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Old 06-14-2003, 08:31 PM   #1
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Default Colder t-stat myths

Here'* a few things I didn't know about t-stats, I took snips from a web page I'll post later


A colder thermostat will NOT cause your car to run open loop all the time. The engine goes closed loop based on time, not temperature. A colder 'stat may not make the car run much cooler unless you calibrate the electric fans to turn on sooner. If you have enough air flow (when cruising down the highway) then the engine will run cooler. Around town, in city traffic, it probably won't run much cooler without the fans turning on sooner.

Damn I thought it did...On the bright side

On a supercharged engine, the spark calibration is rarely, if ever, at Maximum Brake Torque spark, or MBT. This is because of higher air temp going into the engine along with higher cylinder pressures. Both of these make the engine more likely to knock. With this type of application, a colder thermostat will allow the engine to run more spark, thus gaining power. It may only be 2-3 degrees, but on a blown engine, that can be as much as 10 ft-lbs.

Niiice...But for you N/A guys:

The hotter the engine runs, the more efficient it is. This assumes that you are not knock constrained like on a blown engine. So, if your engine is naturally aspirated, and it is not knock constrained, then you want to keep the hotter thermostat. If you live in a warm climate, like Texas, then you can probably benefit from a colder thermostat, and thus more spark. The hot air in these type of climates tend to make an engine more likely to knock so a colder 'stat helps in these special situations.


Interesting huh
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Old 06-14-2003, 09:53 PM   #2
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Yes, very interesting.
Thanks for the info Jay.
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Old 06-14-2003, 10:49 PM   #3
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I'm going to assume here that the cooling system also cools the transmission. Don (jrs3800) has told me in the past that the number 1 killer of 87-91 trannys is the heat. Hence my decision to go with the 180....

Does this sound right?...I don't mean to misuse what Don has said, but it was good enough reason for me to go to the 180
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Old 06-14-2003, 11:22 PM   #4
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The 92 EGRless though would be the exception to that Rule though still......
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Old 06-15-2003, 12:06 AM   #5
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Default Re: Colder t-stat myths

Quote:
Originally Posted by DrJay
A colder thermostat will NOT cause your car to run open loop all the time. The engine goes closed loop based on time, not temperature. A colder 'stat may not make the car run much cooler unless you calibrate the electric fans to turn on sooner. If you have enough air flow (when cruising down the highway) then the engine will run cooler. Around town, in city traffic, it probably won't run much cooler without the fans turning on sooner.

Damn I thought it did...
I have noticed that exact thing on mine. I get cooler temps and better poweron the hwy but when it hetas up at idle and in traffic I can really feel and see the effects of rising engine temps.

good info...
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Old 06-15-2003, 12:27 AM   #6
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Dr. Jay, I'd be really interested in reading the source material. It seems there are 2 or more sides to every story. No matter what engine modification you do, there is always someone out there getting paid (or not) to tell you if its right or wrong.

Just of out curiousity of course
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Old 06-15-2003, 01:20 AM   #7
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cant you turn on both fans when you put the Climate Control on AUTO??? I thought someone on here said it does that...
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Old 06-15-2003, 01:35 AM   #8
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Well that settles it for me...definately the first mod I'll be doing. Thanks for the clarification.
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Old 06-15-2003, 01:45 AM   #9
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Oh damn sorry I thought I added the web page in there, I said I would but forgot. http://www.fordchip.com/faq/faq.htm#14 Granted its ford but it should be all the same. I know the open loop is on a timer but all this time I thought only the raised RPM'* were on that timer and that the benefits (extra fuel and timing) was until it warmed up to a certain temp. I was half right though, it does work on a supercharged car.

89BonnieSE89 : No your radiator coolant and transmission are separate units. You'll have to get a trans cooler in order to lower your transmission temperature. He'* right though it is the number 1 killer of 4T60-E transmissions. You can learn more here: http://www.pontiacserver.com/ratios.html


Macho_Mike21: Yes you can turn your fans on by turning your heater on but I noticed with mine its a hit and miss. It won't ALWAYS come on when you turn it on, just what I've noticed. The best thing to do is to get an adjustable thermoswitch for your fans or hook them directly to a switch in the dash, which is what I did. Its a lot easier, takes less power from the engine, and is just more comfortable to do than running your a/c when you don't want to.
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Old 06-15-2003, 02:00 AM   #10
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If the transmission and radiator are seperate how come I have transmission lines running into my radiator?
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