zx12adam
Member
Posts: 878
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posted September 25, 2007 10:25 PM
Calculating piston speed?
How do you calculate piston speed of engines with the stroke and the redline? I've heard certain manufacturers stay under certain piston speeds for their streetbikes.
Let's say 56mm stroke motor turning 13,000 rpm's.
728,000mm per minute?
7,280 meters per minute?
12,133mm per second?
121.33 meters per second?
4,368 Kilometers per hour?
Correct?
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CBR1000RR
Best Literbike: Performance Bikes, Superbike, BIKE, MCN, Road Racing World, and Motorcycle USA
  
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted September 26, 2007 06:14 PM
You need to know the rod length also for piston acceleration figures which are just as, if not more important for durability.
So for non ported pistons...
The general rule for max velocity is 4500-4600 fpm. (4500 fpm=51.1mph)
And the maximum acceleration for durability is 280,000 fps. Acutally its really calculated by total load, a function of rpm and piston / rod weight. figured in g forces, but we need a number for discussion and few engines ever exceed 280,000 fps.
ok, so.... lets say its a zx12r with a stock rod length of 4.454"
The rev limiter on the 12r is 11,625
11,625 rpm max piston velocity is 4035 fpm and max piston acceleration is 258,119 fps
13,000 rpm max piston velocity is 4512 fpm and max piston acceleration is 322,791 fps
with a 60mm stroker crank like the 1360/1375...
11,625 rpm max piston velocity is 4370 fpm and max piston acceleration is 269,293 fps
13,000 rpm max piston velocity is 4887 fpm and max piston acceleration is 336,765 fps
hope this helps.
what are you building?
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Y2KZX12R
CompetitionCNC.com
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zx12adam
Member
Posts: 878
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posted September 26, 2007 07:29 PM
Thanks for the info.
I'm not building anything, curiosity always gets the best of me, just one of the those things I sit and wonder about.
Learning is the brain's only food.
____________
CBR1000RR
Best Literbike: Performance Bikes, Superbike, BIKE, MCN, Road Racing World, and Motorcycle USA
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