Guys, I've asked the folks at Summit and am awaiting a response but wanted to get your opinion. Do you think I can sway my FWD LS4 5.3L V8 to their LM7 5.3L V8 crate engine and still use a 4T65e transmission? Link below:

5.3L LM7 Crate Engine

Thoughts, or just a pipe dream??

 

No. The LS4 is the only LS engines with the FWD transmission bolt pattern. No other LS will bolt directly to the 4T65 transmission.

Beyond that, the LS4 is a special crank being shorter on both ends. That FWD bolt pattern also necessitates a smaller diameter flexplate. Lastly, the LS4 block is clearanced for the 4t65 output end (as thats where the starter would normally mount on a RWD LS).

Certainly every single one of those can be overcome with enough time and money, but it certainly wouldn't be worth the time for a basic crate engine like that.

Curious- why are you looking to replace your current LS4?

 

Bumpin, thanks for all the detailed information.

Why do I want to replace the LS4? So I don't necessarily want to replace the engine, but I'm trying to figure out a cost effective way to improve the power of my car. There just don't seem to be as many effective modifications to make to it to improve it's performance. Just flushed, changed the filter and new fluid in the trans and it started to slip a little, just a few times, from 1st to 2nd. I had a 2003 LS that had over 140,000 miles and never had a trans problem, but that only started at 180hp and if I added 30hp to it, it was a lot. The 2007 SS starting at 300hp and 120,000+ miles on it is probably not going to have the trans in good shape much longer. Now, I'm hoping that the trans will settle down after I drive it a little more, but if it doesn't, it'll have to rebuild or replace it. I figure that if I'm going to do that, I may as well upgrade it. And heck, adding some power to the engine to match an enhanced trans just sounds like a good idea.

The appeal of the crate motor was a relatively big boost in power for the money and ease if the LM7 swap was possible. Maybe I'm wrong, but upgrading the LS4 platform seems a bit challenging unless you've got lots of money and/or great mechanical skills. I lack both at this juncture, although I love to learn and get my hands dirty.

On my 2003 LS with the 3.4L engine, I did intake and exhaust related stuff only. Back then, I don't remember at home tuning tools, so I bought a junkyard PCM and had it flashed. For 3.4L without a power adder, and as my daily driver for 13 years, the car was phenomenal. I never got into the engine internals, again, due to my lack of confidence/skill and needing to make sure my only mode of transportation didn't get sidelined because of me monkeying with it.

I see a turbo kit available specifically for the LS4, but it looks a little daunting to install and much more expensive than the crate engine.

I'm completely open to suggestions to improve the HP of the LS4 that I can handle lol!!

 

Honestly its really no different than any other 5.3 LS for making power. NA power will always be somewhat limited on a SBE (sub 400whp?) due to the low displacement, although that can be overcome to some extent by spinning it higher. Boost is where it'll really shine and is how all of these 5.3 LS setups are getting to 1k+ wheel.

So I think its best to decide now which path you want to pursue before you start putting eggs in the wrong basket from the start.

If going the NA route, the best bang for the buck is the intake manifold. Sure there's a minor amount of custom work, but its otherwise a cheap mod as you're using undesirable stock manifolds from other LSs - like the LS2.

Next best mod is a cam. Install sucks due to FWD, but its proven to add really good power. You can also delete the DOD at the same time.

Somewhere in here (when done modding) needs to be a custom tune. This will make the new mods play nice with each other and pick up power on its own.

Headers seem to do OK, although they are pricey. I believe I've seen gains around 20/20 to the wheels on a stock car with the DTs.

Ported heads are an option beyond that, but they really need a pretty aggressive cam to show notable power gains. Ive seen one member pick up single digit whp when combined with a mild cam, so you've got to be a bit careful here to not flush money down the toilet. This is also a chance to shave them to bump the low compression if you've got the pump octane to handle it (or went with a bigger cam / lower DCR).

But to get deep into the 300s, you'll need to do most of these together.

Im sure its about dead. Plenty of stock LS4s (including myself) have broken stock transmissions even without severe use.

