thermostat question??????????

[irfgt]

Most all the comments made here are correct about thermostat operation and I would like to add some other insights. The radiator fans on C-4s and C-5s don't come on while sitting still until over 230 degrees. There is a reason for this. The Radiator fans take a bunch of power to operate. Just listen to the alternator whine when the fans come on! This also takes power away from the engine to turn the alternator with those high amp fans running. The object is to keep the fans OFF until absolutely necessary! This saves fuel, adds power, and saves the alternator and the radiator fan motors. These Engineers are not as dumb as some might think. I had a person call last week wanting to turn the fans on quicker to cool his engine down as he said "It just runs too hot and it just won't last running that hot" I asked how many miles he had on the car and he said "Over 200,000 miles".
Keep another thing in mind, when the air conditioner is on, it also turns the radiator fans on and a properly operating Corvette with electric radiator fans will actually run cooler in traffic than with the air off.

[navy2kcoupe]

Originally Posted by FRC Tom

I perfer the 180 stat and like to keep the ect at 185.
The C5 fan controls can be set to come on at any temp but the C6 fans work on percentage sstarting at 192 degrees.

C5 fans



C6 fans

Tom, what are you using on the C5 that lets you go in and check/adjust fan speed?
Andy Anderson

[navy2kcoupe]

Originally Posted by ADulay

No need to be concerned. It just depends on what type of driving you're doing. Easy city driving with stretches of medium speeds will most probably keep the temps spot on at 195-200. That's pretty standard for pretty much most automotive design these days.

Run it up to 110 mph for 20 minutes on the interstate and it most probably will increase a bit.

I'm sure that somewhere in the innards of General Motors are the heating/cooling calulations that say that at "X mph" the rate of cooling at X temp and X humidity results in X amount of BTU's being removed from the coolant.

Think about what the status of the thermostat is in a 180 degree rig.

At about 180 degrees, it opens up and allows the coolant flow into the radiator. So far so good. The radiator can disperse heat and return "cooler" liquid back to the system. If the cooling system has the capacity to actually bring the coolant temp back down below 180, the thermostat may well close again!! (But not for long)

Now, really start pushing the car and with the engine developing a major session of heat, the 180 thermostat is still open, the coolant is still flowing to the radiator and heat is being dissapated, but the rate of cooling is less than the amount of heat being generated so the temp starts to increase. The 180 (or 160, 195) thermostat is still open, it's just that the COOLING SYSTEM is now being tasked to remove more BTU's than it is capable of, which results in the coolant temp increasing.

The reason it doesn't keep increasing (hopefully) is because the entire system can handle something up to about 254 (234?) degrees before bad things can start to happen.

When I would run the 69 Corvette at 90 mph, the temp would routinely run up to something like 212-215 and sit there all day long. When I came back to 70 mph, the temps settled back down to "normal". This all with a 180 TS. If I had to come to a quick stop from 100 mph and sit and idle, the temps would just keep climbing. Why? Too much residual heat and not enough capacity while idling to remove that heat. My wife's Mercedes is notorious for THAT little trick. Hence the electric fans start coming on!! Good plan, eh?

The bottom line?

As long as the temps return to "normal" under "normal" driving conditions, it's working just fine.

You can get temps from 200-210 easily just sitting in traffic for 10 minutes down here in Florida. Start moving, cooling becomes more efficient, temps go back down. Standard stuff.

AD

It's my understanding that the coolant gets cooled in the radiator, and heated in the engine. The radiator has NO extra help cooling the coolant, but the engine is capable of producing more heat the faster it is run.
As the RPM's increase, so does the water pump speed, and this in turn moves more coolant thru the radiator in a given amount of time. The coolant needs to be IN the radiator in order to be cooled, but at higher RPM's (and water pump speed) it's actually in the radiator LESS time than it would be at idle or lower RPM's. Granted, there is more air flowing thru the radiator at higher speeds, but it isn't enough to offset the increase in heat that the engine is puting out.
As for the thermostat, the older style ones have a wax pellet inside designed to melt at a specific temperature. It doesn't melt all at once, but over a temperature range. The number on the thermostat, 160, 180, 195, is just an indication of where the thermostat will be completely open.
It seems to me that the differences in temps that we are seeing are more indicative of the different (in each car) cooling systems' effectivity. Since no two cooling systems are EXACTLY alike, the temps from them will not be alike either.
I might be all wet on this but MY cooling system (a couple of frosty ones) always gets MY temps down!
Andy

