brycelarson, on Aug 25 2009, 08:46 PM, said:
I'll pass this along to a person better with physics than me. We saw something along a 20-25 fps change from largest bore to smallest bore. That's out of aprox 275 fps - so we're looking at 10% increase in speed - at the highest end of things.
test data the largest bore (.696) shot 9 fps slower than the smallest bore (.682). 9 / 286 = 3.1% slower. But the biggest difference in efficiency was actually between the smallest bore and the bore that matched the paint (.686) with a difference of 11 fps. 11 / 286 = 3.8% slower.
That's just velocity change, the change in efficiency is calculated from the energy used like bryce said. Energy is proportional to velocity squared so the biggest difference in efficiency is between the paint-bore match and the underbore at ((286^2) - (275^2)) / (286^2) = 0.075 So paint to bore match is 7.5% less efficient than underboring.
Between Overbore and underbore, the overbore is 6.2% less efficient.
((286^2) - (277^2)) / (286^2) = 0.062
Obviously all those values are from limited test data with some error. I used the data from barrels of the same length so that the only differences being compared are bore size. There are larger drops in efficiency when you combine overboring with say a really short barrel.
Edit: Haha wow there were 3 posts durring the time it took me to do that. sad for me.
in out testing the CP backs showed significantly less FPS then the back plus a 2 inch front which was ported.
This is interesting. Just goes to show that as long as there is some pressure difference in the barrel the ball will keep accelerating.
This post has been edited by Leftystrikesback: 25 August 2009 - 11:23 PM
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