You'll definitely want to map out your path forward before you rebuild it. I agree though, if you want to do any mods, it needs to be upgraded beyond the basics. Id be careful though- if youre looking for major power improvements (like a turbo kit), its going to be an expensive route. Since the GMR parts were discontinued, its pretty much impossible to build a bullet proof 4t65 anymore. Thats why you'll see a lot of guys on the high end of the power spectrum playing with 4t80s to try to get some life out of it.

Just want to make sure you're 100% clear what you're getting yourself into with this transmission. It is absolutely not an easy road and is the #1 cause of people leaving wbody modding altogether.

I'm not sure which LM7 you were looking at, but you've got to be careful because aftermarket engine builder power #s don't have to be SAE certified like the OEM did. They'll dyno it with no accessories, a high end manifold, no emissions equipment and open long tube headers to get those absurd power numbers. When you bolt all of your engine accessories and exhaust back on (especially the intake), you'll make far less power than advertised.

I did see a $4k ATK LM7 crate on there, and frankly thats a downgrade for you. Its 0.5 lower compression and an iron block, all with stock heads. Literally the only upgrade that has for you is an aftermarket cam- which you could do to your own LS4. Thats also ignoring the thousands in machine work it would cost to even bolt it up. It also looks like its a 24x engine which would need a converter box to work with your 58x pcm (unless there's some way to back convert it on the pcm side).

The killer is the transmission here. You're probably $3k+ just into a good rebuild to make it hold a stock LS4. You're probably $5k to build the best of what's possible today for a 4t65. Start sourcing used GMR parts, and you can quickly push that close to $10k. Thats why some people have started playing with 4t80s - as their stock rating is much higher. But its also far from a drop in golden bullet.

Modding the engine isn't too expensive since its a LS. We're just limited to what parts we can and can't use with the FWD config. Dollar per hp isn't too bad for a NA engine (but of course is nowhere near as good as a factory boosted engine like a 3800 SC). But there certainly isn't much low hanging fruits on modern NA engines, especially ones already doing about 1 hp per CI.

If you were seriously considering an engine swap, then dont at all be worried by the difficulty of installing a turbo kit. Its not even on the same planet for complexity (and also is far easier than doing a cam swap going the NA route).

I'm not sure which crate you were looking at, but the ATK LM7 is $4k. $5500 isnt really that much more, and will make WAY more power. Honestly if you want anything 350+ whp, you should seriously consider this route.

The harder part is the stacking cost. $5k for a transmission + $5k for boost + all of the other odds an ends starts to get up there very quickly relative to the value of the car. IMO, thats why you don't see more LS4 modding (with the garbage stock transmission being the other leading cause).

 

I guess what I need to start with is saying what I plan on using the vehicle for. This is not a strip or autocross car. It's a weekend cruiser, a toy for me to have fun with. With that in mind, I want a vehicle that is not going to blow up when I take it out for a ride lol! But I do want to be able to stomp it a little or get on the highway and make it go. Not often, but when the bug hits I'd like it to be there.

So maybe I'm looking to only gain 50-100hp with reliability for years. Assuming the trans is pooped, and the weakest link, I got a quote of about $3-$3.5k to have a local shop rebuild stock. Hell, for that I'd get a Stage 2 Triple Edge. The website says this will hold up to 350whp on street tires. From what I've read and calculated, that's about 375-425hp at the crank. If I'm starting stock at ~300hp at the crank, then I would hope this trans would hold up for many years, especially with it only going out on the weekends during April-October, and even then only hitting it hard sporadically. So the trans is a sunk cost no matter what, and for just a little more can get something to support additional power.

The rest is now a little thinking out loud...

The attraction to the turbo kit at $5500 is cost per HP increase and ease of installation. No headers with this install, so that saves some money. Still need something like a custom or magnaflow exhaust. The potential power of this car could probably shred the transmission, but I'm thinking if I never really opened it up (or did so only a few times a year), the Stage 2 TEP transmission should be OK. Do you agree? Do you think I need to delete the DOD with the turbo kit, or would programming it off be enough?

