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-   -   Ideal temperture thermostat for SBC? (http://www.hotrodders.com/forum/ideal-temperture-thermostat-sbc-223626.html)

Curmudgeon29 09-02-2012 10:33 AM

Ideal temperture thermostat for SBC?
 
1 Attachment(s)
My new truck has a SBC 383, cam, Edelbrock carb.
No emissions, no sensors.
I would like some input on the correct temp thermostat to run.
I have a flex fan and an aluminum radiator and does not seem to
have a problem with overheating. Keep in mind that I live in Phoenix, Arizona.
I guess I'm trying to decide to use a 180 or 195 degree and what brand?
I am replacing a Motorad Failsafe that fails trying to get the air (steam)
out of the system.
Thanks! Joe

RWENUTS 09-02-2012 11:04 AM

Replace the flex fan. They kill. I had one louvre the hood on my truck.
Use a 180 degree. Drill a 1/16" hole in the thermo beside the spring to release the air.

327NUT 09-02-2012 02:06 PM

X2 on the flex fan, very dangerous.......also you can buy the Stewart 180 stat with the hole already drilled if thats the what you decide on doing....just costs you more with them doing the drilling.....$13

Curmudgeon29 09-02-2012 03:16 PM

Ideal Temp thermostat
 
1 Attachment(s)
I will take a look at the robertshaw stat.
I do think the problem getting the air out of the system is the fill neck in the radiator
is off to one side and probably 3" lower than the crown of the tank as it fits the shape of the deuce grill shell.

against all odds 09-02-2012 05:09 PM

This is a good question as i'm wondering myself; My engine generally does not get hotter than 180. It stays around 170 most of the time regardless of load or outside temp.

i'm pretty sure i put in a 195 thermostat which is what was called for in the service manual.

As far as temperature, i would like to experiment at 200 or even 210 because i feel that more temperature equals more mpg. But i guess the real again is what is the the best temperature for a SBC. Or what temp was the SBC designed to run?

Curmudgeon29 09-02-2012 07:31 PM

Ideal thermo
 
1 Attachment(s)
Thanks guys for your input!

I've decided to go with a 180 degree Stant Superstat #45358

and I will probably drill a 3/16" hole in the flange.

Joe

curtis73 09-02-2012 09:17 PM

Thermostat temp has nothing to do with overheating, so you need to choose one based on your driving.

Cooler stats can make a few extra hp, but it can come at the expense of shorter oil life, fuel wash in the cylinders, etc.

I personally have a 195 in every SBC I have. I would much rather give up a couple ponies for the health of the engine. Remember that overheating is when the coolant boils causing major hot-spots. As long as you aren't boiling (or making enough pressure to blow hoses and radiators), hotter is often better.

A little thing to consider: Coolant doesn't really care what temperature it is. As long as the "heat in" (combustion heat) is less than "heat out" (radiator), the temperature wont rise. That condition can happen if you're using no radiator cap and pure water (as long as the temp at the cylinder head doesn't rise above 212), or a 15 lb cap with 50/50 and 265 degrees.... or pure glycol and 300 degrees. As long as the cooling system is able to remove more heat than the engine makes, (and no boiling has occurred) you won't have any issues.

Drivers like the engine to run cool. Engines prefer to be hot. Thermostat temperature has nothing to do with cooling - only the temperature at which the cooling starts. As long as the cooling system is able to remove more heat than the engine makes, the temperature is irrelevant to cooling. Pick the stat that suits your driving.

Race? No stat. Hi-po street? 160 might give you a few more ponies at the expense of oil health. All street? 195 will give up a few hp but may improve the overall health and lifespan of the engine.

Curmudgeon29 09-02-2012 10:19 PM

On the Stant websight they stated that the thermo would fully open
15 to 20 degrees above temp on thermostat (195 to 200) that,s
partly why I chose a 180. Besides, this is Phoenix, it's almost always hot!
Thanks guys! Joe

75gmck25 09-03-2012 01:11 PM

I live in San Antonio, where it only varies from summer hot to winter cool. It is never cold. I've run both 180 and 195 high flow thermostats, and in summer heat there is very little difference in max temps. The max temp is determined by the radiator/fan setup, not the thermostat.

