Lemans winning Mazda four rotor engine duty cycle at Lemans 24 hour
race.

Paul Lamar

James Russell wrote:

Hi:
        Am I looking at the LeMans graph correctly? I get 93 % time
spent in the 6000-8500 RPM range... That sounds pretty normal - in Formula
Fords we geared to operate between 5000-6500.

        Of course, I know the racing loads aren't like being on the dyno
at WOT for 45 minutes - as an airplane does.

Regards,
James

That's about right but the HP peak is 9000 RPM on that engine roughly and 
percentage of power is not directly related to RPM. Let me explain that further.
It takes RPM AND throttle opening to generate HP.
Lets say you floor the accelerator in a car. You are far from max HP until
the RPM hits the HP peak. When that happens you shift and the RPM drops.
So too does the HP and it does not get to max HP again until you hit
the HP peak yet again. A good driver can shift in less than .1 second.

What we need is a plot of the RPM as the car goes around the track and
sample the HP every 50 rpm only during actual full throttle acceleration and 
add up all the HP numbers looked up from a HP verses RPM curve. This 
will give a true HP duty cycle for a racing car. When a race car is cornering
only partial throttle is typically used and the RPM could be well over 5000. 
When the car is braking the RPM drops way off and the throttle is usually 
closed but not always. 

Aircraft engines on the other hand pound away for hours on end at 75 to 
80% max HP as you mentioned.

Paul Lamar
 
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