Can't make over 750rwhp - why?
 

408 15lbs boost, D1 sc, twin coolers, 8 1/2 compression - pretty much that's everything I have. I need to know, is the problem my SC or my inter coolers???

Did 75 shot nitrous and barely made 50 hp. What is the most hp someone has made with a similar set up w/ D1sc w/ twin intercoolers vs. with a front mount?

What kind of heads are u running? Also whats the cam specs? What is the exhaust setup? Whats your IAT, timing and A/F?

I'd replace those intercoolers, cant imagine you making 15lbs with those things.

I think ya intercoolers are a big reason. Twin intercoolers arent the best at cooling as 1 jsut gets heat soaked and then passes it off to the other. And those intercoolers are horizontal. That definatly dont help. Im sure htere are people that have made more hp on teh intercoolers but it is definatly a killer. 750 horse is big boy power. Need to get big frontmount and get it alot of air. GL man



John

Yeah I hear the stock D1 intercoolers are crap after a certain point.

You've got some high expectations. Most D1SC owners would be thrilled with those numbers. How many are above 700 rwhp?

I wanted to make 800 rwhp. Either or the motor or on the spray. Are you saying that the blower is not capable of making 800rwhp.

It seems to me like a restriction, because I tried a 50 shot and only 30hp and then tried 75 shot and only made 50hp.

My cam specs are 224 234 585 598 114. IAT's top of the run was 130. Timing 15 degrees. The heads are stage 3 6lt heads, 205 intakes. Exhaust 1 3/4", 3" Y pipe, 3" all the way out.

Your timing is fairly low, so that would bump power. Your intake valve is also kind of small so that may be limiting you a little bit. What's your pulley sizes to get 15 lbs.?

I think the cam is your problem. Im almost running the same spec cam in a D-1SC 346 LS1. I think u need something larger such as 238/244 114LSA .595 .610 lift for that 408 engine. The exhaust setup could be better.... Try 1 7/8 headers with 3 inch dumps or cutouts instead of one 3" pipe going to the back. Why dont u try disconnecting the Y-pipe on the dyno and see how much u would gain. That would be a good idea before u spend money on a new exhaust setup. Since the IAT are around 130 i dont see a FMIC helping u that much. I personally never seen a before and after Dyno comparing the Dual intercoolers to a FMIC. Until someone post such results and it better be good then i can say that the stock dual intercoolers need to be changed.
I think a larger cam, better exhaust setup should put u around 750rwhp.
Good luck man.

93 pump gas?

danny,

small cam imo isnt hurting you that much. its the intercoolers. here is the intercooler Futral put on our car....

http://www.revxtreme.com/gallery/alb...ntercooler.jpg

about how many rpm are you turning that blower? (not including the belt slip ofcourse).

imo, 750 rwhp should be no problem on blower alone and 800 rwhp should be a cakewalk on the 75 shot.

are you running out of fuel? exhaust is pretty small. still shouldnt be that much of an issue. esp considering your dyno friendly driveline.

The twin intercoolers are the problem.

The manifold is seeing 15 psi, but I would bet my car that your supercharger is producing in excess of 18 psi prior to the intercoolers.

The higher the discharge pressure at the supercharger, the higher the parasitic losses drawn by the supercharger (HP Lost = CFM * Boost). So instead of your supercharger producing 15 psi and taking 15 psi worth of HP, your car is only recieving 15 psi, but is working hard enough to compress 18+ psi of air. The difference is staggering at higher CFM (ie your top end).

It is not a definite, but the fact that your motor chewed up that nitrous shot without giving anything back would be an indication to me that you have a very high parasitic loss.

I'm just saying that those are outstanding #'s. It must be a well chosen combo. I thought it was strange that you thought you had a problem. If it's not responding well to NOS though I would guess maybe it could be freed up on the front (intercooler) or back (maybe go to 4" exhaust).

From my understanding, the twin intercoolers are only good to 13# of boost, then they become a restriction.

Like Kevin said, the nitrous shot didn't really do anything, so you have a restriction somewhere, and it's those stock intercoolers.

I wish I had this guy's problem.

you have a pretty much stock exhaust right? Muffler....single 3" pipe. Uncork that bitch and you may be surprised.

Another vote for the intercoolers, and I think my brother would agree they're only good for 12-13psi..

I agree with disconnecting Y-Pipe just to see how much you can gain. If you like what you see, you may be interested in a new exhaust setup too :)

Get a big FMIC and enjoy the power!

I gained 35 HP opening the cutouts ON MOTOR at the 522 rwhp level and I had dual 3" pipes into mufflers. I cant imagine trying to get 800 rwhp through a single 3" pipe and muffler.

It's the intercoolers :) The Cam is perfect for 800hp.