Mean Piston Speed
07-12-2011 | 06:47 AM
#1
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Joined: Aug 2008
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From: Indianapolis
Mean Piston Speed
So I was doing some research on F1 engines today, and came across a term called MPS (Mean Piston Speed). MPS is a formula used to calculate the average piston speed of an engine:
The mean piston speed is the average speed of the piston in a reciprocating engine. It is a function of stroke and RPM. There is a factor of 2 in the equation to account for one stroke to occur in 1/2 of a crank revolution (or alternatively: two strokes per one crank revolution) and a '60' to convert seconds from minutes in the RPM term.
MPS = 2 * Stroke * RPM / 60
For example, a piston in an automobile engine which has a stroke of 90 mm will have a mean speed at 3000 rpm of 2 * (90 / 1000) * 3000 / 60 = 9 m/s.
What excited me was this section of the article:
It is a good indicator of the class and performance of an engine relative to its competitors. The Honda S2000 has the highest piston speed for any production car (25.2 m/s).
and also:
A 2.4 litre Formula One engine at 19,000 rpm has a 25 m/s mean piston speed (39.7 mm×2×19000 rpm / 60), the same value as the Honda S2000 engine (84 mm×2×8900 rpm/60)
It looks like our little roadster really does have F1 roots.
The mean piston speed is the average speed of the piston in a reciprocating engine. It is a function of stroke and RPM. There is a factor of 2 in the equation to account for one stroke to occur in 1/2 of a crank revolution (or alternatively: two strokes per one crank revolution) and a '60' to convert seconds from minutes in the RPM term.
MPS = 2 * Stroke * RPM / 60
For example, a piston in an automobile engine which has a stroke of 90 mm will have a mean speed at 3000 rpm of 2 * (90 / 1000) * 3000 / 60 = 9 m/s.
What excited me was this section of the article:
It is a good indicator of the class and performance of an engine relative to its competitors. The Honda S2000 has the highest piston speed for any production car (25.2 m/s).
and also:
A 2.4 litre Formula One engine at 19,000 rpm has a 25 m/s mean piston speed (39.7 mm×2×19000 rpm / 60), the same value as the Honda S2000 engine (84 mm×2×8900 rpm/60)
It looks like our little roadster really does have F1 roots.
07-12-2011 | 03:46 PM
#6
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From: Maggie Valley, NC
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07-13-2011 | 03:46 AM
#8
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From: Indianapolis
Actually, I think overst33r is right. Every source that I've looked at says the 5.2 V10 FSI motor redlines at 8700 rpm. 2 * 92.8mm * 8700rpm / 60 / 1000 = 26.91 m/s So edit: The F20C HAD the highest average piston speed. It's ok though, we still have 300 extra rpms 
07-13-2011 | 04:53 AM
#9
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From: Palm Harbor, FL
Originally Posted by overst33r' timestamp='1310504424' post='20772366
Actually Audi's V10 for the R8/Gallardo has the higest piston speed of any current engine at 26.91 m/s. It has a fuel cut at 8700RPM.
