Diesel Smoke?

[TURBO 6.0]

Correct me if i'm wrong but excessive smoke coming from a diesel is not the best way to make horsepower, right?

I am wondering about specifics though. What is the argument either way? I'm not trying to start a S#@T talking thread but rather a good place to get some good information on the subject.

I would love to see dyno numbers, hear from the top diesel tuners, etc..........

[Montecarlodrag]

I know nothing about diesel tuning.
But I have seen videos of awfully fast diesel trucks on the 1/4 mile and the exhaust is a big cloud of black smoke.

[kylers2k]

smoke is unburnt fuel. that pretty much says it all. my duramax puffs a pretty good cloud while it spools up but when the turbo lights up it pulls pretty clean. your just wastin fuel and money with the extra smoke.

[GeneralTJI]

Smoke is unburnt fuel... which is a waste... it also carbons up the motor faster and makes for higher EGTs.... non of which is good.

A little smoke at WOT lets you know you have just a tad too much fuel... not a big deal. Billowing smoke is not a good thing. Diesel AFR's are not nearly as important as gasoline afrs for making power (why there are fast diesels that do smoke heavy), but it is a waste. Smoke on spoolup is ok, but you don't want too much once your spooled if possible.

[03 D-max]

the perfect air fuel ratio for a diesel will usually result in a haze at wot even with the turbo spooled, smoke on bottom end gets the turbo going faster, but you can have to much fuel at spool up too.

[waynehartwig]

This is an interesting thread. I have no diesel truck nor experience with it. But if you go to a club sponosored dyno session, you will see some really big numbers - and clouds of black smoke.

The way I understand it is the more fuel in a diesel the more power it makes. You can technically keep adding fuel until it just melts down - maybe that's from the excessive EGT's from having too much fuel?

Keep discussing. I'd like to see some 'experts' in the field chime in. Not that I'm discrediting any of you, nor do I know your experience level. What I mean is I'd lilke to see some big number diesel dyno tuners voice their opinions.

[GeneralTJI]

The way I understand it is the more fuel in a diesel the more power it makes.

Not exactly.... Diesels are still internal combustion engines that take air and fuel to make power.... more fuel means more fuel, if you don't have enough air, you get more smoke / higher egts but it won't produce more power. Lots of air and not enough fuel in a diesel makes for cooler egts, and is pretty efficient (up to the point where you are overworking your turbo) but less power too.

For proper heat control, and efficiency, you want the right amount of air and fuel in a Diesel engine. Though unlike a gasoline engine, Diesels can run very lean or very rich and still make power....

And similar to gasoline engines they need to be timed properly too- only thing is it's not spark timing of course, it's injection timing. The thing that weirds you out if you came from the gasoline tuning world first is that more fuel in a Diesel calls for more timing (you are trying to maintain a ratio of tuel injected before TDC and after TDC... so a longer pulsewidth requires starting the injection event earlier