But Nick... Ain't it a dry heat?Spout all the theoretical rhetoric from the internet and others, but in the real world here it is insane to run a t'stat in the long, hot summer months especially like today when it was 110 deg. in my garage?
Cooling results without Thermostat vs. with
- Thread starter turbo nasty
- Start date
Welcome!
By registering with us, you'll be able to discuss, share and private message with other members of our community.
The problem with no T stat is the DP or lack there of developed in the system, you remove the DP on the radiator return that allows full circulation thru the block and the radiator. You are recircing hot water thru the block. The system does care how fast you are moving the coolant thru the radiator, actually increased velocity will help heat transfer by improving the boundary layer coefficient, hence the need for a restriction if you don't run a T stat. Since the system is dynamic the results vary with engine speed.
- Joined
- Nov 4, 2005
- Messages
- 4,329
I have alot of repect for Nick and Earl, but ive had better success with a stat.
You will have better results with a thermostat provided your radiator can reject all the heat from the engines water jacket.
It's better to have the engine up to temp than it is to run cold. Bench racing with a temp gauge won't win any real races.
It's better to have the engine up to temp than it is to run cold. Bench racing with a temp gauge won't win any real races.
- Joined
- Nov 4, 2005
- Messages
- 4,329
Yep, and I like a heater and a warm motor before a pass.
turbo nasty
Turbo Dojo / MNTR
- Joined
- Jul 19, 2001
- Messages
- 9,478
And don't forget the system runs cooler to 
A flow restriction is needed in the system for both heat absorption and rejection. The restriction slows the coolant for not only the radiator but also for the block and heads to absorb.
For those that are unsure whats what and have some time, just do a search on the matter you will see for yourself that the restriction wins hands down.
A flow restriction is needed in the system for both heat absorption and rejection. The restriction slows the coolant for not only the radiator but also for the block and heads to absorb.
For those that are unsure whats what and have some time, just do a search on the matter you will see for yourself that the restriction wins hands down.
BEATAV8
The Engine Whisperer
- Joined
- Feb 14, 2002
- Messages
- 5,631
Jerryl
Tall Unvaccinated Chinese Guy
- Joined
- Dec 14, 2004
- Messages
- 9,644
This is a similar to the power plate discussions in the sense that there are 2 totally opposing points of view.
Jerryl
Tall Unvaccinated Chinese Guy
- Joined
- Dec 14, 2004
- Messages
- 9,644
Agree. The correct answer usually is "it depends" lol.
dr_frankenstein
Mad Scientist
- Joined
- Mar 17, 2008
- Messages
- 5,126
so you agree with his statements before the myths "Too Always Run a Thermostat?"
In the aforementioned car without the thermostat it would idle and tote around town fine but at high sustained RPM it would climb and climb. That I believe was from the lowered coolant pressure and hence lower boiling point.
BEATAV8
The Engine Whisperer
- Joined
- Feb 14, 2002
- Messages
- 5,631
Yes I run one, and Earl says he does too.
The myth that needs to be dispelled is the whole "coolant moving too fast through the radiator" idea. If an engine overheats due to lack of a thermostat, then the overheating is caused by localized boiling in the cylinder head and insufficient water jacket pressure causing stagnation somewhere in the coolant passages. The thermostat provides restriction and pressure head that allows proper coolant flow distribution inside the engine.
ref FlePro tech tips regarding coolant circulation:
http://www.frontiernet.net/~tmeyer/fpro.html
turbo nasty
Turbo Dojo / MNTR
- Joined
- Jul 19, 2001
- Messages
- 9,478
Slow the water down for absorbing in the engine as nd rejection in the radiator.....
BEATAV8
The Engine Whisperer
- Joined
- Feb 14, 2002
- Messages
- 5,631
that's the myth.
turbo nasty
Turbo Dojo / MNTR
- Joined
- Jul 19, 2001
- Messages
- 9,478
Good luck with that
I already know I'm going to regret posting this, but I can't help myself...
First, as I mentioned in another thread, the title of my Masters thesis was "Investigating the Transient Response of an Automotive Radiator Using Discretization Techniques". No, I haven't built as many engines, run a 9-second 1/4-mile, or blown-up as many cars as others on here, but engine cooling systems are something I know a wee-bit about.
