TPI or TBI

[77crewcab]

Okay I have definately decided to convert my 79 K5 to fuel injection. It will be 350/700R4, with maybe a 383 down the line. I have everything needed for a MAP TPI swap except the harness and ecm. All new sensors, gaskets etc. I have found that I can get a brand new harness/ecm/chip with vats and emissions removed for $320.

Today I was called by a friend with TBI burb he is parting out. He said come get what you want. It is a running engine (not well but running) I can see that it would easily hit $300 in parts needed to get it runnin well.

If you had the choice, which system would you use? The money isn't really an issue, I am just wondering which would be better for low/mid range torque.

 

[Hossbaby50]

either way be prepared to have a couple chips burnt to match your motor, especially when you do the 383. MAP is much more finiky with cams, and motor mods.

If you have TPI run it. It is a better system then TBI. A little more complicated but not much. It has more power potential and is also more efficient then TBI. I have TPI and I love it. Plus TPI just looks WAY sexier then TBI.

Harley

 

[77crewcab]

I already know about the chip burning and have a guy that can do it for me. The wiring harness/chip/ecm combo for the speed density TPI seems like a great deal. A new harness with all the emissions stuff removed other than O2 sensor, and the chip has it all removed as well. The TBI would probably be a little easier swap but I am leaniing towards the TPI for this. Mainly cause I already have all new parts, and with the aftermarket harness it would be a bolt in deal minus the fuel lines. But since I already have the body off the frame I have great access to redo the fuel lines.

 

[chevyuser74]

i did a tbi swap into my blazer, if i had to do it again I'd go tpi, then again what I really want to do is throw a cummins in the thing.

 

[77crewcab]

I have been following this thread on thirdgen.org for a while and think that it is probably the biggest selling point for the TPI in my mind right now. Plus now they are working on addapting coil on plug technology and already have a prototype running.

http://www.thirdgen.org/techboard/tpi/383323-tpi-obdii-thoughts-opinions.html

 

[dyeager535]

Took me all of about 2 minute to dig this thread up:
http://www.thirdgen.org/techboard/e...-cid-motor.html?highlight=tpi+restriction+383

I agree with the posters there saying that TPI strangles even a moderate 350.

We have trucks I understand...a TPI 383 will make great low end torque, but so does my TPI 355. Unfortunately, it peaks too early and isn't as fun to drive as it should be. A 383 would be even moreso. The LS series motors have a VERY flat power curve (note: no long, convoluted path runners) while a TPI 383 would almost certainly be very "peaky".

454 TBI will flow better and *probably* overall make a fair bit more power than TPI, "stock" for stock. Dump the TPI plenum/base/runners, and now you are talking...talking $$$ too unfortunately. There was some movement towards the LT1(?) base at some point, I assume that did away with the entire long runner portion of the TPI.

 

[BGKYK5]

Is it possible to bolt up a stock lower TPI manifold to stock vortec heads without major sugury or $$$ aftermarket heads and/or lower manifold?

 

[dyeager535]

Nope. Vortec head bolt pattern is entirely different, but the reason it's impossible is because the ports don't, won't, and can't line up. OK, that may be a bit strong, you can MAKE anything fit or work, but it's not worth it. You can get the SDPC Vortec TPI base (which is what I'm running, way too much $$$, luckily I got mine new from someone that went another route) but IMO if you desperately want TPI, get an '85/86 TPI base, and aftermarket heads that have the "old" intake bolt pattern, or of course, the '87+ TPI base, and heads with the same pattern.

You could go with the L98 heads and the corresponding base, but you don't get all the benefits of the "fast burn" design of the modern heads. Really, you could use any older stock head if you wanted to.

Of course, TPI doesn't flow for crap, so aftermarket heads will be choked, however, cheaper or similar cost (depending on if you need EGR, etc) than buying the Vortec specific base.