Do I really need a thermostat???

[Jim Wintz]

I have a a 351w approximately 400hp I purchased from The Engine Factory. My question is do I really need to run with a thermostat? I have heard that a lot of people do not use one at all, others say they take them out due to have over heating issues, ect.. ect... talk with the guys at the Engine Factory and they suggested running without one for a while then putting one in at a later time.

Can you guys educate me on this issue. At this time I am not planning on running one and see how it goes. If I do need to put one in what temp. do you suggest adding? Thanks for the help.

[Bob In Ct]

Over-heating is a function of radiator capacity not thermostats. Put in a 180 or so and the engine will be a lot better off. Drill a small hole in it first (at the top) in order to ensure the air gets out of the manifold.

Bob

[chrispy]

I think this thinking is in the past (not running one). Given your climate, I would run one.

Remember heat also helps produce power. Your 400hp might be with the coolant at 195 degrees. Drop the temp down to 150 degrees on a cool day and you might only be producing say 385hp. To me $5 for a thermo is cheap for 15hp (or whatever it might be).

A properly sorted out motor should have one. It has also been said that it can in fact cause more overheating, because the coolant does not stay in the radiator that long.

No expert and just my opinion.

Chris

[chrispy]

Bob,
I have heard this hole trick before. I assume that it is to prevent vapor locks.

Where exacty is the hole? In the flange thingy that holds the thermo?

Chris

[Yetiman]

I think it's odd that a reputable engine builder would suggest leaving it out.

Besides taking longer for the engine to properly warm up without one (and there is no up side to that), you could be crippling your cooling system.

The thermostat also works as a coolant flow regulator. Without one, coolant will often flow through the engine and/or radiator to fast to properly transfer heat away.

Depending on how effective your cooling system is two things can happen.

Often the coolant flows through the radiator too fast for it to remove the heat built up in it, and you will get higher coolant temperatures.

Even more of a problem, if you have a very efficient radiator & fan setup, it will take the heat pout of the coolant, and everything will look OK on the coolant temp guage, but coolant could be flowing through the motor too quickly for it to transfer heat away from the engine properly. The coolant temp guage looks nice and low, but the head temperatures are soaring and detonation becomes a problem (or you simply can't run as much ignition advance as you should be able to).

If an engine has overheating issues, It needs a larger or more efficient radiator or better fans. Removing the thermostat is a band aid, and not a good one.

Often times those people are running too strong a coolant mix (too much anti freeze). Anti freeze does just that. It prevents freezing. It also adds some anti corrosives, but it is less effective as a coolant that water.
A cooling system running 70% water is going to run measurably cooler than one with 70% antifreeze will.

If your in a time of year where freezing is never going to become an issue, and your having high coolant temp problems, try running straight (distilled) water and see if the problem goes away. You should still use at least 15% antifreeze for the anti corrosives.
Try running a wetting agent. They do work to lower coolant temperatures whether your using a 50/50 mix or straight water.
The way they work is, when water does start to boil, the steam bubbles that form will be much smaller than they would be otherwise, which leaves more coolant in contact with the engine and radiator surfaces.

[Excaliber]

Some T-Stats come with a hole in them all ready, others not. It's just to allow a little circulation through the hole. I've never heard of it being for a "vapor lock" situation. The hole sure makes it easier to bleed all the air out of the system before the T-Stat starts to open. Drill a small hole basically anywhere in the body/flange of the T-Stat just being careful not to hit anything else (like the thermal sensor).

I've heard that "theory" about slowing down the water flow by using a T-Stat and thus keeping the water in the radiator longer. I've also heard of high volume water pumps that move more water. The two theorys are opposed to each other, in my opinion. Some people who don't run a T-Stat use a restrictor that is basically a T-Stat with the center drilled out. This restricts the water flow to some degree and mimicks an open T-Stat.

I suspect "slowing down the water to keep in the radiator longer" may work on some systems and won't mean squat on others. Like wise a "high volume" water pump. THAT will sure work if your old water pump has worn out impellers and couldn't move enough water to begin with, but then again a new standard pump may work just as well.

