I have a 1989 RS with a 305 TBI and I am in the process of converting it over to TPI. I am rebuilding the engine and was wondering what I need to change over inside the engine to do this. I know I need to replace the cam but is there any other difference in the heads or compression ratio?

Thanks for any advice,
Cuthby

 

i think the cam and the heads are different.

 

Cam and heads are different. But most would recommend going with an aftermarket cam.

Heads, I forget the part numbers, but there is quite a bit of difference in flow numbers.

If the compression is different, its so small its not really noticeable. If you have to replace pistons and dont mind running premium, you can up the compression and get a few extra hp.

 

Thanks for your help with this, it's a big project.

Cuthby

 

I thought about this as well when I had my 1989 RS with TBI a decade ago. But the work involved is just too much. In the end all you would gain from TPI swap is 20hp. This is without changing the cam and the exhaust manifold. So let's say you do change them you are going to want to change the suspension and the open rear end to posi. It would be so much better to get another F-Body with a 5.7 TPI with all the goodies already.