When I'm cruising in my car, the temp hovers around the first hash mark before 200, I assume that that's around 160, since that is the thermostat I run...maybe that's causing some problems I've noticed lately. In traffic, it will rise up to about 210, it will probably go higher, but I generally get going before that...
I'm running a 6 blade flex fan with the standard short copper radiator. If 180 is ideal, I guess I get to do a thermostat this week.

trw

 

That's interesting... Must be why the stats I see always stop at about 160. Too cold and you can't get the fuel to ignite as easily due to poor atomization/vaporization. I wonder if 160 is the breakover point.

 

Will someone please explain how a thermostat controls engine temperature when it is designed to hold coolant back allowing engine to warm up faster ? Once it is open,the thermostat DOES NOT CONTROL ENGINE OPERATING TEMPERATURES. The fact is,in most cases(while vehicle is moving) the thermostat is open.

 

True, unless the radiator is capable of cooling BELOW the stat set-point...

 

My understanding is that power developed by an engine is proportional to the difference between the intake air temperature (the temperature of the air/fuel mixture in the cylinder before spark plug ignition) and the temperature of the cylinder gas after ignition/burning takes place. From this purely theoretical perspective, the temperature of the engine is immaterial. What does make the engine temperature important from a practical standpoint is that the hotter the engine, particularly the cylinder heads, there's more opportunity for engine heat to elevate the temperature of the incoming air/fuel and thereby cause a loss of power.

Of course another limitation on engine heat is that you don't want the engine so hot that oil breaks down and metal becomes weakened. I think aluminum begins to lose mechanical strength at around 600 degrees F. (Even if the aluminum head has a thermostat temperature of say 200 degrees, temperatures of inside an aluminum head where the exhaust valve seats will probably get up to the many hundreds of degrees F.)

I'd prefer that my engine doesn't get above, say, 200 degrees F. The heat damages wire insulation, gaskets, and also the fiberglass itself.

 

Good question. Is there a dyno guru on this site?

Another point about running at a lower temp is longevity. The least amount of expansion and contraction in the engine has got to help reduce long term wear. I don't know if it's true, but I have heard that, all things being equal, an engine will last longer in a warmer climate. That would jive with the expansion contraction theory.

 

It all depends on how your tuned. On my big inch blower motor every 5 degrees hotter you need to go up on jet sizes by one.180 is totally different than 220 but you can make the same power or even more at a little hotter temp.200-210 is where I run it.On my car it easily can get to 230 and I got the best fans,pump radiator etc, If you are making serious power which translates to a lot of heat it is very hard to keep it cool ,I would like to stay at 200 but I havent found how yet?

 

The thermostat holds the coolant in the radiator until the air flowing thru it has cooled it to the correct temp; then it allows coolant to flow until it becomes too hot and then holds it again until the air can cool it.
Bernie

 

I don't start to worry until my temps reach over 220. Temp's may get up to 200 in heavy stop-and-go traffic but quickly settle down around 185-190 as soon as I get underway. I found that temps became much more stable once I replaced the dried out radiator shroud seals with a fresh set from Dr Rebuild. Oh, and installing a thermostat helped too. PO had removed it at some point...

 

What about my car? It runs at 200 in city driving, stop and go traffic. Usually doesnt matter what the outside temp is. When I get it on the expressway it will go up to about 210. Why does mine seem to be the opposite of other peoples cars? Also, I have a new radiator and fan clutch.

 

From Waterwetters,er,guru......

"Dynomometer tests performed by Malcolm Garrett Racing Engines showed significant improvements in coolant temperatures using WaterWetter. These tests were performed with a Chevrolet 350 V-8 with a cast iron block and aluminum cylinder heads. The thermostat temperature was 160°F. The engine operated at 7200 rpm for three hours and the stabilized cooling system temperature was recorded and tabulated below:

Cooling System FluidStabilized Temperature50% Glycol/ 50% Water228°F50/50 with WaterWetter220°FWater220°FWater with WaterWetter202°F

"These numbers are similar to the temperatures recorded in track use and heavy-duty street use."

Three hours at 7000 RPM....

 

New Fan Clutch ? If I were you I'd check the calibration of your fan clutch,as new ones are for later Vettes and are designed to allow higher operating temperatures(not the same as original GM)...Just learned this today...go to Dewitts-downloads..interesting...

 

As a quick side note...there are actually TWO different "styles" of fan clutches. One uses a bi-metallic strip on the face of the clutch and the speed is regulated by the air heat that passes over it after being drawn through the radiator. The other style doesn't use a strip at all. It uses RPM to adjust when it "freewheels".

Another note...in my experience stock blocks that have had over bores of .060 or higher ran considerably hotter than those with less overbore than that. .030 is about the limit I would do with any stock blocks.

Dep

 

And the 70's GM ones were designed to fully engage at approx 190 degrees,and the ones in the 80's at 210-220.That tid bit should help those wondering about "why is mine running at"......

 

Interesting info on fans:

What IH called the "Modulated Fan Assembly" is in fact a fancy name for a radiator fan with a thermostatically controlled viscose fan clutch.

Yes the modulated radiator fan can be turned by hand with some felt drag, but it shouldn't freewheel. If such a fan spins easily by hand, the viscose clutch is probably worn out. The clutch will always let the fan "slip" to some degree in relation to the engine speed. The idea for operation is that the clutch allows the fan to slip more when the air temperature coming through the radiator is not very hot, verses slipping a lot less when the temperature is higher and maximum cooling is needed. The clutch also allows greater slippage at higher engine speeds simply due to the drag of the fan, so less horsepower is lost in turning the fan when you don't need it (in most cases). So you get a quieter engine compartment and better fuel economy at higher engine speeds and less "roar"... but you still get proper cooling needed at lower engine rpms.

As someone stated on the IHC Digest some time ago... a fixed blade fan is adequate, a flex blade fan (in most cases) is better yet, a thermostatically controlled viscose fan clutch is a better idea than that, and the best idea is a thermostatically controlled electric fan. Each design has its benefits and each has its drawbacks. The electric fan could become inoperative if submerged in water or mud. A fixed blade fan is simple and fool proof, but it uses more horsepower to turn even when its not really needed.

 

You mean "most cases in California". For the rest of the world that also drive cars, when it's cold, the thermostat keeps the engine at operating temperature so it can run efficiently.



My philosophy is to run the engine as hot as possible without detonation while keeping the intake air charge as cold as possible.

Here's another interesting link re:temps
http://www.federalmogul.com/cda/cont...9_7519,00.html

 

But don't forget Arizona,which sees higher ambient temps than we do...smog requirements aside....Look at Phoenix...101 today..108 tommorow
good link btw...

 

I refer all readers to a very informative article on Corvette fan clutches by Dan Tillapaugh in the Spring 2005 issue of NCRS's "The Corvette Restorer." Very useful reading.

 

Here's the problem, yes the motor will make more power at 160 degrees but it will also wear faster. Not a problem for a dragstrip motor that gets torn down frquently, not so good for a Vette owner who wants his motor to last a long time. I like my temp between 180 -190 deg. LD

 

Here's the problem, yes the motor will make more power at 160 degrees but it will also wear faster. Not a problem for a dragstrip motor that gets torn down frquently, not so good for a Vette owner who wants his motor to last a long time. I like my temp between 180 -190 deg.