How do you feel about "coal rollers"?

I'm a 19 year old male in the suburbs, so unfortunately my generation is associated with this. I absolutely hate people that "role coal", and for people that don't know what that is, it's when people buy a diesel pickup truck and spend $5,000-10,000 to customize it just to blow black smoke out of custom pipes, which is done by forcing extra fuel into the engine which is bad for the trucks efficiency and probably the life of the motor. All this is done for typically is to dump a bunch of smoke on a Prius or something and post a video on the internet.

One reason I hate it is because it gives respectable diesel owners a bad name. I'm going to school for landscaping so I may invest in a diesel pickup soon to do plowing and stuff, and personally I'm now sort of embarrassed to own a diesel. Even though I wouldn't have it customized to blow black smoke, people still may think I'm one of those douche bags, especially given my younger age.

Another reason why I hate it is because it's one of the things that represent the downfall of our society. If you pay $5,000-10,000 to customize your truck in a way that actually hurts the efficiency the diesel was designed for, just to look "cool", I find that to be a problem. I always like to say that these guys have to do it to compensate for their 2 incher. Even if you are small, there are so many other ways to look cool; buy a motorcycle or something. Some of these guys like to say "it's a way to teach these Prius drivers a lesson". I personally don't like those kind of cars, but if you really have to dump smoke on a person who's done nothing wrong except buy a car you don't like, I think you're the joke. The Prius guy probably gets a laugh out of it because he's saving a lot of money getting good gas mileage, and this guy "rolling coal" spent a whole bunch of money and hurt his gas mileage just to show off. This kind of thing is also bad for the environment. I know, some of these coal rollers do it just to prove that they don't believe it's possible to ruin the environment, but again, really? Go that far out of the way just to ignorantly prove a point, that's our society?

Like I say, from the viewpoint of a future respectable diesel owner and someone disappointed with our modern society here in the US, these guys absolutely drive me nuts. How does everyone else feel?

I completely agree with you! When I was in highschool years ago, we had a lot of kids who spent mommy and daddy's money to get their trucks customized. I drove my dad's Ford F150 and I was one of the few girls who had a truck in highschool. I felt pretty cool without any modifications! (And gas mileage was terrible to begin with. I couldn't imagine a diesel)

Sounds like you have a good head on your shoulders though! I say get your diesel and don't worry about what others say. You can still enjoy it just as much.

Diesels are surprisingly good on fuel though, and that is why more people buy them. More cars are starting to run on diesel too, because it is more efficient.

Mr MKK FARMS said:

Diesels are surprisingly good on fuel though, and that is why more people buy them. More cars are starting to run on diesel too, because it is more efficient.

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Yea I know, if used right diesel can get up to twice the miles per gallon. New trucks are becoming so much more efficent too. I'm talking about the "coal rollers", and when you modify your diesel to blow black smoke from the pipes, you are doing that by adding a significant amount of fuel into the engine which is obviously a big impact to gas mileage

Farmer Mike S said:

Mr MKK FARMS said:

Diesels are surprisingly good on fuel though, and that is why more people buy them. More cars are starting to run on diesel too, because it is more efficient.

Click to expand...

Yea I know, if used right diesel can get up to twice the miles per gallon. New trucks are becoming so much more efficent too. I'm talking about the "coal rollers", and when you modify your diesel to blow black smoke from the pipes, you are doing that by adding a significant amount of fuel into the engine which is obviously a big impact to gas mileage

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It really depends on the modifications. Not all are like that.

Yes, anyone with any good sense purchases a diesel for longevity, efficiency, and heavy towing capability. You pay a premium for the diesel engine and the fuel. It has to work to pay it back. I've witnessed this foolishness you are referring to and I agree it is just another sign of the "trash culture" which places such a premium on vulgarity.

My wife and I each drive diesels, mine is 17 years old, hers is 13 years old. Each has nearly 200,000 miles on it with a large percentage of those miles spent towing boats, equipment trailers, and our camper. If either one of them smokes, it needs an air filter, fuel filter or an injector replaced!

Get your diesel, let it work for you. Don't spend another minute of your valuable time even thinking about those miscreants.

Mike my DS has a diesel he bought himself. He has customized it but he does not roll coal.
He only every did it once and that was when some guy in a little car cut him off so he had to lay on the brakes to avoid hitting him. Guy was cutting across 3 lanes of traffic. Well they got stopped at a stop light and the guy in the little car was right even with the tail pipe.

