Looking to see if anybody has swapped in a 3.1 out of one of the Turbo Grand Prixs. I recently picked up a complete turbo kit for my Formula for $150. Since Im going to have to convert to DIS to run the 7730 that came with it I figured I would just drop in an engine thats already setup for 7730 and built for boost. Looks like a pretty straightforward swap, Fiero accessories, custom dogbone mount and crossover. Anything I should look out for? How well would the TGP 3.1 do with a larger T3 turbo? Thanks

I have seen a couple attempts mentioned at swapping the TGP McLaren 3.1 into a Fiero, but I don't recall seeing any finished swaps of it.

You aren't required to run DIS with the 7730, btw. You can run a distributor with it still. DIS will be better as it gives you a little more dynamic control of ignition timing.

I wouldn't bother with the TGP engine. If you can manage to actually find one for sale, it's probably going to be expensive, since they're pretty rare. If you want a cheap engine swap and to keep the stock Fiero intake, then a 3.4 out of the 93-96 F-body (Camaro/Firebird) would probably be the cheapest/easiest though. I'd stick with stock and not go too high on boost pressure, and then swap when you have money to do a much better swap (like a 3800), or when the engine blows up.

PFF Member: Mr_jacob7:

I've already thought about swapping in another motor such as a 3.4 or 3800. I know the 3800 is a fantastic engine as I am building on for my GTP but thats not the direction I want to go with this build. The 3800 is far from a pretty engine to listen too also. The 3.4 swap would get me some extra power but I cant justify the gains. The TGP engine has DIS already which would solve the ongoing issue with ignition modules on these cars, it also comes with aluminum heads, better flowing manifolds, and a stronger bottom end. With ported heads, a better turbo cam, and larger turbo there should be no reason that it cant make more than 400hp. The engines can be hard to come by but I have a line on a few for under $500

What advantage is there in going with the 3.1 Turbo over a 3.4 DOHC if you're already planning to modify the turbo? The swap would be of similar difficulty.

quote Originally posted by Formula88: What advantage is there in going with the 3.1 Turbo over a 3.4 DOHC if you're already planning to modify the turbo? The swap would be of similar difficulty.

The downsides I see with the DOHC 3.4 is maintanence on it and lack of aftermarket parts. They look like a pretty tight squeeze and have a higher center of gravity. I've driven stock ones and they have decent power but they are really lacking in torque compared to their pushrod counterparts. The way I see it is the biggest advantage that the turbo 3.1 has over the DOHC is the wide choice of different cams or even custom grinds. Last I checked you cant put larger cams in the dohc because of head design and nobody makes the blanks for them.