In article ,
The Natural Philosopher wrote:
Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
Pretty well any diesel that has been idling for a while - or driven
gently - will smoke badly when pushed. Hence the way the MOT is done
for diesels.

Is that true for direct injection though?

No build up of fuel in the manifold etc..

Aren't pretty well all diesels direct injection? You compress air to a
high pressure and therefore temperature then squirt some fuel into the
combustion chamber which causes the bang?


Nope. Lots squirt it into the inlet manifold I think.

Not much use that. For the fuel to get from there to the combustion
chamber the valve would have to be open. And with a valve open no
compression.

Ah. always find someone who knows more..looks like I was half right.
Neither the inlet nor the cylinder..

http://en.wikipedia.org/wiki/Indirect_injection

That's really just an extension of the combustion chamber for all
practical purposes. The idea being to make the engine less harsh - or more
like a petrol one - for car etc use. But the most efficient designs stayed
with direct injection.

Direct injection is fairly new with common petrol cars, but not
diesels. Perhaps you're thinking of common rail where an actively
powered injector times the injection under the control of an ECU,
rather than the older pump?


I was actually thinking of an ancient tractor..wheer the glow plug was
in the inlet manifold, and the only way to start it sometimes was to
open that up, and pour a cupful of diesel into it, and then if that
didnt catch fire, shove a rag in it and light it..I cant remember if
that had direct injection or not..

Sure it wasn't a paraffin burning type? They are more akin to a petrol
engine.


Model aircraft diesels use no injectors at all..but do require ether in
the mix to ignite it.

And are horrendous, efficiency wise. Diesel of course refers to a
compression ignition engine - which may or may not run on diesel.

--
*Don't sweat the petty things and don't pet the sweaty things.

Dave Plowman London SW
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