Reply With Quotei love that girl! i just wish she was real! hb the rex thermo is 160 all the time. never less, never more. it bypasses through and back in. it is the shit. and i don't have anything to gain from this either. brad
Interesting. For one, 180 degrees in a boat motor is too hot in my opinion. When you let off the gas and begin to idle, what does it jump up to? 200-210 degrees? I run my motor with a water temp of 120-125 degrees. We run the water that cool because I'm running a 10.25:1 compression on 91 octane pump gas. I also run a water pressure regulator off the pump before the water is plumbed to the block, and at WOT, the block pressure was at 25psi, and the water temp didn't get higher then 125 degrees in 100+ degree heat.
My setup is a little different, but I think anything over 160 degrees is too much.
HBjet
i love that girl! i just wish she was real! hb the rex thermo is 160 all the time. never less, never more. it bypasses through and back in. it is the shit. and i don't have anything to gain from this either. brad
fourspeednup.
180 while cruising is good.
if the idleing through the channel is before a run, then the temps will be a bit cooler untill you gain rpm and creat more heat. hence the warm up practice before taking off across the lake or river. try and idle around for a while to warm the engine up as much as possible before you gun it. you will notice it doesnt take a long time to get up to your 180 once you get up on plane. now after a hard run and or a long cruising run, when you come down to an idle you will see a gain in temp for a brief period. dont panic and definatly DO NOT shut her down. idle around for a few and let the temp come down via the water entering through the block and heads. coming down from the sand bar and across the lake is a long run, and that channel is a great way to idle through and let the engine cool down. though idleing for too long can also generate heat build up. i know i know. confusing. remember too that the river water is alot cooler than the lake water, especially further down the lake. so keep an eye on your temp when running up from havasu and entering the gorge. if you set your flow at lower havasu, you may end up closing the valve a bit when you get higher up river. there are devices that can help regulate temp fluctuation in differant waters. a valve/regulator is used in conjuntion with a thermastat. it also prevents too much water presure entering the block and heads and saves your head gaskets. this adjustable regulator (12 pounds recommended) allows full flow to the engine and as your rpms get higher, so does the water presure, and the regulater opens a valve and dumps the excess presure out the bulkhead fitting. this way at full rpm you are getting just enough to keep the engine cool at that rpm, but not so much you are stressing your head gaskets. when coming back down to an idle it allows more flow and presure so you wont over heat at idle. something to ask rexone about. im betting he sells them.
remember too, this is just my opinion. there are alot of much more knowledgable people on here.
HBjet.
wow. thats amazing you run that cool and had no problems. i guess my thoery was just blown out the water.i suppose i am running mine too hot, but i have had problems in the past with running too cool, and the hot hasnt been a problem for me with the olds motor. i suppose ill have to rethink when i start running the BBC.
Consult 10 people on this subject and you'll probably get 10 different answers.
My preference is to run between 160-200. I believe it makes more power in this range, aids in fuel atomization, and it definately aids in allowing the oil to get up to temp and lubricate properly. If you're running 110-120 water temp, the oil never gets where it should be to work properly. Keep in mind cars and trucks operate at 210-230 with no problems, with oil temps pushing 300 in severe use. The "only" reason I prefer to stay under 210 is the fact that you do not have coolent (antifreeze) in these engines and water boils at 212... a problem not present in a closed cooling system in a car with proper coolent mix. If it wasn't for the boiling issue I'd have no problem running an engine at 210-220 all day long with proper tune up. When ski racing I would run the boat at 200 for long periods at high throttle without issue, oil temps in the 240-250 range. Now when I say all of the above I say it with the assumption proper temperature control is in place so overheat at idle does not occur (a whole nother discussion). A restricted inlet (valve) to get running temp up will not allow idle without overheating in many cases.
However with these engines running hard, perhaps not always with the proper tune up (talking enough fuel and not too much timing), 160-180 is a good safe range that will allow the oil to get over 200 to do its job properly.
Here are some links to other older threads on this and related cooling subjects, plumbing etc.
Gate Valve (http://www.***boat.com/forums/showth...threadid=17106)
Temp Control (http://www.***boat.com/forums/showth...threadid=19365)
Water Pressure (http://www.***boat.com/forums/showth...threadid=17206)
The by-pass tstat works great, even better when coupled with a circulating pump on the front of the motor. My water temp comes up to 170 within 2 mins and stays there no matter what the conditions. I just robbed a tstat housing from an omc motor, same principle as rex's just doesn't look as nice.
Most new jets (as well as almost all other new inboard setups)are set up this way. Cycling the engine temp up and down allows components to change in size (pistons, etc,....) and increases wear. Even many drag racers (I know a few promods and others following their lead) are going to closed cooling to run the higher temps like rex mentioned and also keep it consistant.
jd
I run my motor with a water temp of 120-125 degrees
I'm with HB on this one. Mine has always run at 120-125 while underway (slightly cooler in the winter due to reduced water temps) 150-160 while idling.
Pulled my last motor down and the insides looked perfect. No scratching or scoring of cylinders, no egging to speak of................nothing. Heck the compression was still in spec and the crank only had to be ground .010". As far as I know, it was the original motor. If I hadn't been seeking more power, I could've ran that motor for another 20 years. Why would I want to mess with that?
Originally posted by HBjet
Interesting. For one, 180 degrees in a boat motor is too hot in my opinion. When you let off the gas and begin to idle, what does it jump up to? 200-210 degrees? I run my motor with a water temp of 120-125 degrees. We run the water that cool because I'm running a 10.25:1 compression on 91 octane pump gas. I also run a water pressure regulator off the pump before the water is plumbed to the block, and at WOT, the block pressure was at 25psi, and the water temp didn't get higher then 125 degrees in 100+ degree heat.
My setup is a little different, but I think anything over 160 degrees is too much.
HBjet
I don't think 180 degrees F is too hot; frankly, I think it's too little, as far as engine operating temps go. But since our open cooling systems cannot utilize antifreeze, we'd really be pushing it to go any higher. This is because water boils at 212F without any added antifreeze, and we also don't have the benefit of a closed/pressurized system (boiling point of water rises 3*/pound pressure in a closed system).
But I couldn't agree more about the nuisance of my gate-valve cooling system. Temps shoot up after a long run and then putting into a 5-zone. This is because as rpm's drop, pump-bowl-pressure drops...and so less H20 is diverted into our engine...the gate valve cannot adjust for this; it's not a thermostat. So at these temps, I am always tweaking my gate valve a little...
I admit, I'm such a goddamn gearhead that I'm prefectly happy twisting the knob on my gate valve between wake zones and open lake passes; But hey, I get more power that way.
LO
If water boils at 212 at no pressure (1 atmosphere), and goes up 3 degrees per/lb of pressure (i have no idea if that is accurate), why is everybody assuming that an open cooling system will just boil at 212??? Ask anybody who has ever had water in their oil if they think the water in our open cooling systems is under pressure. I think that most people are running somewhere in the neighborhood of 10-30psi off their pump, doesn't that pressurize the water inside the block, aka increase the boiling point??? Am I missing something here???? I haven't had my coffee yet so please somebody let me know-Aluminum Squirt
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