The Natural Philosopher wrote:
On 24/08/15 18:31, Tim Streater wrote:
In article , Johnny B Good
wrote:

On Mon, 24 Aug 2015 15:19:35 +0100, Davey wrote:

On Mon, 24 Aug 2015 15:00:59 +0100 The Natural Philosopher
wrote:

On 24/08/15 14:16, bert wrote:
In article , The Natural Philosopher
writes
On 22/08/15 10:35, Huge wrote:

====snip====

Diesels don't pink and have no ignition timing.

Wrong on both counts. Why am I not surprised?

No sorry Try as I might I can't find any ignition on my diesel.

Try looking inside the cylinders. Without ignition how the **** do you
think it runs at all?

Compression of the mixture?

No, just compression of the impounded air. There is no 'fuel/air
mixture' as such. The fuel is sprayed into the cylinder at very high
pressure to overcome the 'back pressure' of the compressed and heated
air where it is immediately ignited on contact with the air, burning
continuously in a manner analogous to the flame you get by igniting
the spray from a can of aerosol hair lacquer spray (or the way fuel is
burned in a jet engine's combustion chamber).

I don't know the exact details for typical high speed diesel engine
injection timings but, afaicr, the injection can start in advance of
TDC at higher revs and continues spraying for something like 50% of
the power stroke, give or take 25% or so.

Ah, I'd assumed that the fuel/air mixture was ingested on the
downstroke, followed by the upward compression stroke which by
compressing, heated the air until it reached ignition temperature. Was
that never the case then - did diesels always have injectors?

Yes and no.

Manifold injection has nearly always been the case, but cylinder injection is fairly new.

Wrong.

Manifold injection, if it ever existed for diesels, has almost never been
the case. Indirect injection systems into a pre-combustion chamber (one
per cylinder) was the the common method up until about 10-15 years ago (in
cars) as it was easier to make this design quieter and smoother. Direct
cylinder inject has overtaken it though with the development of higher
pressure injection systems and better control of the injection system.

Direct injection systems though have been around for donkey's years in
commercial vehicles where the noise and harshness was less of an issue, but
economy more important.

Tim