Shocked by Dyno Results - 1990 Mark VII with 5.0 HO

88Mark7

New Member
Mar 12, 2018
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#1
Hi everyone, I'm looking for some opinions and help. A few months ago I had my 1990 Mark VII LSC run on a mustang dyno and as far as I know everything was calibrated correctly. Now, having a built AOD which likes to downshift under pressure the guys had some trouble finding a sweet spot in 3rd to run it up, but after 2 pulls the results were shocking. The car made 230.9 HP at 4490 RPM and 290.5 Lbs of torque at 3169 RPM at the rear wheels...do the conversion for 20% drivetrain loss in the AOD and that's 288 Horse and 363 Torque...even if I lose 15% with the trans that's still 270 horse and 341 Torque at the motor...

So here's the thing. My car is a 1990 Lincoln Mark VII LSC with its original 5.0 HO, blueprinted original AOD, Stock exhaust, and 3.27 Traction-Lok rear. As far as I know, the motor has never been tempered with. I have had it resealed and tuned up, but myself and the previous owner do not know if anything else was done to it in its life but we are sure nothing has. So, this leads me to my question...is this even possible? I don't believe so...I don't like to be a Debbie downer but I find it hard to believe that somehow I have some miracle 5.0 that makes 50 horse over factory numbers. The other issue is that when timing 0-60 in the car before the dyno, and before the tune up, I got just around 6 seconds...not exactly that but it wasn't 7. The things with that is the stock 0-60 for a Mark VII is around 7-7.5 seconds, 225 Horse with a weight of 3740 pounds. Now, doing a quick simulation mathematically, my car weighing exactly 3745 (I weighed it at a recycling center weigh station) and using the apparent 288 horse it would have a hypothetical 0-60 of about 6.1 seconds...which is close to what I timed with a chronograph a while ago...

I have asked around, my mechanic, other Mark VII club members and friends, and nobody can honestly tell me what I'm looking at here. To make matters worse though I do not believe the results, there are still a lot of guys that believe that these results are actually accurate and I have a very spunky 5.0... I do plan on building it, doing a cobra motor clone with all the trimmings, smog delete, O/R H, Venom 250s and 2.5" pipes...but before I do any of that I need to figure this out.

So, is this possible? Do I somehow have a miracle motor? I would like to say I don't, but theres a lot pointing towards it being so...and unfortunately I won't be tearing the motor apart until body work and paint are done and summer comes so I can drive the 88 since my 90 is a daily. Like I said, I find this really REALLY hard to believe...either way though I do have a dyno sheet saying its so for bragging rights...so that's not bad even if those numbers are 100% false. I may have another chance to dyno in May or so but its not set in stone...this would be a dynojet...but until then I have no clue what I'm driving anymore...
 
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74stang2togo

Walks Into Lift Arms at Work
Mod Dude
Mar 7, 2002
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#2
If you didn't buy it new, you may have improvements to the engine that you don't know about.
I had a Mustang II that was much quicker than any 139hp car should be. An engine teardown later on revealed that the 302 that still sported the stock 2bbl carb and smog gear was bored .040 over with flat-top pistons and milled heads.
 

88Mark7

New Member
Mar 12, 2018
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#3
If you didn't buy it new, you may have improvements to the engine that you don't know about.
I had a Mustang II that was much quicker than any 139hp car should be. An engine teardown later on revealed that the 302 that still sported the stock 2bbl carb and smog gear was bored .040 over with flat-top pistons and milled heads.
After I got the dyno I called the previous owner. As far as he knows I was the first person to ever touch the motor. It was leaking from every place possible minus the heads so everything but the head gaskets were changed. It wasn't dug into at the time so my mechanic couldn't see what it really has going for it, but there is that possibility that it was tampered with before Matt had owned it prior to me. He has however said that the car was always a lot spunkier than the others hes driven including his 55k mile 91 Mark VII. He also has a 91 Fox LX "Tuxedo" with the T5 which after I drove it once pulls pretty much like my mark does. Its a strange car...I'm usually under 2300 when driving and merging in traffic but when the pedal goes down you feel it. I still don't know what to make of it, its either a miracle motor or its been toyed with, but until I get it dynoed again or tear the motor down I won't know.
 

Mustang5L5

Car used in adult film "Highway Gangbang-InDaButt"
SN Certified Technician
Feb 18, 2001
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#4
What's an LX Tuxedo?
 
#6
@74stang2togo may have answered this. There were a lot of different throttle body intakes of different sizes available by 1990 in the scrap yards. I don't know the exact specs but you car probably left the factory with somewhere around a 50 mm intake and tracking down 65 to 70 mm wouldn't have been difficult and it was a quick and inexpensive way to get power without much work at all.

Then again, the numbers could be bad because of the dyno. Go back and see what the last calibration date of the dyno was. ISO and ASTM specs require a full recalibration at a minimum of every 2 years. And then there are different calibrations. The basic is to just calibrate the transducer and a full calibration calibrates everything. If the shop you had dyno the car can't show you a full calibration has been done within the last 2 years ask for your money back. If they say no, tell them you're going to tell everyone and post the information on places like the local Craig's List. The calibrations are expensive so a lot of shops don't follow the standards or recommendations. But you should always ask to see their calibration records, if they're not framed on the wall, before you use the shop.

Who knows if your numbers are good or not?