wheres chutzell?? i belive he is a diesel mechanic by trade
I'm pretty sure Colby's a driveshaft welder by trade but he may have some specific insight into this matter.
I can give you the skinny however....
Diesel engines don't have a throttle butterfly (slide in blaster terms) and gulp in as much air as possible. Turbochargers help this by ramming air down through the intake valve as quickly as possible. Turning the boost higher and higher increases the ramming effect (until something lets loose)
Everyone who said that black smoke on the street is a waste is absolutely correct, diesel street engines should never roll black smoke out of the tail pipe and doing so increases power by 5% while increasing fuel consumption by 30%.... no brainer bad move for anyone who would ACTUALLY think about it instead of throwing a "tuner box" on their diesel truck and setting it to "smoke out".... but most diesel truck drivers *think* that gives them lots more power (and most aren't smart enough to figure out that 5% < 30%, pretty sad huh?)
The reason why pulling trucks and tractor roll out black smoke is because once they've boosted the engine to just below the physical limits of the induction system blowing apart, they want to use up every single atom of oxygen inside that cylinder to produce power. Think about it, once the valves close, there's a certain amount of trapped oxygen available for combustion. The more of that you can actually get to combust, the more powerful the explosion is.
The reason they need SOOOOO much black smoke is because of the RPM they're turning. The timing event takes place only during the split second the piston is at the very top of it's stroke. A fuel injector (or three, whatever) sprays fuel down into the hot air and the resulting explosion forces the psiton down. In order to get to every single atom of oxygen they have to "flood" the cylinder with enough fuel to get some all the way down to the edges. Normal street diesels run out of steam at anywhere between 2,000 rpm (13 liter+ class 8 trucks) and 4,000 rpm (your typical F250 6L) but pulling vehicles are tuned to run WAYYYY higher than that so the timing event has even lass time to happen than a normal diesel (one reason why rolling black smoke out of a street truck is truly a waste) engine.
