more power?

[RATATTACK]

I have a LS6 crate engine that has been balanced. I have installed a set of DART 325cc heads with the larger 230 valves and 1.625 roller springs with matching cam 106 LS,641/638 4000-7400rpm. I have a wiend team g intake square port and a BG850 flowed 1080cfm carb. msd ignition, jesel belt, and a crank trigger (trying to impress the locals) CC roller rockers, timing is at 38 degrees locked. I dont know compression ratio. static pressure is between 180 and 190psi. All surfaces, bore,piston and rods are stock per the legendary LS6. I have this engine in a 3200# car including driver. Car pulls 1.58 60 foot 10.91@ 126 in 1/4 mi. No aids of any kind.
My buddiess 406 runs considerably better at 10.29- 10.34 126-128mph. maybe about 100# lighter.
What do I need to change to make my 454 run with the smaller 406.:confused: Obviously I have something mismatched maybe the heads and cam. My only othe option is to install the 572 that I have which will be getting the dart heads that are on the 454.
I know this is a simple task for all you engine guru's on here..some day I will be turning wrenches with the big boys:D
I also wanted to add Im running a 350 turbo trans. and a recently installed coan 4800 stall conv. 30 by 9 radial slick.

[Dave F]

To me static compression is important. It sounds like you're in the 262/272 @ .050 range on the cam. (you gave lift and Ls but not duration)

I'd want to know that before we can start with some diagnostics. Example, if your static is say 9:1 with that cam your engine is going to feel lazy.(I know you're not, atleast with that pressure) What's you're CC volume, everything included? Piston, gasket and head.
You need to be around 12:1 with that cam.

DAVE

[Awesome Bill]

You can do anything you want with this puppy and it won't do what you are expecting. Those heads are way to big for this application. @ 3200 lbs with driver your making 450-460 hp. We get that out of 10-1 383 Street Heat Strokers we do. Classic over headed engine then you add the huge intake. The 850 carb is not bad. Your making more MPH than et so your car has no bottem end power to speak of. @ 10.91 you should be around 120-121, so you have 5 mph better to play with. This tells me your engine, once it gets some piston speed up can make a little power. My suggestion is take those heads and put them on your 572 and it will fly. If you want to have some fun, get the smaller 265 cc Oval ports from Dart and watch your car run low 10.s high 9's. I have been there done that with much heavier cars and run 10.00's with stock oval port GM heads so the Dart Ovals would be killer. Or, you could get the smallest set of square ports like what come on that thing and just clean them up and it will run much better. Your heads are way to big, along with everything else. I would be willing to send you a set of heads done for this application along with a manifold, you can bolt your carb on, I will tell you where to put the timing and will refund all monies if it does not run 10.00's. Ofcourse you would have to make sure gear, tire size, converter all worked like they said and you repaired any drive train explosion from the torque you will have after the head change. Either way you would be so satisfied you would not care about a 10th or 2. Its sad when a mouse eats a rat for lunch!

[Dave F]

Bill,

I'm with you on the oval port heads. I'm a big fan of ovals.
I also agree this is most likely the easiest fix.

I have a couple questions of my own;
If everything were to stay the same, would he be able to pick up that low end with a higher CR, say around 13.5 - 14, run C12, leave those heads on and shift around 6500 range?

Do you think he needs to go down to the 265's? Wouldn't that drag his shift down to 5500 or so?

I'm still learnin' too.:D

DAVE

[Awesome Bill]

not at all, it only makes it better, raising the compression may help some, but still will not more air on the bottom end because of the heads volume. You would have to start with a 5500-6000 converter to get the engine up in some air speed that will allow the engine to breath better. The duration @ .050 is critical with engines like this, and its not longer either. These engines are doomed from the beginning to disappoint the owner and he will continue just to try everything everybody says will work and really won't . NOS will wake this thing up?????!!!!! and make a killer engine. But then, with the rpm factor, the valve train will be the culprit and will eventually kill the engine. Either way, NOS it will fly the cheapest. Thats what I would do if it were mine.