Who is a cam expert here?

[Zachalanche]

HI,
I have a camshaft in my 418 stroker that I've never known the specs. its a custom grind, so I also can't just look up a part number. So I got out the degree wheel and as best I can tell here are the specs I came up with



intake lift
0.646


intake duration
325


intake duration @.050
249.6


exhaust lift
0.6494


exhaust duration
320


exhaust duration @.050
257.5


LSA
111.525


overlap
99.45


intake centerline
111.8



this may not be 100% perfect, but it should be pretty close.

This engine ran well and pulled pretty hard all the way to 7000 rpms. it made 449 whp @ 6020 rpm and 420ft-lb @5240 rpm on a dynojet. this was through a T56 magnum and ford 9 in with 315 wide rear tires.

I always thought this engine should have made a little more power since it was supposed to be around 600 crank. Now that I have an idea what the cam specs are, it seems like the cam has quite a bit of duration and lift. although the LSA is on the narrow side, so I'm not sure how that affects the power characteristics. but I'm thinking it should make decent power in a stroker motor. Does anyone know if there is a better cam that would make a little more top end power and maybe be better suited for a track car?

[68Formula]

That's a pretty healthy camshaft even for a 418 stroker. The power numbers aren't too far off going crank to rwhp, but with that cam should be a lot more. Also depends on the dyno calibration and the corrections.

But what's interesting is how low of an rpm the peak hp comes in. Tells me there's probably something else with the setup holding it back above 6k. What header type (shorty, mid-length, long tubes), primary size, collector size, and exhaust size are you running? Which mufflers? What air assembly, throttle body size, intake, and heads are you running?

And finally, what was the air fuel ratio from 5k-7k rpm? Was the timing optimized on the dyno?

And if a new cam makes sense (and it probably will) what's your compression ratio? And rectangular or cathedral ports? Which types of track use are planned?

[Zachalanche]

That's a pretty healthy camshaft even for a 418 stroker. The power numbers aren't too far off going crank to rwhp. Also depends on the dyno calibration and the corrections.

What's interesting is how low of an rpm the peak comes in. Tells me there's probably something else with the setup holding it back. What header type (shorty, mid-length, long tubes), primary size, collector size, and exhaust size are you running? Which mufflers? What air assembly, throttle body size, intake, and heads are you running?

And finally, what was the air fuel ratio from 5k-7k rpm? Was the timing optimized on the dyno?

And if a new cam makes sense, what's your compression ratio? And rectangular or cathedral ports?


Thanks for replying. these are the kind of thoughts I'm looking for. Maybe I need to be finding flow restriction somewhere. here's some more details:

1 -7/8 mid length headers with 3in collector to 3in exhaust X-pipe to 3 in warlock mufflers then smooth transition to 2-1/2 in tail pipes. - I think switching to a better muffler might free up some hp the warlocks probably flow worse than a turbo muffler when the caps are on.

102mm TB, FAST LSX 102 intake, stock LS3 heads

air fuel is 12.5 (on average, with slight variation) from 5k-7k. and a lot of time was spent tuning timing so I'm hoping its good.

Compression ratio is 11.5:1, rectangle port - stock LS3 heads

[68Formula]

Immediately I see 2 issues of using that camshaft in your setup.

First let's talk about Dynamic Compression Ratio (DCR). It's a bit of a misnomer since it's not relative to a running engine, but it's a calculation of the effective compression ratio taking the intake valve closing (IVC) @ .006" lift into account. Too high, is a good indicator of octane needs of an engine. Of course there are other factors that can come into play, but it's a great guide. Second, if the DCR is too low, can cause a decrease across the entire rpm range. For 93 Octane a range of 8.3 to 8.6 is desired.

Second, let' talk valve events @ . 050". Quick terminology: I/O = Intake Open, I/C (or IVC) = Intake Close, E/O= Exhaust Open, E/C = Exhaust Close:

I'm just going to highlight the areas where I feel affect you directly. If you want a little more in depth, read this: https://help.summitracing.com/knowledgebase/article/SR-05440/en-us
IVC is a major player in the rpm range (later moves the power band up, at the sacrificing low-end. I/O and E/C effect the overlap which really affects a lot of characteristics, but even independently how they are biased is also important, especially depending on the combination. Long tube headers with collectors scavenge well. Especially on a dyno where there's usually no simulated exhaust other than those 2 components. They respond well to large overlap and E/C well past piston ABDC on the exhaust stroke. But mid-length and shorties with their shorter primaries do not. With those types, a max of 3-4* ABCD is recommend in order to avoid excessive reversion not only at part throttle, but WOT as well and into high rpm. This is a case where what looks great on a dyno and behave very different when it's in a vehicle. All of these while seemingly smaller, will make power not only below 6k, but above as well.

