And the additional 60-70 hp over the IO 360 should increase speed by

about

10%, or about 18 kts for the standard RG.

Al Gietzen

I agree with Al's numbers and it also illustrates the futility of adding HP
for speed.  By burning around 5.5 GPH ADDITIONAL fuel, you get to go 18 Kts
faster, a return of about 3.5 miles per gallon :-)   The same holds true for
my 20B powered RV-8 project.  My  real reason for adding cubic inches is to
increase cruise altitude where MPG gets better.   My -8 is intended to
cruise at 18,000 ft (actually 17,999 so I don't have to file IFR) where the
manifold pressure will around 13" Hg.  At this low pressure you need more
cubic inches (or a turbo) to make adequate power.  I expect to get around
35 - 40 MPG at these cruise conditions.  The higher aspect ratio of extended
wings (I'm adding about 3 feet to wingspan) also helps.

OK, I admit it, I'm an efficiency freak.  Speed addicts may ignore the above
comments.

The other benefit of HP is a big boost in climb rate for getting you up
there quickly, or for recreational use down lower :)

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

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