What Compression should I run

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Feb 17, 2006 | 04:50 PM

JD_Z28

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From: Arizona

What Compression should I run

I have an 02 Z28 with an STS kit and im gonna be getting a block built by HPE. Im gonna be building a 346 short block with forged internals, Z06 cam LQ9 6 liter heads. I live in CA so I only have 91 octane to use. I was wondering what pistons should I get and what would be an ideal compression for what I want? a fast weekend car. The turbo im running right now is the 60-1 but im planning on going bigger.

Last edited by JD_Z28; Feb 17, 2006 at 05:16 PM.

Feb 17, 2006 | 05:11 PM

Spenser309

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From: Coppell,TX

Its really up to you, but the higher the compression the more "out of boost torque" with side affect being more prone to detonation. Do you wanna feel like driving a honda, and hit boost and move or do you wanna drive a V8 and know it all the time at the expense of max power? Also, what size turbo are you running? small turbos like more Compression, big turbos like less. Making a turbo system is all about setting your balances. Personally, what i would do is sell the sts, make a truck kit, purchase a 91mm turbo and lower my compression to around 7.5:1. Because i would like to be a dyno king, lol. 30psi here i come, on pump gas, too.

Feb 19, 2006 | 08:16 AM

EPP

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I'd shoot for 8.5/1 for your compression ratio for the turbo. Bob

Mar 8, 2006 | 06:12 PM

buck2769

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what does this do to the bottom end? At what RPM does this pay off?

Mar 8, 2006 | 11:11 PM

Spenser309

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From: Coppell,TX

Dropping the compression just means increasing the area in between the piston and cylinder head. It can be accomplished with head swaps, and piston changes.

That depends on cam specs. A drop in compression should generally decrease power throughout the entire RPM range.

Mar 8, 2006 | 11:42 PM

Dragframe

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From: wyoming @ 12000 DA...

i would personaly never go below 8:1 compression because then the motor would LIVE off boost. You want something that has at least a lil ***** off the boost. My recommendation would be 8.4:1 to 8.7:1. aYou could run a ton of boost still, and make massive power.