Now let's look at your current setup:
@ .006" the IVC = 94* That leaves you with a dismal 6.7 DCR. Waaayyyyy to low.
@ 0.050": 13.5 I/O, 56.5 I/C, 60.5 E/O, 17.5 E/C for 15 degrees of overlap.
Too late an I/C, Overlap is a crazy 31*! And the E/C too late for mid-length headers. And honestly, a 418 shouldn't need this much intake duration to reach it's peak power within a 7k operating range (240* should be enough), especially with square ports.

You could solve this with a custom camshaft. But Summit actually created camshafts for caters to exhausts limitations to scavenging and wave effects from a full exhaust. Note the overlap (OL) and EC events.

Big Gun 1 SUM-8729R1 is a 10 I/O, 50 I/C, 65 E/O, 3 E/C for 13 degrees of overlap. (240/247 115.5 LSA + 5.5 Adv. .625/.605). The I/C @ .006 = 74* resulting in a 8.5 DCR.

Big Gun 2 SUM-8730R1 is a 11 I/O, 51 I/C, 67 E/O, 4 E/C for 15 degrees of overlap. (242/251 116 + 6, .625/.605). The I/C @ .006 = 76* resulting in a 8.3 DCR.

Big Gun 3 SUM-8731R1 is a 14 I/O, 53 I/C, 71 E/O, 4 E/C for 18 degrees of overlap. (247/255 117 + 7 .625/.605). I/C @ .006 = 79 resulting in a 8.1 DCR.

There's also a 4, but you'll see why I'm not bothering about that.

The BG3 has a low DCR for racing. It's going to be down on torque though low & mid-range compared to the other 2. And it still has more intake duration than the engine can even take advantage of. So BG4, which you can imagine is even bigger isn't even a thought.

So we're narrowing in on BG1 vs. BG2:
The BG1 is on the upper end for DCR, but still within premium gas capability. Least amount of OL, earliest E/C. It'll have the most low/mid=range torque. t's going to have very long powerband. On tracks with tight turns, it'll give the best torque off a corner, and still with a long powerband. It could also eliminate the need to downshift which can save a lot of time. Normally with a 418 and headers the BG2 will have just a few more ponies (<10hp) right at the top (6500rpm-7500rpm). But with the mid-lengths, it may have no gain at all.

Since you do have the mid-lengths the BG1 has the best compatibility, and for it's size, to me, it's ideal choice for your setup. In any case, either BG1 or BG2 will be a huge improvement to your current setup.

If I was to do a custom cam, it'd probably be a 240/254 117+7 (assuming a .006 to .050" delta of ~50*). 10 I/O, 50 I/C, 71 E/O, 3 E/C for 13 degrees of overlap. So the I/C and OL, same as the BG1. However it allows more exhaust duration to evacuate the system, but still with same E/C of BG1.

If you decided to swap out the mid-length for long tubes, I'd still pick a different cam than your current one. And if you do switch, try to go with 2" primaries. Haven't seen data on the Warlock mufflers, but from the cut-away I'd expect it to be relatively restricted compared to other designs.

[Zachalanche]

Immediately I see 2 issues of using that camshaft in your setup.

First let's talk about Dynamic Compression Ratio (DCR). It's a bit of a misnomer since it's not relative to a running engine, but it's a calculation of the effective compression ratio taking the intake valve closing (IVC) @ .006" lift into account. Too high, is a good indicator of octane needs of an engine. Of course there are other factors that can come into play, but it's a great guide. Second, if the DCR is too low, can cause a decrease across the entire rpm range. For 93 Octane a range of 8.3 to 8.6 is desired.

