Some Dyno Data

Tom W · Tom W's Garage

FWIW, I had some dyno runs done at the last track weekend I though I would share. We ran a number of runs with some tweeks to the MoTeC after we had a baseline. By changing where the flapper in the air intake opens and closes there were minor improvements.

For my race class (PRC's GT-L), the intake and headers limit the power the engine can make, so we didn't expect much gain from any tweeks. Another car in my class was run the day before - we were within 3 hp but he had about 8 more ft-lbs of torque. The rules appear to be accomplishing the objective. At 2375 lbs (with me) and 277 rwhp, the weight to hp ratio makes for a fun car.

I also had a run done that looks at power train loss. It appears I lose about 20 hp at 110 mph with my G50/32. All runs were done in 4th gear.

Bill Verburg · Bill Verburg's Garage

This is your 964? stock cams? stock valves?

Tom W · Tom W's Garage

Yes, my 964 with the engine built to class rules by Jerry Woods. Stock air intake and stock cams. I don't remember if the valves themselves are stock, but stronger JWE valve springs, Carrillo rods, ARP rod bolts, JWE rod bearings. It's built to allow it to rev to 8k rpm, but we run it lower as it makes no power up there. It was built to last and make rebuilds infrequent.

This was done for my information as the only other data we had on the engines built to class rules is they run about 300 hp at the flywheel when tested and tuned at JWE. I wanted to verify that I was using the right shift points. I have been running with my MoTeC shift lights set to tell me to shift at 6500.

Do you have your fancy spreadsheet that you can input weight and hp to output the thrust as a function of rpm? It would be an interesting comparison ...

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by Tom W

Do you have your fancy spreadsheet that you can input weight and hp to output the thrust as a function of rpm? It would be an interesting comparison ...

Yes, I need the torque #s in ft-lbs at 100rpm, 200rpm or 500rpm increments, I have the gearing, cwp is stock 9:31? also need the rolling radius of the tires, better to have the tire revolutions per mile but either rolling radius or roll the loaded tire out as many revolutions as space allows, the length of the rollout & tire revolutions(whole #s are easiest to deal w/)

I'll put it together and send you a copy

Tom W · Tom W's Garage

I sent an email with the data in Excel ...