I never knew that these horsepower ratings were possibilities for the VW. Of course, if I'd probably build it to Great Plains standards for aero engines, (dual ignition systems, etc.), but I'm wondering what would be the right horsepower/prop/reduction unit combination to squeeze out a 95-100 mph cruise, keeping reliability (primary concern), fuel economy, and longevity in mind?
Several reputable options for increased power (however no where near the numbers you show in that link). Imagine that durability might be an issue.
Hummel and Revmaster two options which may be familiar with. However, airframe wise, I see the V-Max listed for 50 HP, so not sure how it would accommodate the higher HP
This is the real world HP numbers for aircraft VW engines. The ones you show in your list are for road going vehicular use, and can use elevated rpm's to make that kind of power.
For the vmax, I would probably not use the 85 hp engine option......the others are all the same weight......and you DONT HAVE to use full power......
But then I am building a vmax, but engine selection is a ways a way for me.
Yeah, that's what I figured (about auto applications making higher HP, and the V-Max being rated for 50-60). I guess a better question would be whether or not to use a reduction drive, longer prop, and maybe a 60-65 hp variant to get that extra 100 lbs of thrust. My main objective would be to shorten the takeoff roll somewhat, and maybe have some more quick thrust on tap for safety. If the average cruise went up 10 mph or so, without hurting fuel use (range), that could be useful, I'd think.
I just read a very enlightening article by one R.S. Hoover, concerning the realities of VW engines used in aircraft, and outrageous horsepower claims. Seems I forgot the old adage about things that seem too good to be true...
There is a guy on HBA that had a vw 1835 or so, 60hp, direct drive on a single seat wood fabric plane just slightly bigger than a himax. He was very happy with it. Long time vw guy.
Continuous power limit for vw derivatives has mostly been cylinder head cooling issues. They work great up to a point, then have problems, according to everything I've managed to find on the net anyhow. I've only had one though, and it was in an old bus.
I've been wondering if a guy could get the largest great planes direct drive model, and prop it down to 50 to 60 hp, getting the rpm down as low as possible for better thrust......
The HP numbers shown by CBP are made at very high rpm....too high for aircraft use. You could use a reduction drive as sold by Valley Engineering but that adds weight and complexity and isn't necessarily ideal for a V-Max airframe. A friend of mine has a Valley Engineering VW with belt drive turning a 90 inch prop in a full size WW I Nieuport 28 replica. He has had some challenges.
My old Sonex had a 2180cc Aerovee (VW based engine) rated for 80 hp at 3500 rpm. A more realistic figure for continuous operation is about 60-65 hp. This was with a 54x48 prop turning about 3150 rpm and at an airspeed of 115 mph. You should be able to get 95-100 mph from a clean V-Max.
There is a guy on HBA that had a vw 1835 or so, 60hp, direct drive on a single seat wood fabric plane just slightly bigger than a himax. He was very happy with it. Long time vw guy.
Continuous power limit for vw derivatives has mostly been cylinder head cooling issues. They work great up to a point, then have problems, according to everything I've managed to find on the net anyhow. I've only had one though, and it was in an old bus.
I've been wondering if a guy could get the largest great planes direct drive model, and prop it down to 50 to 60 hp, getting the rpm down as low as possible for better thrust......
My understanding is that overloading an engine will result in overheating, poor efficiency and possibly other undesirable internal loads.
Direct drive. Firewall mounted 60 hp 4 cylinder V-dub in my max from Scott Castler is doing great. I would be very wary adding a prop rpm reducer and longer prop. Lots of modifications needed here. Ground clearance would require longer LG. Heavier weight would mean added lead in the tail or a longer fuselage. My 2 cents B-😀👍
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