supermarket fuel

[NY]

Irrespective of *where* the fuel is injected (manifold, pre-combustion chamber or direct into cylinder) it is the injection of a dose of fuel as a spray of tiny droplets which determines the moment of combustion - isn't it?

Or are you saying that some engines injected fuel into cool air during the induction stroke, then compressed the fuel-and-air mixture (as opposed to just the air) and let combustion occur when the air had been compressed to a high enough temperature? Didn't that make the timing of combustion extremely variable, without any control over the duration of combustion, whereas injection into the pre-heated air allows a long period of injection to give prolonged burn.

[dennis]

There are engines like that. I once had a two stroke compression ignition engine that did that. Used to drive a six inch prop.

[NY]

Also, you don't want the chance that detonation could occur *before* TDC otherwise the increased pressure of the combustion gases would try to turn the engine backwards - which at the very least if it only happened occasionally would result in dramatic loss of power as the engine has to "fight against" the rogue pre-TDC explosion.

It only needs the engine to get a bit hotter than normal and ignition-by-compression could occur before TDC.

Anyway, all modern diesels have one injector (at least) per cylinder and it is the moment of injection which determines the moment of combustion. I've never seen a diesel engine (turbo or non-turbo, direct or indirect injection) which didn't have one injector per cylinder.

[NY]

OK. Fair enough.

But as the title of the thread is "supermarket fuel", let's confine ourselves to car (and van/lorry) engines. Are there any of those that ignite a fuel-and-air mixture by compression, rather than injecting fuel into combustion-heated air?

[Mark]

completely wrong unless you are thinking of the early hot bulb diesel engines from 1891

and even then the fuel was not injected into the manifold

-

[Tim+]

I can only assume that he's got it muddled with petrol injection. Not that he'll ever admit that...

Tim

[The Natural Philosopher]

yes,. yes and yes, which is why it aint used much these days - i've only seen it on tractors

bastard to start - we ended up throwing a diesel soaked rag into the manifold and lighting it. Once started we closed up the manifold after removing rag

Gloplug was ineffective

[The Natural Philosopher]

I have - ancient tractor thing.

[The Natural Philosopher]

Not made in the last 25 years, no

[Tim+]

So which car/van/lorry used manifold injection in 1990, or 1980, or 1970, or 1960, or even 1950?

Tim

[Capitol]

I've seen crankcase injection on small petrol engines, don't know if it was applied to larger two stroke diesels.

[Tim+]

I can't see it ever being an attractive way of doing things. No control over "ignition" timing so probably only suitable for engines with very limited rev ranges.

Tim

[Dave Plowman (News)]

But don't run on diesel.

Oh - their efficiency is horrendous. Scaled up, the equivalent of a car doing about 1 mpg.

[Mark]

Every Diesel car/van/truck engine made from as for back as 1950 has used either a swirl chamber or direct injection

the ignition, firing or start of burn call it what you like of a diesel is at the moment of injection of fuel into compressed heated air.

excluding of course model plane/boat CI engines that use "glow fuel" which is not a heavy Diesel oil at all.

[Adrian]

Injection into the manifold separates the injection timing from the combustion, promoting valve timing instead.

[Adrian]

Ah, the Perkins Prima, as used in Maestros and Montegos...

[The Natural Philosopher]

none. twas a tractor

[The Natural Philosopher]

Glow engines are methanol engines that ignite via catalytic reaction with a platinum glow plug.

They are NOT model diesel engines which are compression ignition 2-strokes running off paraffin and ether.

>

[Tim+]

So which part of " let's confine ourselves to car (and van/lorry) engines. " did you fail to understand?

I don't believe the tractor was only 25 years old either.

Tim

[The Natural Philosopher]

The part that came after I had made that comment.

Believe what you want. I cant stop acts of faith and dogma ;-)