Why do big diesels belch black smoke
 

and MB diesel cars don't? Same engine. Same fuel.

Nope not any more with the USLD fuel,all the new trucks have to run on this fuel,maybe trains and ships.

I've seen trucks still belching smoke.
It must be that their max fuel flow rate is less restricted.
Similar to what our turbo cars could do if the IP rack limiter and alda were removed.

Most of these trucks also have manual transmissions, which means they can have very high fuel flow and high revs at the same time, which most of us don't do with automatics. The older trucks also have near no emissions controls, which means more particulate exhaust.

Our cars CAN belch heavy black smoke if they're not tuned well, or if someone unrestricts the fuel flow by the steps above. Why you'd want to, outside of a modest performance increase, I don't know. Black smoke=wasted fuel.

They don't if they haven't been modified. The black smoke is simple overfueling, regardless of how much sulfur is in the fuel, no difference there, and some shops will defeat the emissions and other systems to overfuel the engine in an attempt to produce more peak power.

Some truckers also like noise and smoke, thus the 8" straightpipes and overfueling just for effect.

All Diesels can smoke for a variety of reasons:

Puff of smoke on acceleration - Turbo has not had time to build boost or ALDA or "initial smoke" out of adjustment. On electronically controlled engines, fueling curve is too rich for a given boost level.

Trails smoke continuously under a light or moderate load - Possible failing turbo or leaking induction system, hose intercooler, etc... Also can be poor fuel atomization.

Thick black smoke under heavy load - Over fueling for a given level of boost, possible failure in the induction system, possible turbo failure, poor fuel atomization. Can also be a result of purposefull activity such as a "performance" pump setup or fuel map in electronically controlled engines.

Smoke can also come from lugging an engine at too low an RPM where the engine is getting a lot of fuel but it can't get enough air due to high loads and low RPM's.

If you want smoke, come by sometime in cold weather and I'll start my CAT 3208. It's not black, but I guarantee you'll be hard pressed to find another motor that puts out more smoke. Lasts until it warms up.

That's why it came with a block heater Kerry!

I'm not sure which smokes more, a 3208 or a 2-stroke DD. The answer is easy when it gets below about 20F though, since the Detroit won't start!

I've seen the Ford POS, Dodge Cummins, and GM all belch smoke when accelerated heavily.

;)
It's a goofy setup. A block heater powered by a diesel generator which itself has no block heater. If it gets really cold I'll be carrying my Honda 2000 generator.

True, one of the best winter-use mods is a diesel-fired hydronic heater tied into the coach systems and both engines.

You should get a block heater for that diesel generator. :D

I think a lot of the trucks that put out the soot just need an air filter cleaning. Especially if they smoke while cruising as opposed to just accelerating.

All vehicles with diesel engines sold in USA are REQUIRED to be fitted with a diesel particulate filter beginning model year 2007. ULSD is the concurrent requirement to provide protection to these filters. My GL320CDI produces no smoke and at 21K miles there is zero soot on the chrome exhaust extensions.

Black smoke is of course visible particulates, and there shouldn't be any emanating from MY 2007 and newer diesels, even the big trucks.

VNT's solve this problem better than filtration setups...

At least not until you "fix" them:smoking: