Question on 1990 5.0 IROC TPI swap

[PBGBodyFan]

From what I remember the TPI harnesses went from separate stand alone engine/computer harnesses, like our g-bodies are, sometime in 88’ or so for the f-body. The one harness setup would be harder for a conversion, if you can find an earlier one but if you want to keep it speed density you basically need an early 88’ harness, or go mass air flow with and 85’-87’ harness, but don’t use the 85’ ECM since they are inferior ....it’s a slippery slope 😃. I think I retained alot of (useless, some useful) info about TPI swapping from when I did mine nearly 20(!) years ago. I haven’t done much of anything on mine in almost 10 years just turn the key and go.

For a stockish mild motor TPI is fine, if I’m swapping engines(TPI or not) I probably wouldn’t bother with a 305 when a 350 is as much work and not expensive to source. Even if you find one with crappy swirl port heads you are a little ahead, TPI 350 iron heads should be very cheap or if you are willing to spend a little money on an intake, Vortec heads are a great budget head as mentioned.

 

[Cuse99]

Not sure where you got the 275hp number but 305 TPI was nowhere near that.

I found a YouTube video where a guy put what he claimed was a stock 305TPI on the dyne and it made 265hp. (I thought I heard 275, but I double checked) After some bolt on parts were added the motor made 350 hp. But the bolts ons are not cheap. Wikipedia says this motor made between 215-230 hp. If I get this motor I'm sure I can figure a simple way to get it to 275-300 without too much fan fare. The low end torque is where all the fun is on a daily driver. If I can get this cheap enough and spare parts are readily available, I might just do this.

Do we have a stick or vid on how to connect a modern wiring harness to an older wiring harness? I know this is done on an LS swap, I can't imagine it would be different for this TPI motor.
Thanks again for all the responses.

 

[PBGBodyFan]

It’s quite a bit different, or can be, if you have and want to use a stock TPI harness, depending on the year/style. I ran mine where the stock Monte computer harness goes, running through the same firewall hole and placing the ECM in the same stock location. Some new wires need to be run and spots added to the fusebox but you can have it look/operate close to the stock harness due to the era it was made. Get wiring schematics and study them for your car and the donor vehicle, it isn’t something a Youtube video will show you.

 

[84dragcutlass]

The engine swap isnt too complex, the computer and making everything happy with that aspect will be your biggest thing with it. The TPI swaps used to be the "big thing" but have since died down once LS swaps got popular. The engine will just drop right in and if you've got the harness then it will be a pretty simple deal. If you wanted to get away from the factory harness and ancient computer you can go to a stand alone unit to control the fuel injectors which i would probably recommend for tuning reasons. Injectors are decently expensive but most of the TPI stuff is pretty available however i would look out for the intake runner tubes to be dented because those are a pain to straighten out. The 1990 i believe had the cold start injector which just spit a little fuel to help cold starts so depending on if you need that or not you'll have to take into consideration provisions for that. Other than those things its just a SBC and simple as can be, as you said they are built for low end torque and run out of steam fairly quick but are a good street engine. They still make intakes to use the stock TPI system on Vortec heads and i've heard those will wake them up some if you do it right. I was going to do that on my IROC but that project is on hold.

 

[ck80]

I found a YouTube video where a guy put what he claimed was a stock 305TPI on the dyne and it made 265hp. (I thought I heard 275, but I double checked) After some bolt on parts were added the motor made 350 hp. But the bolts ons are not cheap. Wikipedia says this motor made between 215-230 hp. If I get this motor I'm sure I can figure a simple way to get it to 275-300 without too much fan fare. The low end torque is where all the fun is on a daily driver. If I can get this cheap enough and spare parts are readily available, I might just do this.

Do we have a stick or vid on how to connect a modern wiring harness to an older wiring harness? I know this is done on an LS swap, I can't imagine it would be different for this TPI motor.
Thanks again for all the responses.

No offense but Wikipedia isn't the best source for reliable info, nor is billybob's you tube claiming to have the baddest mullet engine outta the trailer park (camaro heaven).

On a serious note though, you should be searching threads on thirdgen.org

Lots of guys are posting dyno slips over the years. They report as low as 170s hp on untouched motors.. After doing hundreds if not thousands of dollars in mods they're reporting 210-220hp.

I WOULD believe a stock 305 tpi putting out 270 lb ft torque. But no way on horsepower unless there's a nitrous shot in there somewhere.

Examples:

305 TPI Dyno Results After Upgrades - Third Generation F-Body Message Boards

Tech / General Engine - 305 TPI Dyno Results After Upgrades - After reading a ton on the forum here, I changed my 305 engine upgrade plan to include only those bolt on items I could eventually transfer to a 350 were I ever to go that route. The collective wisdom on the site convinced me not to...

www.thirdgen.org

That's intake runners, headers, ported intake, Flowmaster exhaust, gutted cat, cam swap, egr delete, and got up to 237hp.

My 305 TPI Dyno Number - Third Generation F-Body Message Boards

TPI - My 305 TPI Dyno Number - Hey Guy's. I have been on here for several years but haven't ever posted. Since I actually have some thing to say Now I am:lol: I have been messing with my Iroc on and off for several years and its finally started coming together. Mods (As I can remember them)...

www.thirdgen.org

Edelbrock TES, 3 inch under the car/ Loudmouth muffler/ no Cats, Owner ported/simesed Plenum, Simesed SLP Runners, Simesed/Ported stock intake, adjustable regulator, 1.6 Roller Tip rockers, underdrive pulley, de screened maf, gutted airbox/ K&N filters, 160 Thermostat/cooling switches

And that got 217 hp.

 

[ostrich]

I have an 85 IROC that came with a TPI (1st year), and have a lot of time in swapping, etc. Here are my thoughts/experiences.
The motor and trans physically shouldn't be a problem in a Gbody. The wiring/ECM is a little harder depending on what your goals are. For a stock 90 TPI it's MAP so you will need an ECM (730 ECM) from a 90-92 Camaro. Be careful with the 91-92 PCM's they have VATS in them and require programming to disable or a 91+ steering column and VATS module & key. If you're able to source that you should be pretty good. Like the Gbodies the Camaro has the C100 bulkhead connector that is separate from the PCM harness, so you can use that for sensors gauges etc. Stay away from the 85 ECM, it's slow, and a pain to work with. If you use 86-89 you will need a MAF sensor. If modding I found the 730ECM hard to program, burning chips etc. (never did get good at it, also limited support out there) I eventually converted mine to 'LS' electronics using 'EFI connections' conversion pieces. I re-wired it with a 2002 harness and use HP Tuners for programming now. The car never ran as good with the old ECM. It's still a SBC, (383) Vortech SQ, I did swap out the TPI intake for a TPIS miniram for more upper RPM power. A good resource I've used over the years is www.thirdgen.org. Good luck, I do like the look of a TPI under the hood!!

 

[Cuse99]

I sincerely appreciate all the responses. All good food for thought, but I have 1 last question....
How hard is it to tune these 90's TPI systems? Looking at all the new modern stuff, its all self learning. I wouldn't get the same deal with the older stuff.
Thanks in advance.

 

[motorheadmike]

I sincerely appreciate all the responses. All good food for thought, but I have 1 last question....
How hard is it to tune these 90's TPI systems?

 

[ck80]

Ouch, it appears you misread the question...

He asked how hard is tuning a factory stock TPI, not what are ls motors steaming piles of...

 

[oldsmobile joe]

Ouch, it appears you misread the question...

He asked how hard is tuning a factory stock TPI, not what are ls motors steaming piles of...