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Diesel Smoke Versus No Smoke

The Eternal Battle Continues…

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A few days ago, I posted a video to our YouTube site (www.youtube.com/watch?v=92I3SG_wbSs) of a 6.4L Ford smoking heavily on an acceleration run. It wasn’t going particularly fast, and it wasn’t super exciting, rather, it was done to test something other than the truck entirely—people’s reaction to smoke.

Perhaps the fastest growing segment of the diesel community is young kids who love the power and utility diesels have to offer. Oh yeah, and they love the smoke, too. The Internet is full of people “rollin’ coal” on bicycles, other cars, puppies, and more. It is also almost equally full of performance enthusiasts and trailer bandits telling these young punks that they’re idiots, horrible people, and they need to get hit by a bus.

Both sides are equally as passionate; the coal rollers about their right to blow smoke, and the clean diesel contingent about the need to breathe clean air. Occasionally, these two types will collide on Internet message forums—with hilarious results.

The most common smart-aleck answer to the question, “How do I roll coal?” usually involves people telling the OP (original poster) to do the “plastic bag” modification: the task of putting a large plastic bag over an open-element air filter, shutting off flow to the turbocharger. When this happens, the turbo will never spool, and a bunch of smoke will be the result. The downside to this mod is the fact that the truck will only have maybe 50 hp without the boost from the turbo, which the clean diesel guys can then laugh at.

Interestingly enough for the pro-smoke guys, there are ways for both electronic and mechanical trucks to trick the engine into thinking it is seeing more boost than it actually is. If the injection system thinks it needs a high-boost amount of fuel, that’s what it will give, whether it’s true or not. This means the real amount of boost the truck sees (not much) compared to what it thinks is going on (plenty of boost) results in lots of black smoke. The diesel “smoke switch” is built on this theory. And, in case you’re wondering, no I am not going to tell you how to build one.

Let’s go back to the video. Since it wasn’t particularly interesting other than the smoke, it quickly fired up a smoke vs. no-smoke debate. As of this writing, it is fairly even between likes and dislikes, indicating the diesel crowd is still fairly split about the whole matter. While there are those who believe the smokers can be educated out of their habits, I’m not so sure.

The staff of Diesel Power magazine has always had a pretty consistent stance on smoke. Our motto has been: “Smoke in competition; not on the street.” Part of the reason we have been reluctant to show or condone smoke on the street is that it has no real purpose other than to annoy. The smoke is a result of unburnt fuel, which more than anything actually makes the vehicle go slower. Newer common-rail trucks can make more than 1,000 hp while being nearly smoke-free.

For all their differences, there are also obvious matters on which both sides can agree. A 2,500hp sled-pulling truck can be excused to go outside and smoke, while even the most avid coal roller would probably hate to be stuck in a shop with no ventilation while a truck is trying to spool on the dyno.

At the end of the day, there is only one thing I am sure of: The smoke versus no-smoke debate will continue, and it’s something that won’t be resolved any time soon.

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