best 4.0 year for swap?

Krowzer1139 · Apr 5, 2008

im putting the 4.0 into my 88 bronco II im going to start off useing my 5 speed 2.9 tranny than ill switch to the M5OD-R1HD or if i cant find the HD the M5OD-R1. My question is what 4.0 would best fit in my vehicle with the least amount of headaches? i heard rummors that the 91-92 almost direct fit you need to drill hols in the 4.0 mounts but u can use them. any recomendations?

ZMan · Apr 5, 2008

91-92 is your best bet from what I've read. They would all be almost a "direct fit", its the wiring and sensors and stuff that get complicated in '94 on up.

CJREX · Apr 5, 2008

I used a '94 Ranger 4.0 engine with '91 Explorer ECU, injectors, and wire harness on my '89 Ranger swap.

As far as engine mounts, I didn't have to drill any holes. They bolted right in.

The general wisdom on here is that '91-'94 are the best donor candidate years as OBDII came into the mix sometime in '95.

VaGent · Apr 5, 2008

Need an opinion from you guys who have done the 4.0 swap. Here's what I have in mind.

I have a '89 BII 2 wheel drive that is now a 2.9 with the A4LD transmission running 3.45 gears. I'm thinking about installing a 4.0 & swapping out the gears to 3.08 & running 235/75R/15 tires which should put the actual gearing somewhere around 3.00. The 3.08 rear I have is an 8.8 too out of a Mustang. My thinking is with this combination I would have plenty of power & with running 3.08 gears I should get better gas mileage not to mention much better power. This truck will be used for highway & city driving only & used mainly by my wife & to take some out of town trips.

Since some of you have already done the 2.9 to 4.0 swap, I'd appreciate your opinon as to what you think & I would also be interested in how you fell about the power gain from doing the swap. I already have a '92 Explorer with the 4.0 that is automatic so I have everything I need to do the swap & the engine only has 123,000 miles on it now. Anything you can tell me would ne very much appreciated. Thanks

AllanD · Apr 5, 2008

The "HD" version of the Mazda 5sp isn't a "unicorn" but finding one is only slightly easier than finding a japanese aircraft carrier.

The M5OD-R1 is "good enough" provided you maintain it.
the "HD" unmaintained isn't enough better to justify the effort.

what year is "best" well, you gotta define "best".

Best for What?
Best for an Easy swap?
Best for drivability?
Best for availability?

Most available? 90-92
Easiest swap? 90-92
Best for drivability/reliability? 92, 93 or 94 (each year is rather different for wiring)

Probably as important as anything else is what you can find
AND what you can find MANUALS for because if you don't have the manuals
you will NOT have "fun" (not that the job is "fun" with the manuals...)

I've been there and done that, I've got a 1993 4.0 in my 87 supercab
and no I didn't have t-shirts made to commorate the event any more
than I'd want to remember having a porcupine shoved up my ass...

I built my truck not with what was available but with what I considered
the "best" parts used between '88 and '97.

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Simple_serf · Apr 5, 2008

AllanD said:
I've been there and done that, I've got a 1993 4.0 in my 87 supercab
and no I didn't have t-shirts made to commorate the event any more
than I'd want to remember having a porcupine shoved up my ass...

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!!!!

best 4.0 year for swap?

Krowzer1139

15+ Year Member

ZMan

Forum Staff Member

CJREX

15+ Year Member

VaGent

15+ Year Member

AllanD

TRS Technical Staff

Simple_serf

15+ Year Member

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