There are a lot of threads about which size pulley to run with 42.5# injectors. And I heard a lot of different things being thrown around about what is safe and what is not.

My question is has anyone blown their engine with a GM Stage 2 kit tune with a smaller pulley? I know several people have ran into trouble using custom tunes but I have yet to hear anyone say they have blown their engine using a GM Stage 2 tune.

The reason I ask is as I understand it the GM Stage 2 tune has a by-pass limit on the amount of boost it will allow to pass into the engine. Im very close to sea level and with my 2.8" pulley the max boost I have seen is 16.9psi. I have heard of other usings a 2.85" pulley and getting 17.5psi by using boost by-pass mod or a custom tune.

As I understand it you could put a 2.6" pulley on a GM Tune and still only get 17psi. Is that correct?

Again let me state that I asking about a GM stage 2 tunes only. Not custom tunes or boost by-pass mod.

 

I blew my headgasket with GM Stage 2, but I think something was off from the factory anyhow.

 

my friend put a 2.8 pulley header downpipe and exhaust and his blew.... Piston 2 and 4 blew

 

i wouldnt even try doing that, you wont have enough fuel to that motor with a 2.6, maybe your thinking 2.8

 

I think the lowest U can go on a GM stg 2 Tune is 2.9 Some 1 correst me If Im wrong

 

It isnt the lowest that you can go, but it is the safest size to go down to

 

i have a 2.79, cai, cat back and stage 2 and first off the thing is a whole new car, rips and louder than ever..power was smooth all the way ...i saw a dyno of an ss with a 2.79 and stg 2 tune and there is some knock after 6,500..nothing too crazy

 

was that 2 me?

If it is? sweet. cuz I was probably gunna do that. (or a 2.85) lol

 

Was that on a straight GM Stage tune?

I know that is not what you want to do but the point I was trying to make is the GM Stage tunes have a boost by-pass limit. Is that correct or not. I might be wrong.

 

yup a straight gm tune nothing else

 

What do you consider some knock. On my interceptor I some times see .1 or .2 on the knock retard reading at 6500+ rpm. What does that mean exactly? Is that the amount of timing it is pulling?

ok. Then I have found someone. And he thinks the problem was due to running lean?

 

there is more than .1-.2 degree's of knock. i will bet money on it.

hell i have a log from a stage 2 car, couple of them showing more than this.

 

That is the reading I get from my display. So that means that it is pulling that amount of timing right?

 

what octane fuel.

 

93 octane and 1 stage colder NGK plugs. Every other mod is in my sig.

 

i see. octane has a lot to do with it.

 

Yeah I am lucky in WI we have 93 octane at all the Mobile gas stations I go to. And they just replaced the tanks at the one closest to my house so I know I am getting the good stuff.

As far as knock retard goes I have never seen it higher then .2. Above 6500 it will jump around from .1 to .0 to .1 to .2 to .1 to .0. The only time I ever saw it at .2 I accidently bumped the rev limiter because I was paying too much attention to the scan gauge.