VW Aircraft engines - Tell me about your experiences

I think I have found the airplane I want to build, but what is keeping me from pulling the trigger is the engine.

After a bit of reading, no plane has caught my attention like the Thatcher CX-5. I have inquired about plans, but the thing that is keeping me from ordering them is the VW conversion engine.

I am a 75 hour student pilot (waiting for a check ride) that has never flown in a plane (pilot or otherwise) that wasn't a Cessna (with the exception of airline flights). I don't come from an aviation family, in fact I was 30 before I flew in a plane that wasn't operated by a 121. So for me, the most difficult parts of learning to fly are scheduling time with the professionals I need, paying for it, and understanding risk well enough to make informed, safe choices.

This post is about the third part. I don't feel that at 75 hours it would be safe for me to fly an auto conversion, but I expect the build to take years, and I don't want to dismiss a plane that is what I want otherwise, because I don't understand the risks, or what my own risk tolerance will be.

I have dismissed many auto conversions, but the thing that keeps me from completely dismissing VWs is that there were aviation certified VW engines (Limbach), and that leads me to wonder if engines like the Revmaster are closer to the Continental Titans than they are to the Eggenfeller Subarus.

What are your experiences with VW engines?

Your mileage may vary! How handy are you? Motorhead at heart? Can you follow written directions? If so, I see no problem with it.

I built an AeroConversions engine in 2011 for my Sonex. AeroConversions is the engine side of the Sonex LLC. Well thought-out kit. I had some friends that bought the turbo, but they had problems with it. That was years ago; I would ignorantly assume they improved upon it by now. Stick with the steel cylinders. When I bought my kit, they offered nik-a-sil cylinders if bought during Convention. All of us who did ultimately had to replace 'em. Warped, welded to the heads, etc. The basic engine package is pretty mature.

Great Plains VW conversions may or may not still exist. The original owner retired, but I thought I heard somewhere that the brand continues. RevMaster is another VW brand that I have not heard bad things about.

As with most homebuilt projects, even if using something like an O-200, cooling air / baffles / carb mixture / etc are the big things to get set up properly.

I sold the Sonex in 2015; my wife would not fly with me (a bit too cramped).

The CX-5 is specifically designed around an 85HP Revmaster, that is why I specifically mentioned that one. But I would consider any VW if it had advantages over the Revmaster. (I do not plan on choosing a turbo option.)

I really like my direct drive 1915cc VW turning a 62" prop. Electronic ignition, dead simple maintenance, and inexpensive to operate.

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Originally Posted by Frank Giger

I really like my direct drive 1915cc VW turning a 62" prop. Electronic ignition, dead simple maintenance, and inexpensive to operate.

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My Aerovee came in a box, assembled like the book, and has 270 hours on it today. You didn't mention price but you can't beat this one. If you must rely on someone else to assemble your engine you will pay for it.

I have sent two engines to Hummel Engines. One needed every interal part replaced and he got it as a basket case. The other had to have a complete case replaced along with bearings. Both times I spent around 2500 dilivered. I even sent Scott the paint and he painted these engines the color I wanted. He told me he has never painted an engine purple. The first engine I put around 200 hours on it before selling the airplane and that engine was running great when I sold that airplane. The second is still in service with around 50 hours on it now. It is not broke in yet. If not for the vw, I would have stopped flying. Two strokes are not for me and GA engines are out of my price range. The vw fits perfect for what I want in an aviation engine.

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Originally Posted by 1600vw

I have sent two engines to Hummel Engines. One needed every interal part replaced and he got it as a basket case. The other had to have a complete case replaced along with bearings. Both times I spent around 2500 dilivered. I even sent Scott the paint and he painted these engines the color I wanted. He told me he has never painted an engine purple. The first engine I put around 200 hours on it before selling the airplane and that engine was running great when I sold that airplane. The second is still in service with around 50 hours on it now. It is not broke in yet. If not for the vw, I would have stopped flying. Two strokes are not for me and GA engines are out of my price range. The vw fits perfect for what I want in an aviation engine.

