After Googling for some performance figures :-) I found the following figures to be rather representative of what one may expect from these engines using 15% nitro and rather typical propeller sizes:

OS46AX, APC 11x6, 11.7 krpm
Saito 82a, APC 14x6, 9.2 krpm

According to the manufacturers the OS has the edge with 1.65 bhp at 16000 rpm vs. 1.5 bhp at some unspecified RPM for the Saito.

Because we often use propellers that give RPMs below peak power RPM only some fraction of the peak power is available.
Using Pe Reivers [link=http://home.wanadoo.nl/pereivers/prop-power.xls]prop-power spreadsheet[/link] I found that my RPM measurements are equivalent to power otuputs of 0.9 bhp and 1.1 bhp for the OS and Saito respectively. The static thrust would be 6 lbs for the OS and 8.5 lbs for the Saito.

My interpretation is that the Saito develops its peak horsepower at RPMs that are much closer to the RPMs listed above than is the case for the OS, thus a larger fraction of the peak bhp is available from the Saito compared to the OS.

In my experience the figures above seems reasonable and when comparing my own OS46SF and Saito 72 engines that weigh about the same I have observed that the Saito provides more static thrust, shorter take offs and faster climbs compared to the OS even though the OS have a higher peak BHP.

For high speed aircraft, where high rpm and high peak bhp are both of importance I would choose to use the OS.

/Red B.