Hi. 2007 MC SS with CAI, resonator delete and exhaust. Stock otherwise as far as I know from who I bought it from. I'm getting it dyno tuned here: https://www.holeshottuning.com/. They are supposed to be the best in the area anyways I talked to the owner I believe it was and he said he's going to do a 91 octane tune on it but didn't elaborate too much more. For the people that have had their cars dyno tuned with minimal upgrades what did you feel (if any) differences? Thanks. Not familiar with tuning non carbureted cars.

 

Aren't you selling the car or did you change your mind?

That's a useless statement on these cars IMO. The factory pcm is tuned for the fuel the manual specifies: 'premium reccomended'. So technically, its already got a 91 or 93 tune in it for max timing. Either the person you talked to didn't know your car or they assumed you didn't and were just throwing around common buzz words.

Generally that statement is for cars tuned from the factory for 87 octane only. You agree to only run premium, and they bump the timing up to match to pick up some power. In the case of the LS4, its already got the ability to increase timing for premium fuel. Also, the stock timing is already probably too high for 91 (especially in the warmer months)- Id bet you've got a tiny bit of spark knock thats pulling timing today. So they're not going to make some massive increases by just adding timing like you can on other platforms.

LS4s generally tend to pick up about 10-15 at the wheels on a near stock car like yours (mostly through fueling changes as they tend to be on the lean side from the factory). Its right about at the lower end of a gain you can feel in the seat. They can also tweak the trans a bit, but they're limited as to how aggressive they can go since the 4t65 is such a poor match to the LS4 in terms of torque holding capacity.

Personally, I don't think its worth it (especially if its about $400+ as most dyno tune places seem to be). I owned a GP GXP with the LS4 for about 10 years with a few minor bolt ons, but never spent the money on a dyno tune for that car. Its absolutely worth it when you get into bigger mods, theres just not a lot left on the table with a stock setup like there are on other platforms as the engine has other bottlenecks.

The other downside is if you do end up doing more mods down the road (especially bigger ones where tuning isn't optional) - and you end up paying again for a tune modification.

Just my .02

 

He said the 91 octane tune because I straight up told him I know nothing. Also I thought these cars had the HD heavy duty version of that trans. Either way i'm coming into a nice chunk of money so 3 or 400 wont put any dent in that as i'm not really planning on going crazy with this car performance wise. I'm just being told this by the most reputable guy in Sacramento according to all his 5/5 reviews. He also has an impressive instagram. The cars he builds and works on mannnnnn.....

 

I only mentioned it because thats not a thing on these cars. He probably just got cars mixed up in his head.

They do have an HD trans, but its not really much different from a normal 4t65. The only major difference is a stronger diff (something that almost never breaks without direct abuse) and a different converter / drive ratio. All of the hard parts that fail at elevated power were left untouched. The LS4 cars do have one added benefit with a stronger chain, which while a definite upgrade doesn't address several other key issues.

IMO the trans is by far the #1 reason LS4 cars are as cheap as they are. The original owners often either got mad their trans broke at stock power or were afraid to have to change the trans if it did break so they let go of the car early. Things got worse as the stigma was so bad as the values dropped since very few wanted to take the risk buying one knowing they could have to put a trans in it that equaled the value of the whole car.

What makes it worse is that it doesn't even seem to matter if you beat on it either, there are numerous reports (myself included) of very premature trans issues even while taking it easy. To be honest, its not overly surprising in hindsight. Everyone knew for years that the HD was barely adequate for the L67 it came in for years and didn't have a lot of headroom for mods / hard use. When GM did a few minor tweaks and magically upped the torque rating 50 lb ft, we should've known things wouldn't end well in the long run.

I'm not at all criticizing the shop. Tuning a stock LS4 should be no problem for any tuner that does LS stuff.

I'm just saying that even with the best tuner, you're really not going to gain much: 10-15 is about it. If youre happy with that for the money spent, theres nothing wrong with that. Just didn't want you to expect some huge gains like some other platforms see.

Personally for more power, I'd rather put the money towards a cam or an intake manifold swap, but that's just my preference as I think there are better gains going that route. But if this is likely your last mod and you're not really wanting much more power, then a tune isn't a bad option.

 

The transmission was just rebuilt. I'll see what the numbers are before and after on Tuesday.

 

OK I'm a victim of the PG&E fires that happened in California I'm coming into over a $100000 so I can do whatever I want to my car. Do I want to do all that stuff to it and make it not street legal? No I want a driveable 13 second car. Is a guy with just The Mods I have done and a tune ran a 13.4 with him driving and tons of spin. I'm happy with that these cars aren't meant for much more without tons of $ and they are fwd. Probably selling it and getting a chevelle Nova or skylark but in the meantime I have $ to throw around. I never drive the car either so whatever. I'll see Tuesday.

 

My car was for sale in a classified section if you want to look at it it has a video and everything I should probably take it off though because it's not on the market anymore.

 

No offense intended, but unless it was rebuilt to a stronger level by a reputable 4t65 shop (like triple edge performance), you're still at risk of another failure. Just don't want you to have a false sense of security if it was just a rebuild to spec.

TBH, that stuff isn't necessarily any more or less street legal than a pcm tune. You're not going to get a CARB exemption # with a custom tune either. Id also be worried about CA's threats to verify against the stock tune for pcm modifications. It sounds impossible to me for them to pull off, but the fact that they'd even threaten it makes me think they may have a way to pull it off.

If anything, I'd think a manifold swap is less likely to get detected since it uses a different OEM LS manifold. The inspector would have to be pretty sharp to find the OPSU mod that indicates its not stock.

That's a really amazing time for those mods, I hope you get there too.

My GP with similar mods in PHX (so not an awful DA) ran 14 flat at 100-101. The mph certainly indicates it was capable of high 13s with a better tire. I only mention that because youre probably already very close or at to your goal - especially if you've got good tires / weather/ track conditions.

 

the guy said it will pass if it doesnt he will return it back for free

 

i'm not mechanically sharp enough on these engines to perform those mods