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
 

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
 

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
 

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

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?

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.

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

Re: Theory ... water flow
 

yup and yup

Re: Theory ... water flow
 

Cool, thanks monstaaa!

Pics are worth a thousand

Re: Theory ... water flow
 

Great looking engine.


Could you put and arrow where the thermostat is installed :D :D :D ???

Re: Theory ... water flow
 

right next to my subway sandwich

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.

Re: Theory ... water flow
 

you must have alot of magazine subscriptions,,,,,,,,,,,,,

j.k

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?

Re: Theory ... water flow
 

I only subscribe to having an open mind, because I know I don't know everything.

It's obviously impossible for some.

Re: Theory ... water flow
 

dude j.k meant just kidding,,,,,, but for the record steamhoses from front to back? the water exits the engine thru the water neck into the exhaust, the rear of the intake is purged v.i.a water dumps plumbed overboard in correct diameter as not to decrease pressure too much as stated in an earlier post.
aslo i do not post what i have heard or read or seen in another thread. my advice comes from numerous years of being in this buisness, professionally. their are plenty of o.s.o members who are clients.satisfied clients. for the methods i open my mouth about are in fact proven first hand at high speeds , many times over.
i would not attempt to advise someone to correct their situation and opinionate myself for self gratification, all on an article i read.
i do not know everything, howver their are alot of pro's who perposely keep the general public ignorant for personal financial gain. as are their members of this site who anonamouly hide behind their screen names, and spew arguementative or inflamatory comments, and pretend to have been there and done that.

i am neither................. my comments stand..........
my knowledge is only surpassed by my passion for our industry.


take a joke,,and relax

Re: Theory ... water flow
 

I still don't think you can run water through an engine so fast it will not carry heat off with it. Think of the water as one large heat sink. Have you ever soldered something, and didn't want another part to get too hot while soldering, put a piece of heavy metal against the piece you are soldering to act as a heat sink, to carry away the excess heat you don't want on another part of the same piece.

Take a pot full of water, put it on a stove, with a hose runnign in it constantly. The water will not boil, but the stove is putting out the same amount of heat, that heat is going somewhere, my best guess it's going out with the water overflowing the pot, no matter how fast it's running in the pot. Can you run the hose too fast causing the water to boil? I don't think so.

I think a t stat is all well and good on a closed system, but if your using raw water, and it has salt in it, the salt starts crystalizing rapidly somewhere just over 140 degrees. My dad was chief of the engine rooms in naval ships, and he said ANYTHING they had to use raw water cooling they had to keep at 140 degrees. I'm sure there is a slight safety factor at 140.

As Reed pointed out, the reason they run pressure caps on autos is because the higher the pressure, the hotter the boiling point, but I have yet to see a raw water cooled auto.

Re: Theory ... water flow
 

cuda, I agree. See post 36. In your example the heat is transferring from the flame or electric eye, to the pot, to the water no matter how fast the hose is running into the pot. In the "fast water" posts, you could reach a point at which the water flowed so fast that your pot would melt which simply will not happen. 1. The greater the flow the more turbulence which increases the convective heat transfer which will actually decrease the temperature of the pot (i.e. block and heads). 2. The more water flow the closer the inlet water temp stays to the outlet water temp, even with the same amount of heat input because the heat is distributed into a greater mass of water. #2 is why people see lower temps on their temp gages. NOT because the water is picking up less heat.

Even though there are posts that ridicule heat transfer theory in this thread, there are people on this thread that are trying to rationalize what is happening when you remove the thermostat. I think a little theory and stove top examples are OK.

Re: Theory ... water flow
 

pretty much, and most HIGH PERF applications see about 140 or so water temps while out and about crushin the throttles.

Re: Theory ... water flow
 

to an extent you are correct,, the extent stops when you theorize and your customer is looking at a richie zul 40k engine melted in his bilge.
this is not rocket science. and is not a stove top. nor a difference of oppinion. it is fact.
there is a huge difference between a stock engine / or closed cooling system engine, and a big cube high hp engine designed t orun at 6000 rpm.
this is a" Performance" Boat Enthusiast site.

Re: Theory ... water flow
 

Your $40K is chump change. My customers rely on me to prevent melting $500,000,000 ethylene plants and refineries and I use heat transfer theory along with 24 years engineering experience to do so. You make good points but understanding the basics of the water flow and heat flow is critical to making a setup work if you do not have the experience. What would be sad is for someone to take some of the BS off of this board and tear up their motor because the experienced guys forgot to mention the one point that made the setup work so you could run all day at 6000 rpm.

