90 TBI to Tpi swap

[Slowrooster89]

My 1990 c2500 with 305/3l80 trans has took a ****. Was gonna replace with a 5.7 tpi engine (14093638) out of a Corvette. It's has the aluminum heads also which I've read I wouldn't be able to use my accessory brackets. I have the Vette harness and can get the ECM to match. Is converting the truck to Tpi gonna be a expensive nightmare or not so much? Or should I just slap my TBI intake on and run it normal? Just a Daily so not looking for high performance stuff.

 

[movietvet]

Welcome to the forum from Oregon.

My girl has the 1990 K2500 in my pic. I would never do what you are thinking. Lots of roadblocks and money spent. What do you do with the truck?

 

[Schurkey]

The TBI intake manifold won't bolt to the TPI aluminum heads without ovaling the center two bolt holes on each side, and using angled washers so the bolts don't break.

Swapping the TBI 305 to a TBI 350 is fairly straightforward as engine swaps go. 350 injectors, 350 knock sensor, 350/TH400 PROM in the computer. Swapping the TBI 305 to a TPI 350 is going to be more-complex.

If the trans took a dump, why change the engine? While anything can happen, the 3L80/TH400 is a supremely reliable transmission and very amenable to a DIY overhaul.

 

[Slowrooster89]

The engine took a dump not the trans. But

The TBI intake manifold won't bolt to the TPI aluminum heads without ovaling the center two bolt holes on each side, and using angled washers so the bolts don't break.

Swapping the TBI 305 to a TBI 350 is fairly straightforward as engine swaps go. 350 injectors, 350 knock sensor, 350/TH400 PROM in the computer. Swapping the TBI 305 to a TPI 350 is going to be more-complex.

If the trans took a dump, why change the engine? While anything can happen, the 3L80/TH400 is a supremely reliable transmission and very amenable to a DIY overhaul.

For right now just to get

 

[Slowrooster89]

The engine blew a head gasket. I have a L98 with aluminum heads that is factory Tpi. Just curious of what I'd have to do. I'm planning to swap my TBI intake onto it for now and maybe do the TPI later. I know about the bolt holes and that's no problem along with sensors.

 

[454C2500Longbed]

Paging @Komet
I believe he knows now a good amount about TPI and all that's involved for a swap. Granted, he had to convert his fuel system back to gas from a previous diesel conversion, but no less.

 

[Komet]

Uh oh I'm getting called out on my wacky stuff.

It would be best if you had the L98 Vette or F-Body accessory drive to go with the L98. I put TPI on an L31 and used the L31 accessory drive which has no provisions for front fuel feed and return, so I had to modify the fuel rails to feed and return from the back. I have heard First Fuel Injection will sell you off the shelf rails that will bolt on and do this. I also had to grind stuff in places until it all fit.

If you keep the L98 stock, the factory ecm should work pretty good, might have to delete VATS. Brian from Tuned Performance can get you hooked up with that. I used the FiTech Ultimate TPI setup since I was going full custom and needed a trans controller for the 4L60E anyway.

You'll also need to pull the tank and put a fuel pump in that can deliver 43.5psi. And you'll need the small cap divorced coil HEI distributor if you don't have that.

 

[Scooterwrench]

That stock TPI only makes power to about 4500 but great torque down low so that would be a big plus for a daily driver. I ran across a TPI intake and considered bolting it onto my 355 but after doing some research I realized it wasn't going to perform with the mods I've made to my motor. Should work great on a stocker. In my research I discovered that you can run this setup in speed density mode and batch fire the injectors with your existing ECM and some tuning.

 

[454C2500Longbed]

Uh oh I'm getting called out on my wacky stuff.

It would be best if you had the L98 Vette or F-Body accessory drive to go with the L98. I put TPI on an L31 and used the L31 accessory drive which has no provisions for front fuel feed and return, so I had to modify the fuel rails to feed and return from the back. I have heard First Fuel Injection will sell you off the shelf rails that will bolt on and do this. I also had to grind stuff in places until it all fit.

If you keep the L98 stock, the factory ecm should work pretty good, might have to delete VATS. Brian from Tuned Performance can get you hooked up with that. I used the FiTech Ultimate TPI setup since I was going full custom and needed a trans controller for the 4L60E anyway.

You'll also need to pull the tank and put a fuel pump in that can deliver 43.5psi. And you'll need the small cap divorced coil HEI distributor if you don't have that.

Wacky but cool. It's groovy to see something like that under the hood where it shouldn't exactly be.

 

[Scooterwrench]

Wacky but cool. It's groovy to see something like that under the hood where it shouldn't exactly be.

The factory TPI is a purdy thing to look at,shame it doesn't do more. I read where they bored the intake runners in the manifold and plenum and installed larger runner tubes and still it only made power to 5200. Kind of a potato in the pipe.