4T65E to 4T80E Swap | GM 3800 | GTP | Details and Pictures

Swap details on what goes on to get a 4T80e to fit into a W-Body (GTP) 3800 combination. This is a 1998 Grand Prix 3800 supercharged car. It has the external range switch (neutral safety switch). With the large number of cheap cores one would think this swap would be more popular. If you are willing to put in the effort it works just fine and is cheap alternative to obsolete used GM Racing parts.
No cutting of the chassis harness was required. A jumper harness was made using some of the guidelines of LS4 King. This is not an LS4 car so I had to do a little verification to understand if this could work ahead of doing this swap.
Nobody produces the mounts for this swap. The swap is a bunch of fab work and welding. It is not that hard to do with a grinder and entry level welder. The transmission is a 2005, 3.11 gears, and without the internal manifold switch - this is easy to add if you want to add it in. Drill the valve body - it is spot faced but not drilled from the factory and mount your switch, pin in the wires. The transmission will not shift without using HP Tuners to adjust the ratio. edit- I did have success after looking into the tune again- the input tooth count was never changed.
Drive sprocket ratio - 1:1
Input pulses / rev - 39
Output pulses / mile - 23434 (for 3.11 diff)
Factory Cadillac axles fit the factory spindles on the W-Body. A boss on the engine bellhousing needs to be cut off the engine to make it made together. The driveline needs to be ~ 1 inch forward to make this fit on the subframe. I used a Bonneville (H-Body) front mount and a 4L80e energy suspension mount on the side.
/ @ls4king
Willing to answer any questions and comments.

[@josephnowak]

I found an error in my trans tune. Correcting input tooth count from 25 to 39 allowed tcc to work with pcm command. It also allowed shift adapts to work curing firm shifts durring normal cruising.

[@Turbocharged400sbc]

The Whippled Riviera I did back in 2012 has that in its last pcm file, remember folks ya need to change the gear ratios for each gear if the pcm sees a ratio disparity it will change adaptives. I don't know if hp does but tiny does it. Sprocket ratio should also be 1:1 I've seen odd numbers from some 4t80e swaps lately, mostly seems to be hp folks. 3.11,3.48,3.71 are your Final Drive ratio. You still need to change each gears ratio as they differ. You can use the internal mode switch and wire it to the ext rage wiring. All logic outputs correlate

[@jruzich43]

Going to pick up a 4T80E this week for my build. Always good to see another video come out on this swap to save for later viewing!

[@asotelo2715]

This is Amazing man! Thank you for putting this video out, I’m going to take it as a sign lol I’ve built boosted cars before but they are something i couldn’t afford to build now. I’ve been researching the 3800 and i like the fact that it’s something different and with a lot of potential. I kept finding that the weak links are the transmissions but this changes the game! I have kids now and i think a unsuspecting 4 door car thats boosted would be fun. I see gtps for about 1000 bucks with blown transmissions in my area. This combo could make for a really cool project that wont break the bank for us dads that still want to have fun. Thanks again!

[@w41duvernay]

3.11 gear ratio? The 95 STS trannies had 3.73 posi in them.

[@Casey_and_Cars]

Finally seeing this, makes me so happy. Great work man.

[@josephnowak]

Thank you for commenting.

[@MXZ1983]

Very informative! Great vid!

[@00grandprixgtp]

Man thats cool cant wait to start mine

[@arturozarate1752]

I haven't watched this yet, but I use to pull these monsters out of Cadillacs in the early 2000's for a dealer in San Antonio. That was on a lift! Damn dude.....on the ground d.

[@jplperformance9073]

Very cool video, thanks

[@brandonnicholls6686]

Lockup using a floor mounted headlight switch is a great idea!

[@civicsr2cool]

Performance shift button would be even better!

[@arturozarate1752]

Wow, this takes me way back. For my first car, my choice was narrowed down between a GTP or Thunderbird SC. Good job on that swap.

[@MiladKiani]

Very good session ��🦮

[@chaad44]

Sounds good

[@jplperformance9073]

Very cool video

[@josephnowak]

Thanks for watching!

[@user-oj8xk6kz2u]

Wow

[@RichardDumas-qv6dm]

BRO I REALLY MISS MY 2006 SUPERCHARGED CAR. I GAVE 2000.00 FOR IT WITH 123000 MILES ON IT, I PAINTED THE WHEELS ...I DID A LOT TO IT THEN MY GIRL AT THAT TIME TOOK MY CAR RAN IT IN A DITCH BLOWING THISE PASS SIDE TIRES AND RUINING THE WHEELS I JUST PAINTED, YOU CAN SE IT ON SALEM DOYLE 1500 SUBS, TELL ME WHAT YOU THINK ABOUT IT BRO, KEEP ON KEEPING ON BRO!!!

