Swapping in a 3.1

toadson · Post by **toadson** » Wed Sep 06, 2006 11:08 pm

Friday I am getting a 1990 Lumina with a 3.1 that Im planning on swapping into my Fiero. I have an 86 2m4 with 5 speed and Im hoping this will be a fairly simple swap. What will I need to made this swap go smoothly? Do I need to get some 2.8 motor mounts and alternator mount? From what ive read you need to do something different with the alternator mount. I couldnt find a whole lot on this swap, so Im hoping someone could point out some info for me. Also, is it possible to swap the hubs off the Lumina onto my Fiero? I would like to run the bigger bolt pattern wheels but I didnt know if this was possible. Thanks for the help!

donk_316 · Post by **donk_316** » Wed Sep 06, 2006 11:29 pm

wow where to start here...

OK... the genII 3.1L wont be a straight forward swap. UNLESS you swap over just the shortblock. (no head and intake) and use your fiero heads and intake

BUT then your compression is gonna be way out... lol!

OR you can swap the engine AND wiring harness AND ecm AND then wire to the fiero... not fun.

toadson · Post by **toadson** » Wed Sep 06, 2006 11:39 pm

I figured the wiring shouldnt be too bad since its OBD1. I was going to swap in a 2.2 from an S10, but that had OBD2 so I thought this would be much more practical. Havent people swapped in the 3.1 before?
Also, can I use a 2.8 flywheel?

Series8217 · Post by **Series8217** » Thu Sep 07, 2006 12:19 am

The full 3.1 swap is the exact same amount of work as getting a 3.4 DOHC installed with the exception of having to trim the decklid hinge to clear the 3.4 DOHC.

What transmission are you using for the swap? If you're using a Getrag (esp if its the one from the Lumina) the swap will be pretty straightforward. Use Fiero Getrag mount brackets and just fab a front engine mount. If you want to use the Getrag from the Lumina but don't have access to a Fiero Getrag you're going to need to do some shopping at www.rodneydickman.com. Note that you won't need to buy a rear transmission mount bracket; the Getrag and Isuzu rear mounts are the same (I just found this out after ordering a new Getrag one from Rodney.. d'oh!). If you're using the Isuzu 5-speed from your 86 2m4 you may run into clearance issues with the slave cylinder to the exhaust crossover pipe. This happens with the 3.4 DOHC, and I know the 3.1 crossover is in a similar place.
Your Fiero axles will work regardless of which manual transmission you use. I don't know what to use for the automatic (4t60?).
I don't think the Fiero transmissions send out the right pulses per mile from the VSS. . You may have to have the 3.1 ECM reprogrammed if you use a Fiero tranny.
You'll also need to fabricate a dogbone and exhaust system.
Wiring is the same as a 3.4 DOHC; in fact if the 1990 3.1 uses the 7727 or 7730 ECM with the weatherproof style connectors I think a 3.4 DOHC harness adapted to the Fiero is identical to the one you will be making. If you've wired a car before it'll be a no-brainer. Just takes time.
As for a flywheel, you'll need an 88 and later flywheel from any 60degree V6. Pre-88 are externally balanced and wont work with the 3.1.
I don't think the Lumina hubs are interchangeable. There is some car with a larger bolt pattern that you can swap the entire knuckle and hub assembly from to get like 5x115 or something. Maybe that's the same as the Lumina pattern.

Aaron · Post by **Aaron** » Thu Sep 07, 2006 1:11 am

Agreed with everything Series said. If you want to do a 3.1, you may as well step up to a 3.4 DOHC. For the same price and complexity, you get some 60 more hp, and more low end torque too.

I have a LONG build thread with A LOT of pictures in the tech section. It was pretty much a straight-forward swap, though the wiring was difficult for me (I'm a virgin at that). But Series walked me through every step of the way, and once you think about it, it really isn't that hard.

toadson · Post by **toadson** » Thu Sep 07, 2006 2:30 am

Im planning on using the Fiero Isuzu. Thanks for the info. I really dont want to swap a 3.4 DOHC in my car, I think they are problematic (Cousins GTP has one). I know this 3.1 will be reliable, which is what Im looking for. So I can use the flywheel off of the 3.1? That would be nice. Again thanks for the information.

Aaron · Post by **Aaron** » Thu Sep 07, 2006 2:45 am

toadson wrote:Im planning on using the Fiero Isuzu. Thanks for the info. I really dont want to swap a 3.4 DOHC in my car, I think they are problematic (Cousins GTP has one). I know this 3.1 will be reliable, which is what Im looking for. So I can use the flywheel off of the 3.1? That would be nice. Again thanks for the information.

The 3.4 is just as reliable as the 3.1, it is mainly poor maintenaince that causes problems. But as far as general reliability, the engine is essentially the same as a 3.1.

There's a reason we're all telling you to go with the 3.4. The swap is just as easy, and you'll get significantly more power at every RPM. The only downside, is, well, trying to control the car from going sideways everytime you step on the gas.

Series8217 · Post by **Series8217** » Thu Sep 07, 2006 4:53 am

I never said go with the 3.4 instead. I just said its the same amount of work so he can get an idea of what he's getting into.

I don't think I'll be doing a 3.4 TDC swap again except for helping others do theirs. I'd like to have a 3100 or 3400 turbo someday. They're lighter and the engineering is much better. With a turbo they'll still be making plenty of power.