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What type engines were they and what did you have them flying in?
Bob

I have had a fair amount of experience with VW aero conversions. Good to hear you want to get deep in the build, because there is a dark side to VW that has a very bright light at the end of the tunnel.
DARK SIDE: Standard VW engine blocks (the case) have 3 known cracking areas. The middle main crank bearing journal, the oil galley that runs vertical down the right-forward side of the block (as seen in an aircraft tractor-config, and in the web braces inside the bell-housing (where the generator/stator is placed on these conversions). Many, many of them crack and they mostly can't be welded.
BRIGHT LIGHT: Because there are still scads of air-cooled VW's running around Brazil & Mexico, a Brazilian company named Auto Linnea re-designed the standard block to modern knowledge and has fixed all of those issues. They also still make the old standard design. They even made the top of the case with a domed area for those who want to install a stroker crank (in the past this meant shaving metal from the inside of the case). I can't remember the name, but there is a U.S. company --with catalog-- that sells all manner of after-market VW high performance parts. Any VW shop will know. Just look up their 'premium' case. They and some of the US conversion shops mentioned in this thread also sell a new upgrade head. More fins, stainless steel valves, less prone to the standard cracking issues. I bought one of those cases and had it built up, worked great. If that KR-2 was a little bigger, I'd still have it. VW was easy to work on, reliable other than the crack issues, and CHEAP. The guy in Chile who builds all the Sonex's and VW's for people who aren't doing it themselves saw my KR-2 Barnstormer's ad; after finding out I had an Auto Linnea block built up, he bought it sight unseen and had me ship it to him.
REVMASTER note: The main US companies that make VW aero conversions are about the same to my observation. With the exception of Revmaster. They have a patented oversized bearing at the Thrust Bearing position. You can't beat it! I had the machine shop make that part of the build when my standard case cracked in two of the 3 places.

Speaking of KR-2--- Since you are looking to scratch-build, the upgraded KR-2S is a great plane. Roomier, fast, cheap & easy to build & fly. Designed for VW.

OTHER ENGINES: William Wynne in Florida has a great Corvair conversion kit. All the early issues worked out, many flying, air cooled & direct drive, 6 cyl!! Some in KR-2S are tickling 200mph. Company is FlyCorvair I believe.

My VW is kind of a mongrel, as I had Valley Engineering put it together for me.

Let me clarify a bit - it's a great build they did, with SCAT parts (Great Plains design), but when I had to rebuild it (my fault, prop strike) it was the devil to figure out that they used a Harley Davidson electronic ignition and voltage regulator.

I think the key is to pair it with the right air frame, to where one isn't asking things of it that it just can't deliver. I know of one KR-2 flying with a VW, and the guy is having great results...but another with an O-200 is outperforming him. This only matters as much as it does for the pilot/owner.

In my world of WWI representational aircraft, the VW is just about the standard go-to engine, either direct drive or with a PSRU.

Btw, while I was rebuilding my VW and decided to just spring for a new crankshaft instead of wondering if there was an invisible crack, I was poor mouthing about the two hundred dollars the replacement cost. Unfortunately, I was doing my whining to an EAA brother who was rebuilding an O-200 at the time, and he told me to either shut up or wind up getting a kick to the rear end. 200 bucks doesn't cover new spark plugs on his engine.

Bob one was a 1/2 vw in an Avenger. That engine ran so very well. I loved it. The other is a full VW in a cygnet. That engine is to new for me to give any comments on how I like it. But I am sure I will love it like I did my 1/2vw.

I only have one problem with my Aerovee. After flying, with everything hot, the engine lopes at idle. It runs from 950 rpm up to 1100 and back. The mixture, from rich to lean, doesn't make a difference. The research I've done says it's most likely a vacuum leak. There are only six hose clamps in the intake system and tightening them doesn't help. The only place I haven't checked is the two elbow gaskets on the heads. Any thoughts or suggestions?

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Originally Posted by Morrie Caudill

I only have one problem with my Aerovee. After flying, with everything hot, the engine lopes at idle. It runs from 950 rpm up to 1100 and back. The mixture, from rich to lean, doesn't make a difference. The research I've done says it's most likely a vacuum leak. There are only six hose clamps in the intake system and tightening them doesn't help. The only place I haven't checked is the two elbow gaskets on the heads. Any thoughts or suggestions?

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Get a can of carb cleaner. Put the little red plastic tube on this can. Now with the engine idling spray this around all rubber joints. If one is leaking the engine will pick up RPM's while you are spraying this. If the engine rpm's increase you just found your leak. By the way, I am about one hour south of you. There are a couple of us in this area flying with the VW engine.

Are there any VW engine pilots/builders/mechanics around Atlanta (I sleep in the Class B of ATL) willing to talk me through the VW airplane engines, and possible share some knowledge in person?