84 Fiero 4 cyl engine interchange

[marcusfiero]

My son has purchased an 84 Fiero. The 2.5L (Iron Duke) (85-110HP) needs to be rebuilt, burns oil, spun bearing, etc. It has a 5 speed transmission. I don't want to give him too much power and I want to try to keep some fuel economy without spending a lot of money. So I want to stick with a four cylinder engine.

1.) I have been offered a 2.5L from a '91 Grand Am. It has a different oil pump which causes the oil pan to be a little deeper will it fit into the Fiero without a lot of modifications?
2.) Will a AMC 2.5L (117-120HP) fit into the Fiero?
3.) Will a 2.3L (Quad 4) (150-190 HP) fit into the Fiero?
4.) What are the draw backs from these other engines?
5.) If I use a AMC 2.5L or the Quad 4 will the transmission be able to handle the higher HP?

Thanks for your input.

 

[Oreif]

Which 5-spd is it? The 1984 Fiero's did not originally come with a 5-spd only 4-spd manuals. 1985 and newer had the 5-spd Isuzu transaxles. So someone swapped in a 5-spd. There are 2 that were used. One is made by Isuzu (and used with the 4-cyl engines from 1985 thru 1988) and the other is Getrag (used with the V-6 engines from late 1986 thru 1988). Both of the 5-spd manuals will be fine with a higher horespower 4-cyl. You can even go up to a V-6 with the 5-spd's. A lot of folks who do V-8 swaps use the Getrag 5-spd.

Not sure what would be required to swap the Grand Am 2.5L into the Fiero. As for slightly lower oil pan, Folks have swapped many different engines into Fiero's from the newer 4-cyl's, nearly all V-6's, all the up thru small block chevy V-8's and Northstar's. The oil pan sitting a little lower is not a problem. The mounting points of the engine can be the challenge. Chances are if it is a 2.5L iron duke like the Fiero it will have the same holes in the block as all the other 2.5L engines including the Fiero 2.5L. So you should be able to used the Fiero mounts. But like I stated, I am not sure what mods (if any) may be required.

As for 4-cyl swaps. The Fiero is very swap friendly. Just about any GM engine can be swapped. The 2.3L QUAD4 can be and has been done.
For info on this swap see:
http://www.gigaparts.com/users/fiero/index.html
http://www.calgaryfieros.com/OSGdocs/mod.Quad-4.html

I do not know if the AMC 2.5L will swap only because I am not sure if the bolt pattern of the engine will mate to the Fiero transaxle. Also you will need to be careful if the engine is a FWD block or a RWD block. The S-10 pick-up trucks also used the 2.5L but the RWD block has some casting differences so it will not mate correctly to a FWD transaxle.

The newer ECOTEC is also another 4-cyl engine swap to checkout. There are many different versions from high fuel economy to the supercharged or turbocharged performance versions. The nice thing is you can get a basic ECOTEC and later when he gets older he can increase performance if he wants.
You can find more info here: http://myfiero.oceanmoon.com/engineideasswaps/ecotec/full-ecotec-build-guide-wpns-links

The Fiero Store does sell a 2.5L rebuild kit as well:
http://www.fierostore.com/Product/Detail.aspx?s=52820&d=192&p=1
In case you just want to rebuild the original 2.5L and maybe add a little more power to it.
Here are some websites with more info:
http://myfiero.oceanmoon.com/how-to/engines/iron-duke-performance-faq
http://espolson.com/fiero/fiero-engine-swap/
http://ironduke7.tripod.com/IronDuke.htm

Sounds like you have a good base for a nice Father and Son project.

 

[marcusfiero]

84 Fiero engine interchange

Thanks for the information.
I believe that it is a Isuzu 5 speed.

I looked the AMC 2.5l engine up on Wikipedia and it basically said that originally AMC was using the Iron Duke in their Jeeps until demand rose. They took three years to develop their own engine but wanted it to be able to blot up to the same transmissions so they kept the same bell housing bolt pattern as the Iron Duke. They developed their engine for Jeeps and trucks not cars so I think it is probably beefier. Has anyone done this swap?
How much would it cost to swap in a basic ECOTECH engine roughly? Would it bolt up to the transmission?

I think for cost issues it would be best to stay with an Iron Duke, but 150 to 170 HP would be nice also.