waterpump or watercross over
#21
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#22
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if water moves to fast threw the block,it wont absorb the heat {not enough heat transfer} and the engine can be damaged,over heated, even knowing its not showing on the guage. crossovers are for blower belt clearance. thats it,run the circ pump. thats how merc designs them.
However, with a unlimited supply of cold lake or ocean water flowing thru the engine, not the case. The reason most guys running supercharged engines without water thermostats run oil thermostats, is because the cold water flowing thru the block will not allow oil temp to come up. Oil temp has a direct relation to block water temp. Thats why sometimes, even with a oil thermostat, engines without a water thermostat, can't build oil temp, or takes a long time to do so, even with the external oil cooler bypassed. Any attempt to "slow" the water flow in the block, will lead to high water psi. Use of restrictor plates, etc.
#23
Im no engineer, but not sure i can say i agree with this statement. In a car, where you have a radiator, I understand that running without a thermostat, the coolant will not have enough time to "sit" in the radiator, and cool. It might flow to quickly, and not enough time for a proper heat exchange.
However, with a unlimited supply of cold lake or ocean water flowing thru the engine, not the case. The reason most guys running supercharged engines without water thermostats run oil thermostats, is because the cold water flowing thru the block will not allow oil temp to come up. Oil temp has a direct relation to block water temp. Thats why sometimes, even with a oil thermostat, engines without a water thermostat, can't build oil temp, or takes a long time to do so, even with the external oil cooler bypassed. Any attempt to "slow" the water flow in the block, will lead to high water psi. Use of restrictor plates, etc.
However, with a unlimited supply of cold lake or ocean water flowing thru the engine, not the case. The reason most guys running supercharged engines without water thermostats run oil thermostats, is because the cold water flowing thru the block will not allow oil temp to come up. Oil temp has a direct relation to block water temp. Thats why sometimes, even with a oil thermostat, engines without a water thermostat, can't build oil temp, or takes a long time to do so, even with the external oil cooler bypassed. Any attempt to "slow" the water flow in the block, will lead to high water psi. Use of restrictor plates, etc.
Same thing in the condensers. You really have to watch the temperature and vacuum in them. The seawater supply has multiple speeds, and when you want to use more steam and make more power, you have to kick up the seawater flow, or else you start overheating the condensers, and losing vacuum, which will ultimately cause a main steam supply shutdown as a safety measure. I kept religious logs over a deployment, watching temperature differentials, looking for signs of biofouling,. When you have enough instrumentation to look at, i.e. temperatures at the inlets and discharges of everything, and know flowrates, everything becomes very obvious and linear. We often jump to conclusion on our powerboats due to incomplete instrumentation and relatively crappy innacurate gauges. But then again, almost every piece in a nuke plant is worth more than my whole boat.
#24
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if i understand what you are saying,it means that the more water you run through the cold side,the cooler it will be on the hot side,makes perfect sence to me.
#25
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guess i shoukd mention,if you run a crossover,you do not want to use a thermostat,or the water pressure will increase,because pressure is caused by resistance to flow.this is why some people who switch to a crossover have high water pressure,the water simply cannot flow fast enough through the thermostat,so the pressure increases,espically when the thermostat is closed.
#26
Beak botr
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tcelano - Thank you for your service, I turned down the opportunity you took advantage of in 1980, even with a sizable signing bonus offered, I just couldn't take staying underwater for 3 to 6 months at a time in a steel tube, I know it would not have been too bad for an officer but still. My hat is off to you and to all those willing and able to protect us fat lazy slobs on land from the evils in the world. It takes a VERY special individual to accept this kind of risk for so little reward and even less recognition.
As I would expect, your analysis above, nail meet hammer.
As I would expect, your analysis above, nail meet hammer.
#27
Registered
guess i shoukd mention,if you run a crossover,you do not want to use a thermostat,or the water pressure will increase,because pressure is caused by resistance to flow.this is why some people who switch to a crossover have high water pressure,the water simply cannot flow fast enough through the thermostat,so the pressure increases,espically when the thermostat is closed.
#28
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yes,i forgot about those,i guess the point i was trying to make was the increase in pressure when the flow sees restiance,i have seen the crossover with the fitting & a hose going above the thermostat,looks like it does 2 things,provides water to exhaust system while thernostat is closed,and relieves pressure ,glad you mentioned it.
#29
Ginger or Mary Ann?
Charter Member
This is with the 'newer' 2 hose t-stat housing design. I also had to install the Merc relief valves to bring the pressure down. Kinda makes you wonder why Merc make relief valves, eh?
My previous boat had the older, 4 hose t-stat housing with the brass tee. That setup was fool proof and perfect.
Leave it to Merc to take a working system, and screw it up.
When I ran the blower on this boat, with cross over, I had nothing but trouble getting both WP and temps (both water and oil) dialed in.
__________________
Some people are like Slinkies - Not really good for anything, but they
bring a smile to your face when pushed down the stairs.
Some people are like Slinkies - Not really good for anything, but they
bring a smile to your face when pushed down the stairs.
#30
Registered
I'm not your friend, but I had the same problem on my stock 502's. Pressure so high the hoses where bulging out.
This is with the 'newer' 2 hose t-stat housing design. I also had to install the Merc relief valves to bring the pressure down. Kinda makes you wonder why Merc make relief valves, eh?
My previous boat had the older, 4 hose t-stat housing with the brass tee. That setup was fool proof and perfect.
Leave it to Merc to take a working system, and screw it up.
When I ran the blower on this boat, with cross over, I had nothing but trouble getting both WP and temps (both water and oil) dialed in.
This is with the 'newer' 2 hose t-stat housing design. I also had to install the Merc relief valves to bring the pressure down. Kinda makes you wonder why Merc make relief valves, eh?
My previous boat had the older, 4 hose t-stat housing with the brass tee. That setup was fool proof and perfect.
Leave it to Merc to take a working system, and screw it up.
When I ran the blower on this boat, with cross over, I had nothing but trouble getting both WP and temps (both water and oil) dialed in.