Theory ... water flow
01-13-2007, 06:34 AM
#51
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Re: Theory ... water flow
I have a quick question... when running a cross over, in place of a water circulating pump, and than junking the stat, does the raw water pump now take on sole responsability for providing all water pressure?
Last edited by jdub; 01-13-2007 at 06:37 AM.
01-13-2007, 08:34 AM
#52
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Re: Theory ... water flow
essentially, yes. with the exception of a high speed application where in the drive height(on bravo app.) or pick up depth play a major role in water pressure . as speed increses so does water pressure thru natural process.
01-13-2007, 08:47 AM
#53
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Re: Theory ... water flow
so for a mild 502, a cross over with no stat with just the raw water pump will be fine?
Also I'm ditching fuel injection and going carb. My old system had the mechanical fuel pump mounted on the raw water pump then went to an electric fuel pump to the injectors. Can I run just the mechanical fuel pump off the raw water pump to the carb?
Thanks, sorry for getting off topic
Also I'm ditching fuel injection and going carb. My old system had the mechanical fuel pump mounted on the raw water pump then went to an electric fuel pump to the injectors. Can I run just the mechanical fuel pump off the raw water pump to the carb?
Thanks, sorry for getting off topic
Last edited by jdub; 01-13-2007 at 09:01 AM.
01-13-2007, 12:09 PM
#56
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Re: Theory ... water flow
Great looking engine.
Could you put and arrow where the thermostat is installed
???
Could you put and arrow where the thermostat is installed
???
01-15-2007, 01:37 PM
#58
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Re: Theory ... water flow
Couple of things;
First, Merc builds engines to operate in all types of conditions, in fresh and salt water, in cold deep fresh water and 85° ocean water. High water temps promote crystalization and mineral deposits, which they, no doubt, seek to minimize. I think that they must sorta split the difference on what they aim for, to be safe in all possible air temps, and types of water and water temps, when designing and spec'ing the t'stat/cooling system, to be safe in any region of the world. Of course, blower motors make running a t'stat too difficult, due to packaging, so they have run crossovers with bypass dumps to accomplish their goal. Each has it's place, and every boater is free to do whichever method they choose. As long as they have no under/over pressure or under/over cooling issues, they have succeeded.
Second, bearings in any V-8 like to be a little on the warmer side of 140°, more like about 180°. This is why you don't peg any motor when it's still 'cold'. They accomplish this by the combinations of water system components and the size of the oil cooler, which varies in steps from none on an Alpha to the small one on 7.4L's, to the standard Mag size and so on. With higher cooling needs comes the need for higher capacity oil coolers. This makes warm ups difficult, and so the use of factory oil thermostats to get the oil up to temp, while keeping the water temp cool, from the heat of the 500HP for example.
A thermostat provides for many more considerations in the entire system than just being a water temp regulator. It, coupled with a circulation pump, is also a water pressure regulator; too much pressure and you blow out the intake and head gaskets. This is not the same as normal condensation cured by warm oil burn off; this is having more water pressure than the system, (the gaskets and seals) is able to handle. You MUST have a means to control over pressure; it doesn't matter what MEANS.
Correct water temp and pressure is a balancing act that is extremely reliant on the HP of the motor, the temp and type of the water, the temp of the ambient air, and the rate of flow of the water in the system. A correctly designed system will err to the higher cooling side, to prevent overheating. Richer factory jetting/fuel curve calibration than optimum, seeks to accomplish this in another way.
High HP engines will greatly benefit from an external joining of water from the front of the heads/intake, to the rear of the heads/intake, to alleviate hot spots, and steam pockets, via what are termed 'steam hoses'.
HOW all this is accomplished is up to the indivdiual owner/builder to decide. Adequate cooling and not insufficient cooling. Adequate pressure but not excessive pressure.
I run a circ. pump, t'stat, high capacity oil cooler AND an oil thermostat. Choose whatever method you feel comfortable with, and if it works, you're golden. No matter what anyone else thinks of it.