[@mrmr1532]

Is there a sort of write up for this swap process? I have an 03’ Monte Carlo SS that I plan to top swap and build, and I don’t feel like dumping a ton of money into a built 4t65e that could nuke upon its first launch. Let me know, thanks!

[@josephnowak]

Chicago garage has a bunch of info in one spot. It is probably imo the best one. Its a known enough subject by now theres a bunch of fragmented infomation out there. I used ls4 king for some of the wiring and all data. Lots of work but worth it. I have also tried to answer comments completely for everyone as well

[@calvincrews3885]

Great job building a customized Pontiac Grand Am or Grand Prix

[@LakeshaHaywood]

I have a 1992 Pontiac Bonneville and im tryna build. Engine already rebuild head gasket replaced. Everything. But im just trying get more torque power what do i need to two do?

[@josephnowak]

I am not as familiar with the series 1 3800 which i assume your bonne has. Id look into the supercharged setup that would of came with the bonneville ssei models

[@DailyDriver.]

How strong can these trans be? Can they be built to handle a ton or power or just like 350wheel

[@josephnowak]

They are becoming more fequently used by turbo guys well beyond 350 wheel with stock internals. The advantage of doing the swap is the cost avoidance of the used high cost (discontinued) gmr parts. Gmr chain and gear set, input shaft and diff are thousands of dollars. A couple hundred bucks you have a working 80e core. The internet will tell me that an 80e on a supercharged setup is an overkill and not necessary. The cheap 7/8 conversion chain setups stretch and break in stock supercharged +e85 setups, seen it many times first hand and on tear downs

[@whatluck1508]

What kind of cv axles did you use?

[@josephnowak]

I used 661172 and 661327 cardone axles. They come out of a factory application.

[@Turbocharged400sbc]

Good more of you are finally seeing the 4t80e as our best option... You invert shift solenoid b with electromechanical or through the bin file? Tcc is easiest with a std tcc conversion system like those used with old school th350 to 700r4 retrofits

[@josephnowak]

I did the solenoid method. I didnt know of the other way at the time. Maybe in the future il get rid of the solenoid. So far works good

[@Turbocharged400sbc]

@@josephnowak Yeah, I used a small normally closed Solid state relay to trigger a 10 amp normally open solid state relay as my faster option to a NC wired 5 pin relay to invert the shift logic for solenoid b. I believe that grounding the 4t65e t c c switch in the PSM and disabling the code May allow me to use the 65e p c m to control the 4t80e tcc without an external work. I haven't gotten to test that method yet but I have high hopes.

[@josephnowak]

Im interested in trying to get it to work. I took the vb off and and drilled the holes for a pressure manifold switch and adapted the harness but that didnt satisfy enough of the logic. Or at least it didnt make it work.

[@Turbocharged400sbc]

@@josephnowak The 4t80E never had a tcc psm switch, youkinda have to use a hobbs switch plumbed internally to the tcc pressure or exhaust.

[@Turbocharged400sbc]

@@josephnowak I plan on trying to just ground the 65e tcc psm switch wire m try Mt ext or tu ne for any solution. Hobbs switch internal is next after lol

[@vile001r]

Which starter are you using ?

[@josephnowak]

Factory starter for a 3800 from O reilys

[@Tokio_Tsu]

will the 4T80E work with the TapShift in the ls4 pontiac gtp?

[@josephnowak]

I am not sure on the ls4 tapshift. I know ls4 king has a lot of information on making these work on a ls4 car. His channel is what got me most of the information to get it to work behind a 3800

[@torreypires6192]

I been wanting to this for years I need to do this to a 05 impala I found a 4t80e 2000 will it work on my 3800 la?

[@josephnowak]

Yes its doable. The 2000 trans is a little different from the 2005 that I have. The car is a little different than my 1998. Ls4king part 3 video goes into some of the controls, Very similar to 3800.

[@OmarLuevanos]

What oil pan did you use?

[@josephnowak]

Factory stamped steel 4t80e pan

[@hoover274able]

Hey I have a 2005 Buck Century 3100….I was told that I have to get a transmission out the same car that I have(I thought that all Buick 3100 1997-2005 would be the same would you be able to tell me the difference) thanks a lot ……love your video 💪🏿

[@josephnowak]

Big difference is the neutral safety switch on the early ones are on top and on the outside of the transmission. The later ones have the switch inside of the trans. 2004 2005 will have it on the inside. The later ones also had different type of solenoids if i recall correctly.

[@hoover274able]

@@josephnowak ok thanks man that was very helpful…..I have another question what can I do to make my 3100 more powerful….i really wish they would have put a 3800 in the Buick Century’s

[@josephnowak]

Unfortunately there isnt really an aftermarket for the 3.1/3.4 engines platform. Good engine, but just no easy mods available.

