AvGas vs. Regular gas for Pawnee?

That's what we are running also Frank.. but we changed from the 1A200
propeller to the 1P235 propeller, both listed on the TCDS for the PA-25 with
the O-540 engine. The 1P235 is lighter in weight and also provides an
additional 60fpm climb rate at max GW. We are running about 1250 lbs below
Max GW in our tow configuration. The old propeller was totaled in the prop
strike which drove us to a rebuild on the engine. BT

"Frank Whiteley" wrote in message
oups.com...
Synopsis from our chief tow pilot

"Per Howard Kron's current STC (which I bought and is our basis):
Higher compression pistons (but not actually THAT high; 90/96 or
100LL required); RPM max still 2575, same as 235; prop replaced due to
hub damage ..... which was not previously
picked up, and Factory New prop pitched to the original factory 84-52
(had been whacked back to ~49 pitch).

Net effect, much stronger, climbs like a raped ape. The AirCare
twicepipes (i.e., dual exhaust, NO!! mufflers) STC probably helps
significantly, too. In our operation, 65-68kts TAS is right at redline.
If anyone wants faster, they'll climb slower, owing to
too-flat AOT, and probably have to throttle back to stay legal."

I recall some discussion that the 250 STC is probably a better option
than the 260 (we couldn't find a core), as the 260 has a jump in fuel
burn for the extra 10hp. Apparently a lot of the 260hp cores are on
those air boats we all saw in Louisiana and Mississippi after Katrina,
with no maintenance records and a lot of swamp water exposure.

Frank Whiteley