Vintage Thing No.4.1 - The supercharged two stroke Trojan engine
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| At last - more info including a picture of that weird engine I found backalong |
And the engine featured in this article appears to be the same supercharged engine that I found in an old copy of The Motor Vehicle by Newton and Steeds.
This engine powered the 15cwt & 25cwt Trojan vans after World War II and in general terms the Commercial Vehicle User's Journal matches the technical description provided by Newton and Steeds - to wit 24bhp and 1186cc (65.5mm x 88mm). Although it is a four cylinder engine, it has six cylinders - four of them paired in two split cylinders that share a common combustion chamber.
But the most interesting feature of the design is an inlet rotor in the head of the charging cylinders. This is driven from the crankshaft by bevel gears and a shaft that also doubles as the drive for the contact breakers. This rotor ensures a fresh charge of fuel is drawn into the pumping cylinder on the down stroke and then into the transfer ports on the up stroke.
Despite it's prosaic calling in life, I can't help wondering whether the performance potential was ever explored. I feel that there must have been some. In the usual state of affairs these engines drove through a three speed box to a conventional live axle (i.e. not a chain driven one) and lived in a pressed steel chassis on to which was mounted a fibre board body. Brakes were hydraulic.
A 2.3 litre (3.5" bore by 5" stroke) Perkins P3 diesel option came along in 1953 accompanied by a 1.29 litre variant of the blown four. There was also a version of the Trojan van with an electric motor. The accent was always on economy rather than high performance but you could argue that the Trojan two stroke was actually a 2.3 litre six - although I think including the supercharging cylinders is cheating. Production ended in 1959 when Trojan were gearing up for taking on bubble car production but these little vans were immortalised by Dinky Toys. And I had one of these models when I was a mixed infant at Goonhavern County Primary School! If only I'd known it was a supercharged - I might still have it today instead of later setting fire to it along with all my other model cars.
Gentle reader, fear not - I now weld regularly and this has kept such behaviour at bay.
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| All Trojan life is here. My favourites are the blue van and the lemon yellow coach, both of which could be supplied with the blown two-stroke engine |
When it came to going to racing the Trojan company had links with Elva and even entered Formula 1 with a Cosworth DFV V8. This sounds like an easy alternative to wringing more power out of their two-stroke van engine but "woarr though eh?" Somebody must have had a go at seeing "what'll she do mister?" even if it was out of sheer curiosity.
I had one of these van with the 6 cyl engine i was in the Army n/s i gave it to my uncle for a parafine delivery around the houses the van
ReplyDeletecame to it end when the petrol mix went into the sump then ignited and blew the sump in some one drive plus the rear axle was wrong way round so when you drove a long you would see the wheel come out which one apeared you had to hit the kerp to nock it back in
Avery nice appreciation of the old Trojan engine. I became facinated with these strange engines back in the late 40's and 50's when they were popular on the roads where I lived as a boy in Welwyn. I can recall the unusual uneven exhaust note and a great deal of intake noise as well. Although I spent a lot of time around the breakers yards in my youth I never found one of these engines in pieces so I was never able to learn its innermost secrets. There is very little about this engine on the net and I think it would be helpful for someone more knowledgeable than me to write a definitive description with cut away drawings of this interesting unit.
ReplyDeleteThanks for your effort Bob, very interesting.
David Stringer
Thanks for your compliments David. I was as mystified as you, so sought out what I could find. There used to be a very good animation on the internet of a Trojan engine reciprocating its parts (oo,er) but I can't find it now.
ReplyDelete