Whats the best VW conversion???

PB · Post by PB » Tue Oct 07, 2008 8:33 pm

I'm not going to get drawn in to which engine is best, but to answer the original question:

If you want a cheap reliable and very simple VW conversion go for an 1843 Great Plains and build it exactly as per the instruction book. You can fit an accessory case if you want but if lightweight is the real goal simply fit the Leeburg System.

If you can use a torque wrench, read and follow simple instructions and don't try to be clever it's a really simple job.

To be truthful, it really isn't much of a conversion. The biggest job is building an inlet and exhaust manifold and fitting the carb and heat-box. Baffles can also be fun, though Great Plains do supply a very good set of pattern drawings.

After that, the modifications extend to replacing the original VW cooling fan with a prop-hub, boring the case to fit larger bore cylinders and tapping a second plug-hole in the heads. All done by Great Plains before they send the kit to you. In the case of the Leeburg ignition you simply replace the flywheel with a permanent-magnet alternator and drill and tap four holes to hold the electronics on. Beyond that, it's pretty much standard VW.

For reference, the so-called aluminium cylinders sold by Great Plains (at least the 92mm ones you will need for an 1843) are not really aluminium at all; they are actually a cast iron cylinder with aluminium fins shrink-cast over them. 10lb lighter than cast iron and better thermal conduction.

MDF1 · Post by **MDF1** » Tue Oct 07, 2008 8:48 pm

PB,

Many thanks for that, you make it sound simple!! It looks like I'll be going the 1834 route with Leburg ignition. Weight will be an issue!!

Anyone know of any fuel injection or inverted oil systems ??

Nick Allen · Post by **Nick Allen** » Wed Oct 08, 2008 1:14 am

This chap does lots of juicy tuning parts for aircooled VWs, including fuel injection: http://www.johnmaherracing.co.uk/

PB · Post by PB » Wed Oct 08, 2008 7:26 am

MDF1

You will also need to make sure your inspector is cleared for engine builds.... Not all of them are.

There are various fuel injection systems around for the VW engine but non, other than the unavailable Barry Smith system, which are LAA approved. I know one or two people are thinking about electronic systems.

The basic design for inverted oil is simple. You will need a flop-valve. Barry Smith may be able to sell you one of these. The system also requires a bit of case machining and some additional pipe work.

G-AWMN · Post by **G-AWMN** » Wed Oct 08, 2008 12:26 pm

I have been watching this subject with interest, as I am about to strip and rebuild the VW engine of my Luton Minor re-build project. I am thinking of swapping the Lucas mags for electronic ignition. My main thought was to improving starting as I have been told my example could on occasions be a bit of a pig in this direction.

My engine is 1776cc. I made enquires with a previous owner about this and was told this capacity was used so as to avoid the thin barrel/stud closeness issue with the 1834cc conversion. Any body else with an engine this capacity?

Also bucking the trend a bit my engine has a zenith carb. I have read various references to this carb being recommended but have never spoken to anybody with experience of them. Any advice?

When I took on this crash/rebuild I spoke to Francis regarding this and I have a letter from him suggesting re-building with a more up to date engine. However for me a Luton Minor with a modern engine would be missing the point of what this plane is all about.

As for the day job: I work as a designer in Diesel engine design for Ford. The last thing I want is to start working on Diesels at home as well!

Pete · Post by **Pete** » Thu Oct 09, 2008 4:24 pm

Stay away from SR4s

Spare parts are almost impossible to get - even points.

You definitely need an impulse starter or electronic.

Starting an SR4 equiped engine is an absolute pig especially if it's cold and damp, the only way I could get my Luton to start in winter was by using a hairdryer to warm it up

The Peakcock conversion "works" but is pretty archane compared to a great plains or a revmaster.

Regarding carbs, there is a Haynes manual http://www.autobarn.net/hayweber-zenithcarburetor.html

Bill McCarthy · Post by **Bill McCarthy** » Thu Oct 09, 2008 6:36 pm

How's about a maintenance/familiarisation course on the good old VW then. I don't have one up front, but I would come on an organised course. There must be plenty of them still churning away giving good service.

Rod1 · Post by **Rod1** » Thu Oct 09, 2008 8:12 pm

“Starting an SR4 equiped engine is an absolute pig”

My Nipper was fine provided you got the prime right. The only problem was if you left it ½ an hour after a flight.

Rod1

MikeGodsell · Post by **MikeGodsell** » Fri Oct 10, 2008 11:25 am

If it helps: The cold start procedure on my L2000 Limbach works every time:- Open the fuel cock and run the electric pump till the Stromberg 150 carb float chamber is full, then switch off the pump. Hand turn the prop four compressions (mags off) Then full choke, 1 cm open throttle, both mags on, and press the starter. It fires up after two blades, and the choke is pushed in immediately to give smooth running at 1000 rpm for warm up. Hot starting simply requires the throttle cracked open, mags on and push the starter, never any problem.

Noel Howard · Post by **Noel Howard** » Fri Oct 10, 2008 5:22 pm

My VP-1 with an 1834cc engine, Lucas SR4 mags and a Stromberg CD150 carb normally starts on the first 2 or 3 swings of the prop, but only if the float chamber is full (of course), the choke is set correctly and so is the throttle. Hot starts don't seem to be a problem either.
I had the magnetos overhauled a few years ago. It is most important that the windings are in good condition, otherwise you won't get a decent spark. The plug gaps should be set to 0.020"

Noel.

ivanmanley · Post by **ivanmanley** » Tue Oct 14, 2008 7:55 pm

My T31 (now gone

) Had a VW1834 with Leburg and a C150. It didn't miss a beat, was easy to start, and gave as much power as any VW I've ever flown behind. Great combination!

ivan
________
Medical marijuana card

cardiffrob · Post by **cardiffrob** » Thu Oct 16, 2008 9:27 pm

Gone? Sold, or....

Ian Melville · Post by **Ian Melville** » Fri Oct 17, 2008 2:35 pm

Sold thankfully
Ivan shed a tear, but for a personal reason it had to go to a new home

Rob Swain · Post by **Rob Swain** » Thu Nov 06, 2008 4:43 pm

Nick Allen wrote:This chap does lots of juicy tuning parts for aircooled VWs, including fuel injection: http://www.johnmaherracing.co.uk/

One thing that seems not to have been mentioned in VW conversions is compression ratio.
An 1834 requires shims to stop the compression ratio going too high.
Most of the VW parts places will do shims, but the chappie quoted above does copper head gaskets in varying thicknesses which I think are a much more elegant means of moving the cylinder head away from the piston.