Hey there.. Couple questions.. I have heard tuned port is the best injection system, what makes it so much better than a carb or throttle body? whats the main differences? if you have two identical engines side by side, one with TBI and one with TPI, how much more performance will you get out of the TPI if any? like i said earlier, im in the proccess of getting a new engine put in my car, and i heard i should do TPI, and i am looking for a setup right now, the engine place told me that my TBI crossfire setup will work great on this new 270hp engine with the right fuel chip. is it worth keeping (tbi) or is there not a noticable diff to change to TPI, please give me the low down, i think im going to do TPI if i can just get hold of a setup soon, i need the whole setup, 110% complete, so unless i find it, i am going to use my TBI, what you guys think? sorry im still learning on intake stuff.

Nate

 

If you're comparing stock, unmodified motors, the TPI will have more power. They generally got a better cam, and have more low end torque, and about 20 more horsepower than a TBI system. They can both be made to perform, but TPI systems have a MUCH bigger aftermarket following, so you'll find parts and go-fast goodies much easier. They both benefit from basic engine upgrades common to any small-block of any fuel delivery type.

Compared to a carb, TPI is much harder to troubleshoot, and much costlier to attain the same power levels as a carb. If you're concerned with gas milage and/or emissions, electronic fuel injection will come out ahead. If you're concerned with dumping huge amounts of gas and air into a huge motor without huge amounts of money, carbs will always come out ahead. The TBI is a compromise between the two, but it gets hard to get a TBI to feed a heavily modified motor. But it's a great starting point if you want to learn about working with fuel injection, because everything's right there on top, you can see the injectors at work, and it's pretty forgiving of errors.

Your choice will depend on your individual tastes, preferences, situations, approach, willingness to learn, and the car's final goal.

 

I find hooking up my Diacom to a TPI car is much easier to trouble shoot it than playing with a carb engine. But it is more expensive, like you said.

Also, on the difference between a TBI and TPI engine, my dad put a stock TPI intake on his TBI engine in his 92 RS, and gained 17 horsepower and 70 torque at the rear wheels, and 1 or 2 miles per gallon fuel economy.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

 

The main advanctage of TPI is that it is a MULTI-PORT injections system- one injector per cylinder. It's better at getting the fuel evenly and fully distributed to the cylinders under all conditions- cold, hot, idling, full throttle, everything in between.

It's design, however, is for midrange torque, primarily (with long, skinny intake runners). Good for a street car but not ultimately the best induction system for serious HP.

 

I wholeheartedly agree with you there. I was speaking from the point of view of someone just getting interested in working on their own car. I don't have a Diacom yet, but my AutoXRay has made itself useful many times.