Second, let' talk valve events @ . 050". Quick terminology: I/O = Intake Open, I/C (or IVC) = Intake Close, E/O= Exhaust Open, E/C = Exhaust Close:

I'm just going to highlight the areas where I feel affect you directly. If you want a little more in depth, read this: https://help.summitracing.com/knowledgebase/article/SR-05440/en-us
IVC is a major player in the rpm range (later moves the power band up, at the sacrificing low-end. I/O and E/C effect the overlap which really affects a lot of characteristics, but even independently how they are biased is also important, especially depending on the combination. Long tube headers with collectors scavenge well. Especially on a dyno where there's usually no simulated exhaust other than those 2 components. They respond well to large overlap and E/C well past piston ABDC on the exhaust stroke. But mid-length and shorties with their shorter primaries do not. With those types, a max of 3-4* ABCD is recommend in order to avoid excessive reversion not only at part throttle, but WOT as well and into high rpm. This is a case where what looks great on a dyno and behave very different when it's in a vehicle. All of these while seemingly smaller, will make power not only below 6k, but above as well.

Now let's look at your current setup:
@ .006" the IVC = 94* That leaves you with a dismal 6.7 DCR. Waaayyyyy to low.
@ 0.050": 13.5 I/O, 56.5 I/C, 60.5 E/O, 17.5 E/C for 15 degrees of overlap.
Too late an I/C, Overlap is a crazy 31*! And the E/C too late for mid-length headers. And honestly, a 418 shouldn't need this much intake duration to reach it's peak power within a 7k operating range (240* should be enough), especially with square ports.

You could solve this with a custom camshaft. But Summit actually created camshafts for caters to exhausts limitations to scavenging and wave effects from a full exhaust. Note the overlap (OL) and EC events.

Big Gun 1 SUM-8729R1 is a 10 I/O, 50 I/C, 65 E/O, 3 E/C for 13 degrees of overlap. (240/247 115.5 LSA + 5.5 Adv. .625/.605). The I/C @ .006 = 74* resulting in a 8.5 DCR.

Big Gun 2 SUM-8730R1 is a 11 I/O, 51 I/C, 67 E/O, 4 E/C for 15 degrees of overlap. (242/251 116 + 6, .625/.605). The I/C @ .006 = 76* resulting in a 8.3 DCR.

Big Gun 3 SUM-8731R1 is a 14 I/O, 53 I/C, 71 E/O, 4 E/C for 18 degrees of overlap. (247/255 117 + 7 .625/.605). I/C @ .006 = 79 resulting in a 8.1 DCR.

There's also a 4, but you'll see why I'm not bothering about that.

The BG3 has a low DCR for racing. It's going to be down on torque though low & mid-range compared to the other 2. And it still has more intake duration than the engine can even take advantage of. So BG4, which you can imagine is even bigger isn't even a thought.

So we're narrowing in on BG1 vs. BG2:
The BG1 is on the upper end for DCR, but still within premium gas capability. Least amount of OL, earliest E/C. It'll have the most low/mid=range torque. t's going to have very long powerband. On tracks with tight turns, it'll give the best torque off a corner, and still with a long powerband. It could also eliminate the need to downshift which can save a lot of time. Normally with a 418 and headers the BG2 will have just a few more ponies (<10hp) right at the top (6500rpm-7500rpm). But with the mid-lengths, it may have no gain at all.

Since you do have the mid-lengths the BG1 has the best compatibility, and for it's size, to me, it's ideal choice for your setup. In any case, either BG1 or BG2 will be a huge improvement to your current setup.

If I was to do a custom cam, it'd probably be a 240/254 117+7 (assuming a .006 to .050" delta of ~50*). 10 I/O, 50 I/C, 71 E/O, 3 E/C for 13 degrees of overlap. So the I/C and OL, same as the BG1. However it allows more exhaust duration to evacuate the system, but still with same E/C of BG1.

If you decided to swap out the mid-length for long tubes, I'd still pick a different cam than your current one. And if you do switch, try to go with 2" primaries. Haven't seen data on the Warlock mufflers, but from the cut-away I'd expect it to be relatively restricted compared to other designs.

Dang. that was awesome. thank you for the time you spent on this. This is the kind of expertise I was looking for.

Now I see why my tuner was badmouthing my cam when I had this tuned so many years ago. Sounds like BG1 or similar is a good solution. I already had plans to ditch the mufflers I have, so that should help too. In general, the car already hits pretty hard at any rpm, but I have been in a couple turns where I wish I had more torque in 3rd leaving me either trying to scream through second, or lug through 3rd.