Going the NA route, would definitely need to do the upgraded cam/DOD delete. That's $2k. Headers are $1.2k. Would probably also need to do an air intake-TB-manifold. If programming and exhaust from the headers back are equal for each setup, I'm probably looking at $4k for this versus $5.5k for the turbo. If that is the case, then for the extra $1.5k or so, it would make sense to turbo. Yes, modding the LS4 probably doesn't make the most sense if I was only worried about time and money versus the value of the car. But I love the car, and I plan on having it for a long, long time.

So let's say I go turbo. Is this sound like the right path:

Triple Edge Performance Stage 2 transmission $3.5k (need new/rebuilt trans now or in the near future no matter what)
Magnaflux or custom exhaust $1.2k
Cartuning Turbo Kit $5500
Programming; eliminate the DOD that way or add $2k for the upgraded cam + DOD delete?

Thoughts?

 

The key to that on this platform is the transmission. You're definitely on the right track with Triple Edge. Once you lock in a path forward on the engine, I'd email them/ give them a call and get their advice on a transmission.

If you're certain that's all you want, a cam + intake manifold + a tune should get you there on the cheapest route. Even a hotter factory cam has done + 20 whp alone; going with a better specd aftermarket cam whould yield even more. You could be into it for $1500 or less in engine mods. Youll just have to be careful to either spec a cam that works with the stock converter or get an aftermarket converter while the transmission is out thatll match it.

The other upside is that the resulting power will fall within TEP's off the shelf options, so you'll have more confidence in the transmission staying together.

You just have to be pretty careful in part selection as this isn't a 6.0/6.2/stroker. There are plenty of threads to browse on LS1tech in the LS4 sub forum to wrap your arms around what has and hasn't worked. One thread that stands out to me is the guy that spent $6k on a NA build with very high flow aftermarket heads and a stock cam out of a bigger LS, and only netted +18whp. But there are plenty of threads with good outcomes to learn from also.

You don't necessarily NEED exhaust with the turbo. It comes with an electric cutout that bolts right up to its downpipe. So you can have a nice quiet exhaust when you want, or open it up for more power + sound whenever you want.

That is an upside to that turbo kit - it really is everything you need for power in one box.

That is a definite worry. You probably noticed no transmissions listed over 350 whp, and that's partly because the GMR parts have been discontinued - especially the chain. If you get serious about this route, I'd call and talk to them to see what options they've got. There are plenty of people with huge power setups that never post on the forums- yet they get the feedback of what's breaking and whats not.

I will say that its not just power that kills transmissions at the higher levels - traction is another big piece. You're not going to be nearly as hard on transmissions with a street car on street tires as someone who's regularly running at the strip on slicks.

The other upside with a turbo is that you don't have to run it on kill all the time. You could absolutely turn the boost controller down, shave off 100 whp, and still be well over your target - and be able to crank it to kill mode with a simple spin of a dial.

But it would be good to bounce the question off them to be sure. They could tell you that you need to source at least a GMR chain to keep it together, which substantially drives up the cost.

Ugh... thats a tough one. Plenty of examples out there of DOD lifters failing that make me nervous to say for sure itd be ok. Also plenty of people with high mileage and no issues, so it is a bit of a crap shoot.

The one upside is it isn't generally catastrophic - the lifter just stops lifting. So you could just shut it off electronically for now, and deal with it if it happens down the road. I just think if you've got the cam out for any reason, I'd proactively address it.

Id skip the exhaust as it comes with a cutout. You could swap mufflers later if you want the 'closed' sound louder, but Id at least try it with the cutout first. Itll make max power with the cutout open anyways.

You also shouldn't need tuning if you only shut off DOD. CT should be able to do that for free when flashing your pcm as they have to load a tune for the turbo anyways.

Big question is the transmission going that route- if TEP says you need to source used GMR parts for them to build one string enough, it could practically double the price.

 

Everything you said makes perfect sense.

I've downloaded the Cartuning turbo kit manual and will review 2-3 times. I reached out to Dave @ Triple Edge last week regarding the transmission, but now looks like I'm going to ask a different or additional questions.

No exhaust for now, great suggestion. Let's see how the first things turn out.

