I have a stock gsr motor with a t3/t04e turbo. want to step it up this year with a built bottom end. im going to run eagle rods but am unsure what pistons i should run for around 15lbs of boost on stock sleeves bored 20 over. thanks in advance!

 

bump

 

Most of H-T run 9:1 compression pistons, I would recommend JE,Wiseco, or CP ( make sure you dont get an old batch of CP pistons, I had mine dropshipped from CP and i got a newer set... the old 81.5 CR have issues with their valve reliefs cracking ) 15psi is a good number to run on pump gas.

My setup is 9.8:1 CP pistons,eagle rods,full supertech valvetrain and I plan to go 15psi. I just want over 400whp.

15psi will be alot safer on 9:1 than 9.8:1 though.

 

depends on what type of management you have to tune the setup. If you can fine tune it, you can even go with a higher compression. Most people use 9:1 since there is more room for error with a lower compression in relation to detonation. The higher compression setups are becoming more popular these days since we have better engine managements to fine tune our daily driver setups. We've done alot of 10:1 to 11:1 b-series setups the past couple years and its becoming more popular lately. check those compressions out too to so if its good for you.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by exospeedAMcrx &raquo;</TD></TR><TR><TD CLASS="quote">depends on what type of management you have to tune the setup. If you can fine tune it, you can even go with a higher compression. Most people use 9:1 since there is more room for error with a lower compression in relation to detonation. The higher compression setups are becoming more popular these days since we have better engine managements to fine tune our daily driver setups. We've done alot of 10:1 to 11:1 b-series setups the past couple years and its becoming more popular lately. check those compressions out too to so if its good for you.

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Thanks for all your input!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RS DC4 94 &raquo;</TD></TR><TR><TD CLASS="quote"> im going to run eagle rods</TD></TR></TABLE>

You should rethink this choice before deciding a CR

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowteg90 &raquo;</TD></TR><TR><TD CLASS="quote">

You should rethink this choice before deciding a CR </TD></TR></TABLE>

3 of my group run eagle rods with 500+hp.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowteg90 &raquo;</TD></TR><TR><TD CLASS="quote">

You should rethink this choice before deciding a CR </TD></TR></TABLE>

why is that?

 

i prefer 9:1 personally. there is very little to be gained going from 9:1 and 10:1 on a turbo motor

 

use the flat top wiseco's and eagles, you wont have a problem

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99B16Si &raquo;</TD></TR><TR><TD CLASS="quote">i prefer 9:1 personally. there is very little to be gained going from 9:1 and 10:1 on a turbo motor</TD></TR></TABLE>

You're right, powerwise. No difference in power b/w the 2 ratios. But the slightly higher compression actually does help with added acceleration especially off boost between gearing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheShodan &raquo;</TD></TR><TR><TD CLASS="quote">

You're right, powerwise. No difference in power b/w the 2 ratios. But the slightly higher compression actually does help with added acceleration especially off boost between gearing.</TD></TR></TABLE>

The reason I went with 9.8:1 compression is exactly what shodan said. It doesnt literally spool the turbo faster but it gets the engine to the required 'full spool' rpm faster than a lower compression such as 9:1. How much faster? I dont know, I know TonytheTiger's high C:R turbo setup was mean, hopefully mine will be a smaller example of that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowteg90 &raquo;</TD></TR><TR><TD CLASS="quote">

You should rethink this choice before deciding a CR </TD></TR></TABLE>

I trap more in the 1/8 mile (over 130 MPH) with a 3300 pound car than a lot of people do on here in the 1/4 mile, with my terrible eagle rods. I also go through the traps at over 8000 RPM's. But, you know, eagle rods can't take much abuse....

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JoePSI &raquo;</TD></TR><TR><TD CLASS="quote">

The reason I went with 9.8:1 compression is exactly what shodan said. It doesnt literally spool the turbo faster but it gets the engine to the required 'full spool' rpm faster than a lower compression such as 9:1. How much faster? I dont know, I know TonytheTiger's high C:R turbo setup was mean, hopefully mine will be a smaller example of that.</TD></TR></TABLE>

Honestly the difference is going to mostly be in your head. There will be some difference, but a lot of people on here are making a high compression motor seem like the be-all, end-all to do away with turbo lag. Going from 10:1 on my stock GSR to 9.1:1 with my 81.5mm GSR the power difference was very, very negligible off boost and I really didn't notice a difference on the street. The best cure for a responsive motor is a properly selected turbocharger, not higher comprsesion

 

we use 10.8:1 on most of our 84mm motors.

 

its going to vary accross applications. I do not think it is wise to go above 10:1 on a DD that will be running pump gas 95% of the time. Race motors running high octane fuel or alcohol are totally different monsters tho...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99B16Si &raquo;</TD></TR><TR><TD CLASS="quote">its going to vary accross applications. I do not think it is wise to go above 10:1 on a DD that will be running pump gas 95% of the time. Race motors running high octane fuel or alcohol are totally different monsters tho...</TD></TR></TABLE>

I agree, the tune for a 10.8:1 on pump gas would have to be on the money, if you get a bad tank of gas or whatever it would be dangerous.