Some guys are just jerks to diesel owners no matter who they are. DS and his best friend were both flipped off by some guy neither of them knew, just driving home from school.

We own more diesel trucks then anything. DH bought his first one back in '85, still have that truck. DS has 2 diesel trucks. DH has 2 and I have 1.

My suburban rolled coal cause I used more efficient fuel an cheaper fuel. Everything else was factory. Hauling 8 people at 20MPG on a fuel that cost me 1/3 the cost of diesel.

My brothers 600 horsepower dodge is just as efficient as it was factory. It can get pretty black but only when you need it to create power. It runs as clean as any other truck at cruse speed.

All the emissions junk added to diesels is to hide the smoke not to make it more efficient. Some of that stuff is a bigger bio-hazard than diesel smoke. We are now using urea in the emissions systems to filter an hide smoke. My brother who works at Kenworth calls it cat pee.. I will gladly take breathing carbon over urea. The diesel fuel you are required by law to run in a 2007 an later truck is worthless too. Bad mileage an you engine wears out very fast.

Efficiency of an engine is keyed on how good of an air pump it is first an formost.

Removing restrictions = a better pump = better mileage= more smoke.

Turned up turbo = better pump = better mileage= more smoke.

The only time this stuff makes it use more fuel is when they add bigger injectors or modify the computer to dump more fuel an that only dropped mileage when you have your foot buried in the carpet. An part of that is canceled out by the fact that you are out of the throttle more cause it takes less time to pull big loads up big hills. But even the meanest "paint the sky black" diesels make about the same mileage at cruse speed as they did factory, if not more. If it didn't you would not see so many owner operators doing it. They get payed by the mile not the hour an have to pay for their own fuel. They all want a truck that can pull hills but they need the best mileage they can get.

You want to make someone mad, try hauling a tractor up a mountain with a factory diesel. When you live where I live an have to follow heavy loads up a mountain every day you learn to love black coal. Its a sign of a well built truck that will get up the mountain without adding 10 minutes to everyone else drive home. Sure it is using a little more fuel when it is smoking but the 50 cars he does not have stuck behind him idling are using way less.


Remember a diesel does not meeter the air it takes in. It is always taking in every bit of air it is capable of. The only reason it does not just run away is cause you are starving it of fuel. It is running in a constant lean air/fuel mixture state. Most of what comes out the pipe is unused oxygen which dilutes the burned fuel to the point you don't see it. As you add fuel you burn up more of that oxygen. That means less unburned air is coming out of the pipe an more burned fuel is. That means what you see is darker. If a diesel is creating maximum power it is dumping enough fuel to burn 100% of the oxygen it is taking in. That means 100% of what is coming out of the pipe is burnt fuel which is pitch black. In the real world you will never see a diesel get to this. The closest you will see is at tractor pulls where they get close for 10 or 15 seconds at a time. In a street truck you would melt the engine way before you got anywhere near 100%. When you see a truck "rolling coal," he is still starving the engine of fuel an running lean. Raw fuel is clear so you are not seeing large amounts of raw fuel. You are seeing burned fuel taking the place of some unburned air. So the idea that a street diesel is dumping raw fuel out the pipe dies not work. (well some comes out but thats the nature of engines) The engine would melt well before then.


Stoichiometric air-to-fuel ratio of diesel is 14.5 to 1 or 6.8% fuel. That is what would be perfect an pull the most energy out of the fuel an air but it would create the most smoke. That would empty the tank of most trucks quick at the amount air they can eat. We are talking garden hose flow rates.

Thanks for the detailed response rebelcowboysnb (not even being sarcastic). The thing is though, I'm more talking about people who intentionally role coal. I've never known the direct details behind it, but I know when I'm behind a dump truck going up hill it's gonna role coal, which is obviously due to it needing more power. I'm completely ok with it in that purpose, it's not like I'm annoyed just at the fact of black smoke.

What bothers me though is people that modify their trucks just for smoke, nothing to do with wanting more power. These are the guys that literally leave a giant black cloud when casually driving through a suburban neighborhood. I believe they actually have switches installed which engages the "rolling coal", and then they have their custom pipes to make it look "cool". This is apparently some kind of YouTube trend , so you can look it up. So it's not black smoke that bothers me, it's tools doing it on purpose

Not sure how you would do it just for a look. I dont live in a city though.

I have seen switches to turn the horse power up an down though. Its good to be able to turn it down if you drive in to some states or if you let someone else drive your truck.