Vintage Thing No.77 - 1947 EMC 350

Similarities in layout to the Trojan split single are clear but the conrods of the EMC 350 aren't designed to bend.

I've written about Trojan engines on this blog before, wondering if they could have had any sporting potential. I've a soft spot for two strokes and supercharging them sounds very exotic - almost impossible - and something to crow about if you can do it right.

Dr Josef Ehrlich came from Austria and settled in post-war Britain to develop his take on the DKW blown two strokes that had made such an impression before the war. Unlike the Trojan, which used a flexible single vee-shaped conrod for the two pistons, Dr Joe used a stiffer one with an articulated link that allowed the pistons to travel happily in their separate cylinders without the need for said spindly vee-shaped conrods to flex.

Based in Isleworth in the London borough of Hounslow, EMC never entered quantity production but were available from 1947 to 1952. After that Dr Ehrlich concentrated on competition with support from the aeronautical firm De Havilland but later left to pursue non-motorcycling projects, including an alternative engine for the Austin A30 (a forthcoming Vintage Thing when I get around to it). This project was to have produced a super economy car tentatively christened the Austin A20 but BMC were uneasy about press fit crankshafts with their seals and the prototype was not very refined. Parallel endeavours such as the Mini offered greater potential. If you want to know more about Dr Joe's automotive amusements with Austin, check out Barney Sharratt's book Post War Baby Austins.

I later saw Dr Joe at a Motorcycle Show in the eighties when he was promoting his Rotax-powered two stroke racers. He certainly looked the part of a scientist at the edge of technology. I was on my industrial placement with John Mockett the motorcycle designer at about this time and John knew everyone who was anyone in the British motorcyling industry (it was still quite big even then). John said Joe Ehrlich had been around for years but had never really convinced manufacturers or the public that his designs had much to offer. However, he went on, Dr Joe's tuning abilities and knowledge of two-strokes were never in doubt - he'd recently squeezed over 70 bhp from the Rotax 250 engines when the manufacturers - the manufacturers! - could only manage 62.

Dr Joe Ehrlich died in September 2003 aged 89 after turning his attention to making the two stroke engine more environmentally friendly.

This EMC 350 has Dowty air forks but no rear springing. Some bikes had a doubled up front drum brake.

I eventually eyeballed my first EMC at the Great Dorset Steam Fair this year (2010) and freely admit to being fascinated by it.

The 1947 EMC 350 was a big bike and weighed about 365 lb (166 kg). It put out 16 bhp (12 kW) in as a tourer or 18 bhp (13.5 kW) in sporting form. The sports bikes used a Pilgrim oil-pump, latterly rigged to the throttle to control delivery but the tourers relied on petroil mix.

With its inlet and exhaust at the back the Ehrlich 350 has a delightfully clean, almost unfinished, look about it. Apparently the castings are massive with very thick walls. The engine sounds as different as it looks, too.

I saw this bike ridden round the show ring and heard its exhaust note. Trojan engine sounds like someone shooting off pop guns but the EMC 350 is more like a conventional two stroke in tone. It's slow tickover was particularly impressive.

But it's the components that allow such a slow tickover that count against the EMC 350. Top speed was just 70 mph, achieved by a tall top gear in the four speed Burman gearbox. Maximum revs were 4,000 rpm but this was accompanied by unpleasant vibration.

Solid engineering gives the EMC 350 qualities quite unlike other two strokes. Those are bolts through the gudgeon pins that hold the slugs to the board - they're not part of the original design.

"Look at those pistons!" exclaimed the owner, pointing to them on his display board.

I suggested that they were not exactly low friction items and he laughed.

"One is bigger than the other!" he replied.

But deep down I knew he really liked this strange machine and forgot to ask about bore and stroke, which is probably just as well. The answer could be complicated. Which stroke are we talking about? Should we count both split cylinders? Should we be multiplying by the old theoretical factor of 1.4 since this engine is technically supercharged and - one would hope - punches above its capacity?

"I've put together this little display to help answer people's questions," he went on, pointing to a spare bottom end he'd bolted to  aboard covered in technical magazine articles, "but often they just walk away shaking their heads."

I reckon that's the drive to the Pilgrim oil pump on the side of the righthand crankcase

I gather that once you have an EMC, word gets around and other EMCs seem to come your way. About 1,500 were made and when you consider its price, unconventionality and lack of a dealer network this was quite an achievement even in transport starved post-war Britain. It was a very un-British design, too, in so many ways.

The whole idea of the split single is too alien for most people, which is probably why I like it so much. Maybe it would have found a more receptive market on the continent where they were more (slightly) common and better understood. There they called them doppelkolbenmotors, literally double piston engines, which explains the layout better than our Anglo-Saxon attempt of split single engines. Personally, I like twingle but double them up, as in the Trojan engine, and they become double-twins quadwins or something. Doppelkolbenmotor has to be the best moniker.

I find myself wondering if this layout of internal combustion engine still has something to offer.