VW based engines. Pros and cons from users?

[danny_galaga]

Just curious about vw based motors. 4 cylinder. I hear the propeller is driven from the generator/fan side, not the crankshaft side. Or are some from the clutch end?

 

In any case, what's your experience? Hundreds of happy hours? Had it once, but never again? 

[facthunter]

The flywheel is retained by a single LARGE bolt. The other end you are driving from a keyed parallel shaft though some improvement may have been done to the later developments Most parts are from Brazil where production was kept going for quite a while . An assembled Head was about 200$'s.  IT  fits 2 cylinders but I'd prefer if didn't and the intakes are on the top.   Nev

[Paul davenport]

Some European engines featured main bearings which which got larger to the rear flywheel end of the motor. (Extra webbing on the crank case at the flywheel end helped) To the best of my knowledge VW was one of those engines, so it would make sense to drive from the rear of the engine. I. Have seen pictures of  a reduction unit driving from the rear forward to drive the prop achieving a performance increase at the cost of extra weight

[onetrack]

I was under the impression the Revmasta 2300 engine was among the better VW-based engines for an aircraft, because it was largely re-engineered for aviation use. However, it seems even the Revmasta isn't without its problems.

They're a heavy engine, no matter how much they're re-engineered. Revmasta can apparently build you an R-2300 with a magnesium crankcase, but even then, they still carry a weight penalty.

The basic problem is, that even with all the re-engineering, they're still only good for 85HP. They have one major advantage - they are CHEAP.

 

https://revmasteraviation.com/

 

 

[old man emu]

There is not much talk about the Chevrolet Turbo-Air 6 which powered the Chevy Corvair of the 1960s. A nice 6 cylinder flat 4.

[rodgerc]

I’ve flown a few hundred hours behind a VW conversions….Here’s my experience/opinions:

1. They’re inexpensive,

2. They require a cylinder head overhaul every 120h or so,

3. The electrics (ignition and alternator) can be problematic if not effectively cooled, (Read as: require blast tubes)

4. Whilst many VW users complain about cooling, with a great deal of baffle work and judicious removal of cylinder head casting flash, they can run cool,

5. The AeroVee 2.1 prop hub is heat shrunk and keyed onto a forged crankshaft. This has overcome early VW crankshaft problems, but if I were to ever own another, it would have the Revmaster style front bearing,

6. Almost all heads (EMPI et alia) develop shallow cracks between the valves,

7. Nikasil barrels are to be avoided at all costs. (Long story),

8. They need to have a minor mod to an oil gallery to ensure adequate lubrication of the front bearing, (It’s simple to effect),

9. They require a good deal of tinkering. Expect to remove the engine cowls

after every day’s flying. If you only remove cowls at annual intervals, don’t consider a VW. 

10. The HP claims by the various suppliers are wildly optimistic. Mine ended up at 2297cc and only then did it come close to the 80HP claimed…60-70HP is more realistic for a 2180cc variant,
11. They’re simple engines, easy, fun and inexpensive to overhaul,
12. The “standard” AeroVee 2.1 crankcase is magnesium with reinforcement. Optional aluminium cases are impractically heavy. 

13. No oil filter is fitted (or required) so 25h oil changes and valve adjustments are a good idea. (Always replace the cork rocker cover gasket or you’ll have issues with rockers contacting the covers),

14. Despite claims to the contrary, a well built VW won’t leak oil. 

 

 

Now for some person opinions…

15. Every auto conversion engine is an orphan, irrespective of who the supplier is…The owner must consider themselves to be the manufacturer,

16. Auto-engines are not designed to run at high power settings indefinitely as required by aero-engines. (My car lopes down the highway doing 100kph at <1500 RPM.) The laws of thermodynamics cannot be avoided thus hot-rodding MUST impact reliability.
17. The Type 1 crankcase was originally designed to provide ~30HP, not 80+. Turbocharging a VW to attempt to extract 100HP is an exercise in hope over common sense. 
 

My personal view is that it doesn’t make any sense for me to spend a single cent more on an aero-engine, UNTIL the instant the cheaper option gives a hint of trouble.

 

These days I don’t fly behind VW’s, but I won’t denigrate anyone who chooses to….It’s simply the level of informed risk that the owner/pilot is prepared to accept. If my circumstances changed and I was looking for a VW derivative, I’d lean toward a Limbach. 

