98 GTP swapping non S/C 3.8

**brktracer** · 12-28-2012

My 98 GTP locked up the other day not sure why yet, no noises, miss, or anything just stopped and engine is locked. I have a 99 Non supercharged 3.8 I kept out of a wrecked Gran Prix w/ the computer. Would like to put the non supercharged in for now until I have time to rebuild the other one.. Looks like the wiring is the same with exception of the supercharger wires, any issues I would run into?? I know I am in line to get smacked for not putting the S/C motor back in, for now its a matter of time and money.. Thanks!!!

Mark
1998 GTP
1967 Firebird Super Gas
1968 Firebird 400 Ram Air III

**TLSheff** · 12-28-2012

You'll need to have a tune or PCM swap as well. You won't be able to run that motor on the GTP tune. If you like the idea of the tune and don't mind some wrench work, pull the Supercharger, Heads, and Lower Intake Manifold. Have the heads checked over and make sure they weren't the problem with the motor and if they check out swap them over onto the NA motor.
You will need to make a intake so it can breathe better, and get some headers so it can flow well, but you'd be back to the same power.

search "top swap" and you can get lots of info on it
http://www.grandprixforums.net/top-s...info-7763.html

**RivMan** · 12-28-2012

You should be able to bolt the Non-SC motor in without any issues. A couple things I can think of that you'll need though are a GPGT Torque Converter and a GPGT PCM of the same year as your car. Other then that I think it's just as simple as swapping it out.

-Rob

**Fivefingerdeathpunch** · 12-28-2012

Yes he can just throw the motor in, but there is alot more to it. NA block is high compression, he'll have to work around that.

**darkhorizon** · 12-28-2012

My brain hurts.

Op.... all you need to do is dremmel the flex plate bolts and use your gtp injectors... you will not have to change ecus or anything. If you want together fancy and swap the na pcm in go for it and use the na injectors.

**matt5112** · 12-28-2012

Originally Posted by darkhorizon

My brain hurts.

Op.... all you need to do is dremmel the flex plate bolts and use your gtp injectors... you will not have to change ecus or anything. If you want together fancy and swap the na pcm in go for it and use the na injectors.

Maf's are different.

**brktracer** · 12-31-2012

Thanks for the answers everyone. I have all the parts still from the N/A including the PCM. I even have the trans but didnt want to go that far.. Havent taken the other motor apart yet so not sure what went wrong.. Strange part is I was on cruise at 70, engine temp ok, no light, not a miss or anything just a quick clank and done.. Hope the heads survived.. Find that out later.. again thanks for the advice!!

**BillBoost37** · 01-02-2013

Been there, did this to my car.

Swap the flex plate so the bolt pattern matches the torque converter. (balance is a touch different, but not enough to cause any issues)
Have the pcm tuned for the 2.93's vs the 3.29's that were in the GT if you throw codes
And I'd tune the pcm for the difference in load based on the gear change as well.

Overall it's quick and easy.

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