There's not any one, mandatory way to do it.
First, Merc builds engines to operate in all types of conditions, in fresh and salt water, in cold deep fresh water and 85° ocean water. High water temps promote crystalization and mineral deposits, which they, no doubt, seek to minimize. I think that they must sorta split the difference on what they aim for, to be safe in all possible air temps, and types of water and water temps, when designing and spec'ing the t'stat/cooling system, to be safe in any region of the world. Of course, blower motors make running a t'stat too difficult, due to packaging, so they have run crossovers with bypass dumps to accomplish their goal. Each has it's place, and every boater is free to do whichever method they choose. As long as they have no under/over pressure or under/over cooling issues, they have succeeded.
Second, bearings in any V-8 like to be a little on the warmer side of 140°, more like about 180°. This is why you don't peg any motor when it's still 'cold'. They accomplish this by the combinations of water system components and the size of the oil cooler, which varies in steps from none on an Alpha to the small one on 7.4L's, to the standard Mag size and so on. With higher cooling needs comes the need for higher capacity oil coolers. This makes warm ups difficult, and so the use of factory oil thermostats to get the oil up to temp, while keeping the water temp cool, from the heat of the 500HP for example.
A thermostat provides for many more considerations in the entire system than just being a water temp regulator. It, coupled with a circulation pump, is also a water pressure regulator; too much pressure and you blow out the intake and head gaskets. This is not the same as normal condensation cured by warm oil burn off; this is having more water pressure than the system, (the gaskets and seals) is able to handle. You MUST have a means to control over pressure; it doesn't matter what MEANS.
Correct water temp and pressure is a balancing act that is extremely reliant on the HP of the motor, the temp and type of the water, the temp of the ambient air, and the rate of flow of the water in the system. A correctly designed system will err to the higher cooling side, to prevent overheating. Richer factory jetting/fuel curve calibration than optimum, seeks to accomplish this in another way.
High HP engines will greatly benefit from an external joining of water from the front of the heads/intake, to the rear of the heads/intake, to alleviate hot spots, and steam pockets, via what are termed 'steam hoses'.
HOW all this is accomplished is up to the indivdiual owner/builder to decide. Adequate cooling and not insufficient cooling. Adequate pressure but not excessive pressure.
I run a circ. pump, t'stat, high capacity oil cooler AND an oil thermostat. Choose whatever method you feel comfortable with, and if it works, you're golden. No matter what anyone else thinks of it.
There's not any one, mandatory way to do it.
01-15-2007, 01:55 PM
#59
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Re: Theory ... water flow
Couple of things;
First, Merc builds engines to operate in all types of conditions, in fresh and salt water, in cold deep fresh water and 85° ocean water. High water temps promote crystalization and mineral deposits, which they, no doubt, seek to minimize. I think that they must sorta split the difference on what they aim for, to be safe in all possible air temps, and types of water and water temps, when designing and spec'ing the t'stat/cooling system, to be safe in any region of the world. Of course, blower motors make running a t'stat too difficult, due to packaging, so they have run crossovers with bypass dumps to accomplish their goal. Each has it's place, and every boater is free to do whichever method they choose. As long as they have no under/over pressure or under/over cooling issues, they have succeeded.
Second, bearings in any V-8 like to be a little on the warmer side of 140°, more like about 180°. This is why you don't peg any motor when it's still 'cold'. They accomplish this by the combinations of water system components and the size of the oil cooler, which varies in steps from none on an Alpha to the small one on 7.4L's, to the standard Mag size and so on. With higher cooling needs comes the need for higher capacity oil coolers. This makes warm ups difficult, and so the use of factory oil thermostats to get the oil up to temp, while keeping the water temp cool, from the heat of the 500HP for example.
