4.5l Allante engine (Page 1/6)
Pauljt SEP 19, 08:59 PM
Hello everyone. Been lurking for a while and gathering info. Awesome site to come to for a Fiero education. Can someone tell me if the 4.5l install is basically the same as the 4.9? The engine is out of a 1991 Allante. I've found tons of info on the 4.9 swap but nothing on the 4.5. I have a 1984 four cylinder. I'm not even sure if the swap is feasible at all on that year Fiero. Any info would be appreciated.
Spoon SEP 19, 11:47 PM
Welcome friend. You've come to the right place. Lots of engine swaps have been done on this site. First we need to know what transmission your 4 cylinder 84 Fiero has. Automatic or stick?

** I'm sure others will chime in with useful information for all your questions as well.

If it's a stick go to the front of car and lift hood. On driver side fender well you will see a white sticker with a bunch of numbers & letters on it. Look very carefully for 3 characters showing MY8. Take pic and upload it. If you see the MY8 designation all is not lost. This was the 4 speed Economy transmission for 1984 only. It has a weak case and the thought of connecting a more powerful engine to it is frightening at the least.

I have a spare M17 4 speed with 88k gentle miles on it that is a much stronger transmission. If interested just PM me and perhaps we can cut a deal or swap, trade, etc. If you have an automatic or don't see MY8 anywhere then I refer you back to line ** of this post.

Again welcome to the forum.
Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

Will SEP 20, 09:26 AM
If you're into 4 speeds, a franken-gearbox with the M17 case, 1st gear and 2nd gear with the MY8 3rd, 4th and final drive is basically the ideal stickshift transmission for a 4.5/4.9.

The Allante 4.5 will have the Allante intake, which is different than the PFI 4.5/4.9 intake. Beyond that, the 4.5 & 4.9 swaps should be identical.
olejoedad SEP 20, 09:34 AM
All 84 manuals have a smooth case. The ribbed case was introduced in 85.

One issue you will have is the location of the 84 C-500 connector, it should be moved to the later model location by extending the wiring. The 84 also has only one fuel injector power feed, and no Battery Junction Terminal, which is easy to add.
Pauljt SEP 20, 10:37 AM
My Fiero is a standard four speed. The only designation i could find with "m" as a starting letter were M19 and MM4. Thank-you for responding. This is gonna be a winter project but I don't want to get too far over my head.
olejoedad SEP 20, 10:56 AM
The standard 4-speed (M19) has a 4.10/1 final drive. Its not ideal for a low revving, torquey engine like the 4.5.
I would suggest going with the later 4-speed (M17, 3.65/1), as no changes to the shifter, cables, mounts or backup light wiring will be needed.
Pauljt SEP 20, 11:11 AM
Any thoughts on going with the automatic that is with the 4.5 engine? I know the standard is more fun but read have the automatic.
Raydar SEP 20, 11:16 AM

quote
Originally posted by olejoedad:

The standard 4-speed (M19) has a 4.10/1 final drive. Its not ideal for a low revving, torquey engine like the 4.5.



...except for maybe frying tires (or breaking axles or tranny cases) at will.


quote

I would suggest going with the later 4-speed (M17, 3.65/1), as no changes to the shifter, cables, mounts or backup light wiring will be needed.



Second this.
A five speed is also an option, but it also will add cost and complexity.

(I drive a 4.9 with Allante intake, and a 5 speed. It's not TOO difficult, but will add several hundreds of dollars to the cost of the installation.)
Johns 4.9 SEP 20, 02:11 PM
Hi Pauljt,
The Allante engine you speak of is a great engine for a Fiero swap. It has the same big valve heads and compression as the 4.9 but has a shorter stroke. This allows for more revs. Swap is the same between the 4.5 and 4.9 unless you go manual. The 4.5 engine is externally balanced on the back half of the crank and internally balanced on the front part of the crankshaft. Therefore the two engines have different balance requirements. Bring your 4.5 engines flexplate and the flywheel you plan on using to your local machine shop and have them match balanced. Now you can pretty much use any of the Fiero and related transmissions. Good luck!
Cheers,
John

[This message has been edited by Johns 4.9 (edited 09-20-2019).]

Pauljt SEP 20, 10:27 PM
My research tells me that the M17 transmission is from the 86 model . What about the 85 four speed....or is that one the same as the 84 with the exception of the beefed up casing?