I have a 68 427 and run a 160 thermostst with no problems. If at idle for a long time on a hot day it will go to 200.

 

I know one thing for sure the lower coolant temp = More Horsepower

 

Not true, and this subject has had the crap kicked out of on this forum so I will not elaborate.

 

A cooler intake charge will increase HP. And yet combustion "heat" is also better for HP.

Did I read somewhere that most Nascars run with coolant temps at 260*?

 

You are wrong Reggie, lower coolant temps most certainly WILL make more HP. Ask anyone who has done much dyno work, or anyone who has tried various temps at the drag strip. They will confirm that cooler temps make more hp, no matter what some "experts" on this forum may have said. As I'm sure you have noticed, people are on both sides of any discussion that comes up here. Some are right and some, not so much. Be careful what you believe. Just because something is printed on the internet, does not make it correct.

If the Nascar boys ever see 260* coolant temps, I'd expect its because they have nearly the whole front of the car taped up for aero reasons, which doesn't allow enough cooling air in to the radiator. Of course the Nascar car guys are not dummys, so they would certainly know that cooler motors make more hp. Even so, they will split hairs for aero reasons, which apparently pay higher dividends for them.

 

Are we talking coolant temps or incoming air temps. A cooler incoming air temp will definitly have a denser charge. If a cooler motor will make more HP what is the coldest it should run at. A motor a zero degrees will not run very good due to fuel atomazation not being very good. What is the optimal motor temp and incoming air temp. Too cool of an air charge coming in can also lead to freezing at the carb(s).

 

That info was developed from lab testing decades ago. In fact I have an old text book published in the '70's that says just that. The problem is, lab test motors are not typically V-8 motors. Most often they are single cylinder test motors, that don't really reflect what we have in our cars. Our motors don't always read the same books we read, so they don't know that they should have a problem.

Many, many people, myself included, have run 160* thermostats for many, many years in our Hotrods without issue. And that means no unusual wear, no corrosion, no sludge, no problem. In fact, 427 Hotrod, who many folks know from this forum, runs NO THERMOSTAT AT ALL in his 825 hp 540 Hotrod, and he says he also has had no issue at all. On top of that, he runs 9.90's at 141 at the drag strip with that setup. Kinda hard to argue with what works, huh?

And for the record, running no thermostat or a low 160* thermostat will NOT necessarily keep your oil from getting over the 212* temp needed to burn off condensation which would otherwise combine with combustion byproducts and form corrosive acids. The only time when you need high coolant temps to get the oil hot enough, is if you drive the thing rather meekly. If you only drive gently around town, cruise lightly down the highway, and simply drive it like your girlfriend, wife or mother, then yes Dark Blue is right, and you should use a higher thermostat. But then you might want to ask yourself why you have a classic Hotrod if that is how you drive. Heck, a Honda Civic can run around like that.

Most "enthusiasts" who like to enjoy the power of a V-8 muscle car, and punch it more often than not, will not have any trouble getting their oil hot enough. On the contrary, the problem is usually being worried about getting the oil TOO HOT. Dino oil starts to break down as you get into the upper 200's oil temp, which is another reason why synthetics can save your bacon, since they can withstand much higher temps than dino oil. Remember, our engine's internals are directly OIL COOLED, not water cooled. The internals are only indirectly water cooled. That being the case, if you are making hp, you are making heat, which heats up the oil. So, if you drive it like you mean it, your oil temp is good to go.

Dark Blue mentioned that GM Engineers know what they are doing, and he is right, they do. However, they were directed to design for the lowest common denominator of the general buying public. And an awful lot of these folks do not take care of their cars the way most folks on this forum do. And GM's design philosophy and smog regs apply to Corvette's just as the do to a lowly Cobalt.

If we change something on the car because we use the thing differently than the lowest common denominator buyer, it does not mean that we are saying GM Engineers were wrong, or that we know more than them. It only means that we are adjusting it to better fit our specific application.

If we run the car hard enough to get the oil plenty hot even with a 160* thermostat (or no thermostat), there is nothing wrong with that. We do it on purpose for our needs, because we know that oil temp is not an issue for us. And the advantages of running lower coolant temps (assuming a robust enough cooling system to make use of a low or no thermostat) are more hp, as well as being much less likely to ping on pump gas. Here in California, we can only get 91 octane at the pump, so every little bit helps, to keep a Hotrod slamming you back in your seat, and perfoming at its best.

