Thermostat Theory

RED92LX50 · 09-05-2001, 07:52 AM

Just Curious: why do you need a thermostat/how does it work? [I understand that it will open/flow when it reaches a set temp]. I was under the impression that the cooler your engine was, the more power it made...if this is the case, why wouldn't you want the lowest possible t-stat (or none at all) so it was always circulating/cooling the coolant?

PKRWUD · 09-05-2001, 09:24 AM

The thermostat maintains a consistant temperature. An engine with no t-stat will usually run hotter. The fluid in the cooling system pulls the heat from the engine, and transfers it to the atmosphere while it passes through the cooling fins in the radiator. If there was no t-stat, the fluid wouldn't stay in the engine long enough to absorb the heat, and it wouldn't stay in the radiator long enough to release it. The biggest misconception most people have is thinking that a lower temp t-stat will always make the engine run cooler, and that's just not true. In fact, the Ford OEM 192 t-stat will keep a fuel injected 5.0 at a much more consistant temp.

The theory that a cold engine produces more power is wrong, too. What produces the power is a cold air intakle. Colder air is denser, and contains more oxygen, which is where the power comes from. Keeping the engine at a steady 195-200 degrees, and having a cold air system that draws the air from outside the engine compartment will yield the best results.

When it comes to a fuel injected engine, this becomes even more important. The ECU is what decides what your ignition timing and fuel mixture will be at, and it relies on other sensors to to make these decisions. If you try to trick the ECU, you are the only one that will suffer. The ECU stays in a rich mode called open loop until the engine reaches operating temperature, at which time it goes into closed loop, where it starts to respond to the info it receives from the other sensors, and make adjustments acordingly. If you try to trick the ECU into staying in open loop for the richer mixture, then actual damage will start to occur. A consistantly rich mixture will clog up your cats in a month or less, as well as dilute your oil, promoting accelerated wear on your bearings, rings cylinder walls, cam and valve train.

The Ford OEM t-stat is the most accurate one I'm aware of, and is also the only one I know of that has the same pintle valve in it that is used for bleeding the air from the system.

Keep in mind, if your radiator cap isn't up to par, the cooling system won't work very well anyway.

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

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RED92LX50 · 09-05-2001, 12:02 PM

Thanks so much for your reply - that is great information. You are right, I guess I was confusing "Cold Engine" with "Cold Air".

Nomad One · 09-05-2001, 01:30 PM

Now that! is what I call an explanation.

------------------

MikeWeber · 09-06-2001, 04:40 AM

Try a 180 degree Robert Shaw thermostat from Autozone for about $6. It's a very high quality piece. The computer remains in cold start mode until temps hit 170. The 12-15 degrees makes a definite difference in reducing detonation in blown and high compression engines plus makes it easier to cool at the track.

09-05-2001, 07:52 AM	#1
RED92LX50 Registered Member Join Date: Aug 1999 Location: Fairfax, VA Posts: 220	Thermostat Theory Just Curious: why do you need a thermostat/how does it work? [I understand that it will open/flow when it reaches a set temp]. I was under the impression that the cooler your engine was, the more power it made...if this is the case, why wouldn't you want the lowest possible t-stat (or none at all) so it was always circulating/cooling the coolant?

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09-05-2001, 09:24 AM	#2
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	The thermostat maintains a consistant temperature. An engine with no t-stat will usually run hotter. The fluid in the cooling system pulls the heat from the engine, and transfers it to the atmosphere while it passes through the cooling fins in the radiator. If there was no t-stat, the fluid wouldn't stay in the engine long enough to absorb the heat, and it wouldn't stay in the radiator long enough to release it. The biggest misconception most people have is thinking that a lower temp t-stat will always make the engine run cooler, and that's just not true. In fact, the Ford OEM 192 t-stat will keep a fuel injected 5.0 at a much more consistant temp. The theory that a cold engine produces more power is wrong, too. What produces the power is a cold air intakle. Colder air is denser, and contains more oxygen, which is where the power comes from. Keeping the engine at a steady 195-200 degrees, and having a cold air system that draws the air from outside the engine compartment will yield the best results. When it comes to a fuel injected engine, this becomes even more important. The ECU is what decides what your ignition timing and fuel mixture will be at, and it relies on other sensors to to make these decisions. If you try to trick the ECU, you are the only one that will suffer. The ECU stays in a rich mode called open loop until the engine reaches operating temperature, at which time it goes into closed loop, where it starts to respond to the info it receives from the other sensors, and make adjustments acordingly. If you try to trick the ECU into staying in open loop for the richer mixture, then actual damage will start to occur. A consistantly rich mixture will clog up your cats in a month or less, as well as dilute your oil, promoting accelerated wear on your bearings, rings cylinder walls, cam and valve train. The Ford OEM t-stat is the most accurate one I'm aware of, and is also the only one I know of that has the same pintle valve in it that is used for bleeding the air from the system. Keep in mind, if your radiator cap isn't up to par, the cooling system won't work very well anyway. Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

09-05-2001, 12:02 PM	#3
RED92LX50 Registered Member Join Date: Aug 1999 Location: Fairfax, VA Posts: 220	Thanks so much for your reply - that is great information. You are right, I guess I was confusing "Cold Engine" with "Cold Air".

09-05-2001, 01:30 PM	#4
Nomad One Registered Member Join Date: Dec 1998 Posts: 6	Now that! is what I call an explanation. ------------------

09-06-2001, 04:40 AM	#5
MikeWeber Registered Member Join Date: Aug 2001 Location: Louisville, KY, USA Posts: 48	Try a 180 degree Robert Shaw thermostat from Autozone for about $6. It's a very high quality piece. The computer remains in cold start mode until temps hit 170. The 12-15 degrees makes a definite difference in reducing detonation in blown and high compression engines plus makes it easier to cool at the track.