I was talking to a buddy and he said that the upper limits of piston engines was the piston breaking the speed of sound. I expected it would be the mechanical limits of the connecting rod or piston. Looking at one of the mech-tech sites this morning yielded this thread and a part is posted below.

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I work for a company that races and sells high performance motorcycle engine parts...here's a post I put up on one of the enthusiast boards when people started talking about wanting to raise the redline of their bikes from 5K to 6K or more. FYI the bike is Yamaha's Warrior an air cooled V-twin that displaces 102ci stock and the connecting rods are scary long and skinny...lol

At 5000 rpm your piston goes from a complete stop to 66mph in 2 1/4 inches in just .003 seconds.

Interesting Warrior Engine facts/figures:

Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass.

1000 / 13.25 / 40.49

2000 / 26.50 / 161.98

3000 / 39.76 / 364.47

4000 / 53.01 / 647.95

5000 / 66.26 / 1012.43

6000 / 79.52 / 1457.90

7000 / 92.77 / 1984.36

For Comparison at "redline":

Chevy 350

Engine RPM/ Piston Velocity mph / G's exerted on rotating mass.

6000/ 62.20/ 1140.15

Formula 1 engine

Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass.

17,000/ 83.56/ 361.27

2004 R1 Engine

Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass.

12,500/ 78.58/ 250.12

2004 R6

Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass.

15,500/ 79.98/ 315.69

2004 V-Rod

Engine RPM/ Piston Velocity mph/ G's exerted on rotating mass.

9000/ 76.14/ 174.50

OK guys for those who are not bored by this...here's the math.

I did my math in feet, just to keep from having to change the numbers up at the end, but trust me it's the same.

Warrior Stroke=113mm or .370735 feet.

Distance traveled by crank per revolution 1.16632 feet (remember that the circumfrence is "pie"* diameter)

Revolutions per minute=5000.

Distance crank travels per minute=5831.608202 feet

Distance crank travels per hour=349896.4921 feet or 66.2682 miles per hour.

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Link: http://www.eng-tips.com/viewthread.c...SPID=71&page=1

So there you go. The speed of sound is dependant on the atmospheric conditions and pressure so maybe it's as low as 100mph inside a pistion but I doubt it. Now the bonus question is, does it produce a shock wave effect?

PS. did anyone else notice they need a new rainsuit this morning?