Don Terrill’s Speed-Talk

Dan Timberlake wrote: ↑Sun Oct 04, 2020 12:06 pm I believe dual mass flywheels' typical function is to smooth out the power delivery "out the back" at low loads and heavy throttle especially with engines with few cylinders. Variations in instantaneous rpm. Not to tame the crank twisting events.

Yes, I agree that is the typical function. The challenge to the engineer is to abstract from this to the presented task. There is no requirement/law that the second mass be directly connected to the driveshaft.

The crankshaft is a consumable in this racing class. Design a crankshaft with dual snouts with the new snout being directly splined to the driveshaft u-joint. Make it a very expensive consumable.

No-one is going to pay for this.

If a wealthy competitor does and dominates the field then it will be prohibited by a rule.

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In this podcast, Billy @ Comp explains why sprints get away with no damper starting at 1:37:00, and a whole lot more. It is worth listening to :

https://readingtondigital.libsyn.com/11 ... -comp-cams

In this podcast, Billy @ Comp explains why sprints get away with no dampner starting at 1:37:00, and a whole lot more. It's worth listening to :

https://readingtondigital.libsyn.com/11 ... -comp-cams

BlitzA64 wrote: ↑Sat Oct 03, 2020 12:37 pm Another question. If I am driving off of the snout and no room for the damper, if I made an adapter to bolt the damper to the flywheel end of the crank would it be the same benefit as a damper on the snout end where the cam timing is? It would seem to me to be not as effective?

I/We have designed and made a number of flywheels with Salomon type pendulum absorbers in. They work very well at the flywheel end as well as at the free end of the crank. I think in the States the Salomon damper is made by TCI.
They are normally used on historic engines that need to appear "in period". You can hide them beneath a 7-1/4" clutch face too.
The design needs to be done very carefully as they are non-linear and if the amplitude of the rollers becomes too large they can be unstable and actually add to the torsional problems. Roller mass, tuning ratio and type of roller path are factors used to ensure this does not happen.

Dan Timberlake wrote: ↑Sun Oct 04, 2020 12:06 pm
265 AMC AND STUDEBAKER.jpg.

The forthright Studebaker engineer SW Sparrow proclaimed Studebaker provided a curious double plate rubber bushed damper for its "contribution to smoothness."

The Studebaker type damper was invented by Packard in the late 1920's and was used in various forms by several car manufacturers until the 50's/60's. Due to the cylindrical bushes, these are also non-linear in response and therefore need careful design. I do know that once setup correctly they work very well over a wide rpm range. There is a company in Brazil that still make aftermarket versions of this damper design.

maxracesoftware wrote: ↑Fri Sep 25, 2020 3:25 pm Edit : i forgot about Innovators West Dampers ... these Dampers were neck-and-neck HP results as ATI Damper in Dyno tests on NHRA SuperStockers

Did you ever test the Fisher friction dampers back in the day? How did they compare to ATI, etc.? I see the Innovators West one is an evolution of the Fisher design (which is probably the oldest damper design in itself).

surgeline wrote: ↑Mon Oct 05, 2020 2:36 pm In this podcast, Billy @ Comp explains why sprints get away with no damper starting at 1:37:00, and a whole lot more. It is worth listening to :

https://readingtondigital.libsyn.com/11 ... -comp-cams

That was excellent to listen to. Thanks for sharing.

Stef wrote: ↑Mon Oct 05, 2020 4:50 pm

maxracesoftware wrote: ↑Fri Sep 25, 2020 3:25 pm Edit : i forgot about Innovators West Dampers ... these Dampers were neck-and-neck HP results as ATI Damper in Dyno tests on NHRA SuperStockers

Did you ever test the Fisher friction dampers back in the day? How did they compare to ATI, etc.? I see the Innovators West one is an evolution of the Fisher design (which is probably the oldest damper design in itself).

i've had a few engines on the Dyno with a Fisher Damper , but no back-to-back comparisons

i should have a picture of a Dyno test with one , need to search for it .

Best article I found on this subject:

http://www.epi-eng.com/piston_engine_te ... orbers.htm