[Jk918]

Seams to me that its down quite a bit on power for 418, I've seen quite a few ls3 with just a cam BTR stage 4 and a good tune , headers, put down 500+ at tires through 6spd. Although I understand every dyno is different.

[68Formula]

Dang. that was awesome. thank you for the time you spent on this. This is the kind of expertise I was looking for.

Now I see why my tuner was badmouthing my cam when I had this tuned so many years ago.

Haha, I bet. From sounds of it, he did an amazing job considering what he had to work with. That's pretty much a drag race cam meant for a 454LSX with open headers.

[Zachalanche]

Haha, I bet. From sounds of it, he did an amazing job considering what he had to work with. That's pretty much a drag race cam meant for a 454LSX with open headers.

Allegedly (and im not sure theres any truth to this), this engine was built for an air boat. Wonder if that cam makes more sense in that application. Otherwise I'm confused as to why a custom grind like this was needed.

[68Formula]

Allegedly (and im not sure theres any truth to this), this engine was built for an air boat. Wonder if that cam makes more sense in that application. Otherwise I'm confused as to why a custom grind like this was needed.

Well, they do tend to run long tube headers with a few feet worth of tubing and no mufflers etc. Plus high rpm for rotor speed. Still the cam is bigger than the engine can even use. Especially if the heads aren't ported.

[streetk14]

I’m not an expert, but assuming those specs are correct, that’s a big ass cam. As was mentioned, it should be making peak power way higher in the rpm range. Maybe you have a valve control issue or something? My mild cam LS7 makes peak power around 6500 and carries well to 7000. That’s with a little (for a 427) 227/242 116 cam and 2.5” exhaust.

A dyno is a dyno so you have to take baseline numbers with a grain of salt, but my crate engine is rated at 570 hp from GM with Z28 exhaust manifolds. I have long tubes and a ported MSD manifold with a 103 TB. Made 520 whp through a T56 Magnum and 3.89 geared 9”.

[68Formula]

I’m not an expert, but assuming those specs are correct, that’s a big ass cam. As was mentioned, it should be making peak power way higher in the rpm range. Maybe you have a valve control issue or something? My mild cam LS7 makes peak power around 6500 and carries well to 7000. That’s with a little (for a 427) 227/242 116 cam and 2.5” exhaust.

A dyno is a dyno so you have to take baseline numbers with a grain of salt, but my crate engine is rated at 570 hp from GM with Z28 exhaust manifolds. I have long tubes and a ported MSD manifold with a 103 TB. Made 520 whp through a T56 Magnum and 3.89 geared 9”.

Wow, wish my Bird had that setup! :worship:

The LS427/570hp illustrates my point exactly. The cam is designed to be compatible with Z28 exhaust manifolds which are basically a factory mid-length header. Thus the overlap is limited to 2.5*. Can't find any info on the amount of advance if any. But unless it's ground retarded, E/C= 5* ATDC @ the most. They designed the camshaft to work specifically with a mid-length "header" exhaust manifold and full exhaust. Same reason even the largest of the Summit "Big Gun" cams (SUM-8732R1) still keeps the E/C @ 4*.

[slazisme]

I think whats holding you back is the LS3 heads(316cfm) for a bigger cubed engine, you're almost at LS7 size. The GM LS7 cam is milder than what you're running and the newer revised LS7 is rated at 570 hp, now discontinued.
https://www.motortrend.com/news/ls7-engine-discontinued/

I would consider a set of heads like these for the high rpm you're running.
https://www.airflowresearch.com/260cc-ls3-cylinder-head/p582

Maybe even a solid roller again because of the higher rpm and better shaft rockers.
https://briantooleyracing.com/btr-ls3-shaft-rocker-kit.html

I run BTR rocker trunnion kit on my mild 508 hp and didn't want to mess with the factory trunnions. After all is said and done these are just suggestions and you're the master of your own domain.

[streetk14]

Wow, wish my Bird had that setup! :worship:

The LS427/570hp illustrates my point exactly. The cam is designed to be compatible with Z28 exhaust manifolds which are basically a factory mid-length header. Thus the overlap is limited to 2.5*. Can't find any info on the amount of advance if any. But unless it's ground retarded, E/C= 5* ATDC @ the most. They designed the camshaft to work specifically with a mid-length "header" exhaust manifold and full exhaust. Same reason even the largest of the Summit "Big Gun" cams (SUM-8732R1) still keeps the E/C @ 4*.

