Bumping96: I have 814 fwhp. Yes I did consider a 4t80 when I started the project. The car itself would have needed to rework the firewall and the forward floor to make room to fit and I didnt want to cut up the car at that time and thinking back I should have. I thought I could bullet proof the trans. Not that I was wrong I just did not do enough. I found weak areas I will address them and it will be stronger than before. Biggest issue is lack of lubrication which will require machining and possibly some broached channels for oil flow in several areas. I used 1095 (extremely hard) thrust washers and destroyed them. I am going to try and broach in a larger thrust bearing which can handle both high torque, line pressure and even higher RPMs. Simply refreshing the trans by replacing the parts that broke would only result in the same problem. Breaking the same parts. Not this time. I am making structural changes. Improving oiling. Making some design changes. And upping the ante in part strength by making replacement parts that I can’t change out of superior strength metals or composites.

 

ATI, good suggestion. I will give them a call and advise.

 

Well it's almost Xmas....and the spares that go with it. You would love it.

 

Do you have a modified firewall / floor? I only ask because I've not heard of the wbodys having to cut up their body to make it fit. I know the 4t80 swap kit for the LS4 bumps the mounts forward an inch for the whole powertrain, but I thought that was only to get it from hitting the PS rack.

Do you have an internal case support for the rear of the input shaft area added like the ones triple edge used to do? I remember hearing about case strengthening due to flex of the input shaft relative to the output components.

If you figure out how to keep it together long term, you'd be an absolute hero with the 3800 crowd if you shared the mods / vendors used for the one off parts.

IMO people are being driven away from the platform like crazy these days because there are no readily available options to keep things together over 4-450whp. The GMR stuff has been discontinued so long now that its virtually impossible to get, and its discouraging to see people pay big money for those parts on the used market only to end up destroying them (this year one person broke their input shaft due to case flex and another person trashed a chain - a real problem when there are no viable replacements available). It seems like the people heavily invested in a GMR build are too afraid to push it / try for new records and risk destroying unobtainium parts.

I think thats whats given rise to all of the 4t80 swaps lately. Even on the 3800 side, there are road maps to easily make 550-650 whp without getting into crazy custom parts, but no off the shelf trans options anymore to reliably hold it.

 

ATI does not service the 4t65 -

 

Bumping 96 - as you know my car was built at a shop in Utah. I called my builder yesterday and went over the 4T80 again with him. And his response was what I expected and reiterated what he and I discussed when we first thought about the 4T80 swap. In my car with the engine compartment configuration we used - there was no room for forward movement, none - 1" forward would have put the headers touching the radiator. Moving the drive train forward was not an option also because the wheelbase would have changed and the front tires would no longer be in the stock position in the front wheel wells. The other option was cutting the firewall and floor and relocating everything attached to the firewall that had to be moved. He even mentioned that my pedals would have to be moved inward - and there was a good chance the whole dashboard and everything associated with it may have had to be moved. This thought was more than what I wanted to confront myself with. You mentioned the trans internal case support - I am trying to contact triple edge now to see if this is still available - would be a good addition to my trans.

My builder also mentioned in my power range there was a better possibility of making the 4T65 survive better than the options that were available for the 4T80 at that time.

Also if I remember correctly - there was a sponsored FWD Ecotech with 1100 HP that also had a 4T65 (I think) in it some years ago. Not sure who sponsored it but it did exist - it was a 4 cylinder .

 

Interesting issues with the 4t80. I know on Facebook, a guy by the name of Brandon Furches (aka LS4 King) is using the 4t80 on a couple Montes. He has a few YouTube videos about what needs done to mate it to a LS4 and and into the vehicle (a couple of his builds are turbo builds). He also sells a few custom parts to help with it. No mention of issues with the firewall. My guess is the difference is purely with how your turbo setup is built that creates the issues and the only way around that is re-building the headers to handle the 4t80, easier said than done in some cases. Here is a link to his swap kit if you wanted to peak at it:
https://www.ls4king.com/products/4t80e-swap-mount-kit/

But going back to the 4t65, as I understand, all the performance goodies for those have faded away. So if there is a source to rebuild your trans to continue holding that power, you have source a lot of people would be interested in.

 

Out of general curiosity, are you aware of anyone else keeping a 4t65 together at those power levels? I'm just wondering what is fueling your builders confidence that its feasible to get a reasonable life out of a 4t65.

IIRC the highest hp car I know of on the 4t65 was the zzp ttgt/single turbo that peaked at 870 (Id imagine with substantially less torque than you've got and likely lighter too as that thing was half tube chassis) and they broke it the next run from the 8.65 record pass.

AFAIK, at least from the people who publish numbers, the next car is just sub 700s - substantially less than what you're making.

That's very strange - as there's got to be more than a dozen w bodies out there right now with 4t80s - both 3800s and LS4s and no one has had to do that extremely level of cutting - moving pedals and dashboards, etc etc.

I am curious as Maniac mentioned- is it something specific about your turbo manifolds / turbo setup that makes the engine physically bigger than a LS4 with aftermarket headers?

Not trying to start an argument (or even say that a 4t80 is a magic cure to your problems), I just can't wrap my head around why your engine is so much wider to the point that hacking up the entire car is the only option to make it fit - especially since the 80 isn't really that much bigger than a 65.

I'll see if I can dig up a pic. I save all kinds of useless crap like that. I don't think it was ever a production item - IIRC it was something they were experimenting with right around the time the w body market fell apart and people quit seriously racing them.

You are right. The bad thing is that I've never seen anyone outside of that GM sponsored team come up with anywhere near similar results. I think there are a few reasons:

-Weight is a big issue as we've found guys with gutted cars tend to last longer than full weight cars. I couldn't find a weight on the final 1000+ hp version, but the 700 hp version was quoted in one article I found at 2700. Given they're full on race cars, I strongly suspect they're running at or near class minimum to stay competitive.

-Being a 4cyl vs a boosted 6 or 8, I do wonder how the peak torque and torque curve compares. I'm curious if the torque levels they were making were similar to zzp's record setting car (despite having more power and a much lighter car).

-They released a big writeup on the 4t65 GMR trans as a result of that, but it has one interesting note right up front - the modifications shown are not necessarily all that is needed to handle 1000+ hp. Really makes me wonder what else was done that wasn't mentioned to cause the inclusion of that note - especially after a dozen + pages discussing the various modifications.

-Having GMR direct support, I do wonder what was done on the electronics side as they mentioned nothing about control. I know it had 4th disabled, no TCC lockup, and manual control of the shift solenoids - but I wonder if GM did any wizardry with the torque management settings being they had unrestricted knowledge and access.

-They ran a much higher FDR than any street 4t65 Ive seen. I think the original car was 4:1, but I could've swore they went even steeper later on.

-They never did mention the success rate with it. I did find an article on the original ecotec where their initial goal was 700 hp and 25 full power passes between rebuilds on the engine. I never did see anything about how far they managed to push the trans between rebuilds - but back when people were setting 3800 1/4 mile records, it wasn't uncommon for people to rebuild after every season (if nothing else to ensure a minor failure didn't cause catastrophic damage due to debris).

 

There's a couple pics of the triple edge brace. If I remember right, the purpose was to try to reduce case flex because the input shaft was running out of parallel with the output components which was making the sprockets run uneven to each other - thus stretching the chain (a main failure point for the non 1" chains) and causing unnecessary wear.

 

Here's a pic of a GP with a 4t80 swap and a LS. Not sure if this specific one has the 1" forward mounts, but it appears from the picture that this has several inches of clearance to the body (and certainly not at risk of having to cut out the firewall/ relocate pedals, etc).