It IS a good idea (generally speaking) to run a T-Stat to keep the engine temp from staying to low. Many "race cars" don't run them because it's no problem getting at or above operating temp anyway! Formula Fords (for instance) do not use T-Stats and typically run 200-210 during a race, so they don't need one.

I've run with and without one in my 427 FE side oiler. The ONLY difference it makes is on a "good day" my engine temp gets to low. On a hot day with the T-Stat open it makes no difference. IF the car is going to run hot (200-210) it will run that hot with or without the T-Stat.

Strangely enough, advancing my base timing has helped not only my idle and cruise performance it ALSO lowered my engine water temp!

[Bob In Ct]

Put it right in the thermostat, top center. Anywhere the coolant can get at it. Don't damage the working parts.


Bob

[chrispy]

Bob / Excaliber,

Thanks for the info.

Excaliber,

I would assume that if it were easier to get the air out of the block, it would lessen the chance of the lock.

Thanks again,
Chris

[scottj]

I use a thermostat when outside temperatures keep the engine from reaching operating temp. The thermostat I use is the Stewart/Robert Shaw high-flow t-stat. It doesn’t restrict flow and it has the hole in it required for non-bypass, high-flow water pumps. For a street application there really isn’t a down side to using the proper t-stat. You don’t see them used in racing applications because there is always the chance that it could stick shut.

Ideally, you want the coolant to flow through the system as fast as possible and the Stewart/Shaw t-stat will allow this. The greater the coolant velocity, especially in the cylinder heads, the more efficient it is at preventing hot spots. The miss-information on this subject suggests that if coolant flows through the radiator too fast there isn’t enough time to dissipate the heat. But, if the coolant is forced to remain in the radiator longer to cool, it is also remaining in the engine longer as well, increasing the coolant temp in the heads and CAUSING hot spots that lead to detonation. High velocity is was “scrubs” away hot spots and potential steam pockets in the heads.

Scott

[Morris]

Scott

Are you going down to Run n Gun this year..../?/?

I thought we were going to make it but not so....

We'll go anyway and just watch again .....

Morris

[scottj]

Morris-

Right now I have R & G on the schedule. Next weekend I'm doing a 2-day event at Autobahn and last night I saw where there is an other event at Autobahn the same weekend as R & G. If Autobahn is much nicer than Gateway I'll probably go to Autobahn. I really don't have any interest in drag racing (with a button clutch) or autocross, I'd rather just have track time.

How close are you to being ready?

Scott

[ccomt]

You may want to consider one of the "fail safe" thermostats. When a normal thermostat fails, it usually fails in the fully closed position which would probably cause your engine to overheat. Several manufacturers offer a thermostat that will open fully when it fails and thus prevent overheating.

[rdorman]

"Do I really need a thermostat"

Yes

Rick

[Morris]

Scott

We're still a ways away..... still working on the chassis stiffening process.....

And I agree about the track time....


"Do I need a Thermostat"......

Yes ...... not smart to run with out one......

Morris

[scottj]

Morris-

After Blackhawk on 7/1 I'm contemplating the same issue. The chassis flexed enough to pinch the passenger door causing the top rear of the door to crack.

So as to not hijack this thread- I like a thermostat for street use.

Scott

[Morris]

Scott

You have PM

Morris

[Jim Wintz]

Well looks like the majority agrees, and after reading all the info I agree as well, and will be putting in a thermostat in the next few days.

Thanks or all of the help and suggestions.

Jim

[hot427cobra]

Morris,

You have PM.

Mark

[speed220mph]

Jim: I didn't read all of the responses, but I'll just tell you what I know. A good way to wear bores prematurely is run an engine cold. A properly operating thermostat will not cause overheating, but ensure the engine is at operating temperature. The reason it's called operating temperature is that's the temperature at which the engine should operate. Run it colder and bore wear accelerates. I presume the only thing you want to accelerate is your Cobra.