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Re: Theory ... water flow

Not drinking the cool aid. All a proper stat does it bring the temp up to whatever sooner. If it flows the same as a restrictor then is is a restritor (assuming the pressure remains the same and amount bypassed is the same which it would be if it flow the same).

So the real quesiton becomes does a T-Stat flow the same as whatever size restrictor you feel you need. AZ Speed and Marine makes a nice 120 T-Stat that should have a net free area greater than 3/4 restrictor. I make this assumption on running in 40 degree water at wot shows 125 on gauge and running in 85 degree water shows gauge shows about 127. If i used a restrictor to keep block temp at 125 in 40 degree water it would not work worth a dang in 85 degeree water.

The T-Stat just makes life easier.

Re: Theory ... water flow

lets not reinvent the wheel.
Support your local Merc dealer and pick up a couple relief valves. Now you can run your cross over with a t-stat, with or with a bypass hose. The t-stat will take care of your temp and the valve will take care of the pressure. Problem solved.

Re: Theory ... water flow

Quote:

Originally Posted by monstaaa (Post 1990584)

they use the stats on staock, and on efi engines. the efi's need the temps to be at a certain range for thats were the program which haS BEEN DESIGNED TO WORK IN A MULTITUDE OF ENVIROMENTS was set from the start.

also the idea of stats on a high perf engine is not a good one.
many of the conflicting posts, and book theories, and " i read this in hot boat" and the rest of it, is all nonsense. theory is not reality. and until you have been there and done that you should not make a decision for someone else.

i stand as stated ,,,,,,,,,,,, no stat.

has little to do with oil temps and milk shake. thats what the oil cooler and stat take care of.

why is it no auto's have oil temp gauges.

you are talking about an engine which is designed to run at high rpm's for an extended amount of time.not idlinmg in traffic or shifting.

heat transfer, molecules, intimate contact.

horse poo, none of that truly has a dramatic effect at 5500 / 6000 rpm when you have it bricked for an hour on a poker run. do you really think your gonaa remove all the little tiny air bubbles,,,,,,,,,,,,,,,,,,,,,,no..

stock being too critical, aand go blow your stuff up.

lol, good luck

Yeah, all that.
So to sum it up- Stock engines, esp EFI-stock cooling system with thermostat.
HP engines-easiest way to do it is run crossover, no thermostat in cooling system, but a thermostat in the oil cooler lines to keep from the milkies. Watch your pressure, use a relief if it gets too high......but no one knows what too high is :eek:

Re: Theory ... water flow

Oh, and Porsches have oil temp gauges :D :D

Re: Theory ... water flow

BTW, monstaa, while you are holding forth,

What's your favorite Subway sub?????:evilb: :evilb: :D :D

Re: Theory ... water flow

Quote:

Originally Posted by Mike Paula (Post 1986517)

Cuda
There is Some truth to that. The theory says you need to slow (regulate) the flow of water so you have some heat transferred to the coolant. You don’t need a t-stat, a restriction will do the same thing. Negative affect will be a build up of pressure.

That is total bull$hit... you DO NOT need to slow the water for heat transfer. There will be more heat removed the more cold water you flush over the surfaces. You may be thinking about problems with cars when you remove thermostats. Automotive water pumps are designed to pump enough water at slow engine rpm's to keep the engine cool ( remember, they are belt driven and run at the same rpm as the engine )... but... they are also designed to not create a lot of head pressure at high rpm's. What happens to some motors if you don't have either a restriction plate or a thermostat is the chicken-$hit impeller on the water pump cavitates and flow comes to a standstill. So then the engine overheats. Not because it's flowing too fast.. but because it's not flowing at all. The water passes through the engine passages much more readily than it passes through the tiny radiator passages. So what happens is you get a steam bubble in the eye of the impellor. Remember, when you take the pressure off of water, it boils at a lower tempurature. That is the reason modern cooling systems on autos are pressurized to 14 or more lbs. For every 1 lb of pressure you get 2 degrees higher boiling temp. That is the reason a lot of High performance boat motors only have a crossover and not an automotive style pump. They rely on the pressure generated in the pick-up by the forward motion of the boat . The sea pump aids in pushing the water when the boat is standing. If the boat were always moving, you wouldn't need a sea pump.

Re: Theory ... water flow

Quote:

Originally Posted by stevesxm (Post 1989464)

my solution has always been.... define the water cooling to make the water temps 180, make the oil cooling such that they are between 210 and 240 all the time including during the most extreme sustained conditions. don't try to make one system do the job of the other.

.

Those figures are all fine and dandy for an automobile. I don't know of any automobile that has salt water for coolant. The oil temps are good. You should run your oil at those temps. But if you have raw salt water at those temps you will quickly dissolve your engine from the inside out. I know the thermal efficiency is better with the engine temps up that high, but it's not practical with raw water cooling in the ocean. So many boat engine builders think like auto engine builders and get into trouble.

Re: Theory ... water flow

geeze... why is it so hard to understand ? the principles of thermodynamics don't care whether its cars or boats. they don't care whether its sea water or jello. the science and truth are just that.

if you want to say that you can make a badly designed and executed system function... then yes... you are correct... if you want to make your pistons out of wood, the motor will certainly run... but thats not the point and the insane rational and cereal box theory that you suggest to justify it doesn't make it correct.

please... take a minute... read a bit about the specific heat of various cooling mediums.... read a bit in a real text book about thermal transfer between a liquid and a solid and have a look at the equations that govern it.... note the COMPREHENSIVE differences between closed loop systems and total loss systems

those are the truth....

now... the rest is, as i said, what you want to make of it... you can flush a billion gallons of water thru your motor at 0 psi and get away with it... just like wooden pistons. you can run your water temps at 120 deg and wear out the pistons and rings at probably 400 % the rate that they would if the motor was at 180. you CAN do all of those things... and i am not saying that in some extraordinary circumstances with some combinations those might not be the correct answers... IF you can live with the consequences...

but in the infinitely vast majority of nominal cases... like probably 95 % of the motors in the boats here and being used like 95 % of the boats here get used, then a thermostatically controlled temp system that regulates and maintains the temps at something above 165 and below 210 and a oil system that keeps the temps above 200 and below 240 will be the one that gives best performance, longest life and superior driveability in virtually all circumstance. you can run it in the carribean in 85 deg water or cape cod when its 45... the motor wont care whats on the other side of the hull or how the water gets to it... because it will nice and toasty warm and all that good work that real engineers and metallugists did will be humming along just fine.

it is SO SO simple....

Re: Theory ... water flow

I doubt if there is much difference in ring wear between running at 120 or 180. There is a big difference in the tendency for an engine to detonate with those high temps. All of the Merc carb engines used to come with 140 therms. What do they know?

Re: Theory ... water flow

first off ,,,,,,,,,,,,,,,,,,,,,,

i like the cold cut trio, with all the dressings.

secondly too high of pressure , i'll assume you meran water.
most cases 15-22 psi is sufficient. no poping intake manifold gaskets or head gaskets being pushed out.
although on a couple of stock applications it may require a little more pressure for the monitoring systems.

as far as relief valves , your correct. on a high speed application you may want to start with an adjustable relief valve early in your watewr system, like in a bung in the strainer, or just buy a quality strainer with one built in to start with. set it to pop at say 25-30 lbs so as not to exceed that 25 psi mark in the engine. then as stated plumb accordingly to set desired water psi. 15-22 psi. the water system will remain stable and will not spike upon re-entry.

and no stat.

lol fosheezeee neezzee