BeechTalk - BT

Username Protected · **Posted:** 22 Apr 2022, 19:38

I have flown the naturally aspirated Dakota a lot and its performance even with the low compression pistons is definitely better at altitude (going over Monarch pass into Gunnison) than an IO360 powered Cherokee. the tapered wings help but the engine seems to not derate as much at altitude because of the larger displacement I think.

Higher compression pistons would probably help more.

Username Protected · **Posted:** 22 Apr 2022, 21:09

The Dakota has the higher compression pistons. Likely can get STC for 94UL.

As a rule, all parallel valve Lycoming’s were originally approved for 91/96.

Username Protected · **Posted:** 26 Apr 2022, 05:58

Username Protected wrote:

Update, I was able to successfully obtain a field approval for installing the high compression pistons, so this type mod is still possible, but took about 9 months!

Stephen, I must ask, what did it do for performance? If you have a fat wing 28 like mine I would not expect much more in cruise and a bit better take off and climb. Did you document before and after. No more auto gas STC and likely no 94UL with the high compression pistons.

Cherokee 250?