 

Hotter engine components will heat up the intake charge as it makes its way through to the cylinder. And the hotter underhood temps that go along with higher engine temps, also add to the heating of the incoming air. Everything you can do to provide cool incoming air to the cylinders, the better. And in anything approaching normal conditions, you will not see an icing problem. Alaska in January, may be a different story, but I don't believe too many folks would be thinking of extremes like that. Hotrods usually get parked until reasonable weather is present.

 

Also, a hotter motor means hotter pistons. Hotter pistons expand more creating more friction reducing power and creating even more heat. Other parts also expand increasing friction.

 

I know guys running 140 degree marine thermostats in there cars to make more HP. I run a 160.

 

I am sure there is a correct operating temperture for the engine to produce power and not have the problems with excessive carbon buildup and engine wear and overheating and the engineers who designed the engine know best, so I am going to stick with the manufactures spec, even in my owners manual (which I should of consulted) it calls for a 180 degree thermostat. At this point I want reliability and I want to thank all for their inputs and thats what makes this forum invaluable.

 

I have a stong opinion of engineers so I yield to the folks who design, R&D, and study failures.

I like to read data and I've never read a thing that supports the notion that a 160 degree thermostat is recommended for street performance. Also, I've never heard of oil temp running 50 degrees hotter than coolant temp. Again, on my newer Vettes (with oil temp gauges), there's about a 20 degree delta.

I strongly suggest you get an oil temp gauge (easy to install) and see for yourself.

I will agree, a cold engine will pick up a HP or two but at what cost?..engine wear at twice the rate according to the engineers.

Also, a cold engine is picking up HP because the intake charge and underhood temps are cooler; not because the block is cooler.

Also, I know of no dyno operator that suggests making pulls on a cold engine.

Lastly, if you have supporting documentation, I'd like to read who and why a 160 would be recommneded.

Meantime, read some docs that say 160 stat (or no stat) is a bad idea (here's a half dozen links; I can obtain 100 more if needed):

From the Dewitt's Radiator web-site:

http://www.dewitts.com/download/cooling.pdf

...is this direct quote:

"Furthermore, 160º is too
cold; OEM testing has proven that the rate
of cylinder bore and piston-ring wear at
160º is double the wear rate at 180º, and
a coolant temperature of 160º won’t let the
oil in the pan get hot enough to boil off
condensed moisture and blow-by contaminants,
which then remain in suspension
and accelerate the formation of acidic and sludge. 160º thermostats were specified in
the 1930s for the old alcohol-based antifreezes,
which would boil off and evaporate
at 185º; there’s no other reason for
them."

From this site:

http://www.johnnysradiatorshop.com/files/32341017.doc

...is this quote:

"If the thermostat needs to be replaced, install one with the same temperature rating as the original. Most cars and light trucks since 1971 require thermostats with 192 or 195-degree ratings. Using a cooler thermostat (160 or 180 degree) can increase fuel and oil consumption, ring wear and emissions."


From this site:

http://www.carnut.com/ramblin/cool3.html

...is this quote:

"Years of research show use of 160 degree thermostats is way too low to be considered for performance or engine longevity. As the chart above illustrates, engine wear increased by DOUBLE at 160, than at 185 degrees."

From this book:

http://books.google.com/books?id=lZ5...esult&resnum=8

...is this quote:

"Don't let the would-be automotive expert talk you into taking out the thermostat. If there was a way for Chevy's engineers to ensure that the engine got fast warm-ups to avoid sludge and acid formations - and therefore engine wear- other than controlling the water temperature, you can be sure they would do it in a minute...The hotter the cylinder walls, the less friction loss."

From this site:

http://www.lincolnvscadillac.com/tec...tems/page2.htm

...is this quote:

"To help alleviate a hot-running engine, some think that removing the thermostat and allowing full-time, unrestricted flow of coolant that the engine will run cooler. If your engine is running hot and overheating, assuming that the rest of the cooling system is in good working order and has the capacity to keep your high-dollar, big-horse motor cool, then removing the thermostat is NEVER the correct thing to do."

And from this site:

http://auto.howstuffworks.com/cooling-system1.htm

...is this quote:

"Inside your car's engine, fuel is constantly burning. A lot of the heat from this combustion goes right out the exhaust system, but some of it soaks into the engine, heating it up. The engine runs best when its coolant is about 200 degrees Fahrenheit (93 degrees Celsius). At this temperature:

* The combustion chamber is hot enough to completely vaporize the fuel, providing better combustion and reducing emissions.

