After doign a search it seems like all the z6 with JRSC are running stock compression. What my question is, could a 10.5:1 c/r be used with a SC'd z6?? I'd be using SRP pistons with Scat rods & ACL bearings and either AEM EMS or s200b. Also would upgrade all fuel components. My z6 already has a built head from a previous owner so that is fine. Any help would be great

 

Bump....

I have a very similar question.

 

It can be done, as I ran my b16 setup with stupidly a high 10.8:1 CR. You're limited in two areas. First, you won't be able to run a ton of boost. 8psi will be pretty damn close to your max, although with the high CR, you'll get a good amount of power. The second issue is that you won't be able to run as much timing advance as you could with a lower CR.

Other than that, you'll be fine.
Spend the time/money to tune properly, and you're laughing.

 

Do you think the stock sleeves could take the 8-9 psi with a 75.5 bore or should i just Darton the block and be done with it right then and there??

 

leave them stock, and the money you would have spent on machining, and Dart sleeves, etc should go into both an EMS and proper tuning. With tuning, you can run a lot of power on the stock sleeves.

 

Well if i did chose to run 10.5:1 compression with 8+/- boost wouldn't cylinder pressure be very high even with proper tuning?? Because i look at most of the turbo'd guys on here with stock sleeves and they arent running anywhere close to 10:1 c/r. Everyone pretty much says, if you're gonna boost lower the compression, thats why i ask.

 

The bottom line is that you're not running a lot of boost, and in the grand scheme of things, 10:1 CR isn't that high. In my experience you'll need to be more careful with the amount of fuel and timing you run. Once again, it all fals down to tuning. If you knock, you need to spend more time tuning. If not, then run the *** of that thing and be sure to monitor your plugs. Cylinder pressures can shoot up to 4 times higher during knock, I'd worry more about controlling that than running a 10:1CR.

Be aware that you have less margin for error, but it can definately be done.

As for those who say "boost with low CR" they don't know anything other than what they've read (just like the turbo>jrsc guys ). Ask guys like Arturbo, or EFIGUY about 10:1 CR and 8psi, and they'll say the same thing I did. Be careful, and enjoy the additional power by running a higher CR.

 

Thanks man for all the help

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eXcelonTypeR &raquo;</TD></TR><TR><TD CLASS="quote">Well if i did chose to run 10.5:1 compression with 8+/- boost wouldn't cylinder pressure be very high even with proper tuning?? Because i look at most of the turbo'd guys on here with stock sleeves and they arent running anywhere close to 10:1 c/r. Everyone pretty much says, if you're gonna boost lower the compression, thats why i ask.</TD></TR></TABLE>

I have the SRP 10.5:1 pistons in my setup. Actual compression ratio calculates out closer to 10.1:1. I would like to hit 300whp on pump 93 gas. I'll let you know how it goes in a month or so when everything is finished.