Well, after feeling everything is done on the 86 GN before it goes into paint this winter I took it down to DeCordre Automotive in Spring City PA so Brandon DeCordre could finish things up before racing begins next Spring. This past April, my son and I took it to Lebanon Valley to “check things out” while it was still on street tires. We did several ¼ mile passes there getting as expected terrible 60 foot times on the street tires (around 2.5-2.6) but nevertheless turned in times of around 13.6-13.7 at around 103-104 mph. Not bad for an exploratory day. However the turbo inexplicably jumped up past 27-28 pounds of boost and the head gasket let go in the final run. We were able to drive it home although we used five quarts of oil to get there. That led to the removal of the engine and complete rebuild using comp cams roller cam, forged pistons, new valve springs, etc. as well as a rebuild of the turbo which had bad bearings and seals after the adventure in Lebanon Valley. Thanks to John Csordas and all the gang at the Auto Center in Chappaqua, N.Y.
And so now we went on to the DYNO to see how to get the most out of this wonderful car. I learned so much on this trip:
1. First the final results so you don’t have to remain in suspense. Best run on the Mustang DYNO yielded 337.8 hp and 388.0 lb ft of torque (both at 4,579 rpm) at the rear wheels. This translates roughly to about 397 hp and 456 lb ft of torque at the crank (assuming 15% loss through the drive train. Much more than I expected.
2. Using the air fuel sensor Brandon installed we were able to increase power by flattening out a richness using the turbo tweak adjustment procedure.
3. We were nly able to go to 21 lbs of boost (at #7 on my alky controller) because after tha the installed boost controller let go and boost would go uunabated (Now we know what happened at Lebanon) Brandon recommended I install a Walman controller for more precise control. He expects that the car would be happy up to around 25-26. I would probably limit it to 23.
4. At the end of the day we opened up the exhaust (car has the qtip electric cutout) to see if that helped or hurt. We’ll never know because the knock sensor would interpret the noise as knock and it retarded the timing 5-6 degrees cutting power. Solution is to leave them closed or remove knock sensor. I’ll leave the cutouts closed except at cruise nights LOL.
5. During the process Brandon noted small amounts of oil smoke at idle and part throttle and by looking at the plugs suggested we might still have a partially leaking seal in the turbo as no oil was going through the engine. We’ll check that out.
6. Speaking of plugs he pointed out that colder plugs (NGK #6) would reduce chance of detonation. Good tip.
7. We identified a mysterious lean spot in the early part of each run. It lasted for almost exactly one second. Eric at turbo tweak will discuss this with Brandon when the two of them connect but Eric suggested it’s a common showing on DYNO’s that may not apply to real life runs. We’ll see.
8. Discovered for sure that my lockup converter isn’t locking up. On the dyno at 2050 rpm’s it dropped to 1800 when he jumped the wires. Looks like just a loose wire/bad connection somewhere under the dash. Should be fixable.
9. Brandon demonstrated that if I want best performance in the ¼ mile I should do the runs in Drive and not overdrive. I hadn’t been sure of which is better until he showed me. Also he showed me how ¼ mile times ( though not fuel economy) would improve with 3.72 gears. He showed me that with the 3.41’s I would have to reach 126 mph to get to 5,600 rpm’s. His opinion is that the car would be good up to around 6,000 if I wanted to push it that hard.
So all in all a wonderful day and so educational. I recommend it to all who can’t do it for themselves. I am thinking of all the testing and tuning this one day saved. Total cost $750. Well worth it.
And so now we went on to the DYNO to see how to get the most out of this wonderful car. I learned so much on this trip:
1. First the final results so you don’t have to remain in suspense. Best run on the Mustang DYNO yielded 337.8 hp and 388.0 lb ft of torque (both at 4,579 rpm) at the rear wheels. This translates roughly to about 397 hp and 456 lb ft of torque at the crank (assuming 15% loss through the drive train. Much more than I expected.
2. Using the air fuel sensor Brandon installed we were able to increase power by flattening out a richness using the turbo tweak adjustment procedure.
3. We were nly able to go to 21 lbs of boost (at #7 on my alky controller) because after tha the installed boost controller let go and boost would go uunabated (Now we know what happened at Lebanon) Brandon recommended I install a Walman controller for more precise control. He expects that the car would be happy up to around 25-26. I would probably limit it to 23.
4. At the end of the day we opened up the exhaust (car has the qtip electric cutout) to see if that helped or hurt. We’ll never know because the knock sensor would interpret the noise as knock and it retarded the timing 5-6 degrees cutting power. Solution is to leave them closed or remove knock sensor. I’ll leave the cutouts closed except at cruise nights LOL.
5. During the process Brandon noted small amounts of oil smoke at idle and part throttle and by looking at the plugs suggested we might still have a partially leaking seal in the turbo as no oil was going through the engine. We’ll check that out.
6. Speaking of plugs he pointed out that colder plugs (NGK #6) would reduce chance of detonation. Good tip.
7. We identified a mysterious lean spot in the early part of each run. It lasted for almost exactly one second. Eric at turbo tweak will discuss this with Brandon when the two of them connect but Eric suggested it’s a common showing on DYNO’s that may not apply to real life runs. We’ll see.
8. Discovered for sure that my lockup converter isn’t locking up. On the dyno at 2050 rpm’s it dropped to 1800 when he jumped the wires. Looks like just a loose wire/bad connection somewhere under the dash. Should be fixable.
9. Brandon demonstrated that if I want best performance in the ¼ mile I should do the runs in Drive and not overdrive. I hadn’t been sure of which is better until he showed me. Also he showed me how ¼ mile times ( though not fuel economy) would improve with 3.72 gears. He showed me that with the 3.41’s I would have to reach 126 mph to get to 5,600 rpm’s. His opinion is that the car would be good up to around 6,000 if I wanted to push it that hard.
So all in all a wonderful day and so educational. I recommend it to all who can’t do it for themselves. I am thinking of all the testing and tuning this one day saved. Total cost $750. Well worth it.
