Engine load vs RPM and torque

[Greg Hermann]

>Greg,
>
>> >I'd like to be able to input the weights of the piston and rod, and the
>> >torque value to obtain their loadings. Most people will tell you the largest
>> >loads are seen on the exhuast stroke at TDC,
>>
>> This is in tension---
>>
>>  but that doesn't explain why
>> >those turbo Honda's start bending rods at 10 psi...
>>
>> This is instability under compressive loading (column failure.
>
>I realize the difference, even though my first year statics course was 5
>years ago ;-). What I'm getting at is most references say that the tension
>loads are so much greater that you don't have to worry about the compressive
>loads. Not so when artificial aspiration or severe knock is encountered.
>
>> Aluminium is not good for SUSTAINED high revs because of no fixed endurance
>> limit in tension.
>
>Drag racers sure can get away with a lot that OEM's or even oval/road racers
>can't. Are you uncomfortable driving cars with Al suspension pieces due to
>no endurance limit...?
>

YES!! Also uncomfortable on ski lifts that use cast aluminium balancer arms
between sheaves on their towers!! Use a Ti alloy if weight is that big an
issue!! (Nothing beats cubic $$$$$!!)

Forged Al is OK in cyclic compressive loading (like a full floating wheel
hub), but, as much as I like the forged (6061 alloy) Alcoa wheels, even
they crack quite a lot in the wrong kind of service!

Regards, Greg

>Matt Beaubien
>mbeaubie at ualberta.ca
>3 x 510
>1 x 300ZXT