fatbillybob

Anyone race the C5 or C6 without a thermostat? It would seem that under race conditions the Tstat would always be full open so why not just do without it?

Hi Volts Z06

Yes you can do this but there is a bypass you need to block off to make it work properly. The guys at Evans water pumps do this on ALL race applications. (Hence the reason I'm not sure exactly which one- they built mine). I've even gone as far as to port out the water neck, removing all of the T-Stat mounting boss.

The best way to cool is increase flow as much as possible. Don't listen to old wives tales about "water moving too fast to absorb heat". As long as you don't have cavitation- you neeed maximum volume of water flow.

db2xpert

Contact time is important both to absorb heat, and to dissipate heat.

Move your hand quickly over a bar-b-q then try it slower and slower...
You'll easily see the difference.

Not that I've spoken to dozens of IMSA and TransAm racers, but every one I have spoken to over the years uses either a thermostat or a restrictor ring.

When I tried running without a thermostat years ago, I overheated.

Hi Volts Z06

I used to believe that myself until I spent several HOURS talking to a cooling engineer. (These guys don't just do race cars.....the do medical grade cooling and systems for the aerospace industry). The real issue here is VOLUME more than pressure. As your car is warming up....put a glove on and feel the volume of water flowing through the upper radiator hose. You can literally feel that it's less than half full of water. After I installed my Evans unit the upper hose became rock hard due to the huge amount of fluid the special impeller design flowed. It IS important to watch speed of the pump but I was assisted in selecting the proper pulley based on my operating RPMs and crank pulley size.

Trust me. I spent a season and a half monkeying around with every "forum" fix I could find and was pretty much "Mr. DNF." I spent time reviewing my system with them before ordering one. As soon as I bolted the Evans on and dropped oil temps 40 degrees in similar ambient conditions. Others have taken my advice and found the same results. Search the forum and see.

db2xpert

As the engine is warming up the thermostat is closed restricting water flow - this is the reduced flow you feel. Flow is not reduced when the thermostat is fully opened.
We're not talking about oil temp, we're talking about coolant temp.

Evans is completely different pump and system. I hear good things about it, and don't have ant experience with it. Your good experience with Evans is not equivalent to a stock system.

Taking the thermostat out of your stock system will not result in lower operating temperatures.

69427

Apples and oranges. Your hand is a one time exposure to the heat. Coolant is constantly there exposed to the block/heads/radiator.

The whole idea of a cooling system is to remove BTUs (heat energy), not make a significant temperature drop across the radiator. The slower the coolant moves through the radiator the bigger the temperature drop across it (meaning that the down flow/exit side of the radiator isn't doing much work, and is essentially just weight/ballast), but that also means a corresponding large temperature rise across the block. Not good for durability. Faster coolant flow means a more even temperature across the block, and gets the heat energy out through the entire radiator. The name of the game is to steadily get the correct quantity of BTUs out of the coolant (to maintain a safe constant coolant temp), not to get a significant temperature drop across the radiator or engine.

As long as there's hot water in the radiator (at any flow speed short of cavitation) it's going to dissipate heat into the air stream.

GO_BLUE_VETTES

I agree with you. From the equation below, heat transfer is a direct function of mass flow rate of the fluid to be cooled, m-dot. If you increase m-dot, then the amount of heat transferred increases as well. Also, if you increase delta-T (i.e. cold day vs. hot day) the amount of heat transferred will increase.

Thus, having the water pump move more GPM will increase cooling, up to the point where either the pump is putting in more work (heat) into the fluid than the heat exchanger can remove. Also, if you increase the flow rate to the point where the pump cavitates (occurs when there is not enough water to supply the suction side of the pump, causing gas voids to form and the pump to operate much less efficiently) - then the flow rate will go down and heat transfer will go down.

the question I have, is what is the right size restrictor to have in the system to maximize flow without cavitation in a corvette racecar? LS6 motor with LS2 water pump, custom radiator using stock 1.25" outlet and 1.5" inlet hoses! Remove the thermostat, or drill out parts of it?



http://jullio.pe.kr/fluent6.1/help/html/ug/node245.htm

AND0

From Small block chevy experience, part of the purpose of the thermostat was not necessarily to reduce flow to allow "time for the heat to transfer" or any such, but to increase the water pressure inside the engine. If you had a small block chevy and you removed the thermostat and did not install a restrictor it would overheat. The restrictor increased the water pressure inside the block by reducing flow. The increased pressure would prevent the small hot spots inside head from creating micro boiling points and preventing the coolant from reaching and cooling those areas. This was an especially prevalent problem if you were running straight water or water and a treatment like water wetter.

A system like the evans uses an entirely different coolant that basically will not boil at any temp the engine will reach and thus has no benefit from the increased pressure a thermostat will provide because no boiling hot spots will form and coolant will reach all areas of the engine.

