Post by cyphron on Nov 2, 2009 1:40:25 GMT 1
I've been reading about thermostats, and I would like to share with you some usefull information I found about running a water cooled engine without a thermostat.
As you all know I removed mine temporarily because it wasn't working at all...
It seems like one of the biggest problems of running an engine without the thermostat is that the coolant "short circuits" the engine. This results in portions of the engine that are very cool, and others that could actually be overheating.
Running a water cooled engine with no thermostat causes coolant to flow from the pump, through the front of the intake manifold, to the radiator, and then right back to the pump, often times skipping the entire rear portion of the engine (Think conventional V engines).
This problem has been reduced by re-engineering engines so that coolant flow traverses the block, and leaves from the cylinder head on the opposite side, but that does not actually eliminate "hot spots", where the coolant flow is allowed to bypass a particular area.
When coolant can bypass an area, it is taking a "shorter path" and is the reason for overheating.
"Normal" coolant flow has coolant circulating the block and head and picking up heat until the thermostat opens. Then you should get in effect a "figure 8" with coolant circulating the engine block, as well as the radiator.
The thermostat serves as a baffle to prevent all of the coolant from only flowing through the radiator.
The fluid in the cooling circuit is under pressure to raise the boiling temperature. The thermostat, even being 100% open at normal working temp still acts as restrictor. At high RPM, pressure will build up inside the engine because the pump flow pushes against the thermostat.
This helps in avoiding steam pockets forming around hot spots eg. between spark plug and exhaust valve seat.
I guess we are taking a risk when removing the thermostat.
I know that there are some users who have run their bikes without a thermostat with no problems but after reading about it, I think its wise no to do so. I guess these honda V-2 engines must have high tolerance levels to these situations :-)
As you all know I removed mine temporarily because it wasn't working at all...
It seems like one of the biggest problems of running an engine without the thermostat is that the coolant "short circuits" the engine. This results in portions of the engine that are very cool, and others that could actually be overheating.
Running a water cooled engine with no thermostat causes coolant to flow from the pump, through the front of the intake manifold, to the radiator, and then right back to the pump, often times skipping the entire rear portion of the engine (Think conventional V engines).
This problem has been reduced by re-engineering engines so that coolant flow traverses the block, and leaves from the cylinder head on the opposite side, but that does not actually eliminate "hot spots", where the coolant flow is allowed to bypass a particular area.
When coolant can bypass an area, it is taking a "shorter path" and is the reason for overheating.
"Normal" coolant flow has coolant circulating the block and head and picking up heat until the thermostat opens. Then you should get in effect a "figure 8" with coolant circulating the engine block, as well as the radiator.
The thermostat serves as a baffle to prevent all of the coolant from only flowing through the radiator.
The fluid in the cooling circuit is under pressure to raise the boiling temperature. The thermostat, even being 100% open at normal working temp still acts as restrictor. At high RPM, pressure will build up inside the engine because the pump flow pushes against the thermostat.
This helps in avoiding steam pockets forming around hot spots eg. between spark plug and exhaust valve seat.
I guess we are taking a risk when removing the thermostat.
I know that there are some users who have run their bikes without a thermostat with no problems but after reading about it, I think its wise no to do so. I guess these honda V-2 engines must have high tolerance levels to these situations :-)