Re: Theory ... water flow
 

your plants and refineries are adifferent animal. i wouldny go into a forum on those subjects and lead people onto something i was not absolutely sure of.

to you and the other poster, my comments were not and are not meant to be offensive. if they were then both of you have my appologee's. i understand heat tranfer theory. very well actually.

point is, i am not getting in debth as to educating the public, rather trying to keep those searching for correct answers on a specific topic a shorter route to the answer for said topic.
these engines have run exactly that ground.

Re: Theory ... water flow
 

Cuda, right about the 140 thermostat deal; it is because of mineralization/crystallization.

The deal with using NO thermostat is you will run too cold. It acts to restrict the QUANTITY of water, so that the block CAN warm to 140-ish. Maybe not too cold in FLA, or FLA in the summer, I couldn't say, I live quite north; but IF you run with no T-stat and NO circ pump, the pressure in the block WILL be more than the gaskets can take. Instant milkshake following a WOT run, or dyno pull. Watched two buds do this for themselves; I don't need to go there, myself, to see I don't want to. This is where the Merc pressure relief valve dumping overboard, comes in. Merc found this when they used cross-overs on the SC's.

If going away from a stock type water circuit, I STRONGLY SUGGEST using a block mounted water PRESSURE guage.

Monstaaa, as I said, there is no ONE way to do it. If you have success in plumbing YOUR water circuits, that's cool. Your dumping from the back of the intake, and the specific size of that hose reduces the internal block water pressure. But, as I said, there is no ONE way to do anything; if it works for you, fine, no matter what ANYONE says. Do you KNOW what water pressure your systems carry? I have not seen dumps from the rear of the manifold, thanks for sharing.

I'm just an enthusiast, but I've seen a lot of 'steam hose' plumbed boat and race car motors. Most AM intakes have the ports, or at least the bosses are cast in for them.

And I don't have ANY subscriptions. I don't pretend anything. I just pay attention, and listen to others. I've found the smartest people aren't very belligerent.

Re: Theory ... water flow
 

stingray. all the water systems i have plumbed have been set to run no less than 12 psi and no more than 22 psi( spike psi of 25) with the exception of stock monitoring systems that require more. also a stat is a restriction in thw water system at the higher rates of speed boats are going these days.
many bord members have experiencved this problem in 1 of 2 ways ( to sum it up as an average). the repowered and picked up big speed or the installed a shortie imco lower which put there water psi thru the roof . in alot of cases more than 40 pounds. havind no stat, or a crossover will not push out intake or head gaskets. its the increase in the increase in other areas that help this to happen.
which is why i suggested using a pop off vave, prior to the raw water pump to dump excess before it even gets close to the engine. the intake dumps are to regulate.
again my knowledge comes from countless hours of r and d and alot of high speed applications.

Re: Theory ... water flow
 

I am also running steam hoses on my intake. It is common enough that most hi perf intake makers cast bosses in the proper place so you can drill and tap them.

Re: Theory ... water flow
 

running with cold water is not a big deal, IF your oil temp is where it should be, which is above 212*. As far as the pressure into the block no thermostat and no circ pump has very little to do with it. There are a ton of restrictions there already, starting with the thermostat housing. Its a function of several things, the main one being how fast you are running the boat. At X speed, you are pushing X amount of water into the pickup. At that speed, the amount of water being pushed into the pickup doesn't change if you do or don't have a stat/circ pump. Your gauge should show just about zero water pressure when you are not moving, and it increases to a certain point as your speed increases. In most cases, water dumps are not needed until you get into very very high performance/high speed boats. I've run in boats at near 100 with no dumps,no circ pump, and they are only making in the low 20's water pressure. An OL running 150 with twin blower motors is a totally different story.

99% of what applies to cooling in a car does not apply to a boat. Cars are not running at anywhere near the load that boats are. Plus they have computers and emmissions that need the high temps to run correctly. I run 130 water/230 oil in any temp lake water from 50* to 75*. I do run a restrictor in place of the stat, BUT that is because without it my oil temp was not running above 180, which caused condensation. It runs right about 20 psi at WOT of 5600 RPM.

what water/oil temps are you running, and what water pressure? and at what speed

Re: Theory ... water flow
 

exactly.

Re: Theory ... water flow
 

some times oversizing the oil cooler for the application causes the issue of lack of temp , as far as low oli temps.