Optimum piston speed?

[George Tyler]

if you driving at, say 35MPH then your required power to maintain that speed is around 300 Whr per mile, or about 10kW? If your engine is capable of 100kW then it is 1/10th of the maximum. If that was at 5000RPM and the RPM was 2000 at 35MPH then there would be 40% of that power available, or 40kw, so to keep at that speed you would have to have a 25% open trottle. The engine in my Previa won't run smoothly below 2000 RPM with the torque converter locked, and that is in overdrive. in practice i think the trottle is open much less that 25%, and there is nothing I can do about it!
If I changed the gearing it would not run in overdrive, I would just have to change down (turn the overdrive off) In actual practice the RPM range I use is 2000-3000 max so I can ignor anything outside that range. I can't drive at that optimum piston speed range because there is too much vibration in the drive chain.

[Frank Lee]

If your Previa has the 3.385" stroke engine, 1000-1200 ft/s piston speed occurs at about 1800-2150 rpm.

[Ladogaboy]

So what would the piston speed be @ 11,000 rpm with an 88 mm stroke?

[Frank Lee]

wallaceracing.com/piston-speed-velocity.php Plug in to your heart's content!

[gone-ot]

Here's another collegiate presentation explaining the Z mach number and gas flow (volumetric efficiency) in ICE (specifically see pages 10 & 18 of 20):

http://teacher.buet.ac.bd/zahurul/ME...efficiency.pdf

[aerohead]

Originally Posted by Frank Lee

I wonder how much throttle opening those 30mpg Vettes are running?

Frank,I'm not sure about the 2011 'Vettes,but some recent C7 articles are talking about cylinder deactivation,and running as a 4-cylinder car in top gear,at 55-mph to see that kind of mileage.
The V-8 engine was chosen over a V-6 so it could run as a 4-cylinder most of the time,something of which a '3-cylinder' 6-banger would not be up to the task.