Hello, everybody Im new to this site and I own a 1991 firebird with a basic 3.1L engine. I really want to keep the v6 in and make a nice street racer to go after some of these imports. Over the past year or so the motor has been out and has been striped and bored. Now im finding out that theres not really much that I can do to get the power out of it that I want to get. I really wanted to do a twin turbo set up.

Im thinking now that it would be pretty cool to get that 1989 3.8L turbo engine in the car and maybe convert it to a twin turbo down the road. I didn't really see any other threads on here about this topic. Can anyone help me out. what is the first thing that I would need to do besides finding the engine ofcourse which im sure will be fun. What parts will I need to change and get, like the computer wireing harness, etc. I also would like to convert the tranny to a standard. Any info. on that?

 

Welcome aboard thirdgen.org.

It isn't often discussed on the BB, but it is available from the homepage FAQ section https://www.thirdgen.org/buick-3.8L-...ne-swap-f-body

 

Welcome I just did the swap over the last few months to my 1990 Firebird w/ a 3.1L V6. It is a fairly easy swap to do if you know how to turn a wrench and read wiring schematics. Besides the engine, you'll need;

BOP Transmission(or Chevy Trans w/ adapter, stock GN trans was a 2004r)
GN, TTA, or custom engine wiring harness
GN or TTA ECM
Custom length driveshaft(almost a guarantee unless you switch to a 2004r)
Trans Crossmember to fit new tranny
TTA Frame Pads & engine mounts
TTA Radiator Hoses (rock auto.com)
GN or TTA Intercooler(or FMIC if you choose)
Hot and cold side piping
Custom downpipe(or TTA style if you use the TTA heads which are FWD 86-90 Lesabre heads)


If you use the buick 8445 GN heads you'll need to either clearance the factory AC box, delete it or get a 1LE heater box. If you choose to use AC you'll need TTA or custom AC lines.

There is alot more stuff to buy as well, like patience!! Good luck

 

Welcome to the comunity!

I'm in the process of doing that very swap. What I have done is use a BOP (buick, old pontiac) to Chevy Trans adaptor (I ended up having to get a different tranny anyway becuase of the messed up bell housing bolt pattern on the 2.8L 700R4). I did not use a different tranny cross member, I just relocated the motor mounts on the frame. A brake line had to be rerouted to acommodate the change. Standard Grand National headers will work if you are using the GN heads. An AC delete plate is needed to clear the GN heads. I used a stock GN down pipe by cutting the last bend off the bottom, and turning it 90 degrees the rewelding it. A custom pipe was bent to connect the down pipe with the Catalytic Converter. Any exhaust shop can do it. I recommend welding on a flange so the down pipe can easily be removed in the future.
You will also need the GN heater control valve if you plan on keeping your heater.
Other mods you might want to consider is a remote mount oil filter (Available from Precision Turbo), a FMIC (front mount intercooler), and a big a$$ set of tires for all the tourque that you'll be making!!
Wiring is probably the most difficult and time consuming part of the swap. Thats where I am in my swap now. Finding a used GN harness or even a new aftermarket one will make the job easier, however, any way you do it there will be a certain amount of splicing in to the old harness to make everything work so keep the old one until you are done.

Anyway, good luck with your project and keep us informed of your progress

 

hello, thanks for the info. do you know what the casting number and vin number is for the buick lesabre heads? what do I do about the intake manifold and fuel injection system? what do I use for a computer and wireing just reg. GN parts? can you buy any of these parts new from the dealer for the tta?

 

Nope sry . we've all figured out that alot of the thirdgen parts have been
discontinue by GM, and the TTA and GN are rare cars. Hawks and evil-bay (ebay) sells used parts, local junkyards. Everytime I go to a GM dealer for a part for my RS its always discontinue makes me want to cry. I can barely get my hands on a VATS key, takes a week to get in

 

this all seems very interesting, and props for doing it in a thirdgen....but why a v6?

why not do the same with a v8; you start off with more CUBIC INCHES?

 

Most of us Buick guys are hard of hearing, or just obstinent. We like the Grand National power and the third gen handling package. It was just made to go together.

As for Lesabre Heads, you need vin code "c" engine from 1988-1991. Any GM car with this engine vin in those years are the heads you need. They will bolt to the grand national or Turbo Trans AM intake manifold. Make sure you get the matching valve covers with the heads. If you run these heads you will not have to mess with the heater box. The wrecking yard is full of these cars so you will not have to look too hard.

Good luck!

 

did you just put the entire engine from a GN in or did you have to change some things? what should I do about heads? I want to keep the ac


----------
yes id agree I think that the buick v6 and the f-body is a perfect combo from what i hear. what should i use for the intake manifold, computer and wireing harness?

 

You should use a GN intake. The Computer is the same for the 87 GN or the TTA. You can still get them from auto parts stores. You will need a GN or TTA harness.

You can run a rear wheel drive Buick V6 front accessory drive and keep all of your accessories. You can also get a lot of help from turbobuick.com. They have some people there who have done this swap in Camaros and Firebirds.

So, first you need an engine. Get a 3.8 or 4.1 V6 from 1981-1987 rear wheel drive. This will most likely come from a Buick Regal or Olds Cutlass. There are lots of them out there. Keep the block, front accessory drive, motor mounts.

Next, get your junkyard 88 Buick lesabre heads. Then you have to eBay or whatever to get your GN fuel injection intake. You'll need GN headers.

That should get you started.

Oh, you also need a new transmission. Easiest is to get a V8 700r4 and put a Buick to Chevy adapter on it.

Have fun!

 

i personaly feel that if u dont have a turbo TA or a grand national; its a waste of time and money...

but, no offense intended: to each him own!

 

Hello...

You can use the GN heads. You'll need to do some fiberglass work on the A/C box but that's no biggie. All the GN parts will fit. I've done several 82-92 F-bodys with the GN engine.

The TTA stuff is a pain. They only made 1500 or so of those cars. Not easy finding headers/downpipe ect.
E-mail me for details and pic's of my setup.
Here's a engine bay pic.
~~Scott