Progress Thread Beginner 4cyl to v8 conversion

86&92foxbods

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Hey fellas, I'm a newbie to the 4cyl to v8 swap game. I have a 1986 gt hatch with rusted rails, when I had it on Jack stands in the garage to replace them my son backed a truck into it and bent the front end real bad. So I just left it for a while. Now my friend had a 1992 4cyl coupe that he was going to build and he bought a 351w to build to go in it. So I had a old Chevy avalanche that needed a fuel pump, so I called him and ask him to trade he said yes so I got the coupe and the engine. Now, since it's going be long build on th 86 why not take the 5.0 out of there and put it in the 92 and make it a daily driver and build the 351w to put in the 86. Ok I said all that to say I am using the 86 gt as the donor car for the swap. What do I have to take off the 86, or what will work off the 86 and what do I have to get new. Please Help Me☹☹
 
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90sickfox

I didn't really have an issue with the stink...
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You need a v8 computer ....you'll need a 92 engine harness and v8 injector harness. You'll need v8 front spindles and brakes...along with the 8.8 rear out of the 86. You'll also need the fuel lines and brake lines....master cylinder and booster.

Basically, you'll need everything excepr the dash and interior bits. None of the 86 wiring will swap easily into the 92.
 

86&92foxbods

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Jul 11, 2019
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You need a v8 computer ....you'll need a 92 engine harness and v8 injector harness. You'll need v8 front spindles and brakes...along with the 8.8 rear out of the 86. You'll also need the fuel lines and brake lines....master cylinder and booster.

Basically, you'll need everything excepr the dash and interior bits. None of the 86 wiring will swap easily into the 92.
Can I use the computer out of the 86 for now? I do want to go to MAP eventually.
 

General karthief

wonder how much it would cost to ship you a pair
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Read through this thread, just substitute 92 for the 86 stuff.
Also google mustang 4cyl to v8 swap.
There is a lot to it.
 

90sickfox

I didn't really have an issue with the stink...
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The computer does not have to be specific for 92....but has to be an 87 and up for fuel injection. The o2 sensor harness is different from auto to 5 speed and shouldn't be mixed up ( not sure if the 86 harness will work with 92 engine harness ).

Your 86 5.0 brake stuff will all swap over. Later on you could do a 5 lug newer brake swap. The 86 dash harness will not work with the 92.

The issue with the 92 is the addition of airbags. That caused the dash harness and column to change a bunch.

Your 86 engine would benefit from the addition of MAF. A 92 harness will have the wiring already.

91 and 92 should work together ( i think ). The thread Karthief linked will have all the info you should need.
 
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Mustang5L5

i'm familiar with penetration
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86 brakes are the same as the 92 4 cyl. No need to swap.

The wiring will be your greatest issue as there were a few changes from 86 to 92.
 
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86&92foxbods

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The computer does not have to be specific for 92....but has to be an 87 and up for fuel injection. The o2 sensor harness is different from auto to 5 speed and shouldn't be mixed up ( not sure if the 86 harness will work with 92 engine harness ).

Your 86 5.0 brake stuff will all swap over. Later on you could do a 5 lug newer brake swap. The 86 dash harness will not work with the 92.

The issue with the 92 is the addition of airbags. That caused the dash harness and column to change a bunch.

Your 86 engine would benefit from the addition of MAF. A 92 harness will have the wiring already.

91 and 92 should work together ( i think ). The thread Karthief linked will have all the info you should need.
Ok. My 86 is manual shift and so is the 92.
How about if I delete the airbag steering wheel and go with a aftermarket one, will that make a difference?
I'm pretty good with wiring, so if I get lead I'm the right direction and have the right parts I can put a harness together, I use to do custom sounds and remote starters as well as wire up hydraulic switch panels for people. Just let me know where to get it and how its suppose to go and I'll make it happen. I'll buy new if I have to. I figure I have to anyway because the closest donor cars like mine are in
Philadelphia PA.
Should I use the rear end and the driveshaft from the 86 as well. When I do the exhaust which I have to go new with because mine is rusted out, buy 86 oxygen sensors or it doesn't matter?
 

Boostedpimp

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You won't be able to source all your parts from the 86 I don't think.. I've done the swap and I personally wouldn't go through the trouble of ripping the entire interior and dash out just to use the 86's wiring in the car. I would do it right and purchase the harnesses I need to make the swap plug and play from a car being parted, etc.

Fuel lines, the four cylinder lines cross in the middle of the floor pan which will be trouble for the mid pipe and dual exhaust. Plus they route up into the engine by by the driver which is the opposite side from v8 cars and there lines to the rails.

Brakes lines, the four cylinder main brake line will need to be swapped if you install the 8.8 rear in the car. If not just leave it. Also don't bother swapping the brake system over because like stated above the 86's is the same as 87-93 four cylinder so no gain there and allot of work saved.

Swap the dual exhaust hangers and mounting points from the 86 to the 92

Four cylinder's tach will almost double actual rpms with the v8 so eventually you'll want to swap a tach or cluster in from a 90-93 car because it is annoying. Or rock an aftermarket tach you get the idea.

Wiring harnesses, this is the scary part for most but it's not that bad

Manual transmission harness from a 90-93 car
02 sensor harness from a 90-93 manual car
Injector harness from a 90-93 car

Main harness from a 91-early 92 car or from a mid model 92 to 93 car.. this depends on what your current 92 has. If it has two relays on the passenger side by where the mass air typically is then you need a mid year 92 or a 93 main harness.
If the 92 has only one relay there then you need a 91 to early 92 year harness.
 

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90sickfox

I didn't really have an issue with the stink...
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Didn't know the 86 v8 has the same brakes as a newer 4 banger. Those brakes must really suck...even more than 87 and up v8s.

I'd definitely find the correct harnesses. I've swapped a lot of mustangs. Some of them even got carburetors...or GM engines. Done a couple big blocks...and all sorts of strokers. Having the right stuff makes it all plug and play.

The cluster will be an 85mph 4 cylinder one with the 4 banger tach. The v8 clusters are getting harder and harder to find....but they are out there.
 

Rdub6

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Didn't know the 86 v8 has the same brakes as a newer 4 banger. Those brakes must really suck...even more than 87 and up v8s.

I'd definitely find the correct harnesses. I've swapped a lot of mustangs. Some of them even got carburetors...or GM engines. Done a couple big blocks...and all sorts of strokers. Having the right stuff makes it all plug and play.

The cluster will be an 85mph 4 cylinder one with the 4 banger tach. The v8 clusters are getting harder and harder to find....but they are out there.
I can attest to the ‘86 brakes sucking!!! The bigger brake swap is in my future. @86&92foxbods I would do the better brakes while you have everything else ripped apart, for sure!!
 
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