AvGas vs. Regular gas for Pawnee?

Wondering what the other clubs/glider operations are using in their Pawnees
for fuel?

Would like to hear some informed opinions regarding this issue, please.

J4
Mid-Georgia Soaring Association

100LL, since Pawnee D airframe has no autogas STC, though engine did.

Pawnee 235, we use 100LL, another operator on the field has used both in the
same engine with his Pawnee.

100LL is now 3.05/gal, auto fuel "regular unleaded" is running 2.30 per
gallon but 20 miles away one way.. (local pumps are running 2.65 or higher)

We just upped the HP to 250 with an STC during the engine rebuild.. the STC
takes away auto gas options.
BT

"John Bojack" wrote in message
...
Wondering what the other clubs/glider operations are using in their
Pawnees for fuel?

Would like to hear some informed opinions regarding this issue, please.

J4
Mid-Georgia Soaring Association

I should mention that since we had no autogas option on the Pawnee D
model, we went with the 250HP STC also on our spring rebuild and a new
prop. Result appears close to 100fpm better climb on same fuel burn,
or about one more tow per tach hour.

Frank

I should mention that since we had no autogas option on the Pawnee D
model, we went with the 250HP STC also on our spring rebuild and a new
prop. Result appears close to 100fpm better climb on same fuel burn,
or about one more tow per tach hour.

Frank

"Frank Whiteley" wrote in
ups.com:

I should mention that since we had no autogas option on the Pawnee D
model, we went with the 250HP STC also on our spring rebuild and a new
prop. Result appears close to 100fpm better climb on same fuel burn,
or about one more tow per tach hour.

Frank


Frank,
Is the 250HP conversion louder? Higher RPM? Or, maybe just more
compression and a bigger prop?
-Bob Korves

the 250HP STC for the O-540 engine does not change RPM limits or approved
propellers from the original Type Certificate Data Sheet. It does allow the
use of a different piston resulting in higher compression.

We run "straight pipes" and have noticed no difference in sound.
We also changed to the lighter weight propeller that is approved on the TCDS
And a change to the SkyTec starter.

We have noticed a difference in climb power and resulting rate of climb. It
is an E-Ticket Ride for the 1-26 pilot.. his 10knt vario is pegged all the
way. We've noticed about a 150-200ft rate of climb increase for Grob 103s
and SGS 2-33s with two on board.

BT

"Bob Korves" bkorves@winfirstDECIMALcom wrote in message
. 44...
"Frank Whiteley" wrote in
ups.com:

I should mention that since we had no autogas option on the Pawnee D
model, we went with the 250HP STC also on our spring rebuild and a new
prop. Result appears close to 100fpm better climb on same fuel burn,
or about one more tow per tach hour.

Frank


Frank,
Is the 250HP conversion louder? Higher RPM? Or, maybe just more
compression and a bigger prop?
-Bob Korves

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

Very subjective to say it's noticeably louder though it sounds
healthier and a little different than it did before. Some is prop,
some is exhaust.

Frank

Very subjective to say it's noticeably louder though it sounds
healthier and a little different than it did before. Some is prop,
some is exhaust.

Frank