So just picked up a 93 3.1L motor to replace the "missing" 2.8L in my 87 GT. Been reading all the threads here on the 3.1 swap and the differences with the iron heads, and aluminum heads. I understand all the issues w/ the iron vs alum parts and what I can/can not swap.
I did have a question about the intake manifolds. Other than leaving the stock 3.1L manifold on the motor, will any other 3100/3400/3500 intakes fit. I'm sure they wont, but I just wanted to ask since I know I can't use the stock 2.8L manifold b/c of the alum heads.
Also, i've read about using the 2.8L exhaust mani's if I "slot" the bolts holes, anyone have any pics of this or can anyone recommend any other ideas that may work better?
Thanks in advance.
Rob
EDIT: Thought I'd add some photos of the 3500 exhaust manifolds sitting on my 3.1L motor. They fit fine and the "D" port is slightly larger than the "O" port 3.1L exhaust ports.
[This message has been edited by qwikgta (edited 09-17-2020).]
I think that a lot of the 3x00 parts will interchange, but I'm not certain. There is a FB group for 3X00 swappers. Someone there should be able to answer your question with certainty. Try this link... https://www.facebook.com/groups/639303959567713
The gen3 3x00 intakes will not fit the '89-'94 gen2 heads. They are close, but not the same. Easiest way to run the 3x00 intakes may be to grab some cheap 3x00 heads and swap the whole top end.
Thanks guys. That is what I figured. Not really planning to upgrade this one. I picked up a low mile, damn near perfect 87 GT the other day, only downside, no motor. The original owner sold it to a kid in the Air Force and he drove it for 8-9K miles over 3 years and never changed the oil. I spoke with him on the phone, he just drove it, put in gas and drove it some more, zero maintenance and it spun a bearing. He pulled the original motor/harness/ECM as a package and then life got in the way and he had to move. So it tossed the motor and bits and then sold the car. I got it from my local Pick n Pull out of their "for sale" lot.
Now i'm just trying to get it up and running and I just want to get out of it, what I put into it. I wanted to find a 2.8L but have had no luck, so I decided to pull a 3.1L from a 93 Buick. Its the Gen II w/ aluminum heads but I can use the Fiero motor/trans mounts and I got a 88 flywheel to mate it up with the original Getrag trans.
Having read tons of threads on Pennocks, I was 50/50 that I could just remove the non-Fiero bits off this 3.1 and put on all the extra crap I have for a 2.8 and make this a runner, but after I got home and started reading about it I found out that I can't. I knew to stay away from the 3x00 motors b/c of the difference but I thought the Gen II 3.1 would work. Sticking with the low cost budget on this one i'm not going to rebuild the motor w/ the iron head bits to turn this into a Gen I 3.1, I just hope that I made the best choice on this motor. Still don't know its condition, only that it was running 3 months ago and has 80K on the odometer.
I contacted Ryan at Sinister for info about the tuning and wiring and he mentioned that the Gen II 3.1 did not come w/ a manual trans so I'm looking into whether or not I can get the harness/ECM off a 90-92 Fbody 3.1 (7730) and use that instead. Still waiting for his reply.
Originally posted by qwikgta: Having read tons of threads on Pennocks, I was 50/50 that I could just remove the non-Fiero bits off this 3.1 and put on all the extra crap I have for a 2.8 and make this a runner, but after I got home and started reading about it I found out that I can't. I knew to stay away from the 3x00 motors b/c of the difference but I thought the Gen II 3.1 would work.
Huh?
This here is my Gen II 3.1 engine dressed up in Fiero parts:
Yes, it has a compression ratio of 7.4, and it runs fine.
Yes, there's a turbo, but most of the time when the turbo isn't spooled, the engine works just like any other naturally aspirated engine.
[This message has been edited by pmbrunelle (edited 08-24-2020).]
I did a 3100 SFI aluminum head swap in a pre88. I used the stock Fiero exhaust manifolds and cross over pipe. I believe I used the entire exhaust system. Yes it will bolt on and run fine. BUT I did not have yhe car for long so the reliability of this set up is unknown. I did this one quick and dirty on the cheap and it was a HUGE upgrade over the stock 2.8. I also converted the 4 speed auto over to a 5 speed manual and that was even better.
the Gen II 3.1 did not come w/ a manual trans so I'm looking into whether or not I can get the harness/ECM off a 90-92 Fbody 3.1 (7730) and use that instead.
Rob
The Gen 2 3.1 came with a getrag 5spd in the Cavalier z24.
Since it's a Gen2 engine, you won't be able to mix-n-match parts from the 3100 / 3400 engines (unless you swap over the entire 3x00 top end). IIRC, the Gen2 engines were 2.8 and 3.1 liters. The Gen2 2.8 heads and manifolds should interchange with the 3.1.
You could put the Fiero heads, manifolds, etc onto the 3.1 short block, but then the compression ratio would be really low. Yeah, it'll run. But it'll be a dog. If you just want to be done with it, that would be the way to go.
[This message has been edited by Blacktree (edited 08-26-2020).]
The Gen 2 3.1 came with a getrag 5spd in the Cavalier z24.
yep, the 93, 3.1 I pulled uses the 9396 ECM and in that configuration it did not come with a 5 speed. The 3.1 did come w/ a 5 speed using the 7727 ECM, so tomorrow, I'm going to grab a 90 3.1 harness/ECM off a Chevy Lumina. Once I get that harness/ECM I can wire up this motor and send Ryan the ECM for a reburn of the 7727 w/ manual tune. Then I can get the motor up and running.
