whats a safe psi to boost?

[chester_ff7]

whats up! my buddy is selling me him T3/T4 turbo off his 240sx (KA24DET) my question is: How much can i boost and still be safe? that turbo can hit 27psi.... but thats way to much for me.... what do you guys say?

[lrb_2000]

on a stock motor? i'd keep it around 8-10psi.

[chester_ff7]

cool..... and it wont give me any problem if i boost 8? i mean i wont run the risk of messing anything up? like the head gasket...?

[bone_stock_240]

check this thread for your answer. Someone posted a very very similar question.

zerothread?id=251232

[chester_ff7]

hey thats me! well i think i fould what i was looking for thanks!

[lrb_2000]

I ran 14psi on my T3 Super 60, and 10psi on my GT35 with 400cc injectors almost maxed out, and never had a problem.

[chester_ff7]

dang! cool! good stuff, i have the 370cc injectors and a sard pressure regulator, and i had the 370cc injectors rebuild so they are spraying 370cc again! man i cant wait to put it on my S14!

[silnismo]

cool..... and it wont give me any problem if i boost 8? i mean i wont run the risk of messing anything up? like the head gasket...?

If anything your ringlands would probably go before the headgasket.

[extreme135]

If anything your ringlands would probably go before the headgasket.

I second that

[nissanfanatic]

I don't third that.

[chester_ff7]

well.... i said head gasket because i have some friends with SRs and KA-Ts and they told me that there head gasket went first.... and that happen to 3 on them. so the ringlands ah?

[nissanfanatic]

My headgasket went first. But I believe mine was related to pre-ignition which will push out a headgasket unlike detonation. In detonation, the entire mixture is ignited too early and the majority of it burns releasing the energy contents too early. This pressure wave of energy expansion is absorbed by all components in the combustion chamber and the piston is usually the weakest link. Considering the rise in temperature as the charge compresses, you can see how it burns quickly near TDC.

In pre-ignition, the expansion of energy from fuel combustion related to cylinder heat occurs right when the piston is nearing TDC. So basically, you get a ****-ton of pressure, just like boost, right before the piston hits TDC. Then the piston compresses that, and you can see how that would push the gasket out.

You can see a picture of the inside of the combustion chamber during normal and detonation scenarios here:http://not2fast.com/engine/

Detonation can be a direct result of pre-ignition. Mostly, detonation is when you are getting nearly full energy release from the charge and pre-ignition is when the charge is beginning to burn too early resulting in high cylinder pressures. If you picture it in your head correctly, you will see how the pre-ignition causes a ping sound and detonation causes a knock sound. Note, not all detonation and pre-ignition is audible..

[chester_ff7]

dude thanks alot! that was some good information. well i am going to replace the head gasket with a metal one. and i will give my KA a real good tune up. get it ready!

[chester_ff7]

dude? how did you get it to 400+whp with stock internals? thats crazy!!