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Questions...

I'm a newb... so yeah..

Why do the truck pullers throw so much black smoke out. I know its for looks and what not but black smoke is unburnt fuel right? If they are running so much fuel through the truck to make it that black isn't that a waste? Can't they just "turn" down the fuel so they don't waste as much? I love black smoke but I was juts wondering... I was maybe thinking they run that much fuel to cool EGT's but what do i know. it probably heats it up more hahaha.
 

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Well I'm not a sled puller or drag racer but I'll get this one off to a start. Yes, a lot of people think it looks cool, but that really has nothing to do with it. Sled pullers and drag racers use lots of fuel, and lots of air. The turbos they use are so huge that is takes a long time to get them to spool up. You need a lot of fuel to spool up a large turbo. So, at the line, these guys have to "roll the coal" before the green light for quite some time in order to get the boost to acceptable levels before the light turns green. When a lot of fuel is added at low RPM before boost is built, the engine can't burn all the fuel, so you get smoke. No, they can't "turn it down" cause then the turbo will never spool up. Also, it is air that keeps things cool, not the fuel. That's why these guys also have propane, or nitrous, or water, or whatever else shot into their intake as well. That was my long answer. The short answer is they have to do that to build turbo boost on a huge turbo.
 

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With a diesel, all other factors being equal, smoke means power. Black smoke means that not all the fuel is burning, just the heavy end of the hydrocarbon molecule is unburned.

In the old days, even turbcharged big truck diesels would smoke like Hell when backing off the throttle and acceleratng again. At night we frequently got a nice blast of flame out the stack when changing gears. The NA trucks would flame all the time when pulling hard.

We figured out we weren't running full power unless the exhaust manifold had a nice dull glow on it. Times sure have changed.

Ops
 
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