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How to Blow Black Smoke

The Art of the Coal Roll








Disclaimer: This article has been published for entertainment/educational purposes only. We do not recommend you modify your truck in any manner for the sole purpose of soot/smoke production. Not only may excessively high EGTs cause engine damage, but these acts are having detrimental repercussions on our industry. Consider reading the article "Smoke Responsibly" for further information, including how you can help. There is a time and a place to roll some coal - don't give the tree huggers any ammunition to support further emissions restrictions.


The key ingredient to a thick coal roll is fuel. Black exhaust smoke, or soot, is partially burned carbon molecules. When fuel is not completely burned it leaves the engine as soot. There are many ways to make your Duramax, Power Stroke, or Cummins diesel blow some black smoke. We've listed them in order of estimated cost.


Smoke Switch

A smoke switch tricks your engine into thinking it needs more fuel and you end up with a thick cloud of black smoke do to excessive fueling. Smoke switches work in different ways depending on the manufacturer. For Cummins diesels. they tie into the MAP sensor. With the flip of a switch, the MAP sensor is turned off, making the engine think it needs more fuel. This is especially effective in leaving a thick trail of smoke if you have an aftermarket tuner or module. For 6.0L Power Strokes, a smoke switch wires into the VGT solenoid to lower boost levels, allowing the engine to over fuel and release clouds of black smoke. Smoke switches for Duramax diesels are less common. A smoke switch is not the safest way of blowing smoke, so be forewarned that your engine may through trouble codes (check engine light) under these conditions. Used conservatively, this is the cheapest way to roll some coal. We have not ran into many commercially available smoke switches - most are the result of backyard builds so you'll need to wire your own.



Aggressive tuners and modules will get your coal rolling on the highest performance settings because they fuel the engine excessively. Edge tuner & module combinations are pretty good at getting the smoke flowing. Other turners focus on "smoke free" power, so be picky. How much smoke you'll get depends an awful lot on your application as well. Tuner and module combinations are a much safer way to get your oil burner smoking, as most of them have safety provisions to prevent excessive EGT and some even have built in EGT gauges.


Roll Coal The Right Way

The best way to blow some serious black smoke is to go all out. Larger injectors combined with aggressive custom tuning will let you lay down some massive clouds of black smoke - the ultimate coal roll. Injectors increase the amount of fuel that can be dumped into your engine per injection cycle, while the tuning keeps the engine thinking it needs more diesel. Throw in a larger injection pump to keep fuel pressures high and add a water-methanol injection system to keep EGTs down and you have the perfect combination. With the flip of a switch, leave your challengers in a stream of thick black soot and then clean up the exhaust stream to keep the authorities happy.


IDI & DPF Trucks

If you have an older, mechanical IDI engine (or 12v Cummins) you can lay down a pretty nice haze of smoke simply by turning up the injection pump. Be careful, excessive fuel will cause those EGTs to rise rapidly so it's wise to install a EGT gauge. Lastly, if you have a DPF equipped truck, you'd better delete the diesel particulate filter before attempting to blow smoke. Remember, the DPF catches soot, and all you'll do is clog the filter or send you truck in active regen over and over again.