How much power are we talking about here?

[Bandit]

My buddies and me have been bench racing this new engine for the past couple of weeks. It has not been fired up yet. Unfortunately, I won't be able to engine dyno it, and although I will chassis dyno it as soon as possible, I want to see if anyone has a rough idea of what kind of power it will make at the crank.

Here's the specs:

Big Block Chevy 468

(4.00" stroke/4.310 bore)

Eagle forged I-beam connecting rods

Speed-pro forged 10:1 pistons (.060 over)

Brodix Race-rite aluminum large oval port heads BRO-2061003
(no porting done)
Intake Runner Volume (cc): 270cc
Intake Valve Diameter (in):2.250 in.
Exhaust Valve Diameter (in):1.880 in.

Crane Gold Race roller rockers 1:7:1 ratio

Holley 750 vac. secondaries

Edelbrock Air-Gap dual plane intake

Comp hydraulic roller cam -- Grind Number CB 290H-R10
Gross Valve Lift .578/.578
Duration At 0.05 232 /232
Lobe Separation 110

Crane hyd. roller lifters

Clevite bearings

Moroso oil pump

Windage tray in oil pan

Mallory distributor

Fluidamper balancer



I will be running full-length exhaust headers with 1 3/4 primaries and a 2 1/2" exhaust with H-pipe and high-flow turbo mufflers. I will also be using the TKO manual trans (of course!), and my 3:73 rear gears.

What's the consensus?

[bigvegan]

How long is a piece of string?

Probably anywhere from 375-525hp at the crank, depending on how well you get everything tuned, 5-20% less at the wheels.

Let us know how it comes out when you put it on the chassis dyno.

[Goatman]

I'd say 425 at the crank...

[Lowend]

I'll make a few suggestions


Throw away the Fluiddampner they are just a bad idea... I know of more than a couple of engines that have spun off crank snouts due to them. Just use a good SFI balancer, nothing fancy

I don't love the cam choice... in a street car with street exhaust a dual pattern setup will work better I'd look at the Crower 236HR245 (http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=01405&x=0&y=0)

In my experience big blocks respond very well to single plane intakes... what you loose on the bottom end is torque you can't find traction with anyways and what you gain in the mids and topend is more than worth it. The Edelbrock vic Jr (2904) will serve you well here

There is only one company in the world that makes hyd roller lifters; everyone just repacks them. Don't bother buying a specific brand, buy the cheapest ones.

750cfm may prove to be a little small for the car, espically with vac secondaries. Go with an 850.

I'm not a big fan of Mallory distributors; the Unilite is outdated and unreliable by today's standards. Use an MSD Pro-Billet (http://www.msdignition.com/dist_3.htm) with a Digital 6 Plus box (http://www.msdignition.com/ignition_18_6520.htm) and a Blaster SS Coil (http://www.msdignition.com/coil_blaster_6_8207.htm) best street ignition setup money can buy.

[Bandit]

:crying: Darn you guys are depressing me!
Sounds like I should have stayed with the stock 301 4-bbl...sure would have been cheaper...

[chicane67]

A 468 with 1 3/4" primaries ?? Uhm... no. The combination would best be matched with a 2.0" primary and a 3" exhaust system.

Ill second on the whole fluidampr idea... just get a quality SFI unit and be done with it.

The carb is a little small.

I will also second the distributor and ignition recommendation... the unilite is just a failure waiting to happen.

How about an HO455 with a good set of rods... alone with what's already been stated ??

[Goatman]

How about an HO455 with a good set of rods... alone with what's already been stated ??


That's twice the price for the same power.....

[chicane67]

Uhm... didnt know we were concerned with the price of a bench race engine ..!?

But since we are... just drop an LS2 with a cam swap in it for 540hp.

[Bandit]

Huh? Dudes, does anyone read the first post in a thread or just the last post before they post? This engine is already built! And yes price was a concern. But I found some deals and already had some parts. I wanted a BBC.

Anyway all I wanted to know was what people think the approximate power level the motor SHOULD be. I realize it's not a twin turbo LSx but it is what it is.

If someone has a software program to help compute it maybe you could hook it up--I'd much appreciate it.

[chicane67]

Uhm... yeah. Since it was already built, the cost is a null arguement. I was just commenting to Goats blurb about the money to power ratio... as a joke... that's all. The LS2 comment as well, is a joke... as it seems to be everyone's bandaid answer to an engine for every application.

But since you did ask, my earlier post merely just blurted out what could be improved upon... there are too many variables that are not present (or un answered) to even give you any idea, of what any software, could give you for an approximate. So what you are really looking for is a WAG.

But Ill take a stab at 425-450hp. The exhaust is your biggest chock point... or I would guess differently.

[bigvegan]

Here's a big list of engine calculators - http://www.hotrodders.com/kb/browselinks.php?c=58

Using the "Rough Engine Horsepower Calculator" - http://www.bgsoflex.com/roughhp.html , and punching in the stats for your engine - (468ci, 10:1 compression) I got 293hp at 3500rpm, 383hp at 4500 rpm, 469 at 5500 rpm, and 554 at 6500 rpm.

I'm guessing that's a little low on the low end and a little high on the high end (assuming your engine can safely rev to 6500 rpm), but you can take a look at the links above and check out the different calculators and adjust the numbers.

