit speed and not elapsed time vs. distance.

Dennis

Yep, the VBOX type equipment is used by GM for testing. As stated the gain shown is valid. It's just that you can't compare that test speed to the normal test results seen in Super Chevy, PHR, etc..

Exit speed would always be much faster than average speed since you would not have to negotiate the last cone and can "gun it" after the last turn. So, if you were doing say 47mph average through the cones you could smash the gas at the end and exit at say 58mph..

We prefer to use an average time through since it's a larger sampling compared to using exit speed which is smaller moment of data. However, both methods are valid for showing a performance gain or loss. They just can't be compared to each other.

[Steve1968LS2]

Maybe I'm just not a member of the club.

I don't have a copy of the SuperChevy article so all I can go by is what I've found on the Net. SuperChevy in describing the tests to be conducted said:
So assuming the tests were done as SuperChevy claimed, all we can say about the DSE test is that a 4 link car with 335/30 18's (of unknown composition and tread design) was faster in the slalom and the 1/4 mile than a leaf spring car with Michelin Pilot Sport 275/40's. That result, frankly, doesn't surprise me, and could be largely (if not entirely) attributable to the tires used. So far as I'm aware, we don't know the complete suspension setup for the leaf spring car and, given the nature of the results published, we can't compare the 4 link car to any other car that's ever been tested by PriMedia magazines.

So I guess I have the same questions I'd ask about a new company publishing these same results: please give us a full description of the front and rear suspension setups for both cars, how much of the difference is the result of wider and stiffer rear tires on the 4 link car and how much is attributable to the 4 link (in other words, why not use the same size tires for both suspension setups) and why not use a standard way of stating the results so they could be compared to a database full of comparable tests?

As I say, I guess I'm pretty much alone out here in not being willing to go on blind faith even though I respect what DSE does and has done for our hobby.

I thought the car tested originally had the same exact type of tire and they were new. I recall Kyle telling me that they even bought NEW pilot sports so the test would even be more apples to apples. I would assume this to be the case since the story only involved the 4-link and did not mention doing a mini-tub. I would have to re-read the story.

I don't see how it's blind faith.. they tested the car to establish a baseline. They installed the 4-link then retested using the same methodology in the same location and the car picked up performance.

People always harp on the mfgs to put thier stuff to the test and when they do there is always a group of people who still complain (not necessarily you). I'm sure this really turns off aftermarket companies from going through the exercise.

As for your last paragraph.. they didn't use timing lights because they didn't have timing lights and, being ex-GM engineers, are used to using technology like the VBOX.. It's like asking why someone from Europe used the metric system to measure something, it's just what they are used to using.

[gchandler]

The metric system can be converted to standard and standard can be converted to metric.

[Mkelcy]

I thought the car tested originally had the same exact type of tire and they were new. I recall Kyle telling me that they even bought NEW pilot sports so the test would even be more apples to apples. I would assume this to be the case since the story only involved the 4-link and did not mention doing a mini-tub. I would have to re-read the story.
As I said, I don't have the article and can only go by what SuperChevy said the tests WOULD be. I'd be curious to know what details they give about the test and whether they affirmatively say both cars used the same size pilot sports.


I don't see how it's blind faith.. they tested the car to establish a baseline. They installed the 4-link then retested using the same methodology in the same location and the car picked up performance.
If they used the same size, brand and type of tires on both cars, then we have an improvement of performance. We don't know the baseline leaf spring car's rear suspension parameters and can't say against what the 4 link improved. Most of us aren't running OEM rear suspensions. I guess I'd find the improvement they posted more impressive if it were achieved running against a full DSE rear leaf spring setup. Not knowing how the leaf spring car was equipped kind of makes the results meaningless.


People always harp on the mfgs to put thier stuff to the test and when they do there is always a group of people who still complain (not necessarily you). I'm sure this really turns off aftermarket companies from going through the exercise.
While I respect the willingness DSE has to subject their product to testing, if an unknown company published these results, I believe people would be asking the questions I'm asking. I don't understand why DSE seems to be getting a free pass.


As for your last paragraph.. they didn't use timing lights because they didn't have timing lights and, being ex-GM engineers, are used to using technology like the VBOX.. It's like asking why someone from Europe used the metric system to measure something, it's just what they are used to using.
Let me say this as plainly as possible: I find it virtually impossible to believe that the Vbox technology cannot establish the elapsed time it takes a car to go from point A to point B. As a result, the test results COULD have been published as elapsed time of X, with an exit speed of Y. For whatever reason, that data was either not collected or not reported. I can only speculate why that might be.

