thermostat for LS Engine

To clear up some confusion,

The thermostat is the part in the housing where hose hooks up,
Where you see the freeze plug, THAT IS NOT A THERMOSTAT AREA, That is the Pressure Relief or the bypass

The Bypass is intended to keep the flow down so it does not blow plastic side caps off the radiator on passenger cars,

People put a hole in the free plug to allow some water to bypass, the hole is not needed, Redline and Katech do not use a hole, so any of the water flowing though the hole in a free plug will not flow through the head, but if you feel you need a hole in your delete, then put it one in,

If you block off the heater inlet and outlet with the U rubber tube, all that water will not run through the radiator, so you cut the cooling down by a large amount,
 
I'm not a big fan of running no thermostat. as has already been pointed out, it takes longer to warm up. to me ( a wiring and electronics guy) the real issues is you now only have the fans to regulate engine temp. that means the fans are cycling on and off way more than if you had a thermostat.

trouble is, no one makes a relay worth a crap any more. The large shock load the fans put on the electrical system at start up is massive.....all this is hard on your alternator and entire electrical system.

the only way I would run without a stat is if i had speed controlled fans. This is the correct way to do it is where both fans come on simultaneously, speed controlled by the ecu, and entirely regulate fan speed vs engine temperature. when properly controlled with the ECU, vehicle speed and even ambient temperature can be factored in to the control strategy.
 
wesinls said:
Few people mentioned no thermostat - I use one and have never gone above 195 - but it's also my understanding that a thermostat also slows the circulation of water through the entire system - meaning, it keeps the water in the radiator longer allow it to cool down more (make sense to me at least). I'd image that's also why Redline created and sells this thing - removes the thermostat but restricts the flow:

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The thermostat isn’t there to slow water flow, it’s there to act as a diverter between the too cold recirculating path, or the too hot radiator path. If you just remove the thermostat, coolant can flow through both paths and you end up recycling a significant amount of hot coolant fresh from the engine right back into the engine.

The holes are drilled in the freeze plug to aid with burping since that path will never open.

Slowing coolant flow is not good for cooling. If it was, thermostats wouldn’t work. The slower the coolant flow, the cooler the water in the radiator, yes, but the flip side is the coolant in the engine is hotter because it can’t leave. The radiator will actually shed more heat from the overall system if the coolant inside is hotter because the temperature difference between ambient and coolant is higher, so keeping the coolant flowing as much as possible is important.
 
Rockwood said:
The thermostat isn’t there to slow water flow, it’s there to act as a diverter between the too cold recirculating path, or the too hot radiator path. If you just remove the thermostat, coolant can flow through both paths and you end up recycling a significant amount of hot coolant fresh from the engine right back into the engine.

The holes are drilled in the freeze plug to aid with burping since that path will never open.

Slowing coolant flow is not good for cooling. If it was, thermostats wouldn’t work. The slower the coolant flow, the cooler the water in the radiator, yes, but the flip side is the coolant in the engine is hotter because it can’t leave. The radiator will actually shed more heat from the overall system if the coolant inside is hotter because the temperature difference between ambient and coolant is higher, so keeping the coolant flowing as much as possible is important.
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I'm not sure if I agree with the slower flow being not good...I'm no expert of course - but water will cool more in the radiator if it sits in there longer...but to your point the water will then heat more if sitting in the engine longer. I'm surprised I couldn't find a YouTube video where someone tested the differences - with, or without a thermostat...a google search results in mixed opinions on the topic - but leans more towards no thermostat causes excessive flow resulting in over temps. Even AI agrees with me - :)


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Thermostat is a process control tool. You want your engine at a single operating temp under all conditions. The thermostat adjusts water flow to keep the engine at a set temperature.

Idle, low energy into engine: Thermostat closes to let the engine maintain heat
WFO: max energy input. Thermostat opens to pump heat out to radiator.

With no thermostat:
-If your cooling system is too small you can't get enough heat out and you over heat. Over heating is not the thermostat, or your flow... your system isn't big enough to dissipate the heat.
-If you cooling system is too large, your engine will get cold under low load situations. Might be fine under power but at idle the temps will drop. (Never seen this by the way... your system would need to be huge!)

With the thermostat out, your fans and ECU control the operating temp. If they can't ... your radiator is too small

Note: Higher fluid speed improves heat transfer....
 
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wesinls said:
I'm not sure if I agree with the slower flow being not good...I'm no expert of course - but water will cool more in the radiator if it sits in there longer...but to your point the water will then heat more if sitting in the engine longer. I'm surprised I couldn't find a YouTube video where someone tested the differences - with, or without a thermostat...a google search results in mixed opinions on the topic - but leans more towards no thermostat causes excessive flow resulting in over temps. Even AI agrees with me - :)


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It makes sense if you think about it. When you slow coolant flow to get lower radiator output temps, you’re holding the coolant in the engine longer to accomplish this. Since the engine continues to make heat, it’s transferring it to the coolant in the engine longer. When that coolant finally exits, it then languishes in the radiator while the coolant in the engine gets fried. This results in increased coolant outlet temperatures, which is what we all care about.

Why? Because the average temperature of a cooling system, given the same rejection (airflow and radiator) and load, will remain roughly the same (hotter water in the radiator is actually more efficient, but we can leave that out for now) at most reasonable flow rates. If your coolant in the radiator is lower temp, that means the coolant in the engine has to be higher to compensate and bring the average in line.

So, yes, slowing the coolant means it will enter the engine cooler, but since it spent more time in that hell hole, it’s hotter when it leaves.

Having significant temperature differences from one side of an engine to another isn’t good for longevity either, especially if it’s an extreme case where the cylinders at the radiator outlet never reach operating temp.

Computer shit, but here’s a test:


You CAN have too much water pump flow, which causes cavitation and all sorts of other issues, but that’s a pump RPM vs inlet design/diameter thing.
 
I too have heard the theory of slowing down the water. Additionally, I've heard that it helps slow down the flow leaving the engine which helps pressurize it, a bit, which reduces it wanting to form steam. Alls I know, it that a lot of people say that it is better to run a gutted T-stat than nothing at all....that is fairly close to being what that $55 radiator bypass is.
 
I run the Redline block off that was mentioned. Solved all my issues, works great.
 
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