James Montigny

Has anyone sucessfully done (and preferably documented) a TBI - TPI conversion? It doesn't look all that complex (having seen a few articles on the subject) But I would like to feed off of a few people's experiences before I start planning it.

The quest for more HP continues.



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James D Montigny
1992 Pontiac Firebird 5.0
Bone Stock (For Now)

The members of this board are enthusiasts, not experts.
Please consider everything that you read an opinion.

91RS5speed

You really wont get a lot of hp outa it but you will get a ton of torque and inproved throttle responce. what all do you want to know? I got about 10rwhp and 40rwtq from the swap.

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91 RS Camaro 5-speed black w/t-tops 305 TBI now TPI
MODS: SLP cold air intake w/K&N, air foil,Accel 19 LB injectors, March aluminum under drive pullies, Alburn pro posi, Aluminum drive shaft, Random Technology 3'' cat-back, 8.5mm MSD wires, 160 thermo, jet fan swich, Custom chip with 91 vette computer, SSBC slotted rotors, optima battery in the rear, BMR adjustable lower control arms and panhard rod, Kenny Brown strut tower brace, TB bypass, no egr, no air

James Montigny

Every little bit helps
Where did you get your information for the
project? And did you happen to document it
somewhere? Parts you used, time you spent, tools you needed, Gochas you came across... that kind of stuff.

I don't need a cookie-cutter mod howto, just looking for insight or even pictures to look over while I plan my own conversion.



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James D Montigny
1992 Pontiac Firebird 5.0
Bone Stock (For Now)

The members of this board are enthusiasts, not experts.
Please consider everything that you read an opinion.

NJ SPEEDER

i don't really wanna start a huge debate about tbi vs tpi again, but you may wanna look into the performance that you can gain from your existing fuel injection. tpi set ups commonly sell for 250-400 complete, for that amount of money you can really do a lot with tbi and most likely end up with a greater gain.
the biggest problem in tbi is not the induction method, it is the cam. it is almost teh smallest cam that gm ever put in a smallblock(i think the lg3 cam is the only smaller one and the lg4 is almost teh same, just flat tappet instead of roller.)
for 25-50 bucks you can pick up a stock LT1 cam that a 4th genner took out of his car and in a day have it in the car adn ready to run. add to that free mods and other easy to swap parts and you can pick up a lot of performance for your dollar.

later
tim

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NJ SPEEDER
91 Camaro RS
305TBI/700R4
12's Coming Soon
2nd Annual East Coast F-Body Nationals
July 20,2002
www.geocities.com/njspeeder
My MAFB.ORG Home Page
http://www.mycar.net/mafb/registry/detail.cfm?id=299

91RS5speed

If I were you I would do a full exhast first. i mean headers and 3 inch catback.

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91 RS Camaro 5-speed black w/t-tops 305 TBI now TPI
MODS: SLP cold air intake w/K&N, air foil,Accel 19 LB injectors, March aluminum under drive pullies, Alburn pro posi, Aluminum drive shaft, Random Technology 3'' cat-back, 8.5mm MSD wires, 160 thermo, jet fan swich, Custom chip with 91 vette computer, SSBC slotted rotors, optima battery in the rear, BMR adjustable lower control arms and panhard rod, Kenny Brown strut tower brace, TB bypass, no egr, no air

James Montigny

I was postponning the cam until I found a good head setup to match it. (Past experience has taught me to make damned sure I design them to compliment each other)

However, if TBI doesn't cause me any significant disadvantage I may just keep it for now.

Headers will be done when I do heads/cam - since they have to come off anyhow. I just purchased the car this week, I havn't had a chance to look under the car and determine what exhaust work has been done. It definitly doesn't sound stock, but may just be a muffler. I am a huge fan of flowmaster's products

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James D Montigny
1992 Pontiac Firebird 5.0
Bone Stock (For Now)

The members of this board are enthusiasts, not experts.
Please consider everything that you read an opinion.

NJ SPEEDER

for a 305 the two most popular head choices are prolly teh vortecs or the world products torquer 305's. the vortecs are a great head. you may wanna get tehm milled a little to help support your compression(they are 64cc and stock is 58cc). vortec intakes are also more costly than standard small block intakes. vortecs also have no built in egr port for your smog equipment if that is an issue for you.
the world products torquer 305 heads have a 58cc chamber and are equiped for egr. so they are pretty much a swap and go proposition. you will likely get a bit more power from the vortecs, but you will get less hastle and expense from teh world products heads.

later
tim

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NJ SPEEDER
91 Camaro RS
305TBI/700R4
12's Coming Soon
2nd Annual East Coast F-Body Nationals
July 20,2002
www.geocities.com/njspeeder
My MAFB.ORG Home Page
http://www.mycar.net/mafb/registry/detail.cfm?id=299

James Montigny

As long as removing the smog equipement doesn't throw a code; it would not bother me in the least. I drove around with a SES light on for months in my 95 - until I had that part of the program "fixed" I just hate to ignore the light and be paranoid that there is a second problem I am unaware of.

Do you think I could aquire flowbench numbers for either from the manufacturer? It's so much easier than gussing what % of their claims are fact

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James D Montigny
1992 Pontiac Firebird 5.0
Bone Stock (For Now)

The members of this board are enthusiasts, not experts.
Please consider everything that you read an opinion.

