Tims 88gt

Hey guys/gals whats up? Im Tim and im new here, I have a 1992 Mustang GT lol dont flame me for it. Im just a ford guy. Anyway My cousin has a 1988 trans am GTA that is TBI and we found a 1989 thats TPI. we want to take the top end of the TPI car and put it on his TBI. what all needs to be done? What wiring do we need? thanks for the help

Tims 88gt

Come on someone has to know. im a ford guy i have no clue what im doing here.

fire350tpi

im not to knowledgeable about tbi to tpi swaps but as far as i can see you need the engine wiring harness, the tpi ecm ( May as well get the whole harness?) theres probly more, someone who knows more can chime in

1993formulav8

Better check your car again, I dont think they used the tbi setup in GTA cars I think they only used tpi since they were the top of the line model.

Tims 88gt

well we know its a gta because the vin says gta. it has a 305 tbi. any help would be great, were going to swap this thing next weekend.

3.8TransAM

If its a GTA is has TPI period. No ifs ands or buts.

If it has TBI its more likely a TA or someone has been rebulding the car before u bought it. Read the FAQ's and stickies here for more info.

Get the entire setup, get the entire engine harness and ecm.

I do recoomend going slightly custom on the chip and running the 89 MAF code and this will also eliminate the POS cold start injector and its issues.

Also hit the stickies on this board and the PROM board. More so here if u are just reharnessing the car.

There are several detailed ecm pinouts and which wires neeed to be where and which stuff need to get tied into the dash side for the speedo, etc.

AS ALWAYS, HAVING THE FACTORY MANUALS ON HAND MAKES ANY JOB LIKE THIS EASIER BY FAR.

later
Jeremy

Tims 88gt

ok wow it sounds like a lot of work.

3.8TransAM

ITs not alot of work at all.

Just need to take some time and reasearch it before u start :-)

Get it all laid out before hand.

We reharnessed a car we swapped a TPI v8 in from a six and had it running in 3 hrs :-)

Course thats a long story but having a whole harness to begin with makes it alot less painful.

later
Jeremy

Evil 88IROCZ

Here is a quick write up, of the swap I did.

https://www.thirdgen.org/forums/engi...s-305-tbi.html

Tims 88gt

thanks for that info.

87TPI350KID

Just remember TBI cars have crappy heads and your going to make a butt load of torque, but absolutely no horsepower or topend.

vipershark11

iTrader: (6)

so if i swapped the 305 tbi to a tpi would i be seeing any gains?

Evil 88IROCZ

Well TBI are a step up from regular heads, not that it matters much. You will pick up some power however not in a huge amount. Still worth the swap, then the next upgrade is a 350.

vipershark11

iTrader: (6)

about how much power? plus will it run in a different rpm range now cause when i drove my dad his 350 tpi stock liked the upper rpms as my tbi hates them

vipershark11

iTrader: (6)

sorry to hijac but maybe whoever posted this has the same question if i put in an L98 cam will that make it run better since the computer is tuned for it already?

92 Formula

iTrader: (2)

I did the swap in 2001 with my old 92 Formula. But, I went with a speed density setup. In case you decide to do that I still have a lot of the part numbers available here:

12080890 Speed Density Wiring Harness
25027221 TPI Fuel Pump Sending Unit
25116163 TPI Fuel Pump
16151348 MEMCAL for SD ECM
10456549 Speed Density 350 TPI Knock Sensor
10108425 Corvette TPI Distributor Cover
10108427 Speed Density Ducting (air)
10163822 TPI Throttle Cable
12146312 Coolant Sensor/MAT Sensor
12146312 Coolant Sensor/MAT Sensor
14094720 Speed Density Ducting (frt)
1638566 Speed Density Clamp
10186112 Speed Density Clamp
14082425 TPI Distributor Cover Bolt
14082425 TPI Distributor Cover Bolt
14082425 TPI Distributor Cover Bolt
554665 Charcoal Canister mounting clip
1227730 ECM (Speed Density)

Evil 88IROCZ

You will pick up some low end torque and some HP up top, well up top compared to a TBI. The problem is the stock TBI cams sucks really bad. If you have a MAF computer then you can put in a larger cam without needing a custom tune and it will run great. I run a 305 and it pushes my IROC into the 13s. You would be surprised how cheap you can build a 350 or add a cam, port you stock base manifold, runners and plenum, add an airfoil and exhaust and your 305 will actually make some power.

vipershark11

iTrader: (6)

whats this MEMCAL?

92 Formula

iTrader: (2)

The chip to the ECM.

vipershark11

iTrader: (6)

so id end up being a nifty set up if i did all the tpi set up and an L98 cam what kind of gains would i be seeing then?

Fast355

iTrader: (2)

Not enough to justify swapping to TPI.

92 Formula

iTrader: (2)

My Formula was a 305 TBI. When I did the swap, I also swapped in a 350. So, in my case it was worth it to me at the time. I will say now, in hindsight, that I would have been better off selling the Formula and buying an L98 car...but I was attached to the Formula and stuck it out.

EDIT: I also did a full exhaust with SLP headers, dual Catco cats and a Flowmaster American Thunder catback exhaust and got rid of the peg leg 2.73's and went with a posi 3.42's (should have gone to 3.73's IMHO).

I definitely would not do the swap and stay with a 305. But that's just me...

HTH,

James

Tims 88gt

Thanks for the info. my cousin does not have a lot of money to spend, so im going to tell him to part the car out that he bought and sell his other car and find a good 350tpi car. that way he can have a bette car. He is trying to get it to keep up with my stang but he is not having much luck. im getting trick flow TW heads next month i cant wate for that lol.

Mongoose

iTrader: (2)

Do you have to swap the fuel pump sending unit?