this is a motor swap question about the turbo trans ams. can you replace the 4.9L 301 with a 350 or 400 small block? i know 305 and 350s are the same size, im just not sure abot 301s. also, what size is the stock turbo on the car? whouls the stock exhast manifolds bolt up as well?

 

Nothing from the 301 will bolt to the SBC, with the exception of the accesories, maybe. The exhaust manifolds, intake manifold, would all have to be changed. It would be damn expensive. You would probably be better off looking for a solution inside the pontiac family.

 

Nothing whatsoever will interchange.

Well, I take that back.... a few internal parts of the distributor will, and maybe the spark plugs, and a couple of the bolts.

The accessories are completely different. Exhaust is different (there goes the factory turbo setup...). Transmission is different.

In short, if you want to build a turbocharged SBC, you'd probably spend less money and end up with a better finished product, by simply starting out from scratch, rather than using the 301 as a base. That way you wouldn't have a whole bunch of money already tied up in a worthless motor you can't use a single piece of for anything.

 

As stated above, not much will directly "swap" from the Pontiac engine to the Chevy....

However..... If you're interested in making a draw-through carb or TBI system, you might be able to take quite a few ideas (and at least one part) from the 301 setup. You could potentially use the plenum where the carb and turbocharger meet on a non-Pontiac engine. You would have to fabricate an adapter to go from the plenum outlet to the intake manifold (keeping things as low profile as possible). Your passenger side exhaust manifold would need to be modified as most DIY turbo installs are done to feed the turbo. Then, take it to an exhaust shop to get your crossover and turbo pipes done!

While I don't know the exact specs on the stock 301 turbo, I understand it was sized at the low end of what would be required for the application. Since the 301 turbo was designed more for fuel economy than performance, just enough was done on those applications to try to smooth the transition from the 400/403 V8s to the 301....

 

But it's not a 3rd gen swap question, because no 3rd gen came with a 301, and you're not asking about putting a 301 turbo into a 3rd gen.