I've been toying with the idea of converting my carbureted V8 to TPI system but really can't decide whether there is sufficient benefit to spending a substantial amount to make the change.

I know a TPI motor will run more efficiently and consequently have better mileage but am not totally convinced that it will have better top end power and/or torque. I've seen some magazine write-ups that seem to say the same thing.

Does anybody have actual experience using both systems in either a 4, 6 or 8 cylinder car?

Farknocker

I started with a carbed V8 and switched to a TPI system.

Hands down if I build another V8 Fiero thats not an LT1, it will definetly be TPI.

Reasons? twice the fuel economy, excellent drivability, Fires up on first crank everytime, Gobs of low end torque, maintenence free, looks so much nicer.

The carbed motor seemd a bit stronger above 4500 RPM, but that may be due to the Camshaft that I put in with the TPI/ Engine rebuild.
But then you don't spend much time above 4500 RPM in a V8 Fiero, so I didn't really notice any overall benefit of the carb.

The only thing I liked better with the carb was the wonderful sound of the 4 barrels open inchs behind your head...mmmmmm.... hehe.

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[This message has been edited by jelly2m8 (edited 04-04-2002).]

What was the difference in mileage with the carb and the tpi? I am considering a swap for the end of the summer and was debating the carb/injection issue with the v8.

quote Originally posted by jelly2m8: I started with a carbed V8 and switched to a TPI system. Hands down if I build another V8 Fiero thats not an LT1, it will definetly be TPI.

Jelly,

which tpi unit did you use or should I say, what car did it come off of? From what I've heard, some of the stock TPIs are only good for say, 250 - 300 ponies. Any more than that and you're looking at bigger injectors etc. I'm trying edjumacate my self on these sytems but there doesn't seem to be a whole lot of books out there about TPIs (or at least I haven't found 'em). I have the TPI Swapper's Guide that I picked up from Barnes & Nobles but that book really sucks!

Farknocker

[This message has been edited by Mr. Farknocker (edited 04-05-2002).]

i hate going there my self, but try the corvette forum, mainly the c3 section. that was about the time vettes went from carbs to fuel injection and quite a few people make that upgrade.

You may want to pick up the current issue of "Car Craft Magazine". It has an good article compairing fuel injection and carburation using the same motor. To paraphrase the article... "At WOT, carbs and FI can make the same power if tuned properly. For drivability, it's tough to beet FI."

My two cents worth... If you making a drag racer, go with a carb. If you actually going to drive it in the real world, either will work but FI will make it more enjoyable. Be aware that, unless someone is giving you a TPI setup, you'll have about $1000 into it before you fire it up or the first time.

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Roy :D
Just another stock Blue 87 GT
Suncoast Fieros

JUST ADDED: YELLOW 1988 GT w/ T-Tops, 5-Speed, and Performance Sound.

Ive seen complete TPI systems selling on ebay for less than $500 USD. including harness and computer.

Installation I wouldn't think would be too hard, question is what SBC heads will they bolt up to.

quote Originally posted by Mr. Farknocker: Jelly, which tpi unit did you use or should I say, what car did it come off of? From what I've heard, some of the stock TPIs are only good for say, 250 - 300 ponies. Any more than that and you're looking at bigger injectors etc. I'm trying edjumacate my self on these sytems but there doesn't seem to be a whole lot of books out there about TPIs (or at least I haven't found 'em). I have the TPI Swapper's Guide that I picked up from Barnes & Nobles but that book really sucks! Farknocker [This message has been edited by Mr. Farknocker (edited 04-05-2002).]

I used a TPI setup from a 91 F-Bird. It is the speed density system.

I went with a mild rebuild, and ended up with 270 hp, and 328 ft/lbs of torque. An adjustable fuel pressure regulator is needed with stock sized fuel injectors. I used a fuel pump for the 91 5.7L engine

I used the new style heads (86+), but the TPI intake will bolt to the early style heads by simply oblonging the 2 center holes on both sides of the intake.

Gas mileage went from an estimated low 20 mpg to an easy 35+ mpg at hiway cruising.

I used a F-body wiring harness and modified it to plug into the existing Fiero harnesses. The TPI swappers guide really does suck, the only useful information in that is how to bypass the vats module.
I took a Fiero Helms manual, and a F-body Helms manual and worked with those to change the wiring. Some wires needed to be lengthened, and the C203 and C500 connectors needed to have the pin-outs moved around to match the fiero connectors.

The wiring was fairly straight forward once I had the 2 manuals to see which wires needed to go where. The hole in the bulkhead needs to be englarged slightly for the engine harness mount to snap in place.

You should be able to find a complete TPI setup with the harness, sensors, ECM and vats module for under 500$ I got everything for mine for 300 canuk.

Let me know if you need anymore info on certain points, I will try and go into detail on them.

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quote Originally posted by jelly2m8: Gas mileage went from an estimated low 20 mpg to an easy 35+ mpg at hiway cruising.

WOW! That is seriously impressive. And here I was all happy that my car pulled low 20's on the highway. I know I've got it set running a little rich, but WOW!

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Hartz

'84 SC 5.7L V8
'85 SE 3.1L V6 Turbo
Hartz's Toys

quote Originally posted by Hartz: WOW! That is seriously impressive. And here I was all happy that my car pulled low 20's on the highway. I know I've got it set running a little rich, but WOW!

Ya I was amazed too. At 90kph cruising in 5th ( Isuzu) it is using only 7 % throttle.

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[This message has been edited by jelly2m8 (edited 04-05-2002).]

quote Originally posted by jelly2m8: Ya I was amazed too. At 90kph cruising in 5th ( Isuzu) it is using only 7 % throttle.

Geez Louise,

I think I need one. I'm getting 6 to 13 mpg!

Farknocker

Is there that big of a difference also on the 4.9L...??? I'm going to be doing this swap some time this summer/fall and I'll probably just go with the carb. as it'll be easier on me... ehh?? anyone running the 4.9L with a carb?? "Smooth GTS"

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