MEAN PISTON SPEED

Mean piston speed. This is a great calculator to help you understand the level of parts needed for your build and the limitations that reciprocating  components can have. 

 

Most older street engines operate up to 3500ft/min fairly well. At those low stress levels even basic components can do millions of cycles. An example of this would be an old  350 chev. It has a 3.48 Stroke and from factory revved to around 5500 rpm. That works out at around 3200ft/min. well within the save area of reciprocating stress. 

From here we move up to mild street strip performance engine  at speeds up to 4500ft/min.  This would be something with an average to good quality aftermarket rod preferable a 4043 H-beam and a forged piston and perferably runner a forged steel crank to help with the increase stress. Now lets take that same 350 chev and increase RPM to 7500. MPS is nearly 4400ft/min! Clearly far more stress on the internal components and also massive reductions in cycle life. of course depending on the quality of your components. but also we need to consider its intended use too, as this will effect service/cycle life. The best example of this is a circuit engine.  Due to the increased prolonged high rpm the quality of components would have to be far higher the a similar combination build for street/strip. 

From here we head into the realm of competition endurance circuit engines and rather serious street/strip engines. These engine should be limited to around 5000ft/min. A great example of an serious endurance engine would be NASCAR. with a 3.25 stroke and 9000 RPM they are just under at 4900ft/min.  this is pretty much the limit for anything endurance based, even the impressive 20,000 RPM V8 F1 engines were only around 5300ft/min. 

Now for engines that see up to 6000ft/min, they are going to be very high quality drag racing engines with some of the best quality steel rods you can buy. or maybe even Aluminium rods. An example of this would be an big stroke LS or BBC with a 4.25" stroke doing 8500 RPM. Thats going to be right on the 6000ft/min mark.