100 HP NA 2180 Aircraft VW ... is it possible?

[Daleandee]

It was a dark & stormy night a few days ago when someone on another site mentioned that a friend of theirs had a 2180 VW aircraft engine (naturally/normally aspirated, direct drive) rebuilt to put out 100 HP. I commented that I didn't belive it was possible to do so at the prop speeds we use nor keep the engine cool when producing that kind of power. A couple of replies indicated that I was not correct such as:

"It is probably possible given the low compression ratio's we set these to vs what it could be set to."

"100hp doesn't seem like a stretch. Higher compression will quickly get you more horsepower. Dual carbs. Higher RPM."

Certainly higher RPM will generate more power but that ignores my original statement that it can't be done with "the RPMs in a range where our small prop size would still be efficient." I pointed out the Revmaster R-2300 (2331cc, 142.2 cu.in.), a larger engine, that is rated 85 HP at 3350rpm but that is not continous power.

So with my small & limited amount of knowledge I wondered why, if it is so easy/peasy, that it hasn't been done yet. I know that adding the turbo gives a claimed 100 HP but that seems the equivilent of using a compression ratio of ~13:1 or an RPM of 4400 or higher. (Who would run a VW aircraft engine at such a high CR?)

So can I emplore the wizards of smart to help me so I can construct one of these engines that Bob Hoover said he could not build: https://bobhooversblog.blogspot.com/2006/11/av-christmas-engine.html

See that 2180cc VW hanging on the test stand out behind the shop? That's my Hangar Queen. Since 1968 or thereabouts she's racked up better than fifteen hundred noisy hours testing everything you've ever heard of and a lot that you haven't. (I've torn-down the poor thing so many times I've lost track.) See that box of wiggle sticks over there in the corner? Dig around, you'll find stock VW cams along with several from Engle, Web and Schneider, both solids and juicers, even a couple of special grinds I worked up myself, all chuggers designed to give maximum torque across an RPM practical for a propeller. Forty years of VW engine building experience, nearly two thousand hours of testing - enough gasoline to float a boat - and the best I can do is about 115 lb-ft of torque out of that thing. That's about 55hp. At prop speeds. Not 80 or 100 like all those other guys.

TIA!

 

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