low compression

[no2ricers]

if i am running forged pistions with a 7.96 compression with 68cc chamber, performer rpm heads with 70cc chambers will i have low enough compression for a high boost set-up(10-12)psi and what camshould i run???



\"springs, spindles,4\"blocks,working on 350 now

[mommasboy]

You will probably be about 7.5:1, maybe just a little lower. That should handle so decent boost i would think.



this is what the static compression ratios would be under boost with 7.5:1 comp.(aaprx)



2psi: 8.5:1

4psi: 9.5:1

6psi: 10.6:1

8psi: 11.6:1

10psi: 12.6:1

12psi: 13.6:1

14psi: 14.6:1

16psi: 15.7:1



So on 10-12 psi i dont think pump gas would be an option. http://www.s10v8.com/images/smilies/icon_wink.gif



and about the cam, look into some of the nitrous and blower cams....which are longer on the exhaust side with the duration and taller on the exhaust with the lift.



Chris



91\' S-10,

383 Stroker, World Products Sportsman II heads, Ported Stealth Intake, NOS 150-250 shot,Jethot coated Longtube headers, 3\'\' all the way back. 27x11.5 Hoosier slicks. Competetion Engineering Slid-a-link Traction bars.

[ZZ4Blazer]

Guys at ATI Procharger claim you can run around up to 10 psi with 9.1 compression and 93 octane. At least with a centrifical blower. Just retard your timing correctly, and you should be fine. Intercooling will also let you run higher psi, and have less change to detonate. And you will see higher hp from the cooler intake temps, and from the higher boost.



I will have between 8.8-9.0:1 compression with my motor, and I am shooting for 9-10 psi on 93 octane with minimal timing retard. Maybe more after I intercool it.



You can usually run about another 1-2 psi with aluminum heads over cast, due to the heat transferance.



Good flowing heads will greatly benifit from boost. Even just porting the exhuast will provide a significant gain. Dual patter cams are best. Look for one with around 10 degrees more exhaust duration, and same with the lift. Lobe separation between 112 and 116.

[mommasboy]

At 10psi the actual compression ratio in the combustion chamber is about 14.5:1. thats just a little high for pump gas woul\'nt you think. Thats what my chart shows anyway.

[ZZ4Blazer]

Maybe so, but thats what the guys at ATI claim. THey seem to be very confident in their products. Whipple makes a roots blower specially for my ZZ4, and they just bolted it on and made 517 hp with 93 octane. Thats with the stock 10:1 compression and 8 psi. Both have companies recommend retarding the timing some. Stopping detonation is key.



I am gonna try mine with 9-10 like I said. Blow through ATi P1-SC supercharger w/boost reference fuel pump and boost referenced timing retard. Hopefully shooting for 650-675 hp

[mommasboy]

Sounds badass. I hope we gave him some ideas on what to do though.

[no2ricers]

Thanks for the help it makes it a little easier for me to do this project