I’m pretty happy with it and glad I was able to grab one before they were discontinued. While not cheap, I thought it was a bargain for what I was getting after pricing out LS3 stroker builds.

I never was able to find any info on the 427/570 cam’s advance either, but it’s a mild lobe that uses stock valve springs and the same lift as a stock LS7. But it has good drivability and still makes decent power.

I’m working on phase 2 right now, and have former AFR head designer Tony Mamo building me a set of his 265cc LS7 heads. I still need to pick a cam. Leaning towards a 231/245 116+3 since good drivability is one of my must haves. 6 degrees of overlap is still considered mild in an LS7, and his smaller, higher flowing intake ports should reduce reversion and help it drive better. That’s the goal anyway.

Sorry for the thread hijack, but I guess we’re still talking cams, right?

[68Formula]

I’m pretty happy with it and glad I was able to grab one before they were discontinued. While not cheap, I thought it was a bargain for what I was getting after pricing out LS3 stroker builds.

I never was able to find any info on the 427/570 cam’s advance either, but it’s a mild lobe that uses stock valve springs and the same lift as a stock LS7. But it has good drivability and still makes decent power.

I’m working on phase 2 right now, and have former AFR head designer Tony Mamo building me a set of his 265cc LS7 heads. I still need to pick a cam. Leaning towards a 231/245 116+3 since good drivability is one of my must haves. 6 degrees of overlap is still considered mild in an LS7, and his smaller, higher flowing intake ports should reduce reversion and help it drive better. That’s the goal anyway.

Sorry for the thread hijack, but I guess we’re still talking cams, right?

With the long tubes, but 2.5" exhaust and your compression ratio, and the MAMO heads, I'd:

Bring the IVC earlier
Increase the exhaust duration
Allow slightly more overlap to take advantage of the "5th cycle" but still limit the E/O to 3-4* for driveability.

More like a 231/247 115+5.

But if you work with Mamo and give him all the vehicle details, how you plan to use it, and what characteristics you want and he'll dial it in for you.

[streetk14]

With the long tubes, but 2.5" exhaust and your compression ratio, and the MAMO heads, I'd:

Bring the IVC earlier
Increase the exhaust duration
Allow slightly more overlap to take advantage of the "5th cycle" but still limit the E/O to 3-4* for driveability.

More like a 231/247 115+5.

But if you work with Mamo and give him all the vehicle details, how you plan to use it, and what characteristics you want and he'll dial it in for you.

Yeah, that was one of Mamo’s cams but on a 116 instead of a 115. I’m actually not totally sure on the advance. He was recommending a 115+3, but I’m not sure if that’ll change with the 116. I think we were shooting for 11.4 on the compression. I’m just paranoid about overlap and light throttle drivability, though I’m sure there’s more to it than that. Tony claims his heads really help bigger cams drive better, and the port velocity thing makes sense. I’ll likely do 3” exhaust at some point as I’m sure the 2.5” is costing some power.

What exactly do you mean by limiting the exhaust opening (E/O) to 3-4 degrees for drivability? That’s a new one to me.

[68Formula]

Yeah, that was one of Mamo’s cams but on a 116 instead of a 115. I’m actually not totally sure on the advance. He was recommending a 115+3, but I’m not sure if that’ll change with the 116. I think we were shooting for 11.4 on the compression. I’m just paranoid about overlap and light throttle drivability, though I’m sure there’s more to it than that. Tony claims his heads really help bigger cams drive better, and the port velocity thing makes sense. I’ll likely do 3” exhaust at some point as I’m sure the 2.5” is costing some power.

What exactly do you mean by limiting the exhaust opening (E/O) to 3-4 degrees for drivability? That’s a new one to me.

First, apologies to Zachalanche for the thread hi-jack.

Streetk14:

I was actuall going to suggest going to 3" exhaust setup and then further tweaking the cam specs, but it was already drifting off-topic. And my statements also assumed no change in compression ratio. With the large CID, higher compression, and the right exhaust system it will handling a little more OL.

