After I replaced all 8 NFG rochester injectors with 19lbs ford motorsport ones my car runs like new.
I am very impressed with GM tpi intake system.
GM used TPI from 85-92. The fact that they used it for 8 years must prove it was a great design. Right?
Is there any inherent problems or shortcomings with TPI or is it simply an engineering marvel?

 

Everything has shortcomings. I think that TPI was a marvel in its day, but it's certainly very dated now. LT1 and especially LS1 technology blows it totally out of the water. Even the engine management on the LS1 isn't really any different in concept to TPI, but the subtle changes, along with the substantially improved long block result in a very very efficient design.

That being said... tpi is what basically started it all for GM. It was their first multiport injection system on a V8. The tuned runner length was pure genius and worked extremely well on a 305. The fact that you could get a 305 car to turn high 14 second 1/4 mile times, and get 22mpg coming and going from the track was quite an accomplishment in the 80s.

The biggest drawbacks when you look at TPI now is that it simply can not provide high RPM flow for anything larger than a mild 305. Modifications are very expensive, and ultimately the MAF system becomes a problem above a fairly modest horsepower level.

 

Jim pretty much summed it up

TPI was quite the marvel in its day for what it was.. The gas crunch was hitting hard then and the goal was to keep the camaro reputation of a muscle car, yet conform to better fuel mileage and emissions. It did so well, and held that feeling of muscle by making a little 305 squeek out alot of torque, however the marvel stops there, as soon as you try to modify it it doesn't seem so friendly any more. Costing as much as it does, with diminished returns (as long as you stay LTR) compared to the newer EFI's and the 50+ year old carburetor. When it comes to the management a few things could have been better and have since then been corrected, like batch fire vs SEFI, an 02 sensor for only half the engine ( ) and I personally think that GM could have spent another few bucks and ditched the "Switching" 02 style and improved accuracy for both better mileage, and better performance.

Granted some of the last things are optional and my prefferences, but they have gone that way on later FI vehicles and with the LS1 being all that it is, it certainly appears to be the right direction.


Short story, gm WAS an engineering marvel in stock form, in its day. It hit the v8 efi business with a bang.

 

Plus folks, all the technical stuff aside, isn't the TPI a much cooler, better looking FI system then say the ford 5.0 FI set up? Hot Rod builders, car show builders still seek out TPI for its GREAT LOOKS!
Much better than a LT1 or LS1.
Like my brother always told me, it's better to look good then feel good.

 

TPI was and is a marvel. Looking back just a short 18 years the carb was "it" for fuel delivery, and had been since the creation of the auto engine. There were breif attempts at fuel injection prior to 1985, but they were not very successful to say the least.
In 1985 along comes Tuned Port Injection, and things were forever changed. Engines made more power and got better gas mileage, performance and power were the "buzz words" in GM's engineering divisions again. But to look over the past 17 years there haven't been any real changes in the fuel injection systems, just refinements, with faster computers that can handle more functions and more precicely monitor and control engines.
Even the aftermarket fuel injection systems copied the TPI, it just worked so well, and it looked great in the process. Sure there are now more powerful and better running injection systems, but none look better than a TPI setup.

~M~

 

I would have to offer that computerized engine management and the introduction of overdrive transmissions did more for MPG than any fuel inductions system.

 

Don't forget that multiport injection was around before 85, and it was not much different than the GM TPI setup. I believe the turbo regals were using multiport injection longer than the f-body, and I know that BMW was using an almost identical setup as far back as 77. Computer control was probably primitive, but the same overall system with a MAF, 02 sensor, TPS, etc. was all there.

Bosch pretty much gets credit for the system, not GM.