I'll probably ask both Cartuning and Brandon at LS King what they're thoughts are on the DOD delete, programming it off, or leaving as is. I'm going to have to make that decision prior to having the Cartuning kit sent, or at least before they flash new PCM/TCM. I'll look to keep the boost turned down so it only gains that 100hp or so. Like you said, I can always turn up later.

By the way, is it going to make sense to get something like a HP Tuner in order to make adjustments once this kit is in? If I start with low boost and want to increase, would that require a new tune. What about going from stock exhaust to open? If nothing else changes, same tune? I'll ask same questions from Cartuning.

It's going to be some research, and I don't mind taking it slow. Two weekends ago I did the suspension upgrades and probably have to tweak that. This weekend, plan is for new brakes.

Thanks again, I'll post with additional comments or if I have any questions. You've been a HUGE help!!!

 

IMO, I'd at least turn it off in the tune regardless which path you end up taking. With any exhaust (especially a cutout), it is extremely annoying when it kicks in. I had a cutout on my LS4 GP and it literally sounds like a 2 blade helicopter coming in for a landing when it engages. Even though its running on 4 cylinders, it doesn't sound like any 4 cylinder I've ever heard (and not in a good way).

IMO, I wouldnt bother with either route. Unless you plan to keep modding it in the future, I'd just do your round of mods in one shot and have it tuned to match (either a local dyno tune if NA or just using the CT tune with a turbo). Just an awful lot of expense (particularly the huge time investment) if this is a one and done kind of thing.

Nothing should change once dialed in. The engine has a MAF and MAP sensor so it can adjust fueling based on the airflow its seeing. The big thing is getting those tables updated to match the new mods so the pcm knows how much fuel the engine actually needs when it sees X airflow / pressure.

Not to push you away from this forum, but I'd also poke around LS1Tech in the LS4 sub forum. Thats by far the biggest group of LS4 cars on the web that I know of, and theres a huge amount of historical info to look at.

 

Bumpin', thanks again for the advice. I've been scouring the LS1Tech forum and communicating with a few from the LS4 sub. Some more good people and information! Appreciate it!

I also spoke with Dave @ Triple Edge and he referred me to a tuner in Texas (James Brewer) that really new our FWD LS4 cars. James gave me some great advice and has also referred me to a shop he does work with a couple hours away from me in Virginia. Eventually, with enough knowledgeable support, I'll get something done. Or everyone will convince me that it's not cost effective to modify my Monte and I'll just be happy to keep it fairly stock lol!!

 

You're welcome - thats good to hear you're linked up with some of the true experts on the platform. If nothing else, at least you'll have the best knowledge there is available before diving in. You're certainly taking the ideal approach to gather all of the info on the various options first.

I probably shouldn't be so vocal about mentioning that up front; it's probably scaring some people away from modding at all. Just makes me nervous when people start talking about higher power builds (which isn't nearly as hard to do with the LS) given the sad state of aftermarket on the 4t65 these days.

I was really hoping ZZP would pick up the ball on a GMR 1" chain replacement. I know their focus isn't transmission stuff, but they've brought a few transmission parts to market in the past and have made some big development investments on the 3800 side (including the fairly recent equalizer headers). You'd think if nothing else, it would help them sell more 3800 performance products if they had a solution to make 4t65s hold big power again reliably - especially since they still sell 3800 turbo kits.

At this point, I'm starting to think the ideal situation would be for a place (like triple edge) to start offering drop in 4t80 kits. Those transmissions have proven to hold some extreme power levels even completely stock. But the average user doesn't want to have to deal with figuring out all of the nuances to make it work. While the allure of $200 junkyard race transmissions sounds great, most people don't want to deal with going through all the effort only to find out the one they picked is a dud right out of the gate.

Would be nice for a place to pick the most widely compatible version - stock up on a bunch of them (as theyre still fairly ubiquitous in junkyards), do a basic rebuild so you know its good. Then supply the mounts / axles, wiring adapters (to fix the shift logic). And finally offer a mail in tune to flash the correct settings.

I'd bet you'd see w body performance modding start to pick up again - especially if they campaigned it with a 500+ whp 3800 or ls4 at the drag strip to show what it can do.