Regarding the comment on E/O, I didn't intend to imply it was a direct impact. It s\was it really is a net result of the balance of valve events. There are other factors influencing driveabilty at part throttle. My point on the 3-4 degrees E/O goes back to your particular setup. Where I was going with the E/O, is balancing the need for scavenging of the cylinders as WOT. Even though you have long tubes (normally less sensitivity to E/O), taking into account the I/E flow ratio for MAMO LS7 heads, the 2.5" mid-pipes/mufflers still cause a restriction and possibility. So balancing out the valve events to control IVC, intake duration, exhaust duration, and overlap for driveability, the net result is a lower E/O. My apologies for the confusion.

Now if you increase the compression ratio, you can keep the intake duration the same, move the intake centerline; which moves the I/O a little later and reduces the overlap. Coupled then with bigger mid-pipes/mufflers, you can move the exhaust centerline closer to the intake (tighter LSA), which effectively moves the EVO. In other words, keep the overlap the same but bias it more towards the exhaust rather than intake side.

[Zachalanche]

I’m not an expert, but assuming those specs are correct, that’s a big ass cam. As was mentioned, it should be making peak power way higher in the rpm range. Maybe you have a valve control issue or something? My mild cam LS7 makes peak power around 6500 and carries well to 7000. That’s with a little (for a 427) 227/242 116 cam and 2.5” exhaust.

A dyno is a dyno so you have to take baseline numbers with a grain of salt, but my crate engine is rated at 570 hp from GM with Z28 exhaust manifolds. I have long tubes and a ported MSD manifold with a 103 TB. Made 520 whp through a T56 Magnum and 3.89 geared 9”.


That engine must be making more than advertised. or the dyno is being generous. the 9" alone should eat up more than 50 ponies, and if it doesn't, what sorcery is inside of it?

[Zachalanche]

I think whats holding you back is the LS3 heads(316cfm) for a bigger cubed engine, you're almost at LS7 size. The GM LS7 cam is milder than what you're running and the newer revised LS7 is rated at 570 hp, now discontinued.
https://www.motortrend.com/news/ls7-engine-discontinued/

I would consider a set of heads like these for the high rpm you're running.
https://www.airflowresearch.com/260cc-ls3-cylinder-head/p582

Maybe even a solid roller again because of the higher rpm and better shaft rockers.
https://briantooleyracing.com/btr-ls3-shaft-rocker-kit.html

I run BTR rocker trunnion kit on my mild 508 hp and didn't want to mess with the factory trunnions. After all is said and done these are just suggestions and you're the master of your own domain.


Heads may have to wait for another year. from the sounds of it, I should be able to gain a lot just buy using the right cam. the shaft rocker kit is tempting though.

- - - Updated - - -


First, apologies to Zachalanche for the thread hi-jack.



no worries. there's some good discussions going on here, and I'm learning a lot.

thanks to everyone for the thoughts and advice.

[streetk14]

That engine must be making more than advertised. or the dyno is being generous. the 9" alone should eat up more than 50 ponies, and if it doesn't, what sorcery is inside of it?

Well, it’s rated at 570 hp with exhaust manifolds and the LS7 intake manifold/90mm throttle setup. From the videos GM posted at one point, it looked like this engine was certified just like a new production engine; with an intake, exhaust, and accessories. I have long tube headers and a Mamo ported MSD manifold with a 103mm throttle. Those 2 things could be 50 hp on a cammed LS7.

But yeah, I’d suspect the 9” is reducing the chassis dyno numbers. I used to own a couple C6 Corvettes, so I’m very familiar with what these engines do in those cars. ~450 whp for a stock C6Z is pretty standard. How much more power my 9” sucks up is the question

[Zachalanche]

Now let's look at your current setup:
@ .006" the IVC = 94* That leaves you with a dismal 6.7 DCR. Waaayyyyy to low.
@ 0.050": 13.5 I/O, 56.5 I/C, 60.5 E/O, 17.5 E/C for 15 degrees of overlap.
Too late an I/C, Overlap is a crazy 31*! And the E/C too late for mid-length headers. And honestly, a 418 shouldn't need this much intake duration to reach it's peak power within a 7k operating range (240* should be enough), especially with square ports.




I made the mistake of telling you the total duration based on the moment the dial indicator started to move. I went back through my spreadsheet and calculated the duration and valve events at .006 lift. (keep in mind I recorded readings every 10* of crank rotation, so I did a linear interpolation to find anything in between, so there could be some minor error here, but hopefully not too bad).