[@whaddayawant2197]

Could you give a bit of detail/tips on how you lifted your car to remove your engine/tranny. Looks like your a true diy and dont have acess to a lift like 90% of us shady tree mechanics

[@josephnowak]

The shadow of the car is blocking the ramps i used under the rear tires. Use normal ramps - jack the rear up and slide them under each rear tire. I used an engine hoist to lift the car by the metal bumper. Theres a strap looped around the bumper - bumper cover can be removed for easier access. Theres a harbor freight furniture dolly underneath the engine / transmission. I set the car lightly (dont put full weight of car on dolly, engine oil pan barely needs to touch) on this before removing the subframe bolts. disconnect strut bolts, exhaust, tranny lines, electrical connectors, and steering from the knuckle. I may have missed some stuff but its doable on a smooth flat surface. Dont put your hands in there while the car is up. Pull it out from the side and i lower the car back down when everything is out, on jack stands.

[@whaddayawant2197]

@josephnowak thanks! I had looked into getting a tilting car lift.. but that looks even sketchyer. I think an engine lift would be better

[@alexsimz5933]

Pilow switch on the newer transmission did you hook up those wires

[@josephnowak]

The external switch i transfered from the original 65e. I ground 2 flats on the 80e shaft and repositioned the switch. Made some small tab brackets to hold the switch in place. Didnt have to extend factory wires.

[@josephnowak]

I havent heard the term pillow switch before. I have the manifold pressure switch wired in.

[@alexsimz5933]

So you just matched up the 2 wires on the 4t80e TFP switch with the gtp 5 wires on the TFP. Think only 2 match rest did what leave it?

[@josephnowak]

I ran into this. I was told that to hook up what is available. For a while i drove w the 2005+ switch and through the course of debugging i had pulled the vb off and drilled the remaining holes to adapt the earlier switch. I grabbed a switch plug from a 4l60e and wired it in to where i thought that 3rd wire would go. Long story short a i never changed the input count in my file. Once i changed that everything worked. Although i havent tried it, i believe if my cal was correct from the beginning i would of not had to adapt to the earlier switch.

[@alexsimz5933]

Oh ok cool. I thought it would work as is with Just the 2 wires trail and error. Long as everything else is hooked up it should.

[@Marc_Wolfe]

I'm hoping to get a 4T80E and a 3.9 or 3.5 to throw in some random vehicle.

[@OldSchoolZ-wy2yx]

I wish that combo would fit in my '88 Cavalier Z24

[@Marc_Wolfe]

bet it would.

[@JisINSANE3]

I been hearing alot of stuff that my series III l32 engine I just got with a 4t65e won't work on my series II L67 and transmission pull cause its different. The engine will work but not the transmission. Seeing this video I don't believe it.

[@josephnowak]

The changover year on the transmission for the 4t65 is 2003/2004 ish. Valve body electronics are different. Never tried to get that to work before. Might require some research to get them to work

[@JisINSANE3]

@@josephnowak Found out its from a 05 grandprix. How different is the 04 impala SS HD from this one I have no idea. I may just use it.

[@josephnowak]

As long as the gear ratios are the same. If ones a comp g and the other isnt then thats a problem.

[@Turbocharged400sbc]

Just swap in the HD diff as the gp is probably a 3.05 fdr non hd diff

[@58_sos]

i live in kenosha wisconsin could this possibly for sale

[@josephnowak]

No its not for sale

[@robertrpenny]

Shifts sound firmer than a stock car. Wouldn't it be easier to just upgrade the 4t65 with better internal parts?😊

[@josephnowak]

Thanks for your comment. I think the thing i didnt explain is that there is no shift kit available for the 80e, so you have to make your own. The feed holes for 2nd and 3rd are drilled out. It would probably be tamer w just an unmodded separator plate. One of the key pieces to making a 65e live is a gmr (gm racing) gear and chainset which you do not need for an 80e. Used they go between 2500 and 3500 dollars, its a discontinued item. Even then, a buddy of mine broke a used chainset on 18psi turbo car. The car was leaned on a lot but still.... Thats a lot of working jy 80e transmissions.

[@robertrpenny]

Thanks JN. Seems to me that if you want over 300 hp it makes more sense to get a RWD car. The later GTO's were about the size of your car and had essentially Corvette running gear. So way less cutting, hacking, and custom fab work involved to get any hp number you want. But i appreciate your motivation.@@josephnowak

[@robertrpenny]

I guess the 4T80's are cheap since nobody is looking for them or know they exist. But if a 4L80 hits a salvage yard it is gone before its cold.

[@josephnowak]

Typical working core is 200 to 300 last i checked. It depends on what your working on or trying to do. The rwd stuff can get expensive too but there is potential to be faster. With this setup i just want to be able take it out and not worry about immediately breaking. Im a big fan of rear wheel drive stuff too

[@Turbocharged400sbc]

Tried for a 10-second slip....shredded 11 4t65e's even with 9k$ in the trans (gmr/billet everything) 4t65e sucks

[@Sneakerspolitics]

You got a ig ?

[@josephnowak]

Roaches2racecars