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Discussion Starter · #1 ·
Greetings all,

Looking into getting a Solstice GXP, but had some specific questions for the guys that mod/race them at the drag strip.

Let me start off by saying I am pretty damn familiar with the Ecotec platform, especially that of the LNF and before that, the LSJ. I've had 2 LSJ Cobalt's. I've built bottom ends, TVS swapped another. Ran low 12s. I currently own an HHR SS and want to get something a little bit more drag friendly, the GXP.

How are the auto transmissions as far as E.T.'s at the drag strip, and holding up to power/abuse at track? I am tired of drag racing these glass canon manuals, and want something that is more drag oriented.

Also, I just noticed HPTuners apparently doesn't support the TCM in these cars, what does everyone do for auto trans tuning? I saw that super chips has a GM Cotex handheld that supposedly does line pressure adjustments, and can lock the converter. Was thinking about using that and adjusting everything else with HPT on top of that.

As much as I want to stay away from a manual this time around, how does the manual trans hold up on these cars? The F35's from the FWD Ecotecs I've owned were all delicate and sloshy.

Does anyone have an E85 setup using a 5th injector, or ZZP's cam lobe and raced an auto car at the track? Curious at what kind of times people are getting.
 

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There is a tuner in Canada that does the TCM.
 

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How much power are you planning on putting to the rear wheels, and what tires? I'm newer here, so someone will correct me if they disagree, but from what I've read here is that the auto is a bit stronger, and also tends to consistently deliver a slighty better 1/4. Reason they are not as popular is that most with these cars love the manual control in mountains, or driving around, or track situation.

That said, you can also google this tranny and see that generally it is meant for mid power/torque. Our little 2.0 is interesting because this tranny certainly can handle the little motor, but with forced induction it was actually not meant for the torque it can produce, and my guess is the saving factor is that you are not trying to accelerate an SUV, but rather a small sports car that is well below the 4000 pound vehicle this tranny was meant to deal with.

Here's a little general info:

"The 5L40-E had been designed for 1.8–3.6 L engines with a maximum of 250 ft·lbf (340 N·m) of torque"

So stock a GXP would give you 260/260, so with the light weight of the vehicle this should be fine. But even our mild GMPP puts it up to 290/325, and if you want more, you can more tuning, cat, IC, and be around 320/345 and that is where I think you are really pushing the tranny.

GM 5L40-E transmission - Wikipedia, the free encyclopedia

The BMW X5 with I6 3.0 and 225 HP/215 torque is supposed to have this tranny (up through around 2007). It has had some issues in this application, again reading online. But while the power numbers might make you worry/wonder, the vehicle is also well over 4k pounds, and it shows max towing ability of 6000 pounds. I don't think this motor can cope with that weight at all, hopefully people weren't actually towing more than about 3500 lbs with this motor/tranny. So again if you take away all this hard service with moving weight, the tranny can probably take a good bit above what it's ratings show.
 

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Discussion Starter · #4 ·
One of the main reasons I am looking at this car is because I already have a set of bias ply slicks that will bolt up from racing my other Ecotecs, and also HPTuners already.

The plan would be to take the stock turbo as far as I could, ZZP 5th Injector and Cam Lobe for the HPFP. Full E85 + boltons on an LNF will net around 360/400, on the FWD variants anyway. Little less on an auto rwd obviously.

The main problems I've had in the past is traction and consistency, which I hope I can fix with one of these. My previous LSJ Cobalt SS put down 360/300 with a TVS swap and E85, I was able to crack off a low 12 with that in the 1/4. I'd like to be able to do the same on a stock turbo GXP.
 

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One of the main reasons I am looking at this car is because I already have a set of bias ply slicks that will bolt up from racing my other Ecotecs, and also HPTuners already.

The plan would be to take the stock turbo as far as I could, ZZP 5th Injector and Cam Lobe for the HPFP. Full E85 + boltons on an LNF will net around 360/400, on the FWD variants anyway. Little less on an auto rwd obviously.

The main problems I've had in the past is traction and consistency, which I hope I can fix with one of these. My previous LSJ Cobalt SS put down 360/300 with a TVS swap and E85, I was able to crack off a low 12 with that in the 1/4. I'd like to be able to do the same on a stock turbo GXP.
So traction generally is in favor of RWD as you likely know, however weight of vehicle is often in favor of FWD cars, what was your weight? Auto will give you consistency.

Low 12 is very good. If you watched all your weight points and did many of the things you did in the prior car, you might be there, but you're certainly pushing it with the stock auto. I'd be dang happy to see you hit low 12's with our stock auto :thumbs:

I had been focused on our coupe and keeping the GMPP tune, but adding HF cat and IC (I have the Hahn, just not installed), hopefully being around 310/335. And I figured with several weight savings I'd be about 13.0

With your figures I can see you being mid or lower 12's, but, I don't think things will last with tranny.
 

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Discussion Starter · #7 ·
Good to know, I was originally going to go with a Sky, but once I saw the Solstice came in orange, I started to lean towards that. I was on the Sky Roadster forums and noticed a few guys were saying the engine will throw a rod long before the auto trans will break, which lead me to believe it was a pretty stout transmission.

How are the rear ends on these cars?
 

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Does he use Trifecta or what? I can tune the TCM myself if I had software and access.
Is certainly not Trifecta.
He is a very well known tuner in Canada. I also will not think he would reveal how he does the TCM tunning for auto.
Westers is the name.
 
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