Dyno Results
My partners and I were recently able to dyno our two SMs back to back and were able to collect some interesting data. The cars have the following vital specs:
#43 - Just built on a 1990 192k mile car. Engine has never been opened and the only major services have been clutch (race clutch), rear main seal, timing belt change, as well as new water pump and alternator. Car has a homemade exhaust that is fairly restrictive with some fairly crappy kinks in the pipe after the downpipe. Intake is a $5 cone filter on the AFM directly. Plug wires are not original, but they are not new from me putting them on either. The car only has about 6 hours of track time total.
#39 - We've had this car for over a year. 1990 car and has a 120k mile engine that has not been opened. It does have a race clutch and new transmission, and the only other things that have been done are timing belt change and a good exhaust that is free flowing as well as the intake that curves under the AFM (can't recall the name). Timing is set to 14 BTDC and the AFM is stock, never touched or opened. This car has well over 60 hours of track time, including 13 at last years' Charge of the Headlight Brigade and 7 hours getting me through school in January.
The dyno used was a relatively new Dynojet located here in Raleigh NC at Haywood Custom Performance, a Ford specialty shop and I've know the fellow Randy there for years. Good place. Air temps were about 76F and humidity about 50%, a nice day.
The results:
#43 was up first and made 100hp even and 92 ft/lbs of torque. The pull showed the car was quite rich at WOT at anything over about 4k RPM. We adjusted the AFM slightly with attempts to lean the engine out a bit and it definitely helped, rear wheel hp went up to 105hp and torque hopped up to 96 ft/lbs. After that change we had a look at timing be the motor did not want any more timing - 12, 14, 16 all caused power to drop, and naturally so did 8 degrees just for sake of checking. I suspect that we have a restrictive air intake and exhaust since it just won't respond to any timing changes. Hard to say. At any rate, I was reasonably happy given that the car has known intake and exhaust restrictions.
#39 was up next and made 114 hp and 101 ft/lbs of torque. The plot showed that this car was running significantly leaner at WOT above 4k RPM than #43. We only fiddled with the ignition timing on this car and found that 14 was optimal for it, losing a couple of hp when shifted from 14 degrees BTDC. Since we were pressed for time we did not try anything else with the car since we were pretty happy with the results.
All in all it was a useful session. I'll make some changes to #43 and get it back on the dyno and see if we can improve the numbers. Both cars are running in the 13 hr VIR Enduro that is coming up so look us up there. I'll post the dyno plots as soon as I can get them scanned, but they are nothing really exciting. Any comments are welcome, but don't jinx us by saying "Holy cow, those motors are going to blow any day!"
Ron
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