[Rich Z]

Originally Posted by navy2kcoupe

It's my understanding that the coolant gets cooled in the radiator, and heated in the engine. The radiator has NO extra help cooling the coolant, but the engine is capable of producing more heat the faster it is run.
As the RPM's increase, so does the water pump speed, and this in turn moves more coolant thru the radiator in a given amount of time. The coolant needs to be IN the radiator in order to be cooled, but at higher RPM's (and water pump speed) it's actually in the radiator LESS time than it would be at idle or lower RPM's. Granted, there is more air flowing thru the radiator at higher speeds, but it isn't enough to offset the increase in heat that the engine is puting out.
As for the thermostat, the older style ones have a wax pellet inside designed to melt at a specific temperature. It doesn't melt all at once, but over a temperature range. The number on the thermostat, 160, 180, 195, is just an indication of where the thermostat will be completely open.
It seems to me that the differences in temps that we are seeing are more indicative of the different (in each car) cooling systems' effectivity. Since no two cooling systems are EXACTLY alike, the temps from them will not be alike either.
I might be all wet on this but MY cooling system (a couple of frosty ones) always gets MY temps down!
Andy

Yeah, sounds right to me. As I said before, the best way to cool down the engine more will be to get a larger radiator. That way the coolant can be cooled more efficiently before being pumped through the hot engine again.

And yes, apparently the problem with removing the thermostat completely is that although you ARE removing a restriction to flow of the coolant, that restriction may be necessary for the design. The coolant HAS to stay within the coils of the radiator long enough to drop their heat load before going back into the engine. If this doesn't happen, and in extreme conditions, the coolant may just overheat even though it seems intuitively that it would do the opposite.

Some people also claim that "Water Wetter" helps to cool things down as well. I've got a couple of bottles of it sitting in the work room, but didn't see any sense to putting it in during the winter months.

[Rich Z]

Originally Posted by navy2kcoupe

Tom, what are you using on the C5 that lets you go in and check/adjust fan speed?
Andy Anderson

Not trying to butt in on Tom's answer, but it is my understanding that he uses HPTuners for his tuning. That is the program shown in those screen shots.

[ADulay]

Anyone with a link to that "HPTuners" thingie??

Looks like it could be a very interesting piece of gear to own.

AD

[Rich Z]

Originally Posted by ADulay

Anyone with a link to that "HPTuners" thingie??

Looks like it could be a very interesting piece of gear to own.

AD

http://www.hptuners.com/

Yeah, I have it myself, but am a raw, wet behind the ears newbie with it. Simply because since I had the master (FRC Tom) tune my C5Z, I really don't have much reason to play around with it...... But beforehand, I used it to monitor parameters while driving and it is an EXCELLENT tool for just data logging.

To give you an idea of how helpful this tool is, the following image is from a data logging session I did that showed that I had a problem with the IAT (incoming air temperature) sensor that was throwing the tune out of whack:



See that white line in the second section from the top? That was being caused by a bad wire on the sensor. It would have been pretty darn tough to trace this problem without a tool like this.

Secondly, this is a chart of the data logging done after I had the STS twin turbos installed. It shows all kinds of interesting details indicating when the turbos are actually kicking in.



But like I said, I haven't even begun to scratch the surface of this program!

[thebeepster]

Rich, don't bother trying the water wetter unless you drain all or most of the coolant and replace it w/ distilled water...otherwise it won't work

[Rich Z]

Originally Posted by thebeepster

Rich, don't bother trying the water wetter unless you drain all or most of the coolant and replace it w/ distilled water...otherwise it won't work

Well that SUCKS....... Doesn't seem rightly worthwhile unless the difference is dramatic........