well i think that would be a good compression ratio. right now with my ls i have a 8.99 because of the thick head gasket and 2/1000 taken from the head. any comments?

 

9.5:1 is perfectly fine for boost

 

ok sweet!!

 

i run 9:1 at 15psi from a holset hx35...no problems as of yet...and lovin the torque down low!

 

I run over 10:1 on my turbo D16 so I'm sure you'll be fine.

 

I've got 9.5:1 CP pistons on my ls/vtec turbo pushing 8/12 psi on stk b16 head. There is plenty of torque throught the rpm range and low enough compression to get descent gas mileage when crusing. It was really laggy running N/A during the break in period.

 

well i didnt win the auction so im just going to use gsr pistons and boost 12psi giving me a 10:1 ratio

 

i got 9:5.1 in my lsvtec

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by the.hamburglar &raquo;</TD></TR><TR><TD CLASS="quote">well i didnt win the auction so im just going to use gsr pistons and boost 12psi giving me a 10:1 ratio </TD></TR></TABLE>

why would you use OEM stock cast pistons for boost? you have the engine apart and are spending money to re-build it....spend the extra 400 bucks and get a set of good forged pistons.

at 10:1CR with boost you better be really good with your tuning on those pistons or you will be cracking ringlands or melting them pretty quick.

 

yeah i know but this is my first ls vtec build so ill just wait till the ringland break. i dont really care, then ill buy forged. that extra 400 is going into the vtec kit and a new turbo manfold and downpipe. i know its not the right think to do but it will work for a while. yes im fairly good at tuning now

 

if your dead set on using OEM cast pistons at-least use OEM LS pistons. the lower compression will be easier to tune. and probably be safer.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by non-VTEC &raquo;</TD></TR><TR><TD CLASS="quote">if your dead set on using OEM cast pistons at-least use OEM LS pistons. the lower compression will be easier to tune. and probably be safer.

</TD></TR></TABLE>

If you use stk ls pistons make sure you clay the motor to make sure you have plenty of valve clearance. On some set ups the valve reliefs are not large enough on the ls pistons to run the vtec head.

 

i have 11.0 in my fully built ls/vtec motor and i am running gt 42r 18psi i made 600whp neptune

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbobubble630 &raquo;</TD></TR><TR><TD CLASS="quote">i have 11.0 in my fully built ls/vtec motor and i am running gt 42r 18psi i made 600whp neptune</TD></TR></TABLE>

Now that is impressive, what is you set up?

 

i got 10.6 at 6psi 297whp

 

basic setup 85mm bore 11 cp fully built head r cams full race topmount manifold gt42r 4' exhaust twin 46mm gate thats about it. the turbo blow up on 18 psi i am looking to rum 35 psi and its a street car

 

will i have to clay the motor with gsr pistons? no im not using ls pistons. i think 10:1 is a good ratio.

 

Your compression is optimal for the future Big numbers. 9.5:1 -10:1 is what i usually reccomend for mild turbo builds. People boost 11-12:1 compression motors all the time. Tuning is key to prevent unwated detonation and other factors.