I'm looking at buying an 89 RS 5spd, t-tops, only have about 103k on it. Anyway, it has a 305, I was wondering if it is TBI, or TPI, or how to tell the differance, as well as which one was better. Any information on differant 305's that were used in that year would be very helpful thank you.

 

It's TBI.

TBI looks alot like a carb; has a big round air cleaner with a snorkel (at least from the factory) just like a carb. The injectors are mounted on top of the throttle body, which looks a little like a 2-barrel carb except with the injectors poised above it.

TPI looks like a long narrow box about 8" above the rest of the motor, with 8 large curved tubes going from the sides of the box down to the intake manifold.

Those are the only 2 types of 305s the factory used in 89. The TPI version was not used in the RS model, so it didn't come with that system.

Of course, people tend to change such things sometimes, so that's no particular guarantee that what the factory put there, is still there.

 

as someone on here put it before:: if it looks like a trash can lid on your engine, then its TBI, if it looks like a giant metal spider humping your engine, then it is TPI.

 

How much better is TPI than the TBI, and whats it take to change it around? Thanks for the replies.

 

305 TPIs in 1989 had 30-35% more HP than TBI (220-230 HP vs 170 HP). That's significant.

About the only "power" contributors a 305 TBI engine shares with the 305 TPI engine would be the pistons. TPI got better heads, cam, exhaust; along with being packaged better for performance.