Re: Cooking in the Cab ?

In article <g0euvs$84a$1@xxxxxxxxxxxxxxxxx>,
Mike Civil <mike@xxxxxxxxxxxx> wrote:

In article
<fccd5c32-4d38-42cf-a921-cd4b6e7ec3ed@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Waldviertler <wyrleybart@xxxxxxxxxxxx> wrote:
Re fuel consumption

Not being an engineer I don't know any of the techicals of it, but if
a two stroke engine fires fuel vapor on every rotation, wouldn't it
logically use more vapour than a four stroke engine which only fires
on every other rotation ?

No, because (/very/ theoretically) you'd only need to turn the engine
over at half the engine speed of the four stroke to get the same number
of power strokes.

As far as I can recall, the 'problem' with the two stroke is that the
incoming fuel/air mixture is used to purge the cylinder of the exhaust
gases from the previous cycle. As a two stroke doesn't have an exhaust
valve some of the incoming fresh fuel/air mixture goes straight out the
exhaust port unused.

In the case of big conventional 2-stroke diesels they *do* have inlet
and exhaust valves, not ports like a small 2-stroke (or a Deltic, but
that's a different beast completely).

Some two stroke motorcycle engines have used devices in the exhaust port
to change the height of the port at various engine speeds and/or loadings
to try and reduce this effect. I've no idea if this theory translates
to engines of larger capacity or higher duty cycles.

And some had valving in the ports, IIUC, BICBW.

Sam
.

Relevant Pages

  • Re: OT: Any serious RC modelers in Reeky
    ... than any comparably sized two stroke. ... Well I was thinking the 2smoke 250cc thumper with ABC cylenders. ... Oh I know what the current Model engine lapped pistons ... aluminum rod like the models use. ...
    (rec.motorcycles)
  • Re: OT: Any serious RC modelers in Reeky
    ... poppet valve four stoke and run up to an honest 12,000RPM. ... than any comparably sized two stroke. ... Oh I know what the current Model engine lapped pistons ... aluminum rod like the models use. ...
    (rec.motorcycles)
  • Re: old briggs and stratton engine model number
    ... vs. horsepower, color of the engine, year made, etc. ... I have put a new electronic ignition on it but I'm not ... rider in the back and they have a flanged vs. threaded exhaust port. ... My old engine has a threaded port and I can use an elbow to divert the ...
    (alt.home.repair)
  • Re: OT: Any serious RC modelers in Reeky
    ... poppet valve four stoke and run up to an honest 12,000RPM. ... than any comparably sized two stroke. ... direct, in head fuel injection. ... Below is an odd duck of an engine or a Cox .010 TEE DEE worlds ...
    (rec.motorcycles)
  • Re: OT: Any serious RC modelers in Reeky
    ... flight stuff a few years later. ... poppet valve four stoke and run up to an honest 12,000RPM. ... than any comparably sized two stroke. ... Below is an odd duck of an engine or a Cox .010 TEE DEE worlds ...
    (rec.motorcycles)
Loading