Easy Diesel question can't be answered

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Ask me how I know? A friend and I had his Mercedes marine engine run away when we accidentally started it with the butterfly valve removed. Scared the heck out of us. Don't ever start one of these engines with the butterfly valve removed!

Mark

Well, that is an interesting story!

The little Mercedes diesel was in my friend's 30' Tahiti ketch, vintage 1939. (The engine was a little younger than the boat, 1960s vintage.) When the motor took off, both of us knew we'd made a big mistake. He immediately went to the fuel shutoff valve and started cranking it down. I should note that the shutoff was astern of the engine, and that Tahiti ketches are "double-enders" (two pointed ends, like a canoe). This means that to reach behind the motor, he had to squeeze between the screaming motor on one side and the battery and fuel tank on the other. That done, we both decided to "abandon ship". My friend jumped out the companionway (directly over the motor), but I headed to the bow, only to find my way blocked by a battened hatch. By this time the cabin was full of smoke, but my friend realized my predicament and got the hatch loose from the outside.

After what seemed like an eternity, the Mercedes ran out of fuel and died. I'm sure the whole event lasted less than a minute, but it sure seemed longer. Fortunately, we had a couple of warm beers on hand to calm us down, but we were both shook up for the rest of the day. My friend didn't even try to restart his motor until the next day, figuring it was trashed. Much to his surprise, it started and ran just fine. The Mercedes took him up and down the east coast for the next 13 years, until the ketch was lost in a hurricane about five years ago.

Glad it turned out (except the wrecking).

Mark

This is almost a never ending debate question.

It starts with the basics, fuel & oxygen. From there you add designed componets to make the engine prefrom what you want it too.

When you reached maximum componet design then you can add higher BTU fuel content until you have engine failure then you start designing a new engine thus the never ending debate.

Another good debate is; Whats more important in a diesel engine design for moving weight, torque or HP?

Torque of course :)

T_Bone

Any engine operating at a constant speed is at an equilibrium where the power produced by the engine equals the power required to run the vehicle (or stationary machine) at that particular speed. When the power produced by the engine exceeds the power required, it accelerates. When the power produced by the engine is less that the power required, it declerates.

OK, so what causes the engine to produce more or less power? Simple: power equals torque times engine rpm. More torque at a given rpm means more power. What causes the engine to produce more torque? Answer: the pressure inside the cylinder. Opening the throttle on a gas engine increases combustion chamber pressure; adding fuel to a diesel does the same thing.

Mark