I have a stock shroud and thermostatic fan clutch, and in extremely hot weather (100-110 degrees) while idling it may hit 215-220. However, this is within the normal range with a 16 lb radiator cap. In winter weather it will never go above about 195, which is the rating on the thermostat.

Bruce

curtis73 09-03-2012 07:09 PM

Quote:

Originally Posted by 75gmck25 (Post 1588082)
The max temp is determined by the radiator/fan setup, not the thermostat.

Disagree... If you have adequate cooling, the max temp is determined by the stat. I never design a cooling system where the heat exchange dictates top temp. It will always bite you in the *** on those few really hot days. Engineer a cooling system that will be overkill and then your thermostat will never be an issue.

75gmck25 09-04-2012 04:31 AM

curtis73 - Designing a cooling system that is adequate for all conditions is the goal, but in central Texas we deal with more heat than you do farther north. Ambient temps will routinely hit 105 or more (e.g., it was 102 yesterday), and temperature while idling in traffic on black pavement sometimes shows 115-120+ degrees.

Although not impossible, it would be a real challenge to design a cooling system with a 180 degree thermostat that kept the car at 180-190 degrees max when outside temps are at 105-110 degrees. My point was that under extreme heat conditions a good radiator, water pump, high flow thermostat, fan and shroud are more significant than the temperature rating on the thermostat. I'm not very comfortable seeing the engine hit 215 degrees because I don't have much safety margin above that temp, but it does not hurt the engine.

Bruce

DoubleVision 09-04-2012 01:22 PM

I always use a 180 degree. I also always drill one 3/16 hole in the outer parimeter to act as a air bleed hole. Something I've learned over the years, and it was a hard lesson is never buy 1 thermostat. Buy three.
I've bought the ones that cost $10 and they didn't work correctly, and I've bought the ones that cost $2 and they didn't work correctly. Why I buy three is because usually one out of the three is good. I learned to check them in boiling water to check the correct opening point and then let them cool to check the closing point. If one is good out of the three I take the other two back to the store. Years ago in my Cutlass around town, it would run a solid 190. If I got on the interstate, it would creep up to 210, 220, and sometimes up to 230 if it was real hot outside and I didn't like that. I couldn't figure out why it did that. Finally I tested the Stat which was not very old and it opened at the correct temp, but it wouldn't close until the water had almost gotten completely cooled. So I went to the parts store and bought three new ones and tested each one. The first wouldn't open until it got to around 240. Bad. The next opened and closed as it should so I put it aside. The last one would open but wouldn't close so I took the two bad ones back and told the guy behind the counter they were bum. Odds he sent them back? Doubtful, Odds he put them back on the shelf for the next sucker? Real good. I agree with the rest of the guys as well, throw the flex fan away.

spinn 09-04-2012 01:32 PM

Drill 2, 3/16" holes on opposite flange sides. Ever open a can and try to pour. 2 holes will let cavitation vent before it reaches open temp.

What I see is a replacement new t stat and the 10 year old cap not holding pressure.

DoubleVision 09-04-2012 08:10 PM

One hole always worked for me, as since the T stat doesn't seal around the plunger it acts as the secondary hole. If I did drill 2 holes at idle it wouldn't get hot enough to open, as the coolant flow through the 2 holes would circulate just enough coolant to keep it from getting hot enough to open.

curtis73 09-05-2012 12:03 AM

Quote:

Originally Posted by 75gmck25 (Post 1588247)
curtis73 - Designing a cooling system that is adequate for all conditions is the goal, but in central Texas we deal with more heat than you do farther north. Ambient temps will routinely hit 105 or more (e.g., it was 102 yesterday), and temperature while idling in traffic on black pavement sometimes shows 115-120+ degrees.

Although not impossible, it would be a real challenge to design a cooling system with a 180 degree thermostat that kept the car at 180-190 degrees max when outside temps are at 105-110 degrees. My point was that under extreme heat conditions a good radiator, water pump, high flow thermostat, fan and shroud are more significant than the temperature rating on the thermostat. I'm not very comfortable seeing the engine hit 215 degrees because I don't have much safety margin above that temp, but it does not hurt the engine.

Bruce

Agreed. I used to work for Austin Speed Shop so I'm also familiar with the stupidly hot weather.... in fact its one of the reasons I moved back north :)

Now I'm cursing the rust. :rolleyes:


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