"Ignoramus1841" wrote
The first explanation I had of it had an animated moving parts diagram. Since the fuel/air mixture is forced into the combustion chamber by the downward travel of the piston, it achieves almost a supercharger effect, forcing the air/gas mix rather than working on suction as a four stroke does.
Steve
2 strokes do a great job at high RPMs that is why racing motor cycles and boat outboard motors used to always be 2 strokes. The problems start at low RPMs. You are not moving enough fuel at an economic throttle opening to lubricate the engine so they usually do tricks with the timing and they end up smoking a lot. These days guys like Evinrude are doing things with computers and independent oiling systems to make a clean 2 stroke. The FICHT was their first unsuccessful swing at it but the Etec is doing OK now.
Uh, thats because it's a 2 stroke. Properly cared for they actually last longer than a 4 stroke.
They don't have spark plugs before they are running either.
s
...[top posting repaired]...
He's referring to glow plugs for starting, obviously...
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{bottom posting repaired by deleting}
REAL diesel engines have no glow plugs. Those are on the toy engines.
Steve Barker LT wrote: ...
Not necessarily...depending on age and design there are a lot of very large diesel engines still out there w/ glow plugs.
What's your definition of "real" vs "toy"?
Oh? Never saw the older ones? International TD series had a full gas system that they started on, carb, plugs, everything, using the same engine. Cat used a gas pony engine. I spent enough hours cranking them. Don't know how far they went before the glow plug system came into use.
Harry K
Nope. The old ones (TD6 and a T20 McCormic Deering in my case) started on gas (in the same cylinders).
Harry K
IH also used pony engines on at least some. We had a loaner for a while one year while a major repair on the 560 was underway I remember that was a real pita. The complication and starting difficulty in winter (and the odor) were main reasons Dad never switched over from LP to diesel until the 4000-series Deeres came out in the early/mid 60s. They initially were glow plug. The oldest I have on the place now is the '85 (I think I recall that, at least it's close) 4440 and it is direct start. Recollecting, I'd guess the transition to glow plugs began in the early 60s, direct start pretty widespread in the late 70s/early 80s for farm tractors, anyway. Would presume that to be roughly the same for others.
The 955 is the Yanmar 3-cyl and it still uses glow plugs. The Cat 3208 in the '88 Ford chassis truck was an optional direct start.
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Diesels never have spark plugs. Some designs use glow plugs which are actually just a little heating element to preheat the combustion chamber . Some designs have a heating element in a box in the intake which warms the air before starting.
Its the heat of compression that fires a diesel. If the weather is warm or you had a sufficiently beefy starter you could start one without glow plugs.
on 10/17/2007 11:31 AM Steve Barker LT said the following:
They are on many of the big engines too, especially the big rigs. They are used in cold weather to preheat the cylinders (not to provide an ignition source).
Well, after those went out, glow plugs came in...and, as somebody else already noted, there were also the pony engine starting systems as well.
That there were alternatives before them (glow plugs) doesn't negate the previous comment...
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Like clueless people making typos for 4" when it was obvious that 4' was meant, and Fahrenheit for Celsius, when one responder was using one and another was using the other?
But, technically, he's right. And since we must accept everything EXACTLY as it is written, with no allowance for common sense, colloquialisms, or brain farts, the correction is valid.
I just wish we could get back to a time when everything didn't have to be so damn exact. And netnannyism wasn't so many people's hobby.
Steve
How about 2 stroke engines with glow plugs for running also? Yes, they have them and no, they are not diesel either. They use alcohol based fuel. I bet some of you guys used them.
True, technology tends to advance.
Harry K
link me to any reference to a large diesel engine with glow plugs.
as for the toys:
5.7 Olds conversion 6.2 chevy truck monstrosity 7.3 navistar 6.0 navistar duramax diesel chevy uses. (not sure of the size) And any other diesel engine you can come up with that has glow plugs.
That hardly counts as a diesel having glow or spark plugs.
s
Steve Barker LT wrote: ...
Well, guess that's one definition. Not a very useful, one, but one nonetheless...
Of current production, don't know directly other than the JD 5-cylinder used in their utility tractors (up to roughly 50 hp I'm guessing, maybe?) That they have been replaced w/ direct start w/ usually ether injection combined w/ block heaters for cold weather doesn't mean they weren't a significant alternative until fairly recently (10-15 years or so)...
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