Kevin91Z

TBI is a huge disadvantage to making horsepower. My dad converted his 92 RS from TBI to TPI, and gained 17 HP and 70 TQ at the rear wheels. He went 14.94 ET with the stock TBI engine, with the TPI intake. There are very few 305 TBI's in the 14's, most modded ones run 15's. My dad then swapped in a 350 TPI, and ran 13.94 his first time out. If you can afford it, the TPI swap will give you some huge gains. And yes, change the cam while you've got the intake off.


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1991 Camaro Z28
350 L98 w/ T56 (originally 305 LB9 w/ T5)
318 RWHP, 419 RWTQ
12.803 @ 108.50 MPH (1.932 60')
Member: SoCal F-Bodies
ThirdGen 4-Life!

James Montigny

Only if the heads have to come off. Intake manifold is a breeze to remove and replace. Getting heads and cam out, that's another story.

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James D Montigny
1992 Pontiac Firebird 5.0
Bone Stock Officer, I Swear !

The members of this board are enthusiasts, not experts.
Please consider everything that you read an opinion.

NJ SPEEDER

tbi is not a power disadvantage. the stock tpi intake design is a more refined design and has a greater total volume, so of course it will make mroe power. there are after market intakes available for tbi as well that can give a car 17more hp. horse power tv tested a tbi car with just an intake swap and a full exhaust and found 35hp and 50ft/lbs at the rear wheels. that was without any free mods or even soemthing as simple as an open element.
and if you want to compare swapping motors that is just silly. if you add cubes, of course you will add power. if a stock L98 replaced a stock LO3 then you also switched to a better cam and heads at teh same time. so there are too many changes to even try to compare teh two. maybe if you ran an LO3 with an L98 cam you coudl compare soem of the results, but just saying that a motor with 45more cubes, bigger cam, and better flowing heads made mroe power is the captain obvious statement of the year and doesn't apply to how tbi can build power jsut like tpi or carb.

later
tim



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NJ SPEEDER
91 Camaro RS
305TBI/700R4
12's Coming Soon
2nd Annual East Coast F-Body Nationals
July 20,2002
www.geocities.com/njspeeder
My MAFB.ORG Home Page
http://www.mycar.net/mafb/registry/detail.cfm?id=299

NJ SPEEDER

and since i know peopel are prolly gonna start asking for proof of what tbi can do.
i went 14.209 @ 96.xx with a stock cam, free mods, full exhaust, edelbrock intake and heads, posi w/3.54 gears. that was with a STOCK CHIP!!! if a chip had been burned it certainly would have gone a lot faster.
blackbird305 is running 15.1's @90mph with an edelbrock intake, free mods, full exhaust, and posi w/3.73 gears. he is still on a stock chip!
jprevost has run 13.8 @ 101.xx mph with a vortec HO crate motor, full exhaust, hooley tb, performer rpm air gap intake, and posi w/3.73's. the weight of the and the mph mathed out to 340hp at teh crank, that is 10more hp than it is rated at from gm(funny how that doesn't sound liek a disadvantage). he is runnign a stock ecm and burning his own chips for it.
a guy on thirdgen.org swapped the stock cam out for a stock LT1 cam as his first mod other than free mods adn picked up nearly 4 mph of trap speed while using a stock chip.
camaroracer1992 went 13.18 @ 104.xx with an intake, posi w/3.73's, free mods, and a 125 shot.
it is very easy to make power with tbi. soem people just need to realize it is a reality, not a rumor.

later
tim

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NJ SPEEDER
91 Camaro RS
305TBI/700R4
12's Coming Soon
2nd Annual East Coast F-Body Nationals
July 20,2002
www.geocities.com/njspeeder
My MAFB.ORG Home Page
http://www.mycar.net/mafb/registry/detail.cfm?id=299

ZZ

If you listen to Tim, he makes a lot of sense. In fact I was going to do the TBI mods and was already doing them when I decided to switch to TPI. I found two complete TPI setups that were real cheap, and planned on re-selling them after cleaning them up. Well, after polishing all that aluminum, I couldn't resist seeing how it looked under the hood I also wanted more power from a basically stock setup, and the TBI wasn't cutting it, even with mods. If I did the cam, it probably would have made a world of difference, but since I had it apart..... I put some TBI stuff on the Thirdgen classified board a few days ago if you're interested in prom burning, or looking for TBI parts. They're under ZZsmpch.

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Steve B.

69 Malibu ZZ4-350
88 Camaro SC 305 M5
93 Camaro Z28 A4
01 Silverado Z71 LT
My page

James Montigny

Thanks ZZ

I read a little more about the swap, that's a pretty involved deal. wow . But it's doable.

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James D Montigny
1992 Pontiac Firebird 5.0
Bone Stock Officer, I Swear !

The members of this board are enthusiasts, not experts.
Please consider everything that you read an opinion.

Kevin91Z

Tim, if you read what I said, you would see that my dad gained that power while still using the same TBI heads, TBI cam, and TBI exhaust on the original TBI 305 with 220,000 miles on it. The 14.94 ET is with that TBI engine with a TPI intake on it. The TPI intake was all stock, not even a ported plenum. It made 175 RWHP and 290 RWTQ. Previous best with the TBI intake was 158 RWHP and 220 RWTQ.
The 13.94 run was after swapping in a 350 with an LT1 cam, ported 350 TBI truck heads, and TPI exhaust manifolds and exhaust. My dad loves his TPI engine and never regrets ditching the TBI.

TBI is a disadvantage. 8 injectors at the ports are better than 2 injectors on top. But it all comes down to money and time. If you've got both, go ahead and swap. If not, then deal with the TBI and make it faster. And you dont have to remove the heads to change the cam.