Im in the process of building a ls/vtec turbo set-up. I wanted to run 20psi on a race tune, and 10psi on a street tune. My question is should i keep the same CR or should lower it? also should i stay with the standard bore? I wanted to go forged piston.

 

first and foremost what are your HP goals?

 

You beat me to it.

OP: Pressure doesn't tell us anything. You could be running 20psi on a K03 and making 215whp or 20psi on a S372R and making 600whp. What are your power goals...??

 

LOL yea I remember when I used to ask questions pertaining to PSI instead of my hp goals. And id say if you plan on making alot of HP you should go forged pistons hands down

 

sorry bout that... im looking to see around 400. Anywhere close to that number i will be happy with

 

That's in the range where i'd build it; however, there are a number of guys who have made that power on a stock block with E85. Some days, i wish i would have gone that route. I took the safer bet and built my LS/VTEC since i was looking for over 400whp (although my EBC didnt work and kept me under 400).

Beyond that, your compression ratio depends on which turbo you get and what fuel you plan to run. For example, i knew i was running E85 and an S256 so i went with a higher-than-average compression ratio (9.8:1). If you're hoping to make that power on pump gas, you should probably consider something lower. We need more info from you again....

 

I wanted to run both pump gas, and race fuel. Will hondata let me have 2 tunes like that? Is the stock LS compression ratio 9.2:1? Thanks for helping me through this i appreciate all your help.

p.s Im just trying to get all the research and math done. So I can start the build.