Surefly EI at High DA

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norcal64d
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Surefly EI at High DA

Post by norcal64d »

Can't remember if anyone else here is using the Surefly. I put one on my O-360-C1F and at first was very happy with it. However, now that my plane is back in Colorado and it's warming up, I am noticing a fairly significant lack of power at takeoff on high DA days (8500ft and up). I put in new spark plugs as the old champions were showing high resistance but that didn't change anything. The only way to describe the issue is just that the plane doesn't like high DA, with two slicks it's not a rocket but it climbs reliably up to 12500ft. I called Surefly and they checked their advance table and at takeoff 2700RPM 21" MP it's running at a full 38°. Everything I have read suggests that this is probably significantly past where you would make best power which would probably be like 30°. I switched it over to fixed timing and the plane got off the ground several hundred feet shorter and climbed at 700fpm at 8800ft DA, 1 person and 30 gals of fuel. I was getting 400-500 with the variable timing just for reference, same conditions.

Has anyone else used a Surefly in these conditions? Their tech support is mulling over my numbers and trying to see if I missed anything. I'm wondering if I am just operating in a region where it's not optimised for max power because probably 99% of people would be cruising at this altitude, not trying to take off.

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maules.com
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Post by maules.com »

Norcal, I see a discussion on BCP that might add info for you.
I don't know anyone with a Maule that is using the system.
Jeremy
www.maules.com
Maule AK Worldwide

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norcal64d
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Post by norcal64d »

I posted on the Vans RV forum because alot of those guys use it as well. It sounds like the timing advance that surefly is using is terrible for a back country plane at high DA. Based on all the engine data the RV guys have generated, best power rich of peak is nowhere near the 38 degrees that the Surefly will run once you're above 8500ft DA.

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