84 Fiero V6 swap open to any response. (Page 1/1)
Saggy OCT 17, 04:46 PM
I'm wanting to do an engine swap, and would really appreciate some advice on the more time consuming research. Something to point me in a direction, or knowledge of more difficult aspects of an engine swap. I'm wanting a V6 that runs 300 ft-lbs stock, with room to tune past 500hp alongside other upgrades after the swap. I could use any advice on sturdy transmissions, other drivetrain components like axles, engines, suspension, even stuff like rims, paint, bodywork, or an option to replace my old struggling 84 pop-up motors. I'm not a fan of sacrificing too much power, fuel consumption, longevity, or ease of repair for one another. I would enjoy something newer, and have been thinking about the Nissan VQ engine. I'm also open minded to electric if you happen to know a really good idea.
I do plan to daily drive this car for part of the year, and it would be nice to go on some road trips with it. Currently it has the 84 duke with the 4 speed and so many little issues to track down I figure it's not worth much more than driving around town. Previous owners really did a number on the drivetrain by neglect and poor mentality, however the structure of the car is in beautiful shape, suspension is strong, and the brakes are fair. The a/c compressor was removed, however the rest of the system is still there and appears fine, is it worth fussing with, or should I just replace it entirely with the swap?
I believe the previous owners swapped the differential at some point, as the car redlines at 85mph and is not well suited for highway driving. The Haynes repair manual neglects to include anything on how to get into the transaxle, I cannot find much information on the internet. I also believe the 84 4 speed has a relatively weak casing, so I would need a new transaxle for this job. Is a FWD transaxle something I can do, or would it be much easier to buy a proper rear mounted transaxle? I'm interested in AWD, but have limited ideas of what all would be in the way, short of the fuel tank. This would take some fuel efficiency, however it would add some weight to the front of the car, and greatly improve handling, so I'm happy to spend some extra time on this, but if the Fiero is designed without this in mind, and it would be more difficult or expensive than the swap itself, I'll avoid it. It would be nice to find a car with most of what I need, and swap it in, however I'm not sure if it would be possible to reverse a drivetrain like that, and finding a mid engine vehicle making that kind of power for that price is a bit of a pipe dream under my current knowledge. I desperately need information on transaxles in order to do this to my car.
The team behind the Fiero wanted the car to be worthy of sharing a garage with Porsches and Ferraris, however GM disagreed as this would drive down corvette sales, so they limited the budget of the Fiero. and it was destine to become a sporty economy car. The Fiero was ahead of it's time, and includes futuristic design features still not commonly seen on cars today, and I believe this car can be so much more than the stock duke would let you believe. Apparently, back in the day it was possible for about $10k to order the parts needed to upgrade the duke into the super duty iron duke racing engine pushing 300hp, and they were seen racing up around 140mph.

From when I trailered it home, this highlights the bodywork I briefly mentioned earlier. The previous owners had it roll into a trailer, as when I bought it it had no breaks. I'm thinking of grabbing another $600 marketplace Fiero in the far future for an off-road build as well as parts car, and would swap the panels, unless you have a better idea. I plan to paint the car myself, with the proper tools, and do a better job than what the local shop did to my buddy's car. My Fiero was previously painted poorly, and from what I can tell without primer, so it could certainly use a fresh paint job. Maybe a silver & yellow, or similar to what it has now? A graphite grey with red accents would look cool. It'll be a little while before I get to bodywork, so I've got a while to think about it.
Patrick OCT 17, 05:18 PM

Haven't you already gone down this road?

84 engine swap
Saggy OCT 17, 06:24 PM
yeah but that was a bit of a bad post and did not include enough information. I'm not a fan of scrapping my car as the replies suggest. I know the practical value of this car is much higher than it's monetary value, and I could just buy someone else's project but I'm not going to do that. I want to build my car, that's why I bought it. I know it will be a lot of work, and research. I'm happy to spend the next 2 years building this car, and maybe it drives by then. Right now I'm hoping for some advise and direction to my goals.

[This message has been edited by Saggy (edited 10-17-2022).]

Dennis LaGrua OCT 18, 11:11 AM
The amount of money that you will spend on this swap will always be more than the car is worth. The 84 model year seems to be in light demand. Your expectation for 300 ft lbs from a stock V6 and 500 ft lbs are unrealistic. Only a couple of high buck 3800SC's have done that. The LS4 V8 can provide the highest horsepower stock and it can be modified but its a lot of work. Decide your budget before you start and that should lead you in the right direction.

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theogre OCT 18, 12:47 PM
84 had more transmissions options then other Model Years.
This is likely why the engine runs higher RPM on highway. Assuming the Tach is even accurate... Fiero and other GM Tachs have their own issues.