So, due to my mistake we were thinking this cam was bigger (more duration) than it really is. It's still a very high duration cam, but the IVC happens much sooner (77.5*) than we thought initially with brings my DCR into the 8.1 range. here are my updated cam specs, I threw in the BG1 cam for comparison

214189

The IVC and resulting DCR is not so bad. but the lobe separation is tighter by a good margin. This makes the valve overlap a bit more than the summit cam, and I assume this increased overlap would benefit from long tube headers and a more open exhaust.

Sorry to mislead you earlier, but what are your thoughts on this cam now....if any different from before. I'm thinking exhaust reversion is still going to be a big issue for me.

Cheers.

[68Formula]

I made the mistake of telling you the total duration based on the moment the dial indicator started to move. I went back through my spreadsheet and calculated the duration and valve events at .006 lift. (keep in mind I recorded readings every 10* of crank rotation, so I did a linear interpolation to find anything in between, so there could be some minor error here, but hopefully not too bad).

So, due to my mistake we were thinking this cam was bigger (more duration) than it really is. It's still a very high duration cam, but the IVC happens much sooner (77.5*) than we thought initially with brings my DCR into the 8.1 range. here are my updated cam specs, I threw in the BG1 cam for comparison

214189

The IVC and resulting DCR is not so bad. but the lobe separation is tighter by a good margin. This makes the valve overlap a bit more than the summit cam, and I assume this increased overlap would benefit from long tube headers and a more open exhaust.

Sorry to mislead you earlier, but what are your thoughts on this cam now....if any different from before. I'm thinking exhaust reversion is still going to be a big issue for me.

Cheers.

Corrrect: DCR much closer to where you want it; but still too late EVC and too much OL leading to reversion with the current setup.

[Zachalanche]

@68Formula
Gonna give this cam a go. thanks for your support.
214332

[68Formula]

Welcome. Be sure to post the results!

Oh, and tell your tuner, "welcome" from me.:)

[Zachalanche]

Welcome. Be sure to post the results!

Oh, and tell your tuner, "welcome" from me.:)

lol. still need to get a clutch and some new mufflers and put it all back in the car. I also have an expired fuel cell I need to replace. and I now live 300 miles from my tuner, so it may be a bit before I have some results to post. but I'm eager to see what this car can do now.

[Zachalanche]

Well, a good bit of time has passed and the issues along the way have been plentiful, but I finally have this car back on the road, broken in, and tuned. Now, this is probably going to be the least scientific report out anyone has ever read, but here it is anyway.

I contacted the guy who initially tuned this car when it had the "custom" cam in it to see if he could update my tune for the new cam. He said sure but there was one problem he sold his shop and moved a few hundred miles away. lucky for me he happed to move to a place about 5 miles away from my house. So he came over and street tuned it. The downside here is that now I have no Dyno results to compare to the original, but I'm happy to report that the car absolutely rips now. It also pulls very hard until it hits the 6800 rpm limit, so I may raise that, but i think i'll do the trunnion upgrade to my rocker arms first.

Lastly for what its worth, My tuner said judging by the MAF readings he thinks the car is putting north of 525 hp to the tire. So who really knows, but the seat of my pants would believe that it has 65 more ponies than before.

Ill update this thread at some point once I have some 1/4 mile numbers, or dyno numbers to report.

[68Formula]

Well, a good bit of time has passed and the issues along the way have been plentiful, but I finally have this car back on the road, broken in, and tuned. Now, this is probably going to be the least scientific report out anyone has ever read, but here it is anyway.

I contacted the guy who initially tuned this car when it had the "custom" cam in it to see if he could update my tune for the new cam. He said sure but there was one problem he sold his shop and moved a few hundred miles away. lucky for me he happed to move to a place about 5 miles away from my house. So he came over and street tuned it. The downside here is that now I have no Dyno results to compare to the original, but I'm happy to report that the car absolutely rips now. It also pulls very hard until it hits the 6800 rpm limit, so I may raise that, but i think i'll do the trunnion upgrade to my rocker arms first.

Lastly for what its worth, My tuner said judging by the MAF readings he thinks the car is putting north of 525 hp to the tire. So who really knows, but the seat of my pants would believe that it has 65 more ponies than before.

