Mike Alimov · Mar 28, 2002 01:53 PM
#0 source
I purchased a Double Star 40 last year, in the hopes of using it for a classic design, say a Tucker Special. After some bench break-in, I went on to compare its power output to that of the Fox35 (a well-known benchmark). For the record: both engines are stock, with their respective stock mufflers, both using hot K&B glow plugs (no idle bar). Procedure: I put the Fox on the bench, filled the tank with Powermaster 22% 50-50 oil and 7.5% nitro, and tuned to determine the max RPM with APC 11-5 prop. I think it was about 10,000 RPM. Within minutes, after Fox has cooled, I swapped it for the DS40, same fuel, same prop, same procedure. And... got the same RPM - about 10,000.
Question: does this mean that the two engines have the same power? Or is there a flaw in my procedure? Should I keep increasing the prop diameter, and see which engine drops RPM first (sort of like torque curve experiment, without a torque test bench)? Finally, should I even expect the DS40 to be more powerful than stock Fox35? (I'd think so - bigger displacement, AAC piston/liner, better fit and overall machining tolerances...)
Question: does this mean that the two engines have the same power? Or is there a flaw in my procedure? Should I keep increasing the prop diameter, and see which engine drops RPM first (sort of like torque curve experiment, without a torque test bench)? Finally, should I even expect the DS40 to be more powerful than stock Fox35? (I'd think so - bigger displacement, AAC piston/liner, better fit and overall machining tolerances...)