On Mon, 02 Mar 2009 09:22:20 -0600 Jim Douglas
writes:
> What's interesting to me, and I am NOT a engine type guy, is that I
>
> always thought that
> heat had bad affects on things, in my industry electronics, we are
> always aware of heat
> as it tends to break down materials and thus their life is shortened
> due
> to high heat. I
> believe from what I read that low heat can cause engine issues of
> some
> type? I have
> read the overview of the product but it's not clear to me why you
> would
> want the engine
> to be at a constant (higher) temperature than what was originally
> designed by the mfg?
> Can anyone explain, in no engine expert terms why you would need
> this
> and how it
> would extend the life of some parts of the engine?
>
> Thanks!
<><><><><><><><><><>
<><><><><><><><><><>
Jim,
I know this is kind of beating a dead horse but thought I'd try to give
it one last little gasp of breath as it moves on to wherever dead threads
go. : )
The proper temperature range is important for the proper operation of an
internal combustion engine. Too little heat is bad just like too much
heat is bad. A few examples are:
- heat in the combustion chamber (and tracts both intake and exhaust) for
proper ignition and burning and disposal of the air/fuel mixture and
related by-products.
- heating the oil for proper lubrication i.e. flow, oil wedge in some
cases and an opportunity to help remove combustion by-products. (As a
rough guide you can figure for each gallon of fuel burnt during the
combustion process makes a gallon of water. There are also some acids
and other by-products created that can get captured in the oil. Again as
a rough guide, hotter oil, with in reason, works better than cold oil in
an internal combustion engine.) *Engine lubricating oils have four
functions... (1) They prevent metal to metal contact in moving parts.
(2) Assist in carrying away heat from the engine. (Bottom of the piston
is one example) (3) Cleans the engine as it lubricates. (4) Seals the
combustion chamber between the piston rings and the cylinder wall to
prevent/reduce blow-by of combustion gasses.
- heat in the cooling system for proper temperature control of engine
parts and sealing fixtures. Metal changes size based on temperature.
(If the temperature stays cool like with a stock KLR cooling system, has
lots of wide temperature changes, again like with the stock KLR cooling
system, parts that rub on each other might experience more wear than
parts which are held at a stable temperature.)
A constant engine temperature will help stabilize part dimensions as they
expand to size and then tend to remain at that size. An example would be
piston to cylinder size. When cold you might have 0.0022" clearance
between the piston and cylinder, like with a 685 kit. When the cylinder
gets hot the inside diameter will be reduced just a little bit. The
piston gets hot and it expands just a tad. The expansion is figured by
the engine designers or guys that figured out how to hot up an engine
using some formulas and experience. The cylinder and piston won't expand
at the same rate or amount in most cases. Once the engine gets hot you
might find the piston to cylinder clearance is changed from the cold size
of 0.0022" to less than 0.0010". Of course if the metal gets hotter it
will tend to expand more reducing clearance even more. And if the engine
doesn't get hot enough the metal won't expand as much as desired. Both
situations can affect engine performance and life of the parts and
sealing fixtures.
So figuring out the correct temperature for best performance and parts
life can be important. Most of the folks on this list probably won't
ever design an engine. I know that's a wild guess but I'm thinking it's
pretty accurate. : ) So we'll have to use input from the folks that can
or have designed engines with success, and failure too. Sometimes
knowing what won't work is as important as knowing what does work. An
example might be piston to cylinder clearance. Knowing 0.0022" works is
important. Knowing 0.0018" causes engine seizures would be pretty
helpful too. : ) Knowing oil works well in a environment of about 200
degrees F but begins to fail above 250 degrees F could be helpful.
Knowing it doesn't work quite as well at 165 degrees F would also be
helpful. And I suppose everyone is nervous about lubrication when temps
are below freezing and the oil is slow to flow and maybe doesn't get into
tight spaces quite as well as when warmer.
What's too hot or too cold? I think most engine guys think, as a general
rule, internal combustion engines might work well (best) with a coolant
temperature of around 190-205 degrees F. If the temperature is stable
(this is where a by-pass can really shine) the parts will remain the same
size and reduce clearance issues and wear. Performance will probably be
improved as might fuel economy. Cooler temps will hinder parts getting
to size and lubrication might suffer a tad. Hotter temps like above 250
degrees will probably result in increased wear and maybe failure of
sealing fixtures like valve seals, head gaskets or piston ring sealing.
They could also cause warping of the head. Bearing wear might be
accelerated too from lack of proper lubrication as the oil gets too hot
(thin first and then begins to change properties) to properly do it's
job.
So keeping the engine at a stable, proper temperature can improve
performance, combustion efficiency and help extend oil and engine life.
Allowing an engine to operate at too cool a temperature (by design or
cooling system malfunction like missing or stuck open thermostat or
riding in cold temperatures) can reduce performance, the combustion
process burning the fuel/air mixture can be negatively impacted and
engine life can be shortened by not allowing parts to get to size AND oil
change intervals should be shortened because the oil can't eliminate
combustion by-products since it can't get hot enough.
Allowing the engine to run too hot can cause unrepairable engine damage
as a worse case, like from an engine seizure but also cause repairable
damage like cooked valve seals, warped head/blown headgasket, toasted
bearings from lubrication fluid that is too thin (wrong viscosity at
higher temps) etc. Fuel economy will probably also suffer from too hot
an engine temp.
Guess it's time to close this e-mail but I hope it helps.
The short version is too hot is as bad as too cold. Just right is what
works best. Finding just right can be tricky and not the same for
everyone.
Best,
Jeff Saline
ABC # 4412 South Dakota Airmarshal
Airheads Beemer Club
www.airheads.org
The Beautiful Black Hills of South Dakota
75 R90/6, 03 KLR650, 79 R100RT
.
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all the best,
Mike
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