Lurking behind all of this is the widely held view that a well set-up leaf spring suspension should be able to keep up with a 4 link. In this case the 4 link kicked the bejesus out of the leaf spring car. I simply want to know the details of the test, which otherwise seems remarkable.

[Steve1968LS2]

This is a free pass? lol..

We are only speculating that the VBOX gave exit speed and not some other calculation.. The fact is that they used the SAME test for the before and the after. The improvent shown is valid.

Anyways.. we are beating the proverbial dead horse here. Like all tests you can take from it what you will..

[Steve Chryssos]

None of this is intended to question honesty, it's more simply a request for more details about the testing procedure and a curiosity why (if its the case) the data needed to convert the DSE results to tratidional PriMedia results aren't available.

It's not a "club" thing. You asked why the data conversion is not available. A quick google search provided the response:

Terrestrial vs Celestial

Steve,
Please call or email Kyle and ask if his slalom results are peak or average.

[Mkelcy]

It's not a "club" thing. You asked why the data conversion is not available. A quick google search provided the response:

Terrestrial vs Celestial.
So, you're convinced the Vbox technology has no ability to measure how long it takes to go from point A to point B, say the beginning of a 420 foot slalom course and the end of that same course? That hardly seems like technology that would cost $10,000 plus.


This is a free pass? lol..

We are only speculating that the VBOX gave exit speed and not some other calculation.. The fact is that they used the SAME test for the before and the after. The improvent shown is valid.

Anyways.. we are beating the proverbial dead horse here. Like all tests you can take from it what you will..
It sure seems like a free pass when only one person seems to be questioning the "valid" improvement. I'm sure the 4 link equipped car would have gone through the slalom much faster than my leaf spring equipped mini-van, but what, if anything, does that prove?

I for one don't think this "test" proves anything until the details of the "test" are known. Obviously there are others who believe that DSE has demonstrated the clear superiority of their 4 link over a well sorted out, high performance leaf spring suspension. To each his own, I guess . . .

[Steve1968LS2]

So, you're convinced the Vbox technology has no ability to measure how long it takes to go from point A to point B, say the beginning of a 420 foot slalom course and the end of that same course? That hardly seems like technology that would cost $10,000 plus.


It sure seems like a free pass when only one person seems to be questioning the "valid" improvement. I'm sure the 4 link equipped car would have gone through the slalom much faster than my leaf spring equipped mini-van, but what, if anything, does that prove?

I for one don't think this "test" proves anything until the details of the "test" are known. Obviously there are others who believe that DSE has demonstrated the clear superiority of their 4 link over a well sorted out, high performance leaf spring suspension. To each his own, I guess . . .

Maybe it has the capability, but wasn't used that way.. why don't you hold off judgement till we find out..

Since they used the same equipment both times in the same way the improvement part still holds true. Even if it was based on exit speed (which we still don't know yet).

I guess if they put the quadra-link into your mini-van and got an improvement then your analogy would make a little bit of sense. This however was the same car with the same tires and my understanding was the only thing changed was the rear suspension and them fancy Fiske wheels.

Just re-read the article.. the '69 used was NOT mini-tubbed and ran the same Fiske/Pilot-Sport combo for both the before and after tests.

If you look closely at the picture of them removing the differential it appears to be stock leaf sprung rear end with stock shocks (and even drum brakes). So it was not some super fancy modified leaf spring deal from what I can see.

As much as you would see that we are somehow giving DSE "a free pass".. others could see that you are taking a "guilty until proven innocent" approach..

I will detective it out a bit more..

[alcino]

Just guessing, but I think the Vbox could map(plot) out the path of the car going through the cones. But that’s all that you would see, a line going straight, then wiggling, then going straight again. No start/finish lines or cones. I guess you could estimate the entrance of the slalom and measure out to 420', then see what time that took.

So if you really pester DSE, I guess they could give you an "estimated time". I don't think that classifies as apples to apples but close.

