Questions about boost/ pulley sizes

[MysticCobra281]

I have a 96 cobra. I just switched from a d1sc to an f1a procharger. I have a 15% overdrive crank pulley and procharger told me that a 4.00 blower pulley would put me about 750 rwhp...they weren't even close. I made 668/560 at 22psi. my question is.. what do I need to do to break 700? im tired of buying pulllies and spending money on dyno time. 720-740 would be great.. any help or ideas would be great..this winter im doing ported heads and longtubes but for now I just want to get to those numbers

 

[FastNick01]

Just out of curiosity what shortblock do you have? Pump gas+torco or E85 etc.. 22lbs is already a pretty good amount of boost.

 

[MysticCobra281]

Built short block. Stock 9.76:1 compression. Stock heads, cams and intake. I'm on e85.

 

[01yellercobra]

Do you know the specs of the tune? Like how much timing is being run. How many miles on the engine? Are the rings still in good shape? The stock intake isn't helping things. If you want that kind of power you're going to want to at least port the intake. Or look into a Sullivan if they make one for your heads.

 

[MysticCobra281]

The block is fine. It's good for more power than I'll ever have. It was on 22 degrees of timing. It had a d1sc on 24 degrees of timing at 24psi and made 620 with a 3.4 blower pulley. It made 668 on the f1a at 22psi on 22 degrees of timing. We turned the timing up to 24 and broke a belt.

 

[MysticCobra281]

Idk if I should just finish the tune on this pulley and get maybe 680-690 and be happy or switch to like a 3.55 pulley and spin the blower. This winter I'm pullin the motor and doin long tubes, ported heads and probably a short runner intake.

 

[01yellercobra]

Like I said, look into porting the intake. It can only flow so much air.

 

[98 Saleen Cobra]

22 psi and stock logs huh. There's the bottle neck. Car needs a bigger exhaust imo before u go shoving more air in it. Just my .02