https://www.amazon.com/Innovative-Pe...te+carlo&psc=1

Seems to good to be true for the price, but it's about what I can afford....

 

As you could probably tell by the poor reviews, it's a waste of money. There are only 3 routes I would suggest for pcm tuning:
-taking your car to an LS shop and have them do a custom tune for your setup. This is the most expensive method but will yield the best results.
-buy HP Tuners and learn to tune yourself. This will cost more than option 1, and will likely take much longer as the learning curve is steep. Plus the end result probably won't e as good. The upside is that in the long term, you'll improve your tuning skill and will be able to tune and retune for new mods for free. The downside is that you could ruin the engine, trans, or both.
-send your pcm/tcm in for a reflash from a major vendor on this platform. This is the most cost effective method, but also provides the least results as it isn't customized for your vehicle.

That last option is only about $100-150. I wouldn't bother with options less than that as they're typically gimmicks or provide little benefit.

 

If that's only about what you can afford, I wouldn't bother modifying, and just enjoying what you have.

It's better to get some savings into an account for an emergency if something breaks.

With that said, Chad gave you some great advice as to tuning the car. However, if this is for your 07 Monte Carlo SS, then there are actually a few more options than he has listed.

Check out all of the options that Will @ Overkill offers: :: Overkill Motorsports ::

There are a few options for handheld tuners that you can purchase, and it could potentially be a little cheaper than a dyno tune or HPtuners, but still offer some customization.

Will has helped me tune a few of my cars now, he's been great to work with.

 

That's really good advice. I think with any LS4 car, you should have a few grand ready for a trans rebuild when it does finally come apart. Certainly some people have great luck, but the odds aren't good.

Good point with the handheld tuners. I remembered Overkill did stuff like that but wasn't sure how picky this forum was on posting links to non-sponsors (or maybe he is a sponsor and I just didn't realize it).


One other thing to consider with modifying the pcm- there is only so much you can do to help a stockish engine. If you intend to do more mods in the future (intake, headers, cam, etc), you may want to hold off and get it tuned after those mods. Certainly there is some power to be gained stock, but it isn't much.

 

Why does the tranny typically come apart? I had the same one in my GTP, and I never had a second's trouble with it. (I also drove the GTP much more aggressively, because it actually had acceleration, which this doesn't, which is why I keep looking for help with it.)

 

300 HP is pretty much the limit on the 4t65e, and GM didn't go with the 4t80e like the Bonneville, for some reason (probably the cost).

They are just notoriously the weak link in these w-body cars. Some people have good luck, some people have bad luck, but the majority of people don't get very far past 150,000 miles on the original trans.

 

Then I guess I've had good luck as I'm at 155K, and the only problem I have (as detailed here) is a slow and undetectable fluid leak, which was "fixed" for a quart of fluid.

Next question--if cost control was the issue, why did they go with the HD version of the tranny, if it doesn't help anyway? Having come off 3 miserable (as if there were any other kind) 4T60E's, I was so happy with the 65 in the GTP, when I got my Aurora, I actually looked into upgrading it to the HD. Turns out the only diffferences are the torque converter and the differential. (And no, no serious problems in the Aurora either, aside from an occasional unhappy 1-2 shift.)

 

Because the LS4 really pushes the limits of the stock 4t65 design. Keep in mind that this transmission was intended to be used behind the midsize fwd cars and is generally just an evolution of the old 4t60 layout from the mid 90s. It was also officially rated at only 280 lb ft (ie 45 lb ft less than the LS4 makes) until the LS4 came along and they made some tiny changes to up that number to magically match.

The 4t80 was really the transmission intended for the big cars with higher torque engines, it just wasn't in the cards for this platform.

In my opinion a gtp, especially an L67 doesn't push the transmission nearly as hard as the ls4. Wide open, the ls4 has about 60 more hp, but more importantly is about 45 more lb ft of torque in a transmission that already didn't have particularly high design margin to start with. Not to mention that off boost driving in an L67 (or most of the time you're driving), it will be considerably down on power and torque from an ls4 because it's an extremely low compression engine with a lot less displacement.

 

On the original, non-rebuilt trans? If so, that's really good for an ls4 car. Maybe the car being so far down on power is helping keep it alive? As I'm sure you've heard before in other threads, you really need to have the money ready for a rebuild if you plan to keep it long term. Even on low powered cars, you're getting close to just wearing the thing out on any 4t65.

Im not sure where you heard that the HD version doesnt help in any way, but it's not accurate. There are in fact strengthened parts in the HD transmission, they just happen to not be the parts that people typically break when getting into drag racing. That is why they aren't much of a sought after mod. There are also more differences outside of the torque converter and differential, but they're pretty minor. Actually, the ls4 transmissions do have some other minor design changes as well from the normal 4t65hd, but they're also relatively minor in the grand scheme.

I guess the hard part as auto enthusiasts is that we would expect an "HD" transmission to be able to withstand us racing the car and doing all sorts of upgrades. Unfortunately the let down here is that it just isn't the case. You can certainly build one with aftermarket parts to be nearly bullet proof at much higher power levels, but pushing it that far beyond the design envelope means the days of going 100k+ miles without worry are gone. But I'm sure GM knew that the number of people modding and racing their 4t65 cars was going to be an incredibly small percent of the total population.

You mention cost savings of using a regular 65 vs an HD version, but the engineering work and tooling has been done on that long ago. The delta cost of the parts to GM is virtually nothing in the grand scheme, and the HD is indeed a small upgrade.

What should've happened to keep the 4t65 happy long term was a moderate redesign of the transmission to increase design margin on all of the components. Of course, GM would never sign up to do that- the 4 speed auto was already dead at that point so they would never have poured any real money into upgrading it for the future. Once their calculated cost of fixes and replacements within the warranty period came down below the cost to engineer additional changes, they probably stopped there and called it good enough. Just not worth the effort for a relatively low volume run with no long term benefits.

 

Which is what I thought I actually had at first, for exactly that reason. So I guess my question is, wouldn't it make financial sense (even given that the electronics will need modification) to just swap in an 80, instead of rebuilding a 65? I don't have $3K for a rebuild, nor am I likely to in the near future.