[Paul davenport]

Yep agree with you rogerc except the bit about running at high power settings for long times. Given your experience on VWs I don’t doubt that that is the fact (fan forced cooling in air cooled cars may differ in results as I remember 1200 VWs running almost flat out in my early days in the workshop) . But. Liquid cooled auto conversions now available seem to refute that statement, but as you said if you go down that route you are the the engineer manufacture test person all rolled into one 

[danny_galaga]

Thanks for the info Rogerc 🙂 I've owned a couple of air cooled VW cars so always wondered about them in Drouin Turbulents etc. And yes, I remember they always seem to develop cracks between the valves. And that's just under normal car use, not 80-90 % power all day 😲

 

Seems I'm best sticking to 'on condition ' Rotax for any future projects. My days of constant tinkering with engines is behind me I think 😄

 

Old man and one track, I must point out that 

 

1) the corvair engine 6 is by definition a flat 6, not a flat 4 😄

 

2) vw crankcases were magnesium from the start. The racing guys upgrade them to aluminium because it's sturdier, if a bit heavier.

Edited December 28, 2022 by danny_galaga

[old man emu]

8 hours ago, danny_galaga said:

the corvair engine 6 is by definition a flat 6, not a flat 4

Late night failure to proof-read.

 

What happened to the Corvair-powered Pietenpol that was being built in Tamworth?

[facthunter]

Good comment on the VW engine. They LOOK like an aero engine because they have fins on the cylinders and heads. Porsche ONCE made an aero engine. It wasn't successful and Porsche air cooled motors are not junk.. The GM Corvair is similar and has it's own issues. One head for 3 cylinders and the intakes on the top.. The first really good air cooled aero engine was the Wright J5F.. They were tested 50 hours at full throttle continuous. and powered the Lindberg Plane (a Ryan).. Nev

[Methusala]

I flew a VP-2 over an 11 year period, 1995-2006. I had firstly a Revmaster 2180 followed by an Aeropower 2074. The Revmaster suffered a crankcase crack due to my carelessly misaligning the no 3 bearing when closing the case. The aeropower løgged over 400 hrs with no issues. I would climb initially at 3,600 to 300ft agl then cruise climb at 3250. The jugs hung out in the breeze with air scoops to the heads. No issues with cht or oil temps. The Aeropower was set up with Bosch Jetronic D hardware driven through an Haltech F-9 ECU. Starting was to use injector to the throttle body, turn 8 blades with zero throttle then switches on and 1  or 2 hand flicks. No alternate hot air source and never any icing. The Revmaster has been re-built with new Revmaster cases and Maule 94mm barrels and pistons.

I have a high opinion of these engines being simple and reliable. Parts are redily available from severaal specialist suppliers in the US.

[facthunter]

They do a job for the right person. Nothing's perfect.  Nev

[Ian]

On 28/12/2022 at 9:53 PM, Paul davenport said:

Yep agree with you rogerc except the bit about running at high power settings for long times.

The old Subaru engines appears to be able to cope with extended high revs at max power https://www.torquenews.com/1084/subaru-history-how-they-set-2-world-records-and-13-international-records-set-same-time-video

Of course this is only about 500 hours.

[danny_galaga]

Some info on what's available in the dub world right now 

 

https://www.kitplanes.com/air-cooled-volkswagen-engine-buyers-guide-2023/

 

[kgwilson]

There is a KR2 at our airfield with a Corvair flat 6 in it. It looks a nice engine though with only 1 head for 3 cyls & the carbs on top in the heat. Unfortunately the owner crashed it in a gusty wind takeoff & it hasn't flown for some years but he is finally getting a round tuit so I may see it some time soon. He got the engine running just recently. It will be good to see how it performs.

[old man emu]

1 hour ago, kgwilson said:

he is finally getting a round tuit

Here's one for him

 

 

 

[danny_galaga]

5 hours ago, kgwilson said:

There is a KR2 at our airfield with a Corvair flat 6 in it. It looks a nice engine though with only 1 head for 3 cyls & the carbs on top in the heat. Unfortunately the owner crashed it in a gusty wind takeoff & it hasn't flown for some years but he is finally getting a round tuit so I may see it some time soon. He got the engine running just recently. It will be good to see how it performs.

Corvair engines must be getting a bit thin on the ground. And probably not much in the way of aftermarket aircraft parts like the VW. for that plane, seems to me you would be better off running the Jabiru 3300, which I notice has been done before.

