Whats the difference between TBI and TPI and which is better? I have a 305 TBI 89 RS Camaro. I don't have any understanding of the two.

[This message has been edited by un4givin89 (edited July 12, 2001).]

 

there is an explanation on the site in the FAQ section.

TBI=Throttle Body Injection
TPI=Tuned Port Injection

 

Oh GOd Don't start the which is better.

They both have their good and Bad points. TPI is faster out of the box, but its more expensive to tune and Build with, but can also be faster in the end because of the Ability to "Tune" the engine with a better computer and dry flow system. Where as the TBI is cheaper, easier to learn and deal with, but les tuning capabilities.
All in what you want to do with it.

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Kyle is right in some instances but the ecm is not a problem. Both ecms run the same, TBI is speed density and TPI can be either MAF or SD. The data line might have a different rate/speed but that isn't the speed of the actual mechanics. The TBI ecm is just as fast internally as any TPI ecm, both react instantly to TPS changes or you would have a good .5 second delay in throttle responce with TBI (which we don't). Just look at all the really expensive race EFI setups. They have less options than even the TBI ecms! Mostly because they aren't built for all around, not too many race cars looking for good gas milage (NASCAR but not efi!).
If you search for TPI and TBI in the archives you should look at the large topics (30+ replies). At one point I had a HUGE post that shut up a lot of the TPI die hards from bashing TBI. The real difference is this: Wet flow vs. dry flow
Both are efi but the TBI has some advantages common to the carb but at the same time has some of it's flaws. TBI is a cross between carb and TPI, it gives you a great EFI system that runs like a carb but with most of the advantages of EFI. A cross bread so to speak.

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, Jon (350 TBI!)
91 Red My website

 

Thanks guys, just curious. I have TBI and and the only thing I knew about them was the way the engines looked. But if TBI is cheaper sounds up my alley and something I'll most likely stick with.