What is Tuned port injection, good, bad, ugly?

[kenh]

I'm kind of curious about the tuned port injections systems. I'm sure there are compromises as with anything.

What is the good , bad and ugly with this system.

Fairly close to me is one for sale. Looks pretty much complete for $400.

Ken

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[Schurkey]

Good: Looks sexy
Bad: Was designed for 5.0L, it's undersized for 5.7L even when installed on 5.7L originally. Good torque, not-so-great power. VERIFY WHAT YOU'RE BUYING. Is this a Camaro, or a Corvette system? 5.0 or 5.7? What model year?

Good: Heaps of aftermarket parts to crutch the basic nature of being under-sized
Bad: Aftermarket parts were expensive, now they may be out-of-production; or at least less-popular.

Good: GM engineering, reliable as a brick.
Bad: GM engineering, every model year is different--and they weren't intended to be "aftermarket easy" to tune for power/driveability. They're tuned for EPA compliance, emissions and fuel economy on "stock" engines.

Good: The aftermarket has solutions for the tuning
Bad: Aftermarket solutions won't be smog-legal, and they're not as well-sorted as folks want you to believe they are.

I have heard--but not verified--that the TBI can actually make more power than TPI, but it won't look as cool.

 

[Raspi454]

Just throw a 4 barrel on it lol

 

[Schurkey]

Oh, yeah. A poorly-remembered story about my buddy who stuffed a TPI onto an '89 C1500:

He buys a fairly-complete TPI system, sorta like you picture. Builds a "383" using a bottom-feeder Chinese crankshaft. Puts it all together and in the truck. Has "tuning"--a "chip" and maybe a wire harness from one of the Big Names in TPI performance at the time.

First Problem: Scan tool won't talk to the computer. Bang heads on wall for a couple days, finally figure out that the ALDL connector isn't pinned the way the scan tool thinks it should be. I don't know if they used the C1500 ALDL, or the ALDL and harness that came with the TPI. I think they re-pinned the ALDL and then they had no problems with the scan tool after that.

Second Problem: Big Name "tuner" didn't get the tune right. I think they were still sorting the tune when Problem 3 came along.

Third Problem: Likely not related to the TPI. About fifty or a hundred miles into this mess, the crankshaft obliterates the bearings. Engine comes out, he re-grinds the crank, new bearings. I trust this guy, so I expect the engine was cleaned of debris. Vehicle re-assembled, runs and drives, until

Fourth Problem: First time my friend connects the trailer to the truck, he barely gets out of town and the crank eats the bearings again. Engine pulled, has been parked in his garage for a dozen years. C1500 scrapped. He buys a '97 K2500 7.4L in really nice condition.

 

[kenh]

Yes the little research I've done confirms some of the above. All that is known about the system is it came off a 350. Yes I really likes the looks of the TPI system! BUT, like mentioned, it has it's issues. It looked like somebody used a Vortec or LS computer and additional sensors to make it a better system. Might as well go LS at that point IMO.

I'm gong to pass on this even though it is eye candy .....

Ken

 

[yevgenievich]

There is not much of gain on a stock setup when put on a truck motor, but does have a good torque curve. Had few tpi cars and still have it sitting in one of the projects. One way to fix the flow problem is to essentially replace the tpi part, but no point in getting the base setup then. I did swap out the tpi for ls in one of the vehicles, and actually thought torque curve was considerably noticeable.(as in ls did not perform as well from a dig with the poor gearing the car had).
Had one on a truck with 383 as well, but did not actually get to really drive it. Swapped to a carb in order to recoup some funds by selling the tpi setup

 

[L31MaxExpress]

TPI is a little soft on the low-end but makes excellent midrange power. Had one in my 83 G20 for a while on top of a 305, a 350 vortec and later a 383 vortec.

Scat cranks have held up just fine for me.