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rv7charlie

Well-Known Member
Joined
Nov 17, 2014
Messages
1,017
Location
Jackson
While most would find it impossible to restrain themselves from using all available power, there can be advantages to gearing a VW that don't involve making a lot more power. By gearing the engine, you protect the crank from bending loads, you can operate the engine with lower cylinder pressures (BMEP), lowering stress on the engine's components, and at least with slower planes that can swing a longer prop, you get very significant thrust efficiency improvements. Witness the old red & white Valley Engineering VW powered 2 seater that used to fly off the ultralite field at OSH. It left the ground quicker than anything short of a helicopter, and outclimbed everything there, too. Similar situation with one Kolb owner, who replaced a Rotax 582 with a direct drive VW. It was a dog. He added a gearbox, and is a happy camper.

Having said that, the VW would be far down my list for a new project in that HP/weight category, for the reasons mentioned above. I'd probably pick one of those Chinese UTV engines over the VW.

Charlie
 
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