180 deg Stat for a Merc 888?

[Boomyal]

If you don't run in salt water, any reason not to use a 180 deg stat in the 302? The engine would like it better and unlike the OMC 302 you get some engine cooling water preheat from the exhaust manifolds that would moderate the engine getting cold lake water when the thermostat starts to open.

Combustion chambers flat out do not like engine temperatures at 140-160 deg. You get much better combustion efficiency when the engine runs at 180 deg.

I, of course, do run my Heat Exchanged OMC 302 on a 180 deg stat and have done so for many a year.

 

[rodbolt]

Re: 180 deg Stat for a Merc 888?

shheet put a 195 or 205 in it and roll.
temp is mostly irrelavenat any way. we all know we know more than the engineers that designed it.

 

[Boomyal]

Re: 180 deg Stat for a Merc 888?

shheet put a 195 or 205 in it and roll.
temp is mostly irrelavenat any way. we all know we know more than the engineers that designed it.

ya but, ya but, I thought it was widely accepted that cold thermostats were employed for the purpose of keeping salt from plating out in the engines and that Mfgr'rs could not be sure where there engines would be used?

Regarding 195 and 205, those are for benefit of air polution, specifically oxides of nitrogen, not for any combustion chamber effeciency.

 

[Haut Medoc]

Re: 180 deg Stat for a Merc 888?

I run a 143 with a closed system, what the book says...
My plugs look good when I pull them for inspection....JK

 

[180shabah]

Re: 180 deg Stat for a Merc 888?

shheet put a 195 or 205 in it and roll.
temp is mostly irrelavenat any way. we all know we know more than the engineers that designed it.

ya but, ya but, I thought it was widely accepted that cold thermostats were employed for the purpose of keeping salt from plating out in the engines and that Mfgr'rs could not be sure where there engines would be used?

True, bet even fresh water is not pure water and minerals will be deposited inside your engine, just takes longer to block passages than salt does.

 

[Bondo]

Re: 180 deg Stat for a Merc 888?

Just How Much Added Efficency are you expecting to See,..??....

I've always run the 140* T-stats in my freshwater boats,.....
And I seem to have mine Tuned for it's environment,....
The Plugs are always Coffee w/Cream Brown.......

 

[Paul Moir]

Re: 180 deg Stat for a Merc 888?

As 180shabah alluded, the problem isn't salt but rather minerals. Specifically calcium carbonate, which is what shellfish shells are made of and is present in any hard water. It's unusual in that it actually precipitates out of water as the temperature of the water rises, which is why its forms scale only inside an engine and not in the water pump or water pump lines.

I have no practical experience with it, but I imagine that when operating in fresh water it would very much depend on the local water conditions as to how fast you would build up scale.

Additional info:
http://www.cranfield.ac.uk/sas/water/scale/calcium.htm
http://en.wikipedia.org/wiki/Calcium_carbonate

 

[Boomyal]

Re: 180 deg Stat for a Merc 888?

Paul, calcium carbonates are also components of limestone. Most geology that most aquifers (underground water supplies) are found in are made of limestone with other minerals mixed in to varying degrees. Water, being Natures Solvent, dissolves these minerals where present.

Most surface water sources have never been in contact with these minerals and test very soft (calcium free) and virtually devoid of other dissolved minerals as well.

A simple Total Dissolved Solids test tells the story. TDS is tested by measuring the electrical conductivity of the water. Pure H2O will not conduct electricity. Most all of the surface water in our area have such a low TDS level as to be close to distilled water. Simple dirt (as turbidity) or organic matter (as turbidity) does not count here as they are not dissolved solids and will not 'plate' out.

shheet put a 195 or 205 in it and roll.
temp is mostly irrelavenat any way. we all know we know more than the engineers that designed it.

Indeed rodbolt, the engineers were very sharp. By installing cool t-stats, they came up with a compromise that allowed these engines to be operated in conditions that the manufacturers could not begin to predict when their products were sold.

