Stupid Question...TBI/TPI
Race Director
Joined: Apr 1999
Posts: 15,146
Likes: 477
From: NM
Re: Stupid Question...TBI/TPI (Mystery Machine)
TBI=Throttle Body Injection. Injection system looks like a carb and sets on top of an intake manifold like a carb does. Manifold is "wet" with air and fuel running through it.
TPI=Tuned Port Injection. Injectors are in the intake ports and inject the fuel at the valve. Mainfold in this system is "dry", only air running through it.
tom...
TPI=Tuned Port Injection. Injectors are in the intake ports and inject the fuel at the valve. Mainfold in this system is "dry", only air running through it.
tom...
Just another Corvette guy
Joined: Feb 1999
Posts: 8,518
Likes: 3,865
From: Palm Springs, CA.
Re: Stupid Question...TBI/TPI (Mystery Machine)
Without gettin' in too deep TBI, Throttle Body Injection usually has a single large carb style body mounted on top of a more conventional carb type manifold, or in the case of the '82 & '84 Corvette two of these units. Most common complaint is usually rough idle.
TPI, Tuned Port Injection sports eight separate intake runners or ports and one injector at each cylinder just inboard of the valve covers like '85 & up Corvettes.
This is just the basic "at a glance" differences.
TPI, Tuned Port Injection sports eight separate intake runners or ports and one injector at each cylinder just inboard of the valve covers like '85 & up Corvettes.
This is just the basic "at a glance" differences.
Instructor
Joined: Mar 2003
Posts: 235
Likes: 0
Re: Stupid Question...TBI/TPI (Mystery Machine)
TBI is Throttle Body Injection, It basically looks like a carburetor on top of the intake manifold. The injectors are in the Housing of the throttle body itself.
TPI is Tuned port injection. This is what they used on the 85 and newer corvettes. There is an Intake plenum(manifold) and there is a separate injector for each cylinder. This is a much better system than the older throttle body design. The LT-1 corvette had one of the best TPI setups on the market.
Both ar good systems and the aftermarket has performance setups for both. It all depends on what you want to pay and what you are looking for. I myself prefer TPI. But to each his own.
TPI is Tuned port injection. This is what they used on the 85 and newer corvettes. There is an Intake plenum(manifold) and there is a separate injector for each cylinder. This is a much better system than the older throttle body design. The LT-1 corvette had one of the best TPI setups on the market.
Both ar good systems and the aftermarket has performance setups for both. It all depends on what you want to pay and what you are looking for. I myself prefer TPI. But to each his own.
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Pro
Joined: Dec 2001
Posts: 708
Likes: 0
From: Renton Wa
Re: Stupid Question...TBI/TPI (Mystery Machine)
You could probabily do a TPI swap for around a grand I bet, That is finding a good used unit, computer, all wiring harnesses, and all the sensors. But considerable time futsing around installing it all! TPI or mulitport injection has many advantages in both fuel consumption, and performance no puddeling effect occures with a multiport setup. Throttle body can work, but it's not a far gain from a well tuned carb. Infact I would probabily take a carb over a throttlebody. With a throttlebody injected unit, you have to use 2 or 4 Large injectors, which will be running almost continous, which takes away from tunability. TPI's largest setback is it's small runner size, which limits the Top end capability. Usually around 5.5k rpm. IF you want power, get away from both and go MPFI. single plain large runners.
Thread Starter
Drifting
Joined: Jul 2002
Posts: 1,855
Likes: 0
From: Cocoa Beach FL
Re: Stupid Question...TBI/TPI (nitrocharger)
Thanks guys...I was just wondering as I saw an ad in the paper for a 350 w/ TPI for ~$900 and thought if I could talk him down it might be a cool thing to have.