Anyway, yeah if you have the 3.1 flywheel that will work fine. Any reason why you're not using the transmission that's in the Lumina?

The Dark Side of Will · Thu Sep 07, 2006 9:03 am

If the 3.1 in the Lumina has a manual (RARE in those cars), then use that manual. That's the same internally as the Fiero 282... only the shift linkage is different.

Aaron · Post by **Aaron** » Thu Sep 07, 2006 9:06 am

The Dark Side of Will wrote:If the 3.1 in the Lumina has a manual (RARE in those cars), then use that manual. That's the same internally as the Fiero 282... only the shift linkage is different.

The only time the Lumina ever got a manual was the 284 with the 3.4 DOHC. The 3.1 in a Lumina never got a stickshift. In fact, I don't think ANY W-body with a 3.1 could ever get a manual.

The Dark Side of Will · Thu Sep 07, 2006 9:10 am

Yeah, that's right.
The Grand Prix I saw with a stick was a 2.8 Gen II.
Stoopid GM.

The 3.1 FLEXPLATE cannot be used with a manual transmission, of course.

Pyrthian · Post by **Pyrthian** » Thu Sep 07, 2006 9:36 am

I started to do a full 3.1 swap from a '94 Lumina. after going thru all the crap I had to do, I scrapped it, and went with just the block. I put in the iron head pistons, and used my existing 2.8 heads. this way, I can use the existing wiring, ECM, mounts, etc. - basicly looks like a typical V6 Fiero.

beleive me when I say - you will disappointed. and I have done ALOT to my 3.1

you are doing 200+ HP's worth of work for < 140.....

Kohburn · Post by **Kohburn** » Thu Sep 07, 2006 9:46 am

same deal with the 3.4 pushrod swap - its only good as a replacement for a rundown broken 2.8 shortblock

toadson · Post by **toadson** » Thu Sep 07, 2006 2:42 pm

Thanks for all the replies. I don't want an automatic tranny in my Fiero, thus why Im sticking with the Isuzu. If I remember correctly, dont the newer 3.1s have 160 hp? I wonder if you could put a newer intake on the older style 3.1 or if the heads are different. Its probably not an easy swap like Im hoping. I really cant afford much more than 200 dollars for an engine right now, thus why Im opting for the 3.1. I know if wont have a lot of power, but right now my Iron Duke is burning a quart of oil every 100 miles. I know for sure that this engine is good and does not burn oil. It will take a lot of work, but thats just more experience in my opinion. I have another vehicle to drive so its not like Im limited on time. A turbo 3.1 would be cool but I doubt I will ever get to do that. Im sure this will be one of many engines I will swap in the Fiero. I like the idea of a 4.9 Cadillac V8, but only time will tell what will happen. Thanks again for the input guys.

Kohburn · Post by **Kohburn** » Thu Sep 07, 2006 2:49 pm

the newer engines are completely different animals with only a few interchangable parts.. it'd be just as difficult as a 3.4dohc swap or closer to a 3800sc due to the alternator location and OBD2 wiring

the 4.9 is great on automatics - not as good for stick shifts

Pyrthian · Post by **Pyrthian** » Thu Sep 07, 2006 2:49 pm

toadson wrote:I have another vehicle to drive so its not like Im limited on time.

the most important part of any swap.

The Dark Side of Will · Thu Sep 07, 2006 4:18 pm

Three kinds of work: Quick, Cheap, Good.

You can have any two.

Aaron · Post by **Aaron** » Thu Sep 07, 2006 6:19 pm

The Dark Side of Will wrote:Yeah, that's right.
The Grand Prix I saw with a stick was a 2.8 Gen II.
Stoopid GM.

The 3.1 FLEXPLATE cannot be used with a manual transmission, of course.

Ahh, you're right, I forgot about the boat anchorized GPs :thumbleft:

Series8217 · Post by **Series8217** » Fri Sep 08, 2006 3:35 am

toadson wrote:I really cant afford much more than 200 dollars for an engine right now, thus why Im opting for the 3.1.

You need to just get another Duke, then.

You will run out of money before you finish this swap. Custom fuel lines, aftermarket clutch, all the bits and pieces, custom exhaust, custom front mount, wiring supplies... it all adds up and you aren't going to get it all if $200 for a motor is reaching your upper limit.
I just sold a perfectly running 88 Duke with 50,000 miles on it for $100. They're out there. Look for someone who's doing any engine swap out of desire for more power (rather than replacing a broken engine). They'd love get rid of their old powerplant.

toadson · Post by **toadson** » Fri Sep 08, 2006 11:45 pm

I got the car today. I started taking the engine out and will finish it tomorrow. Its disconnected from the tranny, exhaust, and all the major things and just needs a few more things disconnected until its ready to come out. I found out that the engine is form a 94 Lumina, but I believe its just the same as a 90. I think I read somewhere about buying a Beretta flywheel form Oreillys for 50 bucks without a core charge. Anybody know anything about this? I dont know why I was thinking the auto trans flywheel would work for a manual, I was braindead I guess lol. I havent messed with manuals so I just forgot that they use a much heavier flywheel. I might put up some pics of the engine after I get it out, even though its nothing special. I really wish I could find a thread about swapping 3.1's. Thanks for all the help

Real Fiero Tech

Swapping in a 3.1

Swapping in a 3.1

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