Fox Mustangs 1979-1993 Mustangs Member Tech & Restoration Discussion

Engine Swap: Best Guesstimate on ET for '86 GT

Old Feb 2, 2007 | 06:50 PM
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Engine Swap: Best Guesstimate on ET for '86 GT

I just took the engine out of a modded '91 drag car and put it into the '86 GT. I am looking to see where you guys think the '86 will be for power, ET, and weight.

1991 LX:
1/4: 12.007
Power: 297 RWHP
Engine: stock cam, GT40P heads (10.5:1 compression), FRPP shorty headers, Cobra intake, CAI
Drivetrain: T5 (pro-shifted), aluminum driveshaft/flywheel
Rear: 4.30s, spool
Accessories: electric fan, aluminum radiator, no A/C, no power steering
Suspension: roll-cage, subframe connectors, aftermarket control arms, drag springs (back), coilover kit (front)
Weight: fiberglass hood/bumper, race seats, no rear seat - 3100 lbs (with driver)

1986 GT:
1/4: TBD
Power: TBD
Engine: Same as '91
Drivetrain: T5 (stock WC), steel driveshaft/flywheel
Rear: 3.55s, no spool
Accessories: stock fan and radiator, no A/C, stock power steering - giant pully
Suspension: roll cage, subframe connectors, stock control arms and springs, stock front end
Weight: fiberglass hood/bumper, stock '91 seats, rear seat delete
The exhaust will be the same as in the '91

Check out my cardomain site for the build pics and info. Any input/opinions appreciated!
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Old Feb 3, 2007 | 05:02 AM
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Very cool '86!!

I'm a bad guesser, so I'm not sure what you will run, but keep us posted!
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Old Feb 4, 2007 | 12:59 PM
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1/4: 12.7?
Rwhp: 241rwhp?
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Old Feb 4, 2007 | 01:34 PM
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Originally Posted by TillmanSpeed
1/4: 12.7?
Rwhp: 241rwhp?
Thanks for the reply. I am hoping that the HP will be more in the 270 range. I would be pleased with a 12.7 quarter - still 95% stock on the suspension. My brother's car is set up similarly to this one, puts down 272 to the wheels and has run 12.56 on the stock suspension. He is a much better driver than I am (for now), so that needs to be factored in. Anyway, we will see what happens when the snow melts!
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Old Feb 4, 2007 | 01:39 PM
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I was guessing lower on the HP because of the drivetrain being steel, and the loss of the cooling. I don't think it will be as drastic of a loss as I mentioned either. I think a 12.7 is achievable granted a good launch and perfect shifts.

CR
Tillman Speed
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Old Mar 13, 2007 | 01:30 PM
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I dunno about anyone else but I didn't think 12s was possible with 247whp on anything heavier than a skateboard. How is it that S197s with 282-300WHP are still in the 13s?
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Old Mar 13, 2007 | 01:34 PM
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Originally Posted by 97svtgoin05gt
I dunno about anyone else but I didn't think 12s was possible with 247whp on anything heavier than a skateboard. How is it that S197s with 282-300WHP are still in the 13s?
500+ lbs weight difference is a big factor.
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Old Mar 13, 2007 | 02:04 PM
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Originally Posted by 97svtgoin05gt
I dunno about anyone else but I didn't think 12s was possible with 247whp on anything heavier than a skateboard. How is it that S197s with 282-300WHP are still in the 13s?
I know it's not a Fox, but I have a friend that has run 11.94 @ 111.66 on a PI engine all boltons with 266rwhp in a 1997 GT. And he drives to and from the track in her. She pretty gutted, but that's still **** fast!!
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Old Mar 13, 2007 | 02:37 PM
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Wow 11's with 266rwhp is mighty impressive!
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Old Mar 13, 2007 | 04:03 PM
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Originally Posted by Knight
Wow 11's with 266rwhp is mighty impressive!
Not trying to hijack this thread but . . .

He's also a great driver . . . and crew chief in NMRA.

He was runner-up in UMTR Street Stick this past season. His car is in the bottom right corner.

http://www.umtrdragrace.com/Intro_UMTR.htm
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Old Mar 13, 2007 | 07:52 PM
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i want my mustang to be able to do that.. any information on all that is done to the car?
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Old Mar 13, 2007 | 07:58 PM
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Originally Posted by Knight
i want my mustang to be able to do that.. any information on all that is done to the car?

Sent via PM!

Now . . .
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Old Mar 21, 2007 | 08:12 PM
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I dunno about anyone else but I didn't think 12s was possible with 247whp on anything heavier than a skateboard. How is it that S197s with 282-300WHP are still in the 13s?.

Light + Gears + Traction

The engine that I put in the '86 was in a '91 that weghed 3050 lbs. (with driver and fluids), ran 4.30s out back and hooked with 5500 RPM launches. That combo, even only at 297 rwhp, was good for 12.00.
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Old Aug 26, 2007 | 04:02 PM
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Time for an update:

Ended up going with an aluminum driveshaft, but kept the steel hood. The engine was starving for fuel with the SD computer, so I did the Mass Air Conversion. Here are the results:

HP: 286 rwhp
TQ: 313 trq

As for drag racing, the car has now been to the strip 3 times. It runs like a champ, though the driver needs a tuneup. With some very sloppy shifting:

ET: 12.447
MPH: 108.33
60': 1.631 - with 3.55s!!!
Wgt: 3078 lbs. with driver (~2880 w/o)

That was a Fun Ford Weekend at New England Dragway. I ran it in True Street, so I had to run ET Streets out back. They were hooking great. I will probably put 4.10s out back for next season. With the gears, some minor suspension mods and a better driver, very low 12s should be possible. Not sure if 11s is in the cards with the stock cam and GT40P heads, but I may see what can be done.
Attached Thumbnails Engine Swap: Best Guesstimate on ET for '86 GT-timeslip-86-12.447.jpg  
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Old Oct 21, 2007 | 07:09 AM
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With a more experienced driver behind the wheel:
12.17 @ 110

I am gunning for a new low when we go to E-town in the beginning of November. The combination of better air, a better track, the fiberglass hood (just installed) and a short belt (no powersteering) should be able to shave a few thousandths.
Attached Thumbnails Engine Swap: Best Guesstimate on ET for '86 GT-timeslip-86-12.176.jpg  
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Old Oct 21, 2007 | 01:53 PM
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If you still have the smog pump in place be sure to bypass that too! That plus the fiberglass might be good for a tenth?
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Old Oct 27, 2007 | 02:27 PM
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Originally Posted by DavidM
If you still have the smog pump in place be sure to bypass that too! That plus the fiberglass might be good for a tenth?
Thanks for the idea. The smog pump was taken out as soon as the car got through emissions. Also, the fiberglass hood is only 11 pounds lighter than the stock steel hood (30 lbs. vs. 41 lbs.). I'll post an update after the races (November 3-4.
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