1986 Improving 5.0 Performance

[rose62]

I'm considering the purchase of an '85-'86, 5.0 car. How easy would it be to get Mustang GT performance (7-second 0-60, quarter in the low 14 sec. range) with the T-bird. Are they MAF or MAP? I'd go with an auto.

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[Tom Alpers]

I'm considering the purchase of an '85-'86, 5.0 car. How easy would it be to get Mustang GT performance (7-second 0-60, quarter in the low 14 sec. range) with the T-bird. Are they MAF or MAP? I'd go with an auto.

I had an 88 mustang KX 5.0 with 5-speed. It was the last year for the MAP I think. It was very fast but not sure it was low 14 fast. I beat some corvettes (probably automatics) at stoplight gran prix's. Also had a 90 LX 5.0 which had the MAF but it had an automatic. It did not feel anywhere near as fast as the 88. I have a 99 4.6 GT with auto and it's way faster then the 88 was.

 

[missinglinc]

I'm considering the purchase of an '85-'86, 5.0 car. How easy would it be to get Mustang GT performance (7-second 0-60, quarter in the low 14 sec. range) with the T-bird. Are they MAF or MAP? I'd go with an auto.

It depends a lot on what your budget is, and what your skills and abilities are. It can be done of course, but it's not a simple matter of a bolt on and go. If I remember correctly the 85 models used a TBI or throttle body injection system, while I think the 86 was multi point EFI. I owned an 87 with a 5.0 that I raced once, bone stock and ran 17 second 1/4 mile times. I have also owned several 5.0 Mustangs, but somehow never took one down the 1/4 mile, but seat of the pants feel the Mustangs were noticeably faster, obviously lighter and better gearing.
You could swap in the wiring harness, PCM, etc, but would still not have the H.O. camshaft or cylinder heads, exhaust, etc. I don't remember if the H.O. engines had higher compression ratios or not, but the horsepower rating differences from the Mustang 5.0 to the standard passenger car engine was at least 25 or more.
If you had the budget, I would go with a stroker engine, matched torque convertor, and rear axle gearing to reach your goal. All that aside, my current 97 Tbird 4.6 is likely a good bit quicker than a similar 85 or 86 5.0 'Bird, and my 89 Super coupe 5 speed is a little bit quicker, both are bone stock, have not had either one to the drag strip yet, but plan to one day.

For simple comparison sake, the 1970 Dodge Dart that I built in the late 1990s/early 2000s ran a mild 360 4 barrel with a decent cam, headers, 3 inch exhaust and 3.23 rear gears would consistently run 13.80s in the 1/4 mile at 100 mph, car weight with me was around 3700 pounds and horsepower was around 300-325.

 

[Tom Alpers]

It depends a lot on what your budget is, and what your skills and abilities are. It can be done of course, but it's not a simple matter of a bolt on and go. If I remember correctly the 85 models used a TBI or throttle body injection system, while I think the 86 was multi point EFI. I owned an 87 with a 5.0 that I raced once, bone stock and ran 17 second 1/4 mile times. I have also owned several 5.0 Mustangs, but somehow never took one down the 1/4 mile, but seat of the pants feel the Mustangs were noticeably faster, obviously lighter and better gearing.
You could swap in the wiring harness, PCM, etc, but would still not have the H.O. camshaft or cylinder heads, exhaust, etc. I don't remember if the H.O. engines had higher compression ratios or not, but the horsepower rating differences from the Mustang 5.0 to the standard passenger car engine was at least 25 or more.
If you had the budget, I would go with a stroker engine, matched torque convertor, and rear axle gearing to reach your goal. All that aside, my current 97 Tbird 4.6 is likely a good bit quicker than a similar 85 or 86 5.0 'Bird, and my 89 Super coupe 5 speed is a little bit quicker, both are bone stock, have not had either one to the drag strip yet, but plan to one day.

For simple comparison sake, the 1970 Dodge Dart that I built in the late 1990s/early 2000s ran a mild 360 4 barrel with a decent cam, headers, 3 inch exhaust and 3.23 rear gears would consistently run 13.80s in the 1/4 mile at 100 mph, car weight with me was around 3700 pounds and horsepower was around 300-325.

If my memory is right, my 88 5.0 LX did the 1/4 at about 92 mph. Not sure of the time, I'm thinking it was perhaps around 15. Does that sound reasonable? Been a long time since I had it... my daughter was driving it and got t-boned and it was a total loss. Friend of mine who was a heavy duty DIYer bought it from insurance company and transplanted the drivetrain to a mid 60's stang.

 

[missinglinc]

If my memory is right, my 88 5.0 LX did the 1/4 at about 92 mph. Not sure of the time, I'm thinking it was perhaps around 15. Does that sound reasonable? Been a long time since I had it... my daughter was driving it and got t-boned and it was a total loss. Friend of mine who was a heavy duty DIYer bought it from insurance company and transplanted the drivetrain to a mid 60's stang.

I would say that a trap speed of 92 mph would put it in the 15s, before I built the 360 for my Dart, it was a 318 4 barrel and would clock similar times and et's to what your 88 5.0 did.
My last fox body Mustang was a 20th Anniversary convertible, had a 306 with a 5 speed and 3.55 gears, BBK headers and 2.5 inch exhaust, but I never had a chance to run down the 1/4 mile, so I don't know what it would have run. I do know that it was easily the quickest one of the 6 fox body Mustangs I owned.

 

[rose62]

I've been looking at an '85 with the TBI. Perhaps the comb over intake and a mass-air computer wouldn't be too difficult. But he's pretty firm on price. I don't want to do the FI to carb thing. Really just thinking that I want it to pull pretty good. They were slugs from the factory. But realistically, all I'd probably do is a 5-lug swap so that I could run some cool wheels, add duals and maybe some 3:25 gears. That might improve it enough to make me happy. Wondering what the gearing would do to computer calibrations?

 

[missinglinc]

I've been looking at an '85 with the TBI. Perhaps the comb over intake and a mass-air computer wouldn't be too difficult. But he's pretty firm on price. I don't want to do the FI to carb thing. Really just thinking that I want it to pull pretty good. They were slugs from the factory. But realistically, all I'd probably do is a 5-lug swap so that I could run some cool wheels, add duals and maybe some 3:25 gears. That might improve it enough to make me happy. Wondering what the gearing would do to computer calibrations?

I don't have enough experience with computer controlled engines to give a definitive answer about gearing changes and what effect they may have on calibration. I would expect it to be adaptable to some degree of change, given that factory variation did exist, 5.0 5 speed cars could get a 3.27 gear to my knowledge, so they have to allow some range. Now if you were to go into a 4.88 gear, well that might present problems. My somewhat basic understanding is that the computer uses information from the various sensors to calculate fuel load, which is then limited by injector and fuel pump capacity, ie: 35 lb/hr vs 60 lb/hr, 50 gpm, 200 gpm, etc.

 

[Tom Alpers]

I'm hardly an expert but from what I recall, the 85's didn't have the power of the later ones such as the 88. At some point not sure when, they went from Carb to Fuel injection. UP to 88, which had fuel injection, it used a MAP which relies on a predetermined table of values and can be hard to adjust from factory setting. After 88 they had MAF which has the ability to dynamically adjust things instead of relying on a table of values. If you like the 85 I'm not arguing against it, but if you are just looking, you might want to look for newer as your base of power.