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Old February 20th, 2008, 08:29 PM   #18
chevycummins's Avatar
Join Date: 01-27-08
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Originally Posted by 01explorerrick View Post
i never had a diesel but whenever i saw one at the track i went to in wisconsin they always spooled like hell and bellowed black smoke..

is that something that is bad...always thought that was because they were
Yes it can be bad to have lots of black smoke from a diesel. Black smoke is usually followed by hot exhaust temp which will eventually melt pistons or could cause rings to stick and scuff cylinder walls. Usually black smoke on a stock truck is caused by lack of boost from the turbo. On a modified diesel usually its caused by too small of turbo for the fueling box that is on the truck. More fuel needs more air. My cummins has injectors, delivery valves and a modified stock turbo and has hot exhaust temp at over 2500rpm because the turbo goes out of its efficient compressor map. Just because the modified stock turbo can make 45psi boost does not mean it is efficient. The turbo outlet air temp to the engine may go up to over 600 degrees and when your max exhaust temp should not exceed 1350 to 1400 degrees that hot air coming into the engine does not help. My 2007 duramax with 5 inch exhaust and a pcm reprogram is quicker than most of the trucks that I've raced in this area and the other trucks usually are belching black smoke. You don't always need smoke to make power.
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