I have been trying to find some printed information on the adiabatic efficiency of the eternal combustion engine in regard to the ideal operating temperature of the engine. So far I have not located it but I know it exists and would verify that 180 deg is such a temperature.

 

[Bondo]

Re: 180 deg Stat for a Merc 888?

Well,........
The Surface Water here at the Out-going End of the Great Lakes is Full of Lime,.......
That helps keep the Acid Rain from Up-wind in check,.....
And, leaves Nasty Deposits on your Drive at the end of the season........

But,..... That Aside,.......

Just How Much Added Efficency are you expecting to See,..??....

I've always run the 140* T-stats in my freshwater boats,.....
And I seem to have mine Tuned for it's environment,....
The Plugs are always Coffee w/Cream Brown.......

I still have My Question,..??.............

 

[Boomyal]

Re: 180 deg Stat for a Merc 888?

Well,........
The Surface Water here at the Out-going End of the Great Lakes is Full of Lime,.......
That helps keep the Acid Rain from Up-wind in check,.....
And, leaves Nasty Deposits on your Drive at the end of the season........

But,..... That Aside,.......

Just How Much Added Efficency are you expecting to See,..??....

I've always run the 140* T-stats in my freshwater boats,.....
And I seem to have mine Tuned for it's environment,....
The Plugs are always Coffee w/Cream Brown.......

I still have My Question,..??.............

I suppose when all is said and done, that is a fair question rb. Just that I tend to be a little anal sometimes and shoot for the ideal situation.

 

[ron7000]

Re: 180 deg Stat for a Merc 888?

disregarding the whole coolant scale buildup thing, there's a temp point where too hot hinders power/efficiency and is largely based on induction and cylinder head design. A big factor is how much the block heat heats the intake charge. A good example is the GM LS1/LS2 motors running a composite intake and making max power at 190-210F coolant temps. On older motors with less efficient heads and cast iron intakes max power is found at the colder coolant temps, relatively speaking. In addition you'd need to factor in fuel grade, engine timing, and oil type and oil temp. Run it as hot as you like, it only becomes a problem when it either starts detonating or oil temps get too hot and the oil thins out. Disregarding the coolant mineral/scale thing as a limiting factor still, I would consider oil temp and being able to monitor it the biggest concern running higher than a 160 stat.

 

[Boomyal]

Re: 180 deg Stat for a Merc 888?

disregarding the whole coolant scale buildup thing, there's a temp point where too hot hinders power/efficiency and is largely based on induction and cylinder head design. A big factor is how much the block heat heats the intake charge. A good example is the GM LS1/LS2 motors running a composite intake and making max power at 190-210F coolant temps. On older motors with less efficient heads and cast iron intakes max power is found at the colder coolant temps, relatively speaking. In addition you'd need to factor in fuel grade, engine timing, and oil type and oil temp. Run it as hot as you like, it only becomes a problem when it either starts detonating or oil temps get too hot and the oil thins out. Disregarding the coolant mineral/scale thing as a limiting factor still, I would consider oil temp and being able to monitor it the biggest concern running higher than a 160 stat.

Just remember ron, all autos since the late 50's (up til smog motors) ran with 180 deg stats.

 

[180shabah]

Re: 180 deg Stat for a Merc 888?

180 is pretty much the rule in cars, but they have airflow around the engine and oil pan to help keep things a little cooler.

 

[Tail_Gunner]

Re: 180 deg Stat for a Merc 888?

I ran into this subject a while back, I never could find anything conclusive on the subject other than @ what point do the plug's start becoming fouled or gummed up.

Here's a set with 45 hour's on them, if they were in my car im sure i would have noticed a loss of power or econ but the boat........ there were no changes that i could notice as of yet and i did put in a 160 degree thermo

 

[Boomyal]

Re: 180 deg Stat for a Merc 888?

180 is pretty much the rule in cars, but they have airflow around the engine and oil pan to help keep things a little cooler.

boats have 50-70 degree water to keep themselves cool. Much more effective than a radiator, especially in hot weather. The exhaust manifolds are the ones that need water in lieu of airflow. Engine temperature is engine temperature and that is controlled by the T-stat.