Dave Plowman (News) wrote:
In article ,
Doctor Drivel wrote:
Bikes and boats don't have to meet the same emissions as cars.

But not far off. They are a world away from the 1950s two-strokes.

The orbital engine isn't used on cars

More to the lawmower image of the two-stoke it was not used in cars.
Chrysler did some R&D on two-strokes for cars and came up with a direct
injection with normal pressurised oil crankshaft engine. Only image
stopped it being used - by the marketing men.

Image? You think the average car driver cares what type of engine is in
use?

It's not possible to make a two stroke meet emissions regs in practice.
Their fuel consumption is also poor. This is why they're only used for
purposes where their low production costs outweigh this. In countries
where it doesn't matter.

Almost all large diesels as used in ships are two stroke. They also have
the highest fuel efficiencies of all internal combustion engines,
currently over 50%. Two stroke engines scale up better than four stroke
engines.

Two stroke engines as used in motorcycles and cars are built as cheaply
as possible, so they need to use a fuel/ oil mix. They could be designed
not to, but that adds complexity, cost and weight.

Just why do you think every car maker in the world sticks to four stokes,
given the paper advantages of some other configurations? It's simple -
those advantages are only on paper.

At the sizes used in motor vehicles. At other sizes, other cycles work
better.

People don't generally use four stroke engines either for very small or
very large applications.

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Tciao for Now!

John.