How do you determine maximum safe RPM for a race engine?

[rustbucket79]

Currently 7800 but the car responds positively with added RPM, I'm sure it would like at least 8000.

[David Redszus]

for the same MPS the one with shorter stroke sees higher accelerations

Yes, but.

In order to produce the same MPS, the shorter stroke engine must turn a higher rpm.

Yes that should have been obvious. Therefore the MPS should not be used as an indicator of acceleration.

I agree. Mean piston speed is used due its simplicity; it can quickly be used for any engine requiring only stroke and rpm inputs.

The more accurate metric is maximum piston acceleration which requires several additional measured inputs and a more complex mathematical computation.

Ultimately, what really matters are the forces produced and the ability of materials and design to withstand them.

[ProPower engines]

the way I see it is the only safe RPM is 0.

After that all bets are off. Its like I tell guys after a crash.........if your afraid of wrecking the car you should leave it in the shop where its safe.

[hoodeng]

Your right PowerPro, the best place for a vehicle is in the shed if you are worried about the invoice.

An observation some years back lead to people with advice after negative events being called 'gate shutters or coroners'

A Coroner is a the only person legally authorized to tell you how to avoid an accident after you have had it.

Cheers.

[408swinger]

the way I see it is the only safe RPM is 0.

After that all bets are off. Its like I tell guys after a crash.........if your afraid of wrecking the car you should leave it in the shop where its safe.

You forgot about rust.

[Mesik Motorsports]

When we build anything, it is custom built around an application where all the operating parameters have been determined based upon gear ratio, tire diameter and targeted ET & MPH. The projected RPM can than be used to select the proper CID, heads, cam, compression ratio... Now, "assuming" all of the components used to build the engine have been purchased with piston speed and reciprocating component weights as the determining factors the failure RPM should well exceed the build specs. However, some individuals can destroy an anvil with a dead blow mallet so you must keep that in mind using electronic RPM limiting technology.

[ptuomov]

How do you relate the stroke and piston ring width to maximum rpm at which the engine runs well/safely? I am thinking practical examples for engines with long duty cycles, like marine racing.

[Krooser]

This one went one too many...

[MadBill]

Always a bad sign when the Pentastar emblem bails.. .

[ClassAct]

Always a bad sign when the Pentastar emblem bails.. .

Right next to the Hecho En Mexico