Bare with me, I am new to the world of diesel.

I have a question on tuning and modifying for performance. I look through all the pictures online and in magazines and see modified trucks that are bellowing large plumes of black smoke through the tailpipes. From what I read, that contains unburnt fuel. Isn't that a sign of improper tuning if unburnt fuel is going out the tailpipe? It doesn't seem as effecient as making sure all the fuel is burned up in the combustion chamber.

Or, is that acceptable because diesel fuel contains a lubricant property that is needed even more when higher power is tuned for the engine?

For me it just seems strange. In the gas world, tuning is important to focus on fuel/air ratio. To rich means inefficient tuning for a fuel injected motor.

Thanks!

On a common rail engine it is a sign of ineffecient tuning to be rolling the coal.
On the older engines, such as a 12 valve cummins it is normal due to lower injection pressures causing less atomization.

i dont know all that much either but ive always heard smoke=power yes the smoke is unburnt fuel. this means when your blowing smoke your engine is getting a lot of fuel to make a lot of power. i have a thread about it here

http://www.dieselplace.com/forum/showthread.php?t=201761

Most trucks with big tunes blow allot of black smoke untill the turbo spools up, pictures don't look as good at 30+ psi of boost as they do with 5 psi of boost, unless the boost guage is in the picture:D