on the dyno, 16" or 17" wheels. any difference?
05-09-2003, 10:11 PM
#1
Nordschleife Master
Thread Starter
on the dyno, 16" or 17" wheels. any difference?
My 16" Fuschs have fresh falkens on em (my rain set)
My (Currently mounted) 17" Carrera Cups are heavier and have older worn tires. (But look better)
Which will give me better dyno numbers?
My (Currently mounted) 17" Carrera Cups are heavier and have older worn tires. (But look better)
Which will give me better dyno numbers?
05-10-2003, 12:10 AM
#2
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It depends slightly on the rolling diameter as well as weight. Pick the set with the smaller overall diameter, I would guess. Light weight (Fuchs) will reduce the unsprung mass, allowing faster acceleration.
stjobs
stjobs
05-10-2003, 03:53 AM
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...depends on whether you will be on an inertial dyno or a brake dyno... It won't make difference if it's on a brake dyno. If they're close in total weight, roll them down an incline side by side and the one the that wins should have the lower rotational inertia.
BTW, has anyone ever used a Dynapak dyno? Hub adapters replace wheels, and these attach to the measuring unit, no tire interface losses keep measurements fairly repeatable. Even AWD cars can be measured by using 4 hubs/measuring units. In the L.A./South Bay area, Church Automotive has one and I've seen repeatability to within a few horsepower.
BTW, has anyone ever used a Dynapak dyno? Hub adapters replace wheels, and these attach to the measuring unit, no tire interface losses keep measurements fairly repeatable. Even AWD cars can be measured by using 4 hubs/measuring units. In the L.A./South Bay area, Church Automotive has one and I've seen repeatability to within a few horsepower.
05-10-2003, 04:31 AM
#5
Nordschleife Master
Thread Starter
well, the Fuchs are on now, regardless. The carrera cups are noticeable heavier.
However I tried rolling them and the C2 cup fell over and seriously scuffed one of the spokes. ****.
Good thing they are off the car cuz I'm gonna be re-finishing them.
However I tried rolling them and the C2 cup fell over and seriously scuffed one of the spokes. ****.
Good thing they are off the car cuz I'm gonna be re-finishing them.
05-10-2003, 09:16 AM
#6
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I have seen on Rennlist where the Dynapac dyno may be OK on some 4WD cars, but not on a 996t. The front wheels must rotate at the same speed as the rears or the diffs will burn up. With the dynapac that is not possible as they are seperate drive units and cannot keep wheel rpm the same.
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Len Cummings
BoxsterGT
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Len Cummings
BoxsterGT
Lifetime Rennlister
05-10-2003, 10:22 AM
#7
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AHhhhhhhhhhhhhh stay away from a dynapak dyno. I saw Mike Bucks 951 almost blow up on one. It was vibrating like crazy, apparantly because the load characteristics were wrong. Now I'm not sure if it was the dyno, or the people running it that caused the error...I'm sure Mike can chime in here and give much better explanation
...all I know is it looked scary as hell
...all I know is it looked scary as hell
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05-10-2003, 08:44 PM
#8
Nordschleife Master
My car along with a few others were run on a dynapack dyno with no problems...well...a few of the cars went down with slipping clutches, but if the clutch held the dyno pull was very clean.
05-10-2003, 10:36 PM
#9
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Stay away from the Dynapak units. Like Chas said, my car didn't seem to like it. Guys running the dyno said I had a cheater traction control system . . .riiight! A few days later, my car pulled fine on my shops Mustang Dyno, just as it had back in February!!