Taken in it's simplest form, the heat transfer between a piece of metal and the coolant flowing past it is this:
Q = h * A * deltaT
"Q" is the amount of heat transfer
"h" is the "heat transfer coefficient" (more later)
"A" is the surface area of the piece of metal
"deltaT" is the temperature difference between the piece of metal and the coolant
Without getting overly scientific (trust me, many pages in my thesis are devoted to this topic), the value of "h" INCREASES as the coolant flow rate increases for both the radiator and engine. Obviously, the value of "A" doesn't change - the surface area of the radiator and engine aren't changing.
So, when you remove your thermostat, what is happening? Assuming your water pump is actually pumping more coolant...
1. The value for "h" inside the engine will increase.
2. The value for "h" inside the radiator will also increase.
So, the amount of heat being rejected from the coolant to the radiator will increase. Simultaneously, the amount of heat being added to the coolant from the engine will also increase. But, which has increased MORE? Without doing testing, I honestly don't know. If the value for "h" inside the engine increases more than the value for "h" inside the radiator, then the coolant temperature achieved will be HIGHER. If the value for "h" inside the radiator increases more than the value for "h" inside the engine, then the coolant temperature will be LOWER. This is a simplified explanation, but hopefully it makes sense. So, in our CLOSED engine cooling system, the answer about removing your thermostat is not so obvious.
But, what about Earl's point about pouring water on your arm? Difference - it's an OPEN system. Engine analogy - let's say I hooked-up a garden hose to my lower radiator hose, and let's say I let the water flow out of the upper radiator hose onto the ground. I start the engine. The more I turn on that garden hose, the more heat the water will remove from the engine ("h" in the engine goes up, just like more water will put-out the fire on your arm better than less water). Even so, the more I turn on that garden hose, the cooler the water will be when it exits the engine. It's an OPEN system.
Clear as mud? Now that we're halfway through the bong, let's finish it off with some caveats. Engineers love caveats.
A. Depending on the coolant temperature and flow rate, nucleate boiling can be occurring in some spots in the engine. "Nucleate boiling" is when you look into the pan on your stove and see little bubbles floating up. Nucleate boiling results in a very high "h" value - much higher than the case with no boiling. This can skew our results. This is more likely to happen when cooling flow rates are low and temperatures are high.
B. In extreme cases, film boiling can be occurring in some spots in the engine. "Film boiling" is when you look into the pan and see rolling pockets of steam floating up (just before you put the macaroni in). The entire bottom surface of that pan is "coated' in a layer of steam, not liquid water. Film boiling results in very low "h" value. This can also skew our results. This is more likely to happen when cooling flow rates are really low and temperatures are high.
C. If you remove your thermostat, the water pump will operate on a totally different pump curve. There will be much less head pressure acting on the pump. This could cause strange things to happen like cavitation or changes in flow patterns through the engine (more water through the bypass, for example). So, your pump might be pumping less coolant than you think.
D. The "h" value of the coolant to the radiator is much less important than the "h" value of the radiator to the air flowing through it. The "h" value of coolant to radiator is about 6 to 25 times higher than the "h" value of the radiator to the air. In the cooling game, getting large amounts of cool air through the radiator is by far the most important factor. You can turn the water pump up to 1,000,000 gallons per minute, but if the radiator can't get air flow through it, the coolant temperature will still be high.
If you've read this far, put the bong down and go to bed.
First, as I mentioned in another thread, the title of my Masters thesis was "Investigating the Transient Response of an Automotive Radiator Using Discretization Techniques". No, I haven't built as many engines, run a 9-second 1/4-mile, or blown-up as many cars as others on here, but engine cooling systems are something I know a wee-bit about.
Taken in it's simplest form, the heat transfer between a piece of metal and the coolant flowing past it is this:
Q = h * A * deltaT
"Q" is the amount of heat transfer
"h" is the "heat transfer coefficient" (more later)
"A" is the surface area of the piece of metal
"deltaT" is the temperature difference between the piece of metal and the coolant
Without getting overly scientific (trust me, many pages in my thesis are devoted to this topic), the value of "h" INCREASES as the coolant flow rate increases for both the radiator and engine. Obviously, the value of "A" doesn't change - the surface area of the radiator and engine aren't changing.