Ill update this thread at some point once I have some 1/4 mile numbers, or dyno numbers to report.

Great to hear! That's the type of seat of the pants I was thinking. I bet he spent less time dialing it in too.

Please keep us updated when you get some numbers.

P.S. Should probably leave a rating for the cam on their if you haven't yet. Might help others.

[68Formula]

It also pulls very hard until it hits the 6800 rpm limit, so I may raise that, but i think i'll do the trunnion upgrade to my rocker arms first.

Both good ideas! Definitely do the rocker upgrade, and think about a 7000-7200rpm limit.

[68Formula]

Zach, ever get her back to a dyno for some numbers?

[Zachalanche]

Zach, ever get her back to a dyno for some numbers?

Negative.

I ran 2 tenths faster in the quarter mile (12.3 @118 - car weighs 3480 with me in it) this year at LS Fest in Las Vegas. but since I was in the Grand Champion class, they don't give us much test & tune time - 2 total runs. I was expecting more improvement, but I think I'm losing so much in the 60 ft trying to launch a road course tuned chassis on 200tw tires, its hard to infer real hp numbers from my drag times.

Last year they had a dyno there, so I figured I would get it dyno'd this year just for the data pt. but they didn't do the dyno challenge this year.

On the trackX course I definitely could feel more meat in the middle, and it revealed that my springs are now too soft as I was pulling my inside front tire way off the ground coming out of some of the faster turns. this wasn't something I was able to do last year. could be the engine, could be that my driving is getting better. could be both. hard to say.

[68Formula]

Cool. Too bad about them not having a dyno this time. What was your previous mph? That's a good indicator of a hp increase. And I'm sure the added meat in the middle is a nice added benefit on the course (once you get the chassis re-dialed in).

[Zachalanche]

116

2025 - 12.324 @ 118.36
2024 - 12.536 @ 115.99

what's that? 25ish more HP? seems less than expected. but still an improvement.

[Zachalanche]

I really wish I had done some data logging. Everything is pretty heat soaked by the time I get to the start line, I wonder if any timing is being pulled, and I might be missing some power that's there when the car is moving and things are staying cooler. but the same would probably apply to last years results so that part of it is apples to apples. I was also on 100 TW tires last year, but that didn't make a bit of difference in my 60 ft time.

[andrewb70]

I made the mistake of telling you the total duration based on the moment the dial indicator started to move. I went back through my spreadsheet and calculated the duration and valve events at .006 lift. (keep in mind I recorded readings every 10* of crank rotation, so I did a linear interpolation to find anything in between, so there could be some minor error here, but hopefully not too bad).

So, due to my mistake we were thinking this cam was bigger (more duration) than it really is. It's still a very high duration cam, but the IVC happens much sooner (77.5*) than we thought initially with brings my DCR into the 8.1 range. here are my updated cam specs, I threw in the BG1 cam for comparison

214189

The IVC and resulting DCR is not so bad. but the lobe separation is tighter by a good margin. This makes the valve overlap a bit more than the summit cam, and I assume this increased overlap would benefit from long tube headers and a more open exhaust.

Sorry to mislead you earlier, but what are your thoughts on this cam now....if any different from before. I'm thinking exhaust reversion is still going to be a big issue for me.

Cheers.

I don't mean to downplay the discussion, but moving cam specs a little one way or the other is matter of 5-10HP on this engine. Fiddling around the edges of the cam specs is not going to be a 40-50HP jump.

What I have experienced over the last 5 years of tuning is that most people over cam their engines. The best bang for the buck are the three things that will impact power the most are:

1. displacement
2. heads
3. cam

Big engines with great heads and a modest cam result in the best overall combination for a street car.

Andrew

[streetk14]

I don't mean to downplay the discussion, but moving cam specs a little one way or the other is matter of 5-10HP on this engine. Fiddling around the edges of the cam specs is not going to be a 40-50HP jump.

What I have experienced over the last 5 years of tuning is that most people over cam their engines. The best bang for the buck are the three things that will impact power the most are:

1. displacement
2. heads
3. cam

Big engines with great heads and a modest cam result in the best overall combination for a street car.

Andrew

Thats more or less what I was going for. 427 cubic inches, Tony Mamo LS7 heads, and a 231/245 116+3. I’d like to get it back on the dyno, but this thing really needs a 3” exhaust.