3.1L performance

[Slugger17]

I want to put a 3.1L from a 91 or 92 Chevy Lumina APV into my 84 Fiero Sport. It has a 2.5L and 4 speed tranny but the previous owner said there was a fire and thats about all I know other than it wont start so I have to do some electrical troubleshooting. My main question is is there any performance parts for the 3.1L? I have been doing a lot of different searches on the internet and cant really find anything. Also what do I need to get to make the 3.1L fit on the cradle?

[Ragtop_Renegade]

Did you say a 4 speed tranny? If you have a 4 cylinder 4 speed, that would mean you have an 84 Fiero, is this correct? A V6 won't fit under an 84 decklid, you need modify it with a hump for the intake plenum to clear. As far as performance, little was done for the 2.8/3.1 (they are basically the same engine, only the bore and stroke are different) Though turbocharging/supercharging options are available, a lot of fabrication on your part is required, few if any "bolt on" kits exist. Just an FYI, the 3100 SFI, the second generation 3,1L V6, built from 1995 untill around 98-99, is the same as the 3.1 except it has aluminum heads (as far as I know, all Lumina APVs and TranSports had cast iron heads, any other first gen 3.1 would have aluminum) with splayed valves for better flow, a better water pump and roller lifter cam. The 3100SFI puts out more HP then the older 3.1's The 3400 SFI, big brother and replacement for the 3100, is even more powerfull with it's bigger displacement and needle bearing rocker arms. All 60 degree V6's (2.8,3.1,3100,3400,and the new 3500) bolt right in to a 85-88 Fiero, but I'm not too sure about the 84...... One thing's for sure, your new engine will need a wiring harness and ECU, as the 84 Fiero is not wired for a V6.

[Slugger17]

So the 3.1L is a bad idea and I have been doing a lot of research and the Iron Duke bottem end is weak. I was thinking about the 3.4L or a V8 swap but since the 84 is a abad choice because of the lid I was thinking about hunting aroud for another 2.5L. I was reading about an SD 2.5L but cant find too much info on it. Do you know anything about that. It is a 4 speed tranny and it is an 84 sport. the door said 86 but I looked at the VIN and checked online VIN decoders for proper verification.

[Ragtop_Renegade]

The 2.5L Super Duty was a racing engine designed by Pontiac. It's basically an Iron Duke on steroids, thicker block, stronger internals ETC. They're built for rear driven front engine cars, so the starter is on the wrong side for a Fiero, but it's not too hard to move it to the proper side. (measure twice, drill once) I haven't seen much about them in recent years, but you might be able to buy one new from Pontiac. New or used, they are quite costly, but if you hang around your local 1/8 mile oval enough, and find the right guy who's lost one too many times, you might get one out of a legends stock car cheap. Still, racing or not, it's only a 4 banger, and unless you nO2 the s*it out of it, you'll be lucky to manage 200hp. As far as a normal 2.5, I know they say the bottom end is weak, but as many as I've abused, and I do mean ABUSED, I've never thrown a rod or spun a main, just nuked a head here and there from running it too hot.

The decklid thing isn't THAT bad of a setback, a generic hood scoop or "power bulge" can be installed over the hole you'll have to cut out to fit a 6 or 8 and fiberglassed in, so don't give up on that idea. One thing I did forget, most of the newer v6's have a cast aluminum timing cover with a water pump housing built in. This needs to be retrofitted to a 2.8 external pump and stamped steel timing cover, as the cast version doesn't clear the right strut tower.

[Mailt4]

Hey Guys,
Ragtop, you seem to your sh@#$t man, here is the question: I have a 85 with 2.5L 5spd with a Ferrari 308 skin on it so I want a little more power without doing a Sh$#@t load of work, is there anything to work with on this 2.5L????

[Ragtop_Renegade]

Just about anything worth doing on a 2.5 is gonna be work... Bolt on performance options just don't exist for this engine. The options for decent power are few, either custom made performance for the 2.5, or swap in a different engine. One general rule here always applies, the easier the job, the more money you'll have to spend to do it. There's fast cheap, and there's easy cheap, but fast and easy come cheap just don't happen.

[fierangero]

i found some decent performance goodies for my 2.8, most of it on the fiero store. as far as the turbo, here is the url: http://members.shaw.ca/turbofiero/index.htm

[goatnipples2002]

For a good performance upgrade for the v6 guys get a 92-95 3.4 pushrod camaro/firebird engine. A 3.1 has a different stroke than the 2.8 and that accounts for the 15hp increase and a 3.4 has a different bore and stroke whick accounts for the 20hp/40tq increase. The 3.1 would be a waste of money unless it is for less than $500. And the iron duke is ONLY good for commuter drive not drag racing. In my opinion the 2.8 is junk also. I've been through 2 so far and now I'm saving for a spec stage 3, a 3.4 pushrod,nitrous and a trueleo intake. For the 2.8 if you must keep it get a spec stage 2 or 3 clutch and the truleo intake. The trueleo will allow your engine to rev to about 6.5k if it can handle that. The main problem with the 2.8 is the oiling system.

[Ragtop_Renegade]

Agreed, GM improved oil valleys a LOT when they retrofitted the 2.8 block for the 3.1

[MrPbody]

Actually, the 2.8 and 3.1 share the same bore. The difference in displacement comes from the longer stroke in the 3.1.
The 3.1 block is also improved over the 2.8 in the area of physical strength. There are extra ribs cast into it both inside and out.
I have a real nice package for the 3.1. While not a racer, it drastically improves the low-speed and "seat of the pants" performance in Fiero.
Fiero SEs came with 4-speeds as the "base" transmission and the 5-speed as an option, at least through '86. Mine was a 2.8 version with a 4-speed.

[goatnipples2002]

My bad I got my words confused trying to type and think.....yes you are right the stroke is different between the 2.8 and 3.1. Editing now.

[bigjerr]

Found a site that seems to have some decent fiero engine information. www.freeengineinfo.com Search for fiero. It has some performance tips on 2.8 and some on 2.5 iron duke engines. Enjoy!

[thumper_65590]

ok, here is my question, and this seems to be the right thread for it. I have an 87 with the 4 cyl and an auto tranny. I am putting the tranny out of a 98 Cavalier(4 spd Auto) in it, and I need to replace the engine, as I blew the 2.5 last night. I'm looking for a motor that is going to give me decient performance and good milage with the new tranny, Any suggestions out there?

[fierangero]

dont put anything in thats newer than 95, those are OBDII and are for the most part incompatible with your OBDI vehicle. not even sure if a 98 cavalier tranny will bolt up to the iron duke...not to mention the linkage and such from switching it from a FF to an MR platform

[rigo430]

I have a 84 Fiero SE that i want to upgrade the engine. I have a 89 Grand Prix with a 3.1L v6 that has a bad transmission. I was wondering how hard it would be to swap out the Fiero's current engine with the Grand Prix's. Also what would be required to be able to fit the v6 into the Fiero. I am able to make a lot of custom parts to fit the engine because I have access to a few CNC machines. With the engine would I need to use the computer from the Grand Prix? Also what is the offset on the rims for a Fiero? I would like to get new rims for it possibly so i could use the very new tires from the Grand Prix. If I could find a place that sells wheel blanks that would fit I would be able to make my own custom rims.