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- Jul 8, 2011
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- 2,668
Fast Eddie said:My question to the collective here is, if I ran the same Commando on a dyno with a stock heavy crank, then with a lightweight crank, with everything else being equal, would this show in any different readings on the dyno?
mdt-son said:being exceedingly small, I doubt you will spot the difference at the dyno.
To Fast Eddie - Simply yes.
From first hand experience you can feel a significant difference and anecdotal evidence from others who have lightened their crankshafts has supported this so it is not small.
As an example, see results of dyno testing of a V8 where they reduced the overall flywheel mass from 31 lbs to 24 lbs
http://www.superchevy.com/how-to/en...to-add-hp-with-a-lighter-flywheel-why-weight/
The above is from 7 lbs reduction in overall flywheel mass and we are seeing people reduce a Norton crankshaft from say 24 lbs to around 17 lbs (7 lbs reduction in mass) and, in contrast, much of this reduction is focused on reduction in rotational mass.
It would be great to see a side by side comparison (before and after on a Norton twin) to quantify for that particular Norton twin. These results would vary based on state of tune of the particular bike.
The flywheel is simply an energy storage device so when you accelerate, energy is stored in the flywheel, energy that would have otherwise accelerated the vehicle down the track. This energy is stored in rotation and translation.