GTM Stage 1.5 s.c. tune issue
 

After installing an 88mm pulley ( replacing the 90mm pulley) on my GTM/ Gamma stage 1.5 supercharger I had run into tuning issues.
Because the intake runs parallel to the cat. converter on the stage 1.5 setup, the intake was drawing in hot air during the dyno pulls. The air was so hot that the tuner could not get numbers over 400 hp.
I've rescheduled a tune where I'm going to pull off the metal under tray and I'll have a commercial floor drying type fan underneath the car also to try to cool the air.
My tuner was concerned that the 88mm pulley was overspinning the sc, as the pulley made 11 psi . Thoughts on that?
He now has he car neutered until the new tune... Ughhh

That's strange my intake is also close to the cat converters... I'm sure it pulls in hot air as well ... shouldn't keep you under 400 hp tho.... the 88mm pulley should be match almost perfect maxing supercharger at the same time you hit 7.5 k engine rpm... 11lbs is about right

I never ran into that problem with my kit.
I ran the FI exhaust with in line 100 cell cats

If your running the stock cats, I could see a possible problem.

The 88 mm pulley is perfect and the 84 mm is close to SC overspeed depending on your RPM limit.

Which rotrex unit is utilized in the stage 1.5? Cuz I know like jinxx and my sc units maxed out with the 85mm pulley but they are c38-91s I believe, our cars put off a lot of heat, main intake temp downfall is the stock tow bar blocking our intercoolers, but that moving.

Have you entertained using ecutek at all ?

The stage 1.5 unit is a hybrid ... it's the stage one charger with a stage to intake housing ..and I think it's actually has more effiency that the stage 2 ......if I remember the research correctly when I bought mine... I haven't noticed a heat issue and I dynoed my car in July and it was pretty hot

Just back from my Tune on 3-20 17.

Still have disappointing numbers. 455rwhp/ 337 torque ,90mm pulley

Maybe someone can spot an issue.

First of all , My original stage 1 tune was 405 rwhp and 355 lbs torque , 84mm pulley

Now, with the Stage 1.5 kit

This kit includes 3" intake, 4.5 inch filter, 3" maf pipes, 90 mm pulley.
(Tried an 88 mm pulley also, but tuner could not get that pulley to make good power. )
93 octane pump gas.

Wondering why the numbers, especially torque are so low compared to others.
My tuner suggested HFc's ( I would have to have resonated, noise level wise) to help flow more air out. Then maybe I could use the 88mm pulley also.
So there's my situation...

Not really helpful to you but how did you get a hold of the 88 mm pulley I'm getting the 1.5 upgrade this week but he couldn't get the 88 only the 85 or 90 so I'm gonna get the 90mm also my maf pipes are 2.5 inch my tuner said 3 inch wouldn't matter

Ya, that pulley is hard to find. I sourced it through a member on this site.
I'm going to try to use once I figure out my issues.

I think the older stage one kits had a flaw in the intake piping ....too much restriction to the supercharger and not getting over 8 lbs regardless of pulley size. If that's the case the 90mm will be more matched to the charger. The smaller ones may be spinning the charger but the restriction is choking it out through ing the tune off ... the flaw was corrected by new filter location straight back close the transmission the old design location was 2 filters in the front left area with 90 degree bends ......where are yours located?

I have the stage 1.5 with the filter under the car in between the cat and the tranny. It's the lack of torque that is puzzzling.

That is strange I thought with a 88mm pulley and 11 psi you should be in the low 500s maybe that's on E85 maybe you could try that E85 does cool down the car really well torq number is kinda low but I wouldn't really worry about a 10 torq loss our cars always lacked in torq in general I'm sure on the streets with air flowing under your car the torq is way higher

I can definitely feel a loss of torque from my stage 1 kit.. I'm really disappointed.
I just ordered F.I. high flow cats and am going to slap that 88mm pulley back on when the cats come in. I'm going to flow some air damnit!! lol

Push comes to shove, I may try ecutek . ( now with uprev) I have sunk a boatload of $ in this car.. I want it to make sure it is running at it's best!

That is really strange ...with the that setup you should be able to get close to 500 whp with the 88mm and smaller....the 90mm pulley numbers look about normal....super chargers don't produce high torque numbers ....I'm only at 395lbs TQ with 522 whp...on 93octane and uprev.....everything else is stock on my car as well ...still stock cats and exh

Ya .. it is strange.. Your torque is great! Most 1.5 setups that I've read on here are 475 to over 500 rwhp. and much higher torque than my setup.
I'm curious, what size are your maf pipes? I'm trying to duplicate the original 1.5 setup, but gamma sent incorrect pipes and they had no idea which ones that I really should have gotten..

The 88mm pulley put out 11 psi and the 90mm put out about 9ish

My 85mm was 12.5 lbs ....I have 3inch maf pipes.....you could be pulling timing for some reason and losing TQ and whp I'm not sure about the details of the 1.5 compared to the stage 2 but if you are getting 455/337 with the 90mm pulley that seems about right ...maybe ty another tunner