[Markdun]

I’ll chime in here agreeing with Don and Roger.  I have a bit over 900 hours behind a 1/2VW and a very simple 1835cc conversion.  The pros are that they are cheap and easy to work on; they work and get you flying.  The cons are the poor power to weight ratio, and the required ‘tinkering’.  The 1835 was lucky to produce 55hp (proponents claimed 64hp.... perhaps hp is a unit like the gallon which in the US is a lot smaller than everywhere else?).  I did a valve lap and replaced the piston rings at around 500 hrs.  It was an ultra simple conversion: home made heat shrink hub; std vw crank, a single ignition from a vertex ignition bunged into the std distributor drive ( made an interesting cowl bulge); a Bing CV32 carb from a BMW R80 boxer; & a small 5A Honda charging coil with PM rotor bolted to the rear.  The only issue was the prop to hub flange which delivered me to the canola paddocks twice.  The half VW gave me more woes, but this was more to do with my experiential learning and then belief I could plonk the Minimax (Vso=20kts) just about anywhere for an outlanding, which I did.  This included an EFATO at <100’ from a broken head bolt (lesson: in sub-zero temps warm up engine for longer); broken rocker shaft bolt (dont use really old bolts); broken crankshaft 2 hours after a prop strike (yeh, yeh....how effing stupid was that). and an intermittent ignition coil fault that nearly delivered me into the wilds of the Deua R (don’t mount ignition coil on top of s very vibrating engine).  
In hindsight I’d do it all again. I converted my Corby from VW to Jabiru mainly because Id already done a VW to Jabiru conversion on the Cygnet and was very happy with the extra power and lower weight of the Jab.

[Methusala]

Warning! Thread drift) I'm just back from 1 of my frequent sashays to Tumut Aero Club where, once again, I failed to enthuse the membership with my dream of a club owned, 1 seat, Thruster, Jeep, Mustang ultralight for circuit bashing on calm mornings/ evenings. Just think, a simple lighty for pure fun. Oh the dreams...& joy!🤣

[pmccarthy]

Methusala you will be familiar with this plaque on the wall of the Tumut clubhouse. There was an airshow on opening day and... I was there! My first airshow of many. I remember Tiger Moths doing streamer cutting with bog rolls. Not bad memory for a five-year-old.

[Methusala]

39 minutes ago, pmccarthy said:

Methusala you will be familiar with this plaque

Yes, still pride of place on the wall. Best Aero club I've ever. 1957 was still a year before we moved from Cooma East to Sue City. This was an American construction village at the tailrace portal of Tumut 2 underground power station. I remember our scout Akela, Bill Simpson, a carpenter, introducing us to control line models. He was a Tumut resident and early member of  TAC. Used to tell us of streamer cutting with Tigers. I'm a year your senior. Cheers Don

[facthunter]

I did streamer cutting and balloon busting in Tigers in the early 60's  IF the balloons went through the prop near the hub they usually didn't break and you'd have to find it again. using up more time. It's a seriously good way to learn to do tight manoeuvre's without watching the instruments and mainly by seat of the Pants  awareness..   Nev

Edited December 31, 2022 by facthunter

[Thruster88]

2 hours ago, Methusala said:

Warning! Thread drift) I'm just back from 1 of my frequent sashays to Tumut Aero Club where, once again, I failed to enthuse the membership with my dream of a club owned, 1 seat, Thruster, Jeep, Mustang ultralight for circuit bashing on calm mornings/ evenings. Just think, a simple lighty for pure fun. Oh the dreams...& joy!🤣

The trouble with those light weight early ultralights is they are a little tricky to fly. My ex Holbrook single seat Thruster always has my attention while flying it. Light weight, very low inertia and high drag. Non linear response to throttle inputs. I don't think it is a club aircraft, Could easily end up damaged.

 

The rotax twin cylinder two strokes 377, 447, 503, 532 and 582 from 35 to 65 hp could be considered similar to the VW. In my experience they seem more reliable with almost no tinkering required. They are a great engine for the money. 

 

 

[DeanT]

2 hours ago, Methusala said:

Warning! Thread drift) I'm just back from 1 of my frequent sashays to Tumut Aero Club where, once again, I failed to enthuse the membership with my dream of a club owned, 1 seat, Thruster, Jeep, Mustang ultralight for circuit bashing on calm mornings/ evenings. Just think, a simple lighty for pure fun. Oh the dreams...& joy!🤣

 

[DeanT]

Thruster, Jeep and Javelin at Holbrook Joy indeed!