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The 140 hp gap

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addaon

Well-Known Member
Supporting Member
Joined
Feb 24, 2008
Messages
3,976
Location
Kanab, UT
So in evolving my design, I'm realizing that the ideal engine would generate between 140 and 150 hp at around 2700 rpm, and it would be nice to maintain that power until at least 10k feet. Also, weight is absolutely critical; and I'm restricting myself to aircraft engines.

Currently I'm designing around an O-360-A1A (258 lbs dry, hoping to hit 320 lbs installed with a wooden prop). This is pretty overpowered (at sea level) for me. I'll probably drop to an O-320-A1A for a 14 lb savings on dry weight (and presumably not much more than that on install), but that's sure a small weight gain for a > 15% power drop; and the 150 hp 320s start looking marginal above 8000 feet or so.

Is there anything I'm missing in this power range? Frankly, I'm beginning to wonder whether an IO-233-LSA or ULPower UL350 could be comfortably turboboosted to the 140 hp range, and what reliability and weight would look like there. I know there's nothing wrong (heck, there's a whole lot of appeal) with "too much" power, but the combination of a heavy engine (even looking at the very lightest 360s out there), drastically more power than needed at low altitude, and mediocre altitude performance just doesn't feel like an optimum.
 
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