3.1 to a 4 cylinder Fiero swap
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Topic: 3.1 to a 4 cylinder Fiero swap
Posted By: kole83
Subject: 3.1 to a 4 cylinder Fiero swap
Date Posted: 09 July 2013 at 12:38am
Hey guys I have a couple really quick questions I own two cars one is
an 89 Oldsmobile Cutlass Supreme. It has a 3.1 liter v6 engine. I did
some research online and noticed that the v6 Fiero and the v6
cutlass supreme both use a Getrag standard transmission.
Will the transaxle match up to the transmission?
Or will I have to buy a Getrag standard transmission?
The old mobile have an automatic transmission and I would prefer
to keep it instead of buying the get rag standard.
Last question what kind of hoops am I going to have to hop through
in order to take the front wheel drive engine and transmission and
put it in my Fiero?
Thank you for your time
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Replies:
Posted By: Erwin
Date Posted: 09 July 2013 at 12:45pm
Both 2.8 and 3.1 have the same bell housing pattern.
You will also need to decide if you are running the fiero
intake and computer, or the cutlass intake and computer.
Other issues are converting the 3.1 from flexplate and
torque converter to Pressure plate.
Any swap you do, consider if the benefit is sufficient
for the effort.
Your 3.1 cutlass motor LH0 is rated at 140 hp as opposed
to the stock 2.8 fiero motor making a rated 140 HP
So no real benefit in power over putting in a stock Fiero
V6... That said - if you like tinkering it is perfectly
possible to do the swap.
The Fiero system is essentially a GM front wheel drive
system and suspension put into the back of a car.
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Posted By: kole83
Date Posted: 09 July 2013 at 1:00pm
Ha I never noticed that. Thanks man! Now here is my next problem. I
have a 4cyl frame. Am I going to have some problems with the
transaxle? Matching up the tranny to frame?
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Posted By: kole83
Date Posted: 09 July 2013 at 5:58pm
Also I'm keeping the transmition from the olds to use in the fiero. Do
I still need to worry about the pressure plates?
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Posted By: bcampbell
Date Posted: 11 July 2013 at 3:42am
If you're swapping engine/transmission together then
there should be no reason to worry about the pressure
plate. Rodney Dickman sells some pieces to make the 5-
speed FWD transaxles work in the Fiero easily as well.
As for power, the LH0 actually makes 15 more ft-lbs of
torque than the Fiero 2.8.
Wiring would be pretty easy; you can re-pin the Fiero ECM
connectors for the Cutlass ECM, and you may have to
change out some pigtails as well, but other than that
it's pretty straightforward. The DIS ignition used on
the LH0 is significantly more reliable than the 2.8 iron
head stuff and there's no need to ever mess with a timing
light either. You can also keep the FWD accessory setup
with an idler pulley where the power steering is and you
should never deal with belt squeal again either.
Since you're not starting with a 2.8 already, IMO you
would be going backwards to try putting 2.8 stuff on the
3.1. Not to mention if you didn't also swap in 3.1 iron
head pistons you would end up with something like 6/7:1
compression...
The only downside to the aluminum heads is you have to
re-work or relocate the dog-bone mount.
-------------
'86 2m6 F23 5-speed, LSD, 3.5L LX9
'89 Firebird 3500T, T56
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Posted By: kole83
Date Posted: 11 July 2013 at 10:27am
Thx cambell. Now I have one last question. Is my stock 4cyl fiero rear
axle going to be able to handle the extra torqe? Or am I going to
have to be purchasing a v6 rear axle and place that in?
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Posted By: bcampbell
Date Posted: 11 July 2013 at 12:19pm
Do you mean transmission? IIRC the only stock
transmissions that can be broken with stock V6 power are
the 84 4-speed and the Isuzu 4-cylinder 5-speed. Depending
on how you drive though you can make any transmission last.
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'86 2m6 F23 5-speed, LSD, 3.5L LX9
'89 Firebird 3500T, T56
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Posted By: kole83
Date Posted: 11 July 2013 at 12:21pm
Ok sweet man. Ill let ya know how it
goes.
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Posted By: Dr.Fiero
Date Posted: 11 July 2013 at 12:21pm
All Fiero transaxles are the same (power handling wise), as are all the CV shafts the same.
(edit: but as stated - you CAN break anything! There are guys running V8's attached to Isuzu's for years without issue)
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Posted By: Capt Fiero
Date Posted: 12 July 2013 at 10:49am
Uhm, John what you been smoking? Or are you just exhausted from all the jobs you are working on.
Strength of Fiero Trans from Weakest to Strongest.
Isuzu 5spd 2nd Gear Disintegrates
84 4spd 3.32 Case Breaks
84 4spd 4.10 Case will break eventually
86-88 Getrag 5spd Usually internal failures like shafts and such.
85-86 3.65 4spd Only failures have been age related like snychros or shafts.
Now I have ran the Isuzu on my V8 Fiero with Nitrous. I would blow one about every 6 months.
The only V6 4spd trans I have ever blown was a bad internal shaft. I have never been able to crack a case or strip a gear on a V6 4spd trans. Even when going redline in reverse then quickly shifting to 1st gear and popping the clutch.
I have installed the Getrag 5spd in my V8 now just for better strength over the Isuzu. Gearing is not as good as the Isuzu, but its much more reliable.
The Auto Trans is also very strong, but really crappy gearing.
The reason GM did not install the Isuzu on the V6 is even they knew it would not handle the abuse in the long term.
Now as Erwin said, all Fiero Manual CV's are the same and you will never break one behind a V6 unless its Supercharged and even then it has to be seriously modified. I believe they will fail around 400hp and 500lbs of torque.
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Capt Fiero
88 Fiero GT 5spd V6
Eight Fifty Seven GT V8 5spd.
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