compression!

[red_line]

What is the best way to lower the compression of my 91 eclipse GS. i got a turbo kit from a friend and it is a turbo 1ga. so we need to lower my compression so i can run more boost. what would you do to get this done?

[coolguycooz]

well since you want more boost you might want to worry about your internals breaking first. Since your going to need to do rods and pistons i think you can get aftermarket lower compression pistons? not sure though.

[red_line]

ok now i dont want to run more boost than stock but if we put it on the gs engine we will need to run the boost really low. i want to be able to like stock gst boost. what would be the easiest way to lower compression now.

[coolguycooz]

By stock GST boost do you mean like 210 hp. you wont need to change compression for that. And i think the only way to change compression would be actually changing the cylinder stuff inside either different pistons or a different low compression block or something like that? but for 210 hp you should be fine running like 8-10 psi of boost?

[red_line]

is that stock boost for a a turbo eclipse? a can run the sam boost and not change the compression

[1stGenRocks]

if you hook the wastegate straight to the turbo outlet pipe then you get 11 psi

[coolguycooz]

I dont think you have to change the compression even after that. the 420a is a high compression engine but i think it can go more then even 10 psi i think you can even hit like 250 hp and still not have to worry about compression more about your internals breaking. but yeah you shouldnt have to worry about compression because pistons is one of the internals you do and when you do do them you will get lower compression ones.

[1stGenRocks]

hes talking about a 1g NT which is a 4g63 NT. NOT a 420a. search some more but make sure you are finding info about a 4g63NT and not a 420a

[coolguycooz]

oh damn my bad haha. wait so could the 4g63 NT's support 400 hp on stock internals?

[1stGenRocks]

search they are almost the same. they have the same block but with higher compression pistons. they also have different cams and some other stuff is different

[coolguycooz]

alright well sorry for hijacking red_line's thread but 1stgenrocks how do you change the compression?

[1stGenRocks]

different pistons or a thicker headgasket to lower it. high compression pistons, mill down the head or block to raise it.

[kjewer1]

Using a thicker HG to lower CR will banjax quench though, I personally would avoid that like the HIV. The pistons are obviously not built like turbo pistons, but people seem to do alright with them. I think 200 HP would be just about the limit for my comfort level. The block is the same as the turbo 4g63 however, minus the oil squiters, so turbo rods and pistons would work provided they match the cank (6bolt/7bolt).

[macder]

Originally Posted by 1stGenRocks

search they are almost the same. they have the same block but with higher compression pistons. they also have different cams and some other stuff is different

I believe both use the same cams, they are both the same part # at the mitsu dealer.

[ITSME4G63]

the best way to do is is to sell your n/t and buy a turbo model.