Light Aircraft Association

Does anybody know of a reason that most VW 1600 engine conversions are 1834cc i.e. standard 69mm stroke with an oversize bore of 92mm?

There are 94mm bore barrels and pistons available that result in a capacity of 1915cc, and these barrels have an overall diameter the same as 92mm ones, so presumably are thinner and therefore lighter.

I do wonder if it is a strength or cooling issue seeing as the AeroVee 2200 conversion also sticks at 92mm cylinders albeit with a longer stroke crankshaft.

Rob, I think it's mainly that. Also worth mentioning that 1834 is the first capacity increase where the case is machined to accept the barrels and the amount of metal left around the studs is woefully thin. I gather from reading that 8mm studs in pre-installed helicoil 'case savers' which take the retaining hole out to 10mm is preferable to 10mm studs straight into the alloy.

I shared a hangar with a Sonerai which had an 1834 with 10mm studs and the owner had to make some hasty repairs with helicoils after he had heads constantly coming loose with other attendant problems of tappets closing up etc. In fact, it was the catalogue of tappet and loose head problems that led him to discovering the crankcase cracks.

He got so good at removing and replacing heads etc. it wasn't unusual to find him doing it just prior to us leaving for continental fly-ins!

Rob, I think another reason that the 1834cc conversion is predominant is that at one time it was the only one easily available here.

I recall back in the early 90's when the 1600cc in the Fenland Strut Veep burnt a hole in a piston crown, we decided to upgrade as part of the rebuild and all we could find was the Mahle 1834cc barrel and piston set.

Personally I'd not want to go much bigger than this for the reasons already given by Nigel.

Anyone else think that a LAA course on the good old VW is worth putting on ? LeBurg ignition system and other maintenance items could be covered.

Good idea Bill but with so many VW powered a/c across the country, it would make sense to organise any training courses on a regional basis, as I'm sure not everyone finds it easy to get to Turweston.

Very good idea Bill - Divide into 4 areas; Actual Engine Maintenance, Ignitions, Carburation+Exhaust and cooling. Quite an extensive course, too much to cover in a day.

There's a bit of interest on here, perhaps we want a VW Area where useful articles are kept?

I'd be pleased if folk could comment on the Sauer and Sonex's similar engine from the size, crankcase integrity point of view.

I'd like to do something in RansMail to compare modern developments and mention the semi forgotten origin of the converted car VW. The Duke of Edinburgh flew behind one at the Tiger Club I believe.

AFIR Peacock sold conversion plans. Turbulents, Nippers and Scheibe Falkes had German (?) Ardem, Stark Stamo and/or Holmann Hepu conversions.

Anyone like to provide some pro's cons please ?

mike hallam.

I still have the Peacock VW plans up in the loft - tells you how to machine the extra plug holes, the lot.

Hi Guys, I'll be delighted to put on a VW course or two. Can anybody out there with ideas of who should run them please PM me, I'm not up to speed on who the experts are now that Barrry Smith has retired.
Mike, I'm pretty sure Sauer use a purpose made crankcase which is strengthened in the known weak spots. I think AeroVee is a VW case, but I haven't heard that they are having any problems with it. Don't know if they weld a plate on the bell housing end by the RH cylinder (from the bell housing end) where it cracks either. 94mm cylinders have a bit of a history of warping because they are thin walled but I know Steve Stride has them on his Corby Starlet (a Mosler conversion) and he told me he hadn't had any trouble with them.

I would be interested in Vee Dub course as well

IIRC upto 1834 a lot of the parts are standard VW, so future parts support isn't an issue if a provider goes bust

Bill McCarthy wrote:I still have the Peacock VW plans up in the loft - tells you how to machine the extra plug holes, the lot.

Not sure if it's well known, but the Peacock conversion plans are still available from the LAA shop.

In the VW car world, the thinner walled barrels can distort all too easily. I guess it would be the same for the aircraft conversions. They may be slightly lighter, but at the cost of reduced stiffness.

Dave, do pay attention boy! See the second message in this string

Nigel, post no. 2 mentions case and stud problems. My point is distortion of the barrels themselves. Who's not paying attention?

Yes I did re-read!