The sprint track that I run at has a twist on the Box Stock Project rules - we're required to run a billet steel flywheel. This was originally done to help keep the cost of an engine build down. Our season is coming to an end this Sunday during our final race, and several of us are going to propose that we start running aluminum flywheels next season in an effort to get more aligned with the BSP rules and to make it easier for anyone with a Clone engine running BSP rules to come and race with us at our track in Katy, Texas.
I know the subject of aluminum flywheels has come up many times in the past, but my question is more around the power required to spin any of these due to the wind resistance of the machined cooling fins while confined within the flywheel tin. Is there a considerable difference in the fin design from one manufacturer to another, meaning are they all just hook shaped and designed to be pleasing to the eye, or has anyone done their homework and made a fin that doesn't rob a lot of power just beating a hole in the air. The original plastic fins may have been designed to pump the air at 3600 RPM, but I would question their efficiency of moving that air at twice the RPM. Obviously, zero fins have less resistance than some fins, which is why the Jr. Dragster guys run fin-less, but sprint engines do require the cooling breeze.
I guess some sort of simplified dyno comparison done while spinning all the competing aluminum models would be required. I can see just a simple shaft turning the wheel while it's inside a blower housing is all that would be required, and doing it that way removes all the variables that a dyno run with an engine doing the turning would cause. Differences in ignition timing alone from the location of the magnets in different wheels could cause enough power difference to throw off the results. Has anyone done this sort of simple comparison before and, if so, could you share your results?
Thanks in advance for any responses!
Mark
I know the subject of aluminum flywheels has come up many times in the past, but my question is more around the power required to spin any of these due to the wind resistance of the machined cooling fins while confined within the flywheel tin. Is there a considerable difference in the fin design from one manufacturer to another, meaning are they all just hook shaped and designed to be pleasing to the eye, or has anyone done their homework and made a fin that doesn't rob a lot of power just beating a hole in the air. The original plastic fins may have been designed to pump the air at 3600 RPM, but I would question their efficiency of moving that air at twice the RPM. Obviously, zero fins have less resistance than some fins, which is why the Jr. Dragster guys run fin-less, but sprint engines do require the cooling breeze.
I guess some sort of simplified dyno comparison done while spinning all the competing aluminum models would be required. I can see just a simple shaft turning the wheel while it's inside a blower housing is all that would be required, and doing it that way removes all the variables that a dyno run with an engine doing the turning would cause. Differences in ignition timing alone from the location of the magnets in different wheels could cause enough power difference to throw off the results. Has anyone done this sort of simple comparison before and, if so, could you share your results?
Thanks in advance for any responses!
Mark