drive train losses

[Eric]

-----Original Message-----
>I have to take issue with the idea that you can "lose" 100 hp in the drive 
>train.

>Where does this energy go? 100 hp is (at 33,000 ft. lbs per hp) over 3 
>million foot pounds, at 746 watts per hp, it is 74.6 KW, enough to run your 
>whole house, central A/C, big screen TV and all. This energy simply does 
>NOT "disappear" in the drive train.


I agree with an earlier post that a flat percentage figure is not accurate for all power levels.  However the losses are not insignificant.  Every gear mesh is going to have some loss, plus the preloads on bearings in the system.  The example you are using would be a 500 hp unit with 20% loss.  Like others have stated I don't think it would be 20% at those power levels, but that is best tested emperically with a dyno coast down test.

On your figures remember Hp is a power figure.  It is equal 33,000 lb-ft PER MINUTE.  You can't directly correlate it to torque without speed/time relationship.  You are correct about running the whole house.  Most new US homes have 200 amp service.  This would only equal 64 Hp worth of available power.

I would be good to see some coast down test numbers on a 4 wheel dyno.  Or better yet get someone to run their car on a 4-wheel dyno then jerk the engine and run it on an engine dyno.  That would solve it once and for all.

--  
Eric Sanborn

Http://sofadog.net/4ktq/