So, when you remove your thermostat, what is happening? Assuming your water pump is actually pumping more coolant...
1. The value for "h" inside the engine will increase.
2. The value for "h" inside the radiator will also increase.
So, the amount of heat being rejected from the coolant to the radiator will increase. Simultaneously, the amount of heat being added to the coolant from the engine will also increase. But, which has increased MORE? Without doing testing, I honestly don't know. If the value for "h" inside the engine increases more than the value for "h" inside the radiator, then the coolant temperature achieved will be HIGHER. If the value for "h" inside the radiator increases more than the value for "h" inside the engine, then the coolant temperature will be LOWER. This is a simplified explanation, but hopefully it makes sense. So, in our CLOSED engine cooling system, the answer about removing your thermostat is not so obvious.
But, what about Earl's point about pouring water on your arm? Difference - it's an OPEN system. Engine analogy - let's say I hooked-up a garden hose to my lower radiator hose, and let's say I let the water flow out of the upper radiator hose onto the ground. I start the engine. The more I turn on that garden hose, the more heat the water will remove from the engine ("h" in the engine goes up, just like more water will put-out the fire on your arm better than less water). Even so, the more I turn on that garden hose, the cooler the water will be when it exits the engine. It's an OPEN system.
Clear as mud? Now that we're halfway through the bong, let's finish it off with some caveats. Engineers love caveats.
A. Depending on the coolant temperature and flow rate, nucleate boiling can be occurring in some spots in the engine. "Nucleate boiling" is when you look into the pan on your stove and see little bubbles floating up. Nucleate boiling results in a very high "h" value - much higher than the case with no boiling. This can skew our results. This is more likely to happen when cooling flow rates are low and temperatures are high.
B. In extreme cases, film boiling can be occurring in some spots in the engine. "Film boiling" is when you look into the pan and see rolling pockets of steam floating up (just before you put the macaroni in). The entire bottom surface of that pan is "coated' in a layer of steam, not liquid water. Film boiling results in very low "h" value. This can also skew our results. This is more likely to happen when cooling flow rates are really low and temperatures are high.
C. If you remove your thermostat, the water pump will operate on a totally different pump curve. There will be much less head pressure acting on the pump. This could cause strange things to happen like cavitation or changes in flow patterns through the engine (more water through the bypass, for example). So, your pump might be pumping less coolant than you think.
D. The "h" value of the coolant to the radiator is much less important than the "h" value of the radiator to the air flowing through it. The "h" value of coolant to radiator is about 6 to 25 times higher than the "h" value of the radiator to the air. In the cooling game, getting large amounts of cool air through the radiator is by far the most important factor. You can turn the water pump up to 1,000,000 gallons per minute, but if the radiator can't get air flow through it, the coolant temperature will still be high.
If you've read this far, put the bong down and go to bed.
xrunner123
Member
- Joined
- Oct 2, 2002
- Messages
- 807
It could be cavitation that's going on without the head pressure of the themostat.
I had situation with my pool pump. I had a pump for my pool cleaner that pumped water to the cleaner to make it move and clean the pool. I went with an electrical cleaner so I decided to use the pump to just recirculate water in the pool. Without any head pressure the pump cavitated, made a strange noise, and the flow was low. I had to add a valve to the exit port to restrict it and provide some backpresure. The result was higher flow than when it was cavitating.
Maybe this is what's going on,
I had situation with my pool pump. I had a pump for my pool cleaner that pumped water to the cleaner to make it move and clean the pool. I went with an electrical cleaner so I decided to use the pump to just recirculate water in the pool. Without any head pressure the pump cavitated, made a strange noise, and the flow was low. I had to add a valve to the exit port to restrict it and provide some backpresure. The result was higher flow than when it was cavitating.
Maybe this is what's going on,
With a poor flowing cooling system you'll find all kinds of nucleate boiling around the exhaust port and combustion chambers in the heads water jacket. ESP on #1 and #2.
On the upside, that insulating layer of steam will keep the water cooler before it hits the temp sending unit. Not real good for cooling the iron but it will help the gauge read lower.
On the upside, that insulating layer of steam will keep the water cooler before it hits the temp sending unit. Not real good for cooling the iron but it will help the gauge read lower.
