I have stg 2, 2.85, airbox mod and gmp exhaust. i thought it was just my mind tellin me my car ran better on the stage 2 pulley over the 2.85. until i raced my friends wrx which i usually leave sittin still especially from a roll. but now he can keep up easier. and i got walked by a stage 2 only cobalt. my car runs fine but it seems to pull harder on the stage 2. anyone else experienced this. should i put the stage 2 pulley back on.

 

Maybe you need a tune and bigger injectors? I personally like a 2.9 pulley on a stage II tune. 2.85 could make a differance and could slow you down, its possible.

 

Yup. Get a tune and some #60s

 

you need a tune and bigger injectors fo sho!!! you have more air pumping through there so now you need more fuel, but at the same time your brain(the PCM) is confused as ****!

 

i think ill just go back with the stage 2 pulley because i leave for iraq in may and when i get home in 2009 hopefully the hahn turo kit will be out and bye bye supercharger.

 

Its probably knocking with the 2.85, I know that when I ran my 2.8 pulley, I had to run Octane boost almost all the time to compensate for the knock! I am getting lots of knock with the stage 2 pulley, cant imagine what it was like with the 2.8. The highest gas rating we cn get here is 91. Try some Octane boost, I found it made a big difference. However even with all of the knock from the 2.8 it still had much more noticable power than the stage 2 pulley.

Also did you regap your plugs to a colder setting? I recommend the ZEX plugs.

 

i have same problem im going back to a 3 inch

 

Another reason to not go lower than the 2.9" pulley with the stage 2

 

Tune and 60's FTW

Your PCM is prob pulling timing

 

I have a 2.9 and BKR7E 1 step colder plugs.
On my Interceptor I have seen knock retard hit 7.1 in third gear pull often.
Any lower and you might hit 8 or 9 points of timing being pulled.
Oh and down here we have 93 octane gas which is all I run so I'm concerned for you 91 guys.
It's the reason I'm going to Methanol injection soon.

 

hm, so suddenly some people see the light

 

It's all in the tune...

 

Exactly, I am seeing tons of knock on a 3rd gear pull with my aeroforce, 2.8 is even worse. I am going with methanol injection for this reason also. Plus not going lower than the 2.9 with the stage 2 injectors. I will have my stage 2 tune tweaked for the meth in HP tuners so that I dont get any knock and can advance my timing.

 

does the concept of knock elude people?

 

People only care about there pulley size and not there tune/injectors.

More boost =/= more HP all the time.

 

i have no knock on my 2.9 whatsoever, but i have a dual pass and larger intercooler pump as well. I suggest getting cooling mods like aftermarket H/E and/or dual pass at the least if you go smaller then 3.0" pulley. CrateEngineDepot even recommends this.

My front mount is in the mail as we speak too, i plan on never reaching 130 degree IAT2's at WOT.

 

With the 91 Octane fuel here in Canada on the stage 2 tune, I get like up to 6 degrees of Knock retard, and thats in the middle of winter. Normal cruising IAT2 temps are like 55 degrees and never goes over 125 after a 3 gear run, so its not the cooling its the tune. So I find that you get 0 knock kinda odd, do you run higher octane fuel?? I got tons of knock with my 2.8"

 

God we need a what pulley size is perfect with S2 sticky

 

Whats really weird is sometimes I do a hard WOT run thru the gears doing a 1/4 run and I can top at 7.1 retard and other times I get none or harldy any say 1 at best.
I didn't have my Interceptor the last time I went the track so I can't say for certain but it makes me belive this is why my 1/4 times were always any where from .2 to 1.2 off my best run with exact launches and runs and cool down times.

 

just to stir it up i get no knock with my 2.4 pulley

haha, just kidding, thank god for 93 octane in my area for running stage 2

 

Outside air temp. and how many pulls/previous driving conditions can effect how much knock retard because the intercooler may not be able to cool the air as much as it should.

Its not weird, its common sense.

 

Mine fluctualtes as well, sometimes 6-7 degrees timing pulled other times 2-3 degrees

 

Outside air temp was a constant and I gave the car equal amounts of cool down time between runs and I could line up one run do a 14.5 turn right around and run a 14.1 then once again and get a 14.4. So I would have to belive otherwise as no conditions changed only the outcome which leads me away from that idea.

You have to think scientificly.
If a certain condition (outside temp) which is a variable (It's numbers can change) but it does not change for multiple instances (number of runs with equal cooldown) and both variables do not change the outcome according to math would be the same each time (the time ran should of been constant) so the only explanation is another variable (computer pulling timing due to knock) that would change the outcome.

Middle School Science Fair Projects FTW!!!!!

 

**** with a 3rd gear pull i get bout 3.1 knock with just the stage 2 pulley..but the gas sucks around here..i'm gonna have to run octane boost

 

Maybe it is the cold weather and denser air combined with the 91 octane, i was testing mine before it got cold with 3rd gear runs and just every day driving and my knock was always 0. I stored my car ever since it pretty much got freezing out. 93 octane is very prominent around here so thats pretty much all i run, sometimes i run 92 if i'm desperate.

This is how i might see it:
I guess it makes sense since colder air = higher pressure and if you're still seeing around 125 IAT2's at sub zero ambient temps, higher pressure may be entering the cylinders than in 70 degree weather same 125 IAT2's. Once the cylinder compresses the air, it will take more force and create more heat during the process resulting in more possible knock. Also, with 91 octane early combustion is more liable to happen making it worse.

Thats sucky, i guess during winter it is best to run no less than 3" pulleys