If stick likely has M19 trans on RPO tag.
If Auto likely has MD9 + Fxx w/ low final gear, chain set or both.
See my Cave, Gear Ratio

Can "simply" change the trans to get better gearing.
Stick can use 5 speed but harder to install w/o another Fiero for exact shift cables etc.

⚠️ Engine Swap in 84 has more issues then later Fiero.
Start w/ Cradle and Wiring only made for 4cyl and needs more mod to install even a Fiero V6 and some later 4cyl.
Even w/o swapping, Some change the wiring to move Fusible Links and Alt Wiring to better location so road crap and iffy connection won't fry links or burn C500.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Notorio OCT 18, 02:52 PM
Saggy, I think Ogre raises a great point regarding a transmission change to get better gearing.

On a different note, and I'm warning you that I know nothing about the technical and practical limitations of this suggestion, but you might want to check out this post on the Pontiac Super Duty engine. It seems like that path would relax some of the fitment concerns raised for the 1984 frame, etc.

EDIT -- there are some SD parts still available in the Mall (Click Here) but you missed the Motherload. Potentially there will be people who bought some of those parts who these years later might not want them and be willing to sell ...

[This message has been edited by Notorio (edited 10-18-2022).]

Saggy OCT 19, 11:35 AM
I will defiantly need a new transmission. I may stick to the idea of the v6 even if it doesn't quite hit the numbers I hope it can. A transmission capable of withstanding 300-500 ft-lbs sounds like a good number to me, but what do I know, fastest car I've driven is my 06 ford taurus.
cvxjet OCT 19, 12:28 PM
I would like to make a suggestion; You may want to start with a low-power engine that can later have it's power increased...learn how to deal with some power, then increase the power as you become more proficient at driving the Fiero.

Fieros- like all mid-engine cars- have some quirks to their handling that can get you in real trouble very quickly. The biggest/most dangerous is "DTO"- Drop-Throttle-Oversteer....You enter a turn going too fast, cut the throttle, and the rear-end comes around. A lot of 911 drivers have died due to this. Fieros have relatively mild DTO, but with added power/speed/"Ability" you get into dangerous territory.

Note; It is really difficult to drive your car (Safely) off the road>>>Backwards<<

I practiced the DTO situation every day on my way home from work on a freeway cloverleaf- the turn tightened slightly halfway thru, so instead of turning the wheel, I would cut the throttle and the car would rotate- then get back on the throttle.

Maybe a 2.8, or possibly a 3.8 that can later have the supercharger added.

I worked at Atari in San Jose back in the early 80s- there was a guy (Dennis Barnhart, Eagle computers) who took his computer company public, became a multi-millionaire, bought a Ferrari 308, crashed it and died- all on the same day.

Once again, mid-engine cars handle differently than FWD sedans- or trucks- or basically any other car. Be careful and don't OVER-estimate your skill- DEVELOP your skill.
pmbrunelle OCT 19, 12:42 PM
A transmission from a V6 Fiero will drop in, and be sort of robust. The 4-speed M17 Muncie will drop in most easily; the 5-speed MG2 Getrag will also drop in, but need some more Getrag-specific components (shift lever, cables, etc). Durability depends largely on how you drive the car.

The 3900 LZ9 doesn't have 300 lb*ft, but a stock LZ9 with turbo will reach your 500 whp goal:
https://www.realfierotech.c...iewtopic.php?t=21854

The LZ9 can use an off-the-shelf flywheel and clutch.
Saggy OCT 19, 01:09 PM
I like the sound of that 3.9 lz9, those are found in newer Impalas, right? What kind of power would the newer Fiero transaxles hold up to? I do like my manual 4 speed, but I wouldn't mind something newer, or even an auto so I wouldn't have to worry about a clutch burning up. I wouldn't mind spending a touch extra on a strong transaxle to hold up to whatever power & shenanigans I get up to with it in the future. Is there anything stopping me from using a fwd transaxle? I am very aware of the mid engine's tendency to be extraordinarily difficult to control in a slide, compared to other cars. The front end has no weight, leaving most the traction for the rear tires. I don't plan to drive it very aggressively until I get more used to power. I don't know much about Ferraris, however I am aware that Lotus was using construction materials like plywood and solid fiberglass a pillers at the time. The Fiero was the second safest car of 1984, however without airbags I still don't like my chances. I'd also like to not kill the car, so I'll baby it after the swap until I have been daily driving it for like a year or so. Even 200 fl-lbs would be a lot for a car of this stature, but I don't want to put in all the work of an engine swap just to want to do it again in 5 years, or even worse, be disappointed by the end result.