A thermostat provides for many more considerations in the entire system than just being a water temp regulator. It, coupled with a circulation pump, is also a water pressure regulator; too much pressure and you blow out the intake and head gaskets. This is not the same as normal condensation cured by warm oil burn off; this is having more water pressure than the system, (the gaskets and seals) is able to handle. You MUST have a means to control over pressure; it doesn't matter what MEANS.
Correct water temp and pressure is a balancing act that is extremely reliant on the HP of the motor, the temp and type of the water, the temp of the ambient air, and the rate of flow of the water in the system. A correctly designed system will err to the higher cooling side, to prevent overheating. Richer factory jetting/fuel curve calibration than optimum, seeks to accomplish this in another way.
High HP engines will greatly benefit from an external joining of water from the front of the heads/intake, to the rear of the heads/intake, to alleviate hot spots, and steam pockets, via what are termed 'steam hoses'.
HOW all this is accomplished is up to the indivdiual owner/builder to decide. Adequate cooling and not insufficient cooling. Adequate pressure but not excessive pressure.
I run a circ. pump, t'stat, high capacity oil cooler AND an oil thermostat. Choose whatever method you feel comfortable with, and if it works, you're golden. No matter what anyone else thinks of it.
There's not any one, mandatory way to do it.
First, Merc builds engines to operate in all types of conditions, in fresh and salt water, in cold deep fresh water and 85° ocean water. High water temps promote crystalization and mineral deposits, which they, no doubt, seek to minimize. I think that they must sorta split the difference on what they aim for, to be safe in all possible air temps, and types of water and water temps, when designing and spec'ing the t'stat/cooling system, to be safe in any region of the world. Of course, blower motors make running a t'stat too difficult, due to packaging, so they have run crossovers with bypass dumps to accomplish their goal. Each has it's place, and every boater is free to do whichever method they choose. As long as they have no under/over pressure or under/over cooling issues, they have succeeded.
Second, bearings in any V-8 like to be a little on the warmer side of 140°, more like about 180°. This is why you don't peg any motor when it's still 'cold'. They accomplish this by the combinations of water system components and the size of the oil cooler, which varies in steps from none on an Alpha to the small one on 7.4L's, to the standard Mag size and so on. With higher cooling needs comes the need for higher capacity oil coolers. This makes warm ups difficult, and so the use of factory oil thermostats to get the oil up to temp, while keeping the water temp cool, from the heat of the 500HP for example.
A thermostat provides for many more considerations in the entire system than just being a water temp regulator. It, coupled with a circulation pump, is also a water pressure regulator; too much pressure and you blow out the intake and head gaskets. This is not the same as normal condensation cured by warm oil burn off; this is having more water pressure than the system, (the gaskets and seals) is able to handle. You MUST have a means to control over pressure; it doesn't matter what MEANS.
Correct water temp and pressure is a balancing act that is extremely reliant on the HP of the motor, the temp and type of the water, the temp of the ambient air, and the rate of flow of the water in the system. A correctly designed system will err to the higher cooling side, to prevent overheating. Richer factory jetting/fuel curve calibration than optimum, seeks to accomplish this in another way.
High HP engines will greatly benefit from an external joining of water from the front of the heads/intake, to the rear of the heads/intake, to alleviate hot spots, and steam pockets, via what are termed 'steam hoses'.
HOW all this is accomplished is up to the indivdiual owner/builder to decide. Adequate cooling and not insufficient cooling. Adequate pressure but not excessive pressure.
I run a circ. pump, t'stat, high capacity oil cooler AND an oil thermostat. Choose whatever method you feel comfortable with, and if it works, you're golden. No matter what anyone else thinks of it.
There's not any one, mandatory way to do it.
j.k
01-15-2007, 09:16 PM
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Re: Theory ... water flow
I have redone my 330hp and built it to around 420 specs I am switching from cir pump to a crossover and I found in my water intake hose from oil cooler up to themostat housing is a rubber reducer I left it in what the heck is that for I run a themostat now so why the reducer?
