I have GM stage 2 right now. If i were to get a smaller pully and get a 2.9 or 2.8 will i have to re tune the car? It may be a dumb question but im new to the supercharger thing. Also what kind of gains will i look to get out of a 2.8 pully? Also will i need to get a smaller belt or will the belt tensioner take care of that? Thanks in advance.

 

It will be in your best interest to retune the car. Pushing a 2.8 you should upgrade to 60lb injectors which would require a tune. You should gain a good bit of boost with 2.8 (around 3-6psi). Belt tensioner SHOULD be fine but im not completly sure. Hopefully someone with more knowledge will post this is just all I have read up on so anyone please correct me if im wrong

 

u run rich on a GM stage 2 tune so a 2.9 would run perfect, anything smaller like BODY said will require 60's and tune. just dont go smaller than a 2.8 PLEASE!

 

I ran a 2.9 on my stg 2 canned tune and gained about 1 psi, I was also ALMOST running the injectors above 100% duty cycle.

 

You're car would run better on the 42.5 lb injectors with a 2.9....But like Johns said. You will be running your injectors at or above 100%.

Not to mention an increase in heat.

 

it's y they call it a Heaton.

just go TVS!!!

 

TVS requires a helluva lot of supporting mods.....

Also, with the Killer Chiller, Meth, Heat Exchanger and dual pass or custom single pass you could possibly see IAT2's below 100* at WOT by the end of 3rd @6800 rpm...give or take depending on ambient temps I'm sure.

 

below 100 would be real easy with all the cooling mods and meth will be the kicker. but you add just meth to the car without everything else and you will see a big drop in IATs.

TVS doesnt need as many supporting mods as everyone makes it out to seem...

 

LS4 Throttle Body (optional but should be used)
3" intake with a new MAF sensor
60's
meth
and traction traction traction...

but back to this guys thread....

His best results if he is just going to drop pulley sizes without doing anything else will come from a 2.9...If you run a 2.8 your car will run static and you'll be slower than someone on a 2.9.

 

i would go 2.9. just get a wideband and call it a day.

and LS4 throttle is FTL IMO. a bit touchy. couldnt like it.

 

Wow fast response i like it. So by dropping to a 2.9 am i looking at maybe a couple PSI? And so basicly if i run 2.9 its just more work for the injectors and the car will tend to run more lean, correct me if im wrong. So my car would pretty much probably run better on a 2.9. I think my next step is cooling every one seems to be telling me thats the way to go. What would be the best to start with, i was thinking of jus running a secondary heat exchanger. I cant wait to hit the dyno in the spring i finaly have a car with decent power and good potential to produce power. Thanks for all the help

 

i have a 2.85 and its on the ragged edge. a small shot of meth helps keep the temps down and keep it from pulling timing.

the smallest id go without worrying about anything is a 2.9. id also recomend getting a 2nd heat exchanger to keep the intake temps in check.

 

yea you will be running leaner on a 2.9 and gain maybe 1 or 2 PSI i believe. and cooling is key. these SCs heatsoak like a ****.

 

this is just the answer i wanted... good response guys

i have a 2.9 pully waiting but already stg 2... i just needed to know it would be ok

 

I think im gonna go with some cooling mods first. I think that would be the best bet then add more power. Shoot maybe once i learn more about these ill jsut go 60s with a 2.8 and a nice tune. Gotta wait for 36,000 miles tho lol. What would be a good heat exchange thats and easy install with good performance? And do thoes bad boys void warranty? Yea i know im a stickler. If anyones got a 2.9 GM ill consider buying it. Let me know. And again much thanks. Gotta say this is one of the best Forums iv been on.

 

get a zzperformance.com heat exchanger... bolts right up with no drilling

 

yea def wait until warranty is over and theres a few H/E that fit fine. a Cobra, CX racing and i guess ZZP has one like ike said.

 

Ok here we go.....

2.9 on stage 2 tune = 100% IDC @ 7000 RPM
2.8 on stage 2 tune = 110-120+% IDC @7000 RPM

2.8 on custom 11.9 AFR tune = 93% IDC @ 7000 RPM (recommended)
2.8 + methanol + 11.9 AFR tune = 80% IDC @ 7000 RPM (get meth soon)

You NEED to get a Heat Exchanger if you are dropping from the 3.0 pulley. Or never race it.

IAT2s will not raise more than 5 degrees going from a 3.0 to a 2.8 (I have SEVERAL logs) with only cooling mod being a H/E

Methanol did NOT drop my IAT2s at all but DID prevent heat soak.

IMO 2.8 is fine with a H/E as long as you dont stay in the upper RPM band for long however you still risk static injectors. H/E is mucho needed.