In article t,
Lew Hodgett wrote:

Larry wrote:
Larry wrote in
:


I could see it would carbon up if you just ran the engines in an
unloaded condition in neutral for long periods of time....


Thinking about this, I cannot help but think about those engines in the big
trucks that are left idling for 8 hours, virtually unloaded, while the
driver is sleeping in his sleeper at the truck stop. I suppose he burns
off all the deposits when he drives off down the interstate in the morning.

You need to develop enough reject heat to keep the cylinder walls hot
enough to prevent wet stacking.

The spec I always seen is to idle somewhere between 1,300-1,500 RPM,
depending on engine.

Lew

the above, is really not the problem. The real problem is running a
diesel engine below operating temps, for extended periods (months)
of time, with no at operating temps operation. If the engine is
operated below operating temp, carbon will tend to build up on
combustion path surfaces, and it will not be removed, or burnt off,
by normal temp operation. This is aggrivated in exhaust driven turo
systems, because the Exhaust Side turbo also isn't running at designed
temp and will accumulate excess carbon buildup.

This whole "WetStacking" business is more a minor problem of operational
terminology, that an actual mechanical problem that needs alternate
operational techniques to solve.

If the engine is running at designed temps, with the thermostat in the
open condition, usually will allleviate and excessive carbon buildup.
Any operation with loads of 25% or more of rated HP, for more than 10%
of total operational hours, will be more than enough to deal with an
preceived problems of this nature for Normally asperated diesel engines.
For a exhaust powered turbo diesel, if your exhaust side turbo is
running at operational temp, your fine, no matter what the cooling
system is doing, and that will usually be at somewhere around 10
to 15% of rated HP, loading.

All this is variable, depending on the engineering of the engine design,
and most OEM's will have a Spec published for minimum ehgine operational
temps and loadings for extended operational times.

Me