[Steve1968LS2]

I'm in contact with the guys at VBOX... The unit used in the test is the VBOX Pro Lite. The head guy for VBox USA is sending me over the software so I can check it out. After talking with him I have a much better understanding of how this equipment works. It's pretty high end stuff. They will also loan us a box so we can use it in some of tests as a comparrison to our timing lights.

http://www.vboxusa.com/datasheets/vbprolite-data.pdf

The results given in the DSE were exit speeds. The plot graphs for the tests are givn on page 48 of SC, but are a bit hard to figure out.

<-- on the case

[Steve1968LS2]

So if you really pester DSE, I guess they could give you an "estimated time". I don't think that classifies as apples to apples but close.

No pestering needed.. Kyle has been very forthcoming every time I have asked him for info.. In future testing they will data log for average speed as well as exit speed :)

[Mkelcy]

Maybe it has the capability, but wasn't used that way.. why don't you hold off judgement till we find out..

If you look closely at the picture of them removing the differential it appears to be stock leaf sprung rear end with stock shocks (and even drum brakes). So it was not some super fancy modified leaf spring deal from what I can see.

As much as you would see that we are somehow giving DSE "a free pass".. others could see that you are taking a "guilty until proven innocent" approach..

I will detective it out a bit more..
Just a few responses:

1) My comments and questions about the Vbox are in response to the apparent insistence that the system is INCAPABLE of getting the data that corresponds to the PriMedia method of testing. I believe, based on my own review of the Vbox site and literature, is that the equipment is fully capable of timing a vehicle from point A to Point B.

2) I've asked a series of questions about the test methodology and the decision to report the results in a way that couldn't be compared to a huge database of comparable test results. If asking questions about test methodology and the atypical format for reporting the test results is taking a "guilty until proven innocent" approach, I guess I don't understand why we need test results at all; we could just take DSE's word for it that their 4 link out-performs a stock leaf spring rear suspension and move on.

3) All I've said in a conclusory fashion was that the DSE test doesn't "prove" anything useful to me. Again a test that shows the DSE 4 link out-performing a "stock leaf sprung rear end with stock shocks" doesn't, frankly, surprise me. Perhaps others in this thread are impressed.

4) What does surprise me is the, so far as I can see, uncritical acceptance of the significance of this test vis a' vis the performance of the DSE 4 link. I would think the relevant comparison is the 4 link versus aftermarket leaf spring/shock setups available from DSE, GW, Hotchkis and others rather than against the OEM setup.

4) I have no beef with DSE. I'm sure they reported accurate test results for the tests they did. What I do have a beef with is the apparent insistence that this test tells us anything useful. I sincerely doubt people on this board struggle to decide between the DSE 4 link or the OEM spring/shock combo. Rather, my guess is people who are looking for performance (and not "bling") are evaluating the DSE setup against performance aftermarket leaf spring/shock setups, other 4 links and perhaps even the new Lateral Dynamics 3 link. In making that decision, this test appears to be useless.

[Mkelcy]

<-- on the case
Boy, Steve, you act as if you have an actual job to do beyond posting on this board. :cheers:

[Steve1968LS2]

Boy, Steve, you act as if you have an actual job to do beyond posting on this board. :cheers:

I am a multi-tasker.. lol

Right now I am writing a story on the Super Chevy drag races las weekend. Compiling the next set of Hometown Hotrodding cars, chasing down parts for my LS2 dyno testing in a week, compiling New Products for the August issue and typing this post..

:squint:

[Damn True]

I am a multi-tasker.. lol

Right now I am writing a story on the Super Chevy drag races las weekend. Compiling the next set of Hometown Hotrodding car, chasing down parts for my LS2 dyno testing in a week, compiling New Products for the August issue and typing this post..

:squint:

I'm having a cup of coffee.

Things at Initech are a little dull.

[Mkelcy]

I'm having a cup of coffee.

Things at Initech are a little dull.
I'm pulling my '68 apart trying to get it ready for a cross-country road trip. Need to swap in an LS1 T56 for the after market T56 that's in there (lower numerical first and 6th; will work better with my 4.11's); install the C4 seats i've had sitting around for a while, install the DSE wiper kit and subframe connectors, chase down some electrical gremlins and do some wiring, cut the front springs to drop the front end about 0.5" to 1.0", install a radio, amp, etc., realign doors, fenders and windows from when I threw it together 2 years ago, etc., etc., etc. All this rain hasn't helped.

[Damn True]

Well I'd much prefer to be in the garage working on my car. As dull as things are here at Initech (I think I do 15min of "Actual work" per day) they still want me to be here in exchange for a paycheck.

[DJW32]

Things at Initech are a little dull.[/quote]


LOL!!!:rotfl: :rotfl:

[bretcopsey]

Damn True,

You better get cracking on those TPS reports. The end of the day is fast approaching!! Oh yeah, don't forget to use the new coversheet-you did get the memo on that, right?

[harshman]

So it seems you kids have been busy while I was at Disneyland.:geek:


My opinion: While to the common guy the PHR test looks way more accurate, to compare suspension changes and the likes and to only attain a given 1 mph using PHR's testing method, the common reader will see no point in taking these bolt-ons seriously. But to show the layman reader what a more seat of the pants feel it is to upgrade to these items the Vbox test appears better.


Unless you have seen these tests you can't comprehend how fast these cars are zipping through the cones physics major or not. My car ran a dismal 42.1 mph but compared to a 48 mph that the high end cars ran, well, it just doesn't show up well on paper. Now change that for the reader to a 42 to a 58 mph change using the Vbox and they will see the picture rather clearly.


There are a lot of factors that can change these test as well. Temp, humidity, altitude, sunny or cloudy, cold or hot tires. PHR tries their best to adjust their settings to make them the most accurate. Does the other machine do this? Don't care and it is pointless to debate this unless it's your car.:spank2:

[JV69z/28]

One point that seems to have gotten lost in this is DSE improvements are also retaining ride comfort not aimed at nothing but all out performance.
Maybe one of the magazines (PHR - Steve) could set up a suspension shoot out. Way back when Herb Adams and **** Gulstrand were battling for street supremacy there were more than one magazine doing shootouts where they pitted Camaro Vs Firebird. Set up a loose set of rules like no aftermarket sub frame and the biggest tires that fit in the stock wheel wells or even limit the tire size or one step further supply the tires so there is no advantage in the rubber choise. Then invite DSE - Global West - Heights - Fatman - Hotchkis - Air Ride and any other company to supply a 1st gen F-body to test (skid pad - 420 cones - autocross or lap time - 0-60 or 1/4 mile if space permits) and then you would have numbers to compare were the conditions are not a variable. You could also have subjective opinions on ride and handling. It maybe hard to set this up and the manufactures may not be able to supply the vehicles but maybe some people would be willing to volunteer (like when Carl C did the tire test for Camaro Performers).

[chicane67]

"The VBOX communicates with the U.S. government's global positioning system, a constellation of 24 satellites that orbit the earth 10,600 miles overhead. At least four of the satellites are above the horizon at all times, and each sends a carrier signal that is picked up by the VBOX's antenna (a small magnetic unit that you affix to a test vehicle's roof). As a vehicle travels, it draws nearer to some satellites and farther from others. As this happens, the frequency of the carrier signal shifts minutely. The VBOX senses this frequency shift, which is also known as the Doppler effect, and calculates the velocity, acceleration, and distance traveled."

VBOX communicates with the SPS system, not the NSB-PPS system. The difference here is that the SPS system is the 'civilian network' and the NSB-PPS.... is the 'USDOD network'. The difference here is roughly...... uh..... yeah. Right about 26%. That 26% is "purposeful" error.

FOC 19960428 Block II/IIA: DOT-VNTSC-RSPA-95-1/DOD-4650.5

The SPS system has a predictable position accuracy of 100m horizontally and 156m vertically with a TTA of 340 nanoseconds.

The PPS system has a predictable position accuracy of 22m horizontally and 27.7m vertically with a TTA of 200ns.

As the math works out, that is roughly 4.627m for the SPS system and right about 0.5m for the PPS system.

Let's see here..... 4.627m is right about 14' for the SPS system (and about 19.9 inches for the PPS). So now there is a 14fps error in the elapsed time. Which is right (about) where the USGOV keeps the civilian error tracking. Wow.

Considering that the specified MPH was 58.39... would mean that the car traveled the distance in roughly 4.9 seconds..... without making any lateral transfer to scrub any speed...... in 420'.

Uhm.... no.

Taking into consideration the 14fps error would place that same car in that same distance in at 44.44mph. Which will be around 6.5 seconds. Now, that I believe.


So, you're convinced the Vbox technology has no ability to measure how long it takes to go from point A to point B, say the beginning of a 420 foot slalom course and the end of that same course? That hardly seems like technology that would cost $10,000 plus.