Again, let us know how the engine tests out on the dyno, as there are way too many variables to be able to accurately gauge hp without actually testing the engine.

A big block Trans Am sure sounds like fun. (The NY Times just ran an article on The Bandit Run http://www.nytimes.com/2007/05/27/automobiles/27BANDIT.html, which was pretty cool. Sounds like those cars are getting popular! (Except here in CA, where everything sold post-1975 is doomed to smog inspection and CARB approved aftermarket hell.))

[MonzaRacer]

Well get a life there is nothing wrong with the Mallory. not a thing at all.
Mutilple Stupid Devices will never get another penny of my money if I can help it.
I have had too many friends and customers with dead cars at the most crucial time (ie on the line in a big race) have a bad box and no backup.
buddy had his car going for several years and decided to upgrade to the latest and greatest and actually had a dealer install it all and set him up.
worked great till he got on the line for a $50k win/lose. truns out the wives had made deal before hand, pool money and split it regardless of who won 1st.
now several thousand dollars of MSD and it dies at most inopertune time. Nah
also his old engine dies a violent death because of defective MSD crank trigger sensors(his 10 in about 7 months), it spit the second crank throw out of the block and yanked the second main web too.
The closest I have had to trusting MSD was my old MSD 5.
I ran a Unitlite conversion for almost 10 yrs before it got so dirty it wouldnt fire. sold it and guy cleaned it and still running and I bought it in 85 or 86 at SuperShops.
with the cam and heads I would be guessing in the range of 480hp to 540hp and some serious stout torque numbers.probablt well int othe high 470s up to even in the low 500s
Also there is nother wrong withthat cam is a very solid performer but swapping around on carbs/intakes will help it work best.
If that combo doesnt make over 1 hp per cube its sick as a dog.
Heck it ought to scream.
Yes the 750 is a little small but swap out the base for a 850 base and it will flow quite nicely.
Oh yeah ATI Street Damper is much better than the old bearing grinder fluidamper

[Goatman]

Same guy who claims Amsoil wiped out a couple of his engines. Beware of his comments and/or advice....


MSD is the best ignition out there...

[68Formula]

I pulled the airflow numbers from Brodix's website, put it in Desktop Dyno and got 480hp at the crank. Of course the engine is only going to make this kind of power if the timing and carb are properly dialed in.

If you haven't already purchased the headers go with the 2" primaries. And if the exhaust isn't done, you should use 3" with either header size. It should put you at the 500hp mark.

The Holley 750 is a little small for this engine (as many have already stated), so make sure you have a light enough spring (start with silver and step it down) to get the secondaries to fully open.

Regardless you are going to have a serious traction problem with all the torque it puts out.

[Skip Fix]

I'll agree on MSD boxes going bad. Seen a number do that at the races. Why do you think most circle track cars even Late Models have TWO MSD boxes they can switch between during the race??

Engine bay heat and electronics jus don't get along.

[6'9"Witha69]

The biggest reason I have seen MSD boxes go south: Poor hookup. The unilites and other under cap devices use factory wiring, whereas the MSD box needs to be added into the system. Most times it is practically hotwired to the car and exposed to peaks in voltage normally maintained by longer runs in the harness. That and resistors, diodes and fusible links are not used. When installed correctly, MSDs last forever. Mine is 8 years old. Many of my friends 6 series boxes are also as old and their parents units are even older. One of my buddies lunched 2 boxes and MSD replaced them on their dime. He called me over finally to check it out. Wiring looked like disneyland (Mickey mouse was all over that wiring). And yes, engine bay heat and electronics have a difficult time together, but when insulated and mounted in a thought out location, last just fine. Remember that Cup cars have practically 0 insulation.

Wait, what were we talking about again?:offtopic:

Sounds like a 450ish HP motor to me. Tons of torque though. I agree with the other recommendations those before me have made.

[Goatman]

Wiring looked like disneyland (Mickey mouse was all over that wiring)


Wouldn't have been a Monza, would it? Sounds like a guy that may half-ass his car and engine builds.... Then blame it on the parts......Or oil..... Or weather.....

:drive2:

[jdub396]

Sounds like a pretty solid motor. The fact your running a TKO, I don't see a problem with your cam, you could sacrifice a little tourque for some midrange/top end.

Prediction....Lots of tire smoke!!!

[Bandit]

If you haven't already purchased the headers go with the 2" primaries. And if the exhaust isn't done, you should use 3" with either header size. It should put you at the 500hp mark.

The Holley 750 is a little small for this engine (as many have already stated), so make sure you have a light enough spring (start with silver and step it down) to get the secondaries to fully open.

Regardless you are going to have a serious traction problem with all the torque it puts out.
Great responses--you guys have pretty much confirmed what I was thinking about the carb and exhaust. I will probably be upgrading both in short order. I am only re-using the old stuff from my 402 engine until I get back to the U.S., then I will probably do a Demon and stainless 3" pipes, as well as new ceramic-coated headers with 2" primaries.

500 hp is the goal--I realize traction will be elusive with all that BB torque...:drive2:

[chicane67]

--I realize traction will be elusive with all that BB torque...

I could'nt have said that, better myself.

Yeah baby !! Traction limitations are fun to play with !! :headbang: