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#11
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"Andrew P." wrote in message ink.net... Wandering aimlessly about the Web, I heard Sport Pilot say: You have most of it right. Some things you have wrong, 1. Desiel injection timing is differant than on an Otto engine. The fuel is injected during the intake cycle on the Otto engine and the fuel is injected during the ignition cycle on the Desiel. On the Desiel the fuel injection cycle starts just before TDC and ends well after TDC. The fuel ignites as soon as it hits the hot air. etc., etc. --- SNIP --- It's Diesel, not "Desiel". -- Andrew P. Well if you're going to get picky, it's "Auto" engine, not "Otto" engine. MJC |
#12
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So what I often transpose letters. I don't spend time proofreading
something as trivial as a usenet messsage. |
#13
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Sooo. I oftern transpose letters, I don't proofread something as
triavil as usenet messages. |
#14
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MJC wrote: "Andrew P." wrote in message ink.net... Wandering aimlessly about the Web, I heard Sport Pilot say: You have most of it right. Some things you have wrong, 1. Desiel injection timing is differant than on an Otto engine. The fuel is injected during the intake cycle on the Otto engine and the fuel is injected during the ignition cycle on the Desiel. On the Desiel the fuel injection cycle starts just before TDC and ends well after TDC. The fuel ignites as soon as it hits the hot air. etc., etc. --- SNIP --- It's Diesel, not "Desiel". -- Andrew P. Well if you're going to get picky, it's "Auto" engine, not "Otto" engine. MJC Actually, it is Otto, as in 4-stroke spark ignition. nate |
#15
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N8N wrote:
MJC wrote: "Andrew P." wrote in message hlink.net... Wandering aimlessly about the Web, I heard Sport Pilot say: You have most of it right. Some things you have wrong, 1. Desiel injection timing is differant than on an Otto engine. The fuel is injected during the intake cycle on the Otto engine and the fuel is injected during the ignition cycle on the Desiel. On the Desiel the fuel injection cycle starts just before TDC and ends well after TDC. The fuel ignites as soon as it hits the hot air. etc., etc. --- SNIP --- It's Diesel, not "Desiel". -- Andrew P. Well if you're going to get picky, it's "Auto" engine, not "Otto" engine. MJC Actually, it is Otto, as in 4-stroke spark ignition. nate A 4-stroke diesel is still an Otto engine. An Otto cycle engine is one with four strokes, intake, compression, power, and exhaust. Doesn't care whether SI or CI. |
#16
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Don Stauffer wrote:
A 4-stroke diesel is still an Otto engine. An Otto cycle engine is one with four strokes, intake, compression, power, and exhaust. Doesn't care whether SI or CI. Whoops Before everyone jumps on me, I left off an important qualification. I was specifically talking about cars, airplanes and highway trucks. Large Diesels, (stationary, large ship, etc) do run a different cycle- the true Diesel cycle. However, even the true Diesel cycle of larger engines is not the true cycle Diesel really wanted. He couldn't develop the true cycle he wanted (constant enthalpy), and a large Diesel comes somewhat close. A high speed (vehicle) engine doesn't even come close with even today's technology. It is pretty close to an Otto cycle, though still not exactly. Otto cycle has infinitesmal fraction of cycle for ignition and burn, while even a high speed Diesel (and even the SI engine) still ignites and burns over a finite angle of crank rotation. Still, the result, as I say is MUCH closer to Otto than the cycle Rudy had intended. Still makes a good engine, however :-) |
#17
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Bryan Martin wrote:
Not so. In the Otto cycle, the fuel and air are introduced to the cylinder during the intake stroke. In the Diesel cycle only the air is introduce to the cylinder during the intake stroke, the fuel in injected at the end of the compression stroke. in article , Don Stauffer at wrote on 5/13/05 10:47 AM: A 4-stroke diesel is still an Otto engine. An Otto cycle engine is one with four strokes, intake, compression, power, and exhaust. Doesn't care whether SI or CI. In terms of the thermodynamics the fuel is immaterial. It is only a source of heat for raising temp and pressure. The AIR is the true Carnot working fluid with either a CI or SI engine. In an indicator diagram of the SI engine, one would be hard pressed to see the difference even if fuel were shut off during the induction stroke. The reason a Diesel is not a true (though close) Otto cycle is that in the true Otto cycle the burning is instantaneous (or at least an infinitesmal number of degrees of crank rotation or percentage piston motion. |
#18
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wingsnaprop wrote:
Guess why? *Duh* Pollution laws, and no need for the power to weight requirements of Aviation! Duh... whats that got to do with this topic? Other than to show that 2 stroke Compression ignition engines are a proven concept? As already stated, 2-stroke diesels really don't have a power-to-weight advantage over 4-strokes. They still have to have a camshaft and exhaust valves (they aren't like weed whacker engines, you know), so they don't save that weight. Plus they have to have a blower for scavenge air. The only area where they save weight is in that the connecting rod and crank can be lighter, and that only helps offset the added weight of the blower. |
#19
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MJC wrote:
It's Diesel, not "Desiel". -- Andrew P. Well if you're going to get picky, it's "Auto" engine, not "Otto" engine. No, the spark-ignition cycle is the Otto cycle. Yes, most Auto engines are Otto engines, but don't let that confuse you. |
#20
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Actually, it is Otto, as in 4-stroke spark ignition. nate A 4-stroke diesel is still an Otto engine. An Otto cycle engine is one with four strokes, intake, compression, power, and exhaust. Doesn't care whether SI or CI. No, it really isn't, at least not in common usage. If you want to be ridiculously pedantic, then the "Diesel cycle" is an Otto cycle with constant-pressure combustion under varying cylinder volume, whereas what is commonly just called the "Otto Cycle" is a spark-ignited Otto cycle with constant-volume combustion under varying cylinder pressure. Neither cycle attains that ideal, so there's some overlap, but if you look at real-world pressure-volume diagrams for Diesel and spark-ignition engines, the difference is obvious. |
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