Has anyone ever swapped their Throttle Body Injection over to tuned port? I figured that since the difference in HP was a fair amount this might be a reasonable mod.

 

Yeah, but I did it with a donor car - otherwise you will pay a fortune for parts.
Starting from the rear you will need:
Fuel pump. Fuel lines (the charcoal canister is located on the oppposite side of the car, so the one line is different).
Engine wiring harness and relays. ECM.
Doesn't sound like much, but dropping the rear to get the tank out is fun. It's also easier to get the fuel lines off when the entire drive train is out.
I also swapped out a drum rear for a disk rear. I used the original proportioning valve out of the drum rear, cause the master cylinder and the valve were identical (at least I hope they were - same part #'s).
The battery position is also swapped, so you need the battery cables. Cruise control is in a different place. You have to drill out some holes in the fender well to mount the cruise control. Accelerator cable is different.

And that's what I remember off the top of my head :-) It took me a few weekends to do the entire swap, but I took my time and redid a lot of stuff on the engine - ported the intake, rebuilt the harness cause it was in rough shape. Not to mention I just got the car back from a $5K paint job, so I didn't want to scratch it!

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89 Firebird Formula
WS6 package
ZZ4 Crate engine
SLP 58MM TB
Edelbrock TES Headers
Random Tech 3" cat
SLP 3" stainless exhaust
9 bolt rear
Hotchiss swing arms
Lakewood panhard rod

 

Did you see the tech article here on how to swap TBI to TPI?

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

the tech article is great ..however it deals only with the tbi to sd tpi ..

 

yep I did the swap at age 19 last year. TBI i ran 15.5 at 89 TPI I got down to a 14.05 at 100.5 without my nitrous. It transformed my car. email me at maydays19@yahoo.com if you have specifics. I can answer them all!!

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1991 Firebird
350 L98 (was a 305 TBI)
T-5 transmission
Edelbrock TES and cat back
Accel manifold
NOS
subframes
jegster torque arm
MSD Digital 6
AFPR
Lakewood lcas
hurst linelock
SLP cam
relocated battery
cold air
Hypertech chip
centerforce clutch
poly bushings and mounts
etc..

14.1 @ 99mph with just headers and catback

with NOS and other mods???? twelves??

 

Probably because SD is better? *ducking*

Really, its the same principle. Just make the changes on your notes where it says SD, to MAF. I dont find it difficult.

 

The tbi tpi article was ok if you have the money and resources to get those parts.
I found an article in Chevy High Performance from June 1997 that they swapped a aftermarket tpi sd system into a tbi truck. They used the tbi computer and wiring harness. They had to wire in the extra injectors and burn a custom chip. This is the way i'll go because I don't want to spend 200 to 300 for a wiring harness and 100 to 200 for a computer plus all the other parts.
I'm cheap and with the way they did the swap all I have to do is get a custom chip around 100 to 200 dollars, and install a fuel pump and higher pressure fuel line.
Oh yeah the custom chip was done by Allan Bessant of B.E.P. Performance Center. Phone # (714)744-9275.

 

CHP didnt swap to a TPI system, they put on a multiport EFI system, using the stock TBI throttle body.

My dad is working on his notes right now for a tech article on how to swap to 90-92 TPI from 90-92 TBI using your stock TBI harness.

BEP is right in my backyard, I didnt know they did PROM too. I've been there once or twice.