FMOC Dyno Day 3, Helsinki/Finland, June 8th 2005

Ok, this was our third time we went into the same chassis dyno in Helsinki and dynoed 10 cars. My Mustang had enjoyed the new GEN2 engine for almost two months by the time of the dyno, and had seen around 3500 miles. So far I had used two Autolite 2100 1.14 carbs and one Autolite 2100 1.21, and spent the weeks tuning the car better and better. I do have a vacuum gauge and a A/F ratio gauge there and I find them invaluable for the process to tune up a pretty highly modified power plant like the GEN2 is.

The 1.21 never got into good tune; it ran lean what ever jets I put in it (tested up to 68). So the normal thing happened and something totally untested and unfixed was put into action at the last moment. In a hurry the day before the dyno I swapped the 1.21 to Holley 350, adjusted the idle a little and that was it. Dyno day morning I drove to work using on/off method with the throttle; the 56 jets were way too small and to avoid total lean outs I had to drive throttle pedal depressed or pressed enough to open the power valve. Accelerate - coast - accelerate - coast...

I have basic timing at 28 degrees advanced, vacuum advance not in use, and centrifugals giving some 17 degrees more at high rpms. For the dyno I filled the gas tank up with premium pump fuel (98E). Normally I drive with lower octane stuff (95E).

Anyway, we got to the event after duty hours at work. The pics continue the saga from here on...

First things first; jet change. We opened the Holley and decided to change 64 jets in. They were right on target. Should I leave out the fact that my friend's jet kit started with 64s...

Dyno stuff is preparing for the run. The cars were tied up with strong enough ties and the big fan (seen left) was placed in front of the cars to provide extra cooling.

Almost ready...

...but first everybody had a good laugh at the result to come.

We estimated the possibility to make another run and ended up with changing the 350 out and a Holley 500 in. Luckily (?) the schedule allowed another pull. Cranking to get fuel to dry bowl again, fire up, adjust fuel level, idle mix and speed, and we were readly for the rolls again. The 500 was equipped with 65 jets, has a thirsty 50cc accelerator pump and sure is all rock'n'roll, but proved to give no gains at all to this engine.

Results:

First run with Holley 350

112kW / 152hp @ 5200

226Nm @ 3410

Second run with Holley 500

111kW / 151hp @ 5280

220Nm @ 3470

 

The std rate valve springs gave up first, so we never know what the results might have been if springs would have allowed to measure to at least 5600 rpm (announced range end of the cam) or to 6000 rpm. Higher rpms might have given a benefit to the bigger carb but this is all speculation.

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