Skip to main content ↑ ↓
Topic: 1991 3.8 mn12 tbird engine swap question (Read 4526 times) previous topic - next topic

1991 3.8 mn12 tbird engine swap question

I have a 1991 3.8 tbird that has a blown engine and a slipping tranny.  Next, I have a complete 5.0 and T5 that I want to install in said tbird.  How big of a head ache is it to do this swap? Any leads to some good web sites would be very helpful. In the meantime I'll keep on searching, thanks in advance.

~Jason
88 TC with 93 GT 5.0 (.030 over), XE266HR Compcam, SVO 1.6 Roller Rockers, BBK underdrives, BBK 1 5/8" headers, 2 1/2" exhuast with Americian Thunder Flowmaster lers. Tremec 5 speed and 3.73's and alot of other goodies to list.....

1991 3.8 mn12 tbird engine swap question

Reply #1 –
Shouldnt be too much harder than a Fox swap since 5.0 was an option in the MN12.

But why a rot box?
1986 Cougar LS

1991 3.8 mn12 tbird engine swap question

Reply #2 –
Rot box? hahahaha....is that a term for a mn12? If it is, well there is no rust on this one, plus it was donated to me.
88 TC with 93 GT 5.0 (.030 over), XE266HR Compcam, SVO 1.6 Roller Rockers, BBK underdrives, BBK 1 5/8" headers, 2 1/2" exhuast with Americian Thunder Flowmaster lers. Tremec 5 speed and 3.73's and alot of other goodies to list.....

1991 3.8 mn12 tbird engine swap question

Reply #3 –
Texas.... Lucky
1986 Cougar LS

1991 3.8 mn12 tbird engine swap question

Reply #4 –
The 5.0 for the MN12 uses a lower intake manifold like the 94-95 Mustang GT.
2003 Marauder 300B
1996-97 Cobra wheel straight but weathered (For Sale)
84 TC manual shifter handle no  (For Sale)

BTW, I had a 1988 T-Bird Sport way back when. I found out that it was totalled shortly after trading it in. It still has the ignition switch recall to date.

Special thanx to EricCoolCats for showing me to this site.:bowdown:

1991 3.8 mn12 tbird engine swap question

Reply #5 –
MN-12 uses a shorter upper plenum...a standard HO upper will bolt on and you could make it work with the proper TB adapter available from almost every aftermarket company...however, hood clearance may very well be an issue.

-Don
Project 3G: Grandpa Grocery Getter-'85 Crown Vic LTD 2-door, 351W with heavily ported/polished GT40 heads, heavily ported/polished Typhoon Power Plus upper & lower intake, Comp Cams 265DEH retarded 1*, FAST EZ-EFI, HD T5, 8.8" 3.73 trac lock with extra clutches, 3G alt. swap, '99 CVPI front brakes, '09 CVPI rear disc brakes, '00 CVPI booster&m/c + wilwood adj prop valve.

Parted & Gone-'88 T-bird Sport, 351W swap, ported GT40 heads

1991 3.8 mn12 tbird engine swap question

Reply #6 –
The T-5 shifter will come up through the floor at the wrong place and there will be clutch cable(slave cyl?) issues to consider... No doubt doable, but you'll be scrounging a bunch of small pieces...

1991 3.8 mn12 tbird engine swap question

Reply #7 –
Agreed. You will likely have issues with hood clearance and shifter location. From what I've read, the shifter will want to be somewhere inside the dash underneath the radio.
[SIGPIC][/SIGPIC]

1991 3.8 mn12 tbird engine swap question

Reply #8 –
I don't think a MN12 ever came with a T-5, Did it? The Mazda 5-speed was all they got, the M5R2.
1983 Tbird with '03 Split Port V6 motor swap done! Headers, dual exhaust, 500CFM Edelbrock, 3G upgrade, Electric fan. 3.73 Gears and an FRPP Limited Slip. Five lug complete! 5-Speed conversion complete! Standalone Fuel Injection in progress...

1991 3.8 mn12 tbird engine swap question

Reply #9 –
Quote from: jrad235;293297
I don't think a MN12 ever came with a T-5, Did it? The Mazda 5-speed was all they got, the M5R2.


Might want to check with some supercoupe guys.

ThunderbirdUnderground is a cool bunch of guys.
1986 Cougar LS

1991 3.8 mn12 tbird engine swap question

Reply #10 –
Quote from: jrad235;293297
I don't think a MN12 ever came with a T-5, Did it? The Mazda 5-speed was all they got, the M5R2.

Correct you are.
'98 Explorer 5.0
'20 Malibu (I know, Chevy, but, 35MPG. Let's go brandon, eh)

1991 3.8 mn12 tbird engine swap question

Reply #11 –
Well, after seeing my options, I'm just going to repair what needs fixed on the Tbird. I'll just use that as my daily driver and just find another fox body to donate my drivetrain. Thanks again for the input.

~Jason
88 TC with 93 GT 5.0 (.030 over), XE266HR Compcam, SVO 1.6 Roller Rockers, BBK underdrives, BBK 1 5/8" headers, 2 1/2" exhuast with Americian Thunder Flowmaster lers. Tremec 5 speed and 3.73's and alot of other goodies to list.....

1991 3.8 mn12 tbird engine swap question

Reply #12 –
Use the motor and an M5R2 get a 164 tooth flywheel.

An intake manifold from a 91-93 Cougar of Tbird should not be too hard to score.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

1991 3.8 mn12 tbird engine swap question

Reply #13 –
Nah, I'll just keep this one stock. I'm really not a hugh fan of the MN12 body style in the first place. I'll keep my eyes peeled for a fox body to put my 5.0 and T5 in.
88 TC with 93 GT 5.0 (.030 over), XE266HR Compcam, SVO 1.6 Roller Rockers, BBK underdrives, BBK 1 5/8" headers, 2 1/2" exhuast with Americian Thunder Flowmaster lers. Tremec 5 speed and 3.73's and alot of other goodies to list.....

1991 3.8 mn12 tbird engine swap question

Reply #14 –
Quote from: SR71TC;293483
Nah, I'll just keep this one stock. I'm really not a hugh fan of the MN12 body style in the first place. I'll keep my eyes peeled for a fox body to put my 5.0 and T5 in.


Good plan.
1986 Cougar LS