You would need an "IRIG" clock signal to make the correlation of the start of the data point, to the actual time at the beginning and the end of the 420'. You are correct.... its about $10k for the time code generators alone (and that doesnt include the network) and it isnt available in cililian GPS units.

All in all.... for this to even be a considerable "DATA set" all other vehicles in comparison would have to use the same equipment under the same conditions..... or you will have introduced "the measurement of uncertainty". You can not fool timing lights..... (unless you hang a spoiler out there to trip the beams quicker)..... so 'like' data isnt necessarily 'like' data in this example. Nor is using a 125' skid pad and a slalom (with a collection device that has computable error, but wasnt done, obviously)....... as a comparison to everything else that has been tested, on a 200' skid pad using lights.

And yes..... that would mean that the big three have this same error. Unless they have done the correction factors for the NAVSTAR offsets..... which I doubt that the USGOV has given them that information.

:slap:

[Steve1968LS2]

All in all.... for this to even be a considerable "DATA set" all other vehicles in comparison would have to use the same equipment under the same conditions.....


Uh.. they did use the same equipment under the exact same conditions... the show gain is valid.

The guy at VBOX said that the built in error was turned off on GPS (I think).. and that that even if you exact specific location was off the distance traveled between two points would be exact to within less than an inch. So if you went to a mile marker and drove a mile (going by GPS) you would stop at the 1mile marker almost exactly.

I'm sure the GPS egghead at VBOX could explain it better, nice guy and very willing to discuss the technology.

[chicane67]

Uh.. they did use the same equipment under the exact same conditions... the show gain is valid.

The guy at VBOX said that the built in error was turned off on GPS (I think).. and that that even if you exact specific location was off the distance traveled between two points would be exact to within less than an inch. So if you went to a mile marker and drove a mile (going by GPS) you would stop at the 1mile marker almost exactly.

I'm sure the GPS egghead at VBOX could explain it better, nice guy and very willing to discuss the technology.
Uhm.....Steve. I am talking about every test that is to be or will be compared to the results, of the DSE testing, from here on out. I am aware that their testing was done using the same equipment and under similar conditions for their data collection in this article.

The gain is representative of their collected data and how they interpret it. But, it still doesnt represent the factual error in the data not being measured or compensated. I too can measure a given parameter of a certain object. And then ask you to do the same thing..... now, weather or not you performed the test the same way as I have, there is a 99.9% probability that error has just been introduced into a data set.

I would really like to hear what VBOX's "built in error" is all about. It can only be as good as the SAT that is being used and the error % of the SAT's included in the triangulation (which is actually about 10 or so total SAT's, not just the four for the instantaneous segment.) The GPS/SPS system still has a rough +/- 4.627m smear in tracking in any instantaneous segment.

Then again, bit subframes are every six seconds or so. So I would imagine that their "built in error" is from the "Selective Availability" of the SPS system.
Bias errors result from Selective Availability and other factors
Selective Availability (SA)
SA is the intentional degradation of the SPS signals by a time varying bias. SA is controlled by the DOD to limit accuracy for non-U. S. military and government users. The potential accuracy of the C/A code of around 30 meters is reduced to 100 meters (two standard deviations).
The SA bias on each satellite signal is different, and so the resulting position solution is a function of the combined SA bias from each SV used in the navigation solution. Because SA is a changing bias with low frequency terms in excess of a few hours, position solutions or individual SV pseudo-ranges cannot be effectively averaged over periods shorter than a few hours. Differential corrections must be updated at a rate less than the correlation time of SA (and other bias errors).
Differential Correction (DC)
The idea behind all differential positioning is to correct bias errors at one location with measured bias errors at a known position. A reference receiver, or base station, computes corrections for each satellite signal.
Because individual pseudo-ranges must be corrected prior to the formation of a navigation solution, DGPS implementations require software in the reference receiver that can track all SVs in view and form individual pseudo-range corrections for each SV. These corrections are passed to the remote, or rover, receiver which must be capable of applying these individual pseudo-range corrections to each SV used in the navigation solution. Applying a simple position correction from the reference receiver to the remote receiver has limited effect at useful ranges because both receivers would have to be using the same set of SVs in their navigation solutions and have identical GDOP terms (not possible at different locations) to be identically affected by bias errors.For the non GPS savy crowd, the term "SV" means space vehicle.

Anyway, my whole point was in reference to the data collected from 'here on out' needs to be the same points collected, the same way, for it to be comparable.