Removing the thermostat on an LS series engine is an experiment. Will there be enough pressure inside the engine to prevent the micro boiling spots with the coolant that you are using?

NemesisC5

100%

NemesisC5

That's because the thermostat works with the bypass, plug the bypass and remove the t-stat and you'll run cooler. Compare an LS thermostat with the old SBC and you'll see the difference in looks and functionality.

Hi Volts Z06

Exactly.

Hi Volts Z06

You don't need to use Evans coolant to run their pump. I run straight water and it works beautifully.

NemesisC5

Yes we are because they are both directly heated from the combustion process. Oil under the piston and water from the jackets surrounding bores then passing through heads to scrub heat from top of combustion chamber.


Evans water pump is merely a factory pump with improved impeller design that will continue to pump rather than cavitate at high rpm. Evans has pulley choices to pump the most water and not cavitate. Same design as stock with bypass and all....merely built to higher standards with different pulley sizes available.

The Evans Waterless Powersports Coolant has a higher boiling point and creates less vapor than water so the liquid coolant doesn't get pushed away from metal surfaces and out of the system like with anti-freeze. The metal temperatures are under control because there is always liquid to metal contact.


That's correct, unless you block the bypass in your stock water pump first then remove thermostat. Your oem system with blocked bypass and no thermostat will cool better than just adding a larger aftermarket radiator.

NemesisC5

Water is a better conductor of heat, the Evans product works similar to water mixed with Ethylene Glycol /Antifreeze as we know it. Because it does have a higher boiling point than "water and EG" mix it will create less vapor under extreme heat and stay in contact with metal to scrub heat better. I run straight water or 80/20 mix here in Texas where I live with hot summers and mild winters.

db2xpert

Where is this bypass, what's the best way to plug it?

What happens if you run a 160 T-stat with the bypass plugged?
Will that still provide higher volume and better cooling?

Hi Volts Z06

I believe the bypass is for the heater so basically blocks off the feed line to the heater core. If I recall correctly it can be see when you remove the T-stat.

It's an interesting question- blocking off the bypass but leaving a T-stat. Not sure if you are doing it because you still drive the car on the street in the winter or if you still are in doubt of the need for restriction.

NemesisC5

The bypass is a passage that allows coolant from block and returning coolant (cooled) from radiator to mix and warm up engine quicker. When the bypass is blocked it forces ALL water to pass through radiator vs a "percentage" of it looping. Most people think that all water passes through radiator, it will not unless bypass is plugged. Evans is unique in that they will block it for you before shipping IF you request. Other manufacturers like Edelbrock, etc..just mass produce and sell factory duplicates with maybe improved (equal) distribution. The thermostat in LS motors "partially" closes the bypass with an extra flange once the thermostat temp is reached and this also explains why in 95% of cases cooling will not improve with a 160* thermostat because it merely partially blocks bypass but for most part continues to allow hot coolant to mix with returning coolant and your coolant temps NEVER fall below a given temp. If the LS thermostat would close the bypass completely you would see the same results as bypass being blocked. WE all know the car is designed to operate at certain temp for a number of reasons although this is not optimal for track use in summer.

That should cover it.

The fact that most don't know how a t-stat works in LS motors and that there is a bypass involved can have one scratching their head for hours/years. Merely blocking off a bypass would cool your car better with a stock radiator than an aftermarket piece. However the aftermarket makes their radiators to improve cooling and still retain oem system to gain cooling capacity while retaining benefits of factory design; emissions, cold weather, quicker warm up, less wear, etc...

Almost forgot, the bypass is not for heater but the heater benefits by getting warm sooner with bypass functioning.

If you ever have overheating issues turning on the heater in summer will actually lower your temps slightly, maybe buying you enough time to make it home. THe heater core is just a heat exchanger with your blower fan blowing across it thus cooling coolant passing through it.

NemesisC5

Standard LS water pump, on left of picture in t-stat housing (return side) you can see the back of water pump housing with a hole that mates to block, this is open bypass. When the LS t-stat opens (goes down) it has a flange that moves closer to bypass to somewhat restrict the mixing of hot water with cooled water from radiator.




I know this is a small picture but look in the silver water pump on right, the bypass to the engine block has been sealed off preventing hot water to mix with returning cooled water and recirculating. Now only cooled water is pumped through block exiting at nipple above pulley and returning to radiator.

NemesisC5

A thought...I don't know how the GEN 5 LT1 and LT4 coolant systems are designed but if they have a bypass like the LS there's much additional cooling to be gained if they block it off.

fatbillybob

Well it would really suck if we could have not paid $1000 bucks for the big Ron davis radiator and just blocked the bypass!

Picture is really small.
So the bypass blocking basically covers the inner hole. Does it also prevent the heater from working because no coolant leaves the small stainless steel pipe that goes to the heater block? Or is the bypass block more like a 50 cent piece covering the hole? If so how can we DIY it? Cut a 50 cent piece sized aluminum plate and TIG weld it to the pump body?