* The oil used to lubricate the engine has a lower viscosity (it is thinner), so the engine parts move more freely and the engine wastes less power moving its own components around.

* Metal parts wear less."

 

Get a Mr. Gasket 180* fail safe and be done with it! Period! PG.

 

A BB generates a lot of heat & can easily run none or a 160 which is the opening temp., not runing temp. A SB can run just a restricter or 160 in summer. Most need 180 esp. in winter.

 

What is written here is completely incorrect. If you read this somewhere, be alert that the person who wrote that does not understand evaporation. Water will spontaneously vaporize in an air atmosphere any time that the vapor pressure of the water exceeds the partial pressure of water in the surrounging atmosphere, and there is a source of heat to provide the heat of vaporization. This is why your clothes dry on a clothesline without ever getting anywhere near 212 degrees farenheit.

As someone said before, this seems to be the most commonly misunderstood topic on this forum.

 

PK, I don't even understand what you're saying. Please go back and read my post above. What is it you take issue with? That water doesn't quickly vaporize at 212? Or that water (and other combustion wastes) in the oil isn't harmful?

Clothes on a clothesline?

Try this lab test. Get a quart of oil. Pour it in a pan. Add a half quart of water. Mix thouroghly. Set your concoction outside and time how long it takes for the water to evaporate leaving you with one quart of pure oil.

Now do the same test only put the pan on a 215 degree stove and let us know how much quicker it takes to remove the liquid water.

 

Do you think that all of the oil in the engine is really at the average temperature? Oil slapping the bottoms of the pistons is well over 225 degrees and suspended water is quickly vaporized. Also, if you have a working PCV system, the engine should be under a slight negative crankcase pressure and this reduces the boiling point of water.

Take that oil/water mixture up to 210 degrees. That's not hot enough to boil the water, but see how long it remains. And don't forget to continually stir it so that the water can come to the surface and interface with the air.

I can put a pot of water on the stove at just under boiling temp and still watch it quickly evaporate.

 

I'm saying that you don't need 212 degrees to vaporize the water out of your oil. Anyone who understands the basics of the physics surrounding evaporation will tell you this, but you don't need to study physics to know that the idea that the oil has to get to 212 degrees to evaporate out the water is wrong. Hang some wet towels on a clothesline on a sunny day, come back a few hours and they are dry even though they probably never got over 100 degrees farenheit. Q.E.D.

Of course water in your oil is undesirable, but just because you didn't get your oil to 212 degrees doesn't mean that it won't evaporate out. I have evaporated literally tons of water at 86 degrees farenheit, and it could be done just as easily at 50 degrees farenheit. Yes, water will evaporate faster at 212 (assuming equal access to heat) than at 86, but what is the hurry? Also, the vapor pressure curve for water turns sharply upward at 130 degrees farenheit. Any temperature there or higher will cause fast evaporation. The only thing special about water and 212 degrees is that its vapor pressure is equal to 1 atm at 212 degrees. If you are building a drying system using a steam atmosphere for drying (as I have), this number becomes important. For all other applications of drying the water out of something, it is more or less meaningless, just another point on the curve.

Some people are saying it, but I will try to say it more plainly. Most of us are running cast iron blocks with aluminum pistons. Aluminum expands due to heat at a higher rate than iron does. When an engineer designs such an engine, he is aware of this, so he designs pistons that have a bigger gap between them and the cylinder walls when cold than warm, but not so big that he loses compression in the engine when starting cold. In other words, there will be a temperature at which the piston is too small for the engine to work well, and a different temperature where the piston will be too big (causing wear and/or binding) to work well also. There is a designed operating temperature range for the engine that keeps a healthy gap between the piston and cylinder wall, and this range has NOTHING to do with evaporating water out of the oil.

 

You show a ~20 degree delta between the oil and water on your 'newer Vettes. Put a 160 degree thermostat in one and tell us what your delta is. (I would do this with my '91 but my year doesn't provide a digital temperature readout.)

 

This is silly, as I have already said that the water will evaporate faster at the higher temperature. Besides, your test isn't valid. Try this test, prepare your mixture, keep it on the stove at 160 degrees and time how long it takes the water to evaporate. Then, repeat at 180 degrees. Let us know how it works out.

Point of note though: You will not be left with one quart of pure oil for several reasons.