Howard wrote:

I've been playing around with horsepower formulae.....   mainly the 1.62 CFM
per SAE horsepower.   This formula is very accurate in my opinion, but most
engines these days are rated in DIN.....   Looking for a simple fast way of
calculating projected HP at a given RPM I've come up with the following.

Displacement in liters * HP in 100's  =  DIN horsepower (approximate)

This comes pretty damn close to the mark with allowances of a few additional
points for lower RPM (max torque) or a slight reduction for high RPM (max
power).    To convert to SAE multiply by .87

It's not perfect but an excellent rule of thumb.

for example:

1600 CC engine @ 4500

1.6 * 45 = 72 DIN HP

72 DIN * .87 = 62.64 SAE HP

............  It doesn't get much simpler than this.........  Check it out
on Jabiru which is one of the few engines with an honest rating out there.

                       H.W.

Dennis Simanaitis tech editor of Road & Track wrote an article on the subject
of DIN verses SAE verses JIS verses CUNA in the Aug issue page 146.

Paul Lamar
 
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