Engines - VW or Rotax?

[iburnthings]

I'm considering buying a cheap and cheerful single-seat type and one of the main considerations is the powerplant.

The two types I'm considering are either the VW 1600cc/1834cc or Rotax 532 type.

I'm not exactly familiar with either types so I'm just looking for pros/cons in cost/maintenance/relability/etc...

I'm assuming the Volkswagen being a 4 stroke air cooled is typically 10 litres or less an hour, easy maintenance and parts availabiliy but I hear mixed reports about reliability!?

The Rotax 532 drinks a bit more fuel? I'ts 2 stroke liquid cooled. So I was wondering what it's like maintenance wise and getting parts, etc?

Would the slightly higher cost of the Rotax 532 be worth it for the extra performance/reliability or would I be best sticking with the cost effective VW?

Cheers guys!

[Genghis the Engineer]

I don't know much about the VW conversions, but can offer a few thoughts about the 532.

The 532 is a 65hp 2-stroke liquid cooled engine built by Rotax up until around 15 years ago. It isn't a current type, but so far as I know you can still get spares from Skydrive, the UK Rotax importer.

It's the first in a series of engines that are all pretty much the same in terms of installation into the aeroplane and power output, which are:

532 --> 582/90 --> 582/99 (this last is often called the "blue top", because it has).

They're mildly unreliable, and you want to look after it reasonably well - which is new plugs every 25 hours, an internal inspection every 50 hours, with escalating maintenance requirements up to a biggie at 300 hours. I'd anticipate probably a new crank every 500 hours or so, and a decoke every 100 hours or so. All of this is reasonably do-able yourself, or there are various specialists within the microlight world (where the engine is reasonably well known) who can look after it for you.

Would I run one myself? Yes, quite happily. But, if I had one and it rendered itself "beyond economic repair" I'd look to an LAA/BMAA mod and replace it with a 582 which is a newer and rather nicer engine.

Other 532 points - expect an average fuel burn of around 18 litres/hr in most aircraft types, it does have a gearbox and for smoothness and efficiency generally the higher step down ratios of the C or E box are nicer than the slightly rough A-box which most 532s were fitted with (but you probably have what it comes with!). It needs oil - generally 50:1 good 2-stroke oil with MOGAS (the engine prefers the cheaper MOGAS, and I'd only use AVGAS when away from home base and there's no real choice.)

G

[gasax]

Great info from Genghis - I can only add that if the airframe is capable of reasonable speed all of the 532/582 potentially suffer from weak mixtures and need carfeul handling to avoid partial seizurrs.

VWs? Which and what. They vary from pretty reliable 1200cc conversions which bluntly do not produce much power, to the big bore conversions which at best are Ok and at worst just trouble. They NEED electronic ignition, they NEED to be well engineered and apart from the motor glider conversions very few are.

In summary the two strokes need careful handling and maintenance - and then they are Ok-ish in reliability terms. The VWs need all of that - and to have been well converted - which actually is quite rare.

There is a hue amount of material around on VWs, but real running hours are pretty much the only measure, the majority of conversions have barely a handful of hours and so are very much unknown entities.

[Jucky]

I've flown behind various Rotax engines and VW conversions. Both Ghengis and gasax are pretty accurate with what they say but I would add a couple of points.

The 532 was only single ignition whereas the 582 is twin. The 532's had pretty poor reliability even the early 582's weren't brilliant. If I were to go for one it would be a blue top 582 I wouldn't touch a 532 with a barge pole!

On VW's there are only small number that are worth bothering with. Great Plains, Revmaster and Limbach. Great Plains generally come as kits which you build yourself but you can get various different models to suit your needs. Revmaster are big bore engines and you only get the R2200 80hp engine these days which comes built but is good value for money. Limbach have the widest range of built engines but are more expensive.
The biggest thing with VW's is getting the cooling right, even if the heads hang out in the airflow! You have to make sure you have baffled your engine correctly.

Rotax: Lightweight powerful engine, drinks fuel and you have to constantly use two stroke oil. Unlikely to get any warning if it is going to quit. Need to be de-coked every 100 hours or so and major parts replacement at 300. Parts can be very expensive in the UK.

VW: Lots of different conversions available to suit your needs. Cooling can be a big problem if not done correctly. Parts are easily available and cheap and the engine is easy to maintain. Economical fuel burn, will burn mogas or avgas depending on which conversion you have. They can be quite heavy and low powered, always need tinkering with ie tappets every 25 hours or so. Also watch out for self professed VW experts who don't actually know what they are talking about!

All in all you get what you pay for. There is a lot of fun and inexpensive flying to be had in aircraft powered by either type of engine but be prepared to do lots of tinkering and maintenance to keep them airworthy. I would happily fly behind either type as long as knew it had been well looked after.

[hatzflyer]

Gasax veedubs do not "NEED" electronic ignition. I've flown hundreds of hours behind veedubs, my son has one and a few of my mates have them.None of us have electronic ignition.
If I were building one from scratch ,I admit that I would fit it now but a properly set up mag ignition is ok as long as it is just that ( PROPERLY set up.)
It is easy to maintain,all parts are available.
The problem is that most ( 90%) of the veedubs in the UK are amuteur built and some are not built very well, the rest suffer from a poor reputation.By and large the are very reliable, much more so than any two stroke.
Some that I know of have been used regularly for 30 yrs, you would have had about 15 crankshafts in a two stroke Rotax in that time.

[ExSp33db1rd]

..........Some that I know of have been used regularly for 30 yrs


hatzflyer - just sent you a P.M.

My Turbulent . had a 1200cc VW installed 43 yrs. ago. O.K. it's had some parts replaced, but like George Washingtons' axe is the original. just completed it's 758th hour last night. Beetles went on forever, too.

( now ..... if I could only start it first swing !! )

Never did like 2-strokes, ever since I had one of those Hovercraft style lawnmowers ( what were they called ? ) - and a BSA Bantam.

[joris]

There is another certified VW engine conversion for aircraft SAUER flugmotoren in Germany. The fly e.g. in Fourniers, Taifun's and Carat motorgliders..
They have hydraulic tappets (no adjustement has to be done)..Several power ranges available up 94Hp with Bing carburators..
to be looked at I think

[hatzflyer]

There are indeed several certified derivatives of the humble vee dub, but the criteria in this thread was cheep and cheerfull. Any of the certified types are likely to come in some fibreglass wizzship with a price tag in excess of £30k !

[joris]

Hatzflyer,

One can buy limbach certified 2400 engine second hand for about 5 to 6K euro...Still with plenty of potential
Sauer also have the Ul versions which are non certified and significatly cheaper..30 GBP is slightly exagerated....;)

[hatzflyer]

Joris I think you mis understood me,The person that started this thread is looking to buy a complete aircraft, not just an engine!
I said anything currently flying fitted with a certified saur or limbach, like a grob or taifun etc is likely to be £30k.
I agree you can buy a second hand engine for £5/6k but that won't fly too well without the rest of the plane!

[UAV689]

It's gotta be VW all the way!

I have one in my Rf3 and it is very reliable, single ignition, doesn't even have carb icing as the carb sits in a pool of warm air.

If you get a permit a/c that is a VW is brilliant, they are so easy to work on, so many spares (german and swedish car parts, great shop?!) and if the worst comes to the worst you can buy a new VW engine from the above folks for about a grand (1200cc). Cooling can be an issue, but just make sure you have the correct oil and baffles and all will be ok!

They sould much better than the 5000rpm whine of a rotax in my mind anyday!