LS4 in Reatta?

[ReattaTType]

I am looking to put an LS4 in my 1990 Reatta as the 3800 is not in great order as it was neglected for the past 4 years. For now, the car is going to be stripped down fully, 3800 will be gone and I would like to put an LS4 in to be more original swap than the usual 3800 SC. Anybody know if it will fit for sure with the transmission from the Impala SS for example. What else what I need from the donor car and the Reatta. Thanks.

[Guest Greg Ross]

You're going to install an LS4 V8 and 4T65-E HD FWD?

ECM and BCM will have to go since they are not readily adaptable to managing a V-8 or this later generation transmission. Engine and Tranny management would I think have to be the current type PCM (next generation combined ECM/ BCM) Means you have to get an extraordinary amount of programming done to get the Reatta vehicle systems to communicate.

Practical-I don't think so. Would the engine and transmission fit? Probably, but then that's the easy part.

But it would definitely be original compared to the "ususal 3800 SC", whatever that is.

[Barney Eaton]

That's like asking what you need for open heart surgury besides scalpel and anesthesia.

[Guest F14CRAZY]

I suppose you could figure out how to run the stock Reatta ECM too to retain instrumentation as was done with the N* swap

[Ronnie]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hndblt88</div><div class="ubbcode-body"> I am looking to put an LS4 in my 1990 Reatta as the 3800 is not in great order as it was neglected for the past 4 years. For now, the car is going to be stripped down fully, 3800 will be gone and I would like to put an LS4 in to be more original swap than the usual 3800 SC. Anybody know if it will fit for sure with the transmission from the Impala SS for example. What else what I need from the donor car and the Reatta. Thanks. </div></div>

With enough time and enough money almost anything can be accomplished. I suspect you will need a lot of both. Will the effort be worth it? I doubt it.

[D-a-n-i-e-l]

You may want to just buy a vett rolling undercarage and put the Reatta body on it. There is a lot to do or attempt to do this swap. As stated earlier you will have to piggyback a different ECM. Doing this you will lose much of the TCC. There was a northstar swap done. There is an earlier thread on it with the web site of the company that did it. If yo are serious about this swap I would go with a 90/91. I truely believe that the TCC is the heart of the 88/89s and hav went to great lengths in my upgrades to keep mine.

Now if I were you I would pick an engine or at least managment system from a OBD1 vehicle this way you could make many of the sensors preform correctly withthe stock BCM and ECM. You would still have to run a piggy back ECM but would retain much of the TCC ect.

[ReattaTType]

I have a 1988 Reatta as well which is staying stock. The 1990 was neglected by past owners and is fairly early number too. Engine was really rough, interior is rough but it is also Gunmetal Grey on grey 16 way sunroof car. My friend knows these engines pretty well so it definitely is possible. I have got 4 years or more to do this so I have plenty of time. I have my Lesabre T-Type as a driver/show car and the 88 Reatta as a show car so I am in no need of the 90 for a while. It should be gutted in the next few weeks. I will post pictures too.

[D-a-n-i-e-l]

OK I a ninty will be easier to do, I ass-umed that you were doing the 88. The 90 will lend itself to a better swap.

[mackeyk3]

How about AWD?

[Guest F14CRAZY]

AWD has been discussed on Bonneville Club using the 4T65 trans from the U-body vehicles. The problem is that while the driveshaft to the rear is always spinning, it isn't always putting power to the wheels. There's a clutch pack in the rear diff that only kicks in when the PCM detects slip. If used for drag racing or the like it would quickly burn up...they often fail just in the minivans

[Guest imported_barra]

I'm not a mechanic but would getting the current engine "built" up be easier to accomodate? Certainly, the transmission would need some strengthening as well. Just a thought.

[Guest F14CRAZY]

I would think that the LS4 and 4T65-E-HD would fit but after that you have to figure out how to keep the new drivetrain happy as well as the Reatta. You could go ahead and remove all the stock instruments and use universal aftermarket gauges, which would be easiest but I feel you're losing quite a bit of what makes the Reatta unique in doing that. With a '90-91, not so much, but even then, in my opinion, it doesn't feel like a Reatta anymore.

Or do a piggyback setup and use both the PCM and stock ECM/BCM, but that's as far as my knowledge goes on that. I give a lot of credit to those that can think up new ideas like this, but it isn't easy nor cheap.