Engine Temperture ?
03-14-2015, 04:24 PM
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Engine Temperture ?
What is the reason most boat engines run 140-160 water temp instead of 180-200 water temp? Talking about open cooling system. It seems most people that have upped the HP choose to run cooler thermostat's. Can anyone tell me why so Cool ,,, or ,,, not so hot !!!!!
03-14-2015, 06:18 PM
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for emission purposes a hotter running engine as to cars having a 195 degree t-stat burns cleaner to a certain point. On the marine side, no volume of external air hitting the engine, ignition components, belts, wiring looms, rubber components and no air hitting the oil pan nor cylinder heads, to HOT in a marine app along with in return can heat soak even further hence degrading & melting components in short order plus melting of interior engine hatch materials. It is also important to keep cooler temps for the everything listed above..
Also in marine engine compartments while running needs not to exceed 176 degrees especially incoming air down the intake and around the fuel pumps, fuel lines and so on - hence another reason for the lower -t-stats = lower engine temps as well in which relates to lower engine compartment temps. .
Also Merc in doing testing has shown cooler water temps added longevity to the marine engine. I am not talking about cold engine temps but cooler temps than auto's. For better meeting emission standards every single stock OEM marine engines I/O & inboards since 1998 to currently uses a 160 and closed cooling apps a lot use a 170 degree t-stat. There is more to it than what I posted but here is a few examples -
Also in marine engine compartments while running needs not to exceed 176 degrees especially incoming air down the intake and around the fuel pumps, fuel lines and so on - hence another reason for the lower -t-stats = lower engine temps as well in which relates to lower engine compartment temps. .
Also Merc in doing testing has shown cooler water temps added longevity to the marine engine. I am not talking about cold engine temps but cooler temps than auto's. For better meeting emission standards every single stock OEM marine engines I/O & inboards since 1998 to currently uses a 160 and closed cooling apps a lot use a 170 degree t-stat. There is more to it than what I posted but here is a few examples -
Last edited by BUP; 03-14-2015 at 06:38 PM.
03-14-2015, 06:58 PM
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03-14-2015, 09:09 PM
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Salt.
From yanmars site.
:*A salt water cooled engine operates at about 55degC / 130degF. This means it is quite easy to keep your hand on the cylinder block while the engine is running. If the temp goes over this the salt will precipitate out of the water and restrict the water galleries at an unacceptably fast rate. Because of this the alarm operates at 62degC / 144degF. The steam from your exhaust indicates that the water flow thru the engine may be too low.
From yanmars site.
:*A salt water cooled engine operates at about 55degC / 130degF. This means it is quite easy to keep your hand on the cylinder block while the engine is running. If the temp goes over this the salt will precipitate out of the water and restrict the water galleries at an unacceptably fast rate. Because of this the alarm operates at 62degC / 144degF. The steam from your exhaust indicates that the water flow thru the engine may be too low.
03-14-2015, 10:03 PM
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I've seen many guys with "car" backgrounds scratch their heads with marine guys running our engines cool.
Aside from the salt thing, coolant temps have a direct relation to preignition/detonation. In the old days with cars, when the engine got hot, say over 200*, it was common to hear it ping. Reduce the coolant temp to 160*, and the pinging stopped. In many modern computer controlled engines, the coolant sensor is tied into the ecm. When the coolant temp hits a certain value, the ecm pulls timing back so it doesn't ping, until the engine cools back down. On my GM V8, this is around 195-205, I can't remember exactly. But anyhow , in a high performance hard working marine engine, that isn't subjected to emissions tests, there is no way in helll I'd want to raise the coolant temp to a point at which detonation may be an issue. If its "power" your seeking, there are much better ways to make it, rather than increasing coolant temps in the block. Jmo.
Aside from the salt thing, coolant temps have a direct relation to preignition/detonation. In the old days with cars, when the engine got hot, say over 200*, it was common to hear it ping. Reduce the coolant temp to 160*, and the pinging stopped. In many modern computer controlled engines, the coolant sensor is tied into the ecm. When the coolant temp hits a certain value, the ecm pulls timing back so it doesn't ping, until the engine cools back down. On my GM V8, this is around 195-205, I can't remember exactly. But anyhow , in a high performance hard working marine engine, that isn't subjected to emissions tests, there is no way in helll I'd want to raise the coolant temp to a point at which detonation may be an issue. If its "power" your seeking, there are much better ways to make it, rather than increasing coolant temps in the block. Jmo.
03-14-2015, 10:06 PM
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I've seen many guys with "car" backgrounds scratch their heads with marine guys running our engines cool.
Aside from the salt thing, coolant temps have a direct relation to preignition/detonation. In the old days with cars, when the engine got hot, say over 200*, it was common to hear it ping. Reduce the coolant temp to 160*, and the pinging stopped. In many modern computer controlled engines, the coolant sensor is tied into the ecm. When the coolant temp hits a certain value, the ecm pulls timing back so it doesn't ping, until the engine cools back down. On my GM V8, this is around 195-205, I can't remember exactly. But anyhow , in a high performance hard working marine engine, that isn't subjected to emissions tests, there is no way in helll I'd want to raise the coolant temp to a point at which detonation may be an issue. If its "power" your seeking, there are much better ways to make it, rather than increasing coolant temps in the block. Jmo.
Aside from the salt thing, coolant temps have a direct relation to preignition/detonation. In the old days with cars, when the engine got hot, say over 200*, it was common to hear it ping. Reduce the coolant temp to 160*, and the pinging stopped. In many modern computer controlled engines, the coolant sensor is tied into the ecm. When the coolant temp hits a certain value, the ecm pulls timing back so it doesn't ping, until the engine cools back down. On my GM V8, this is around 195-205, I can't remember exactly. But anyhow , in a high performance hard working marine engine, that isn't subjected to emissions tests, there is no way in helll I'd want to raise the coolant temp to a point at which detonation may be an issue. If its "power" your seeking, there are much better ways to make it, rather than increasing coolant temps in the block. Jmo.
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