Running no thermostat?

this is a two sided answer.Some will claim the water circulates too fast and doesnt transfer heat in the radiator, while others will say it circulates faster so it must cool faster.

I personally have ran without and now with(160*) and i thing it runs a little cooler with

With no thermostat the water will run through the system too quickly to properly perform the cooling task. You will find that even race cars will run a 3/4" restricter plate to slow the circulation down.

grego37 said:

I know , I know. I've heard that too.

It may have been true way back when,with low pressure radiator caps stock down flow radiators, and the waterpump pushing coolant past the cap, so you'd restrict it to slow it down.
But thats not the case any more. With big cross flow radiators, higher poundage caps, inlet/outlet location etc.
The cooling system is a closed loop system. The longer it stays in the radiator, the longer it also stays in the pasages heating up (hot spots).

So I figure the faster the better, as long as its not too fast to create cavitation at high RPM's

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i agree take it out and it will run cooler. I even drilled holes in my 03 cobra t-stat and it runs alot cooler then before.

grego37 said:

anyone out there running no thermostat.

I realize a thermostat is there for a reason , and in colder climates its a must.
But where I live its plenty hot, car is warmed up in just a few minutes.

Im looking to drop a few degrees in the water temp, and I figured without a thermostat, the water would cycle faster, resulting in a drop in water temp.

anyone have any luck doing this

This is in a 67 Shelby clone with a 408W, all other avenues/upgrades of cooling have been addressed.

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It won't hurt anything running without a thermostat. It will just take forever to get the car warmed up. You would be much better off getting the hottest thermostat that you can find.

With my car which has cast heads it runs 20 degrees hotter with the stat removed on average so I put the 190 degree back in. Under boost my gauge will move fast and steady to 220 degrees without the stat.

grego37 said:

I know , I know. I've heard that too....So I figure the faster the better, as long as its not too fast to create cavitation at high RPM's

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Why even post if you already know the answer and you are not going to listen to what anyone tell you. It is not hard to take it out, try it.

It may cool slightly better with no cap... but not a heck of alot better.

There is sometimes a need for a restrictor like realmongo mentioned. Especially in racecars with high-flow water pumps. But these are needed because if the coolant flows too fast the water becomes turbulant and you can get air bubbles in the coolant...air doesn't cool very well. A restrictor plate slows down the flow so this doesn't happen.

Personally, I think removing the thermostat is a bad idea, it won't help anything and will make your engine take a long time to warm up, we all know that a cold engine is an engine that's going to wear out quicker.

How about sticking a 160* t-stat in there?

grego37 said:

Since I have an electric fan, theres no air flow until I drive it. I dont drive it until its 160*. There's no difference in warm up time for my application with or without a thermostat. That is not an issue in MY case.

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Wrong. Even without airflow the radiator is going to cool the coolant. Also you'll have to heat the coolant in the radiator as well as the coolant in the block, this will take more time.

When your driving it you'll see times when the engine runs too cool, such as on the highway during a cool night.

Put in a 160 thermostat. The motor needs to come up to normal operating temp ASAP. We have all seen what happens when a thermostat gets stuck open..esp. in cooler weather..forget about using the heater.

P.S. don't buy the cheapest one at the parts store.

If you wish no stat, at least fab up a 20% restrictor plate.
this will keep the coolant flowing to the rad under some resistence pressure,
and keeping the pump from sucking in the lower rad hose.
But you can springload it to prevent that part, But it also insures coolant completely inside the block and head area.

My 2c

PB

another vote for running a thermostat. take one look at the inside of an engine that's been run without a thermostat (or subjected to a lot of driving without heating up) and you'll never consider running without one again. sludge is some nasty stuff!!

No Thermostat.

One last thing, boil the 'stat before you put it in. I got two bad ones in a row last year. They wouldn't open up. As mentioned before, don't buy the cheapest one.

Another way the Nascar guys slow down the flow is to run a smaller impeller in the water pump. Most pumps come in three versions with three different sized impellers : Low volume (high performance=high rpm applications, small impeller) std volume, and high volume (large impeller) And you can usually get any of these at your local parts house, you just have to know what to order and what you're looking at.

RGS0907 said:

It won't hurt anything running without a thermostat. It will just take forever to get the car warmed up. You would be much better off getting the hottest thermostat that you can find.

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Why the hottest thermostat?

Ok, since no-one has mentioned these Ill point them out... I know you say "all" upgrades etc.. have been done, but sometimes people overlook a few of these.

Is there a gap between the sides of the radatior and the core support? Or is there a big hole in the core support next to the radiator for who knows what reason? If so block it off with some sanitary looking sheetmetal, I like aluminum with a little clear sprayed on it, but stainless is nice too. These holes allow hot air that has just come out of the radiator to circle back around and work thru it again... reducing cooling ability. You want all the cool air that enters thru the grill to go thru the radiator.(and/or the oil cooler, trans cooler, etc...)

Does the car have an oil cooler? If not it could help, it pulls heat out of the motor, it also increases the oil capacity, and if plumbed right, gives a great spot to drain from that is lower than the filter. (so it doesnt piss all over the steering / suspension when you pull it off)

Have you tried Redline Water Wetter? It worked in my 5.0 for about a 10 degree drop all the time.

Is there a fan shroud? If not get / make one. It will help the fan work MUCH, M-U-C-H better. Also if you run an electric, make sure there is no gap between the fan and the radiator (or make a shroud so the fan can draw thru the whole surface area of the radiator).

You may also want to up the pressure of the cap a few degrees (3-4) Sometimes guys run low pressure caps (like 7lbs) but dont realize that while the water in the radiator is ok, the water can be boiling inside the heads/block creating overheating problems. (if i remember right) You gain about 4 degrees of boil over protection for every lb of pressure. If your at 7 or even 9lbs and go to 12 or 16 on the cap, thats 20-30 degrees of safety net against a roadside nightmare.... Now I wouldnt go too crazy with it like a 24lb cap, cuz I think (imho) this leads to changing alott of waterpumps, etc... due to leaks.

Also ceramic coated or thermo-tec wrapped headers / manifolds can cut under hood temps quite a bit. (on mine you could feel the difference when you open the hood, i dont know how much that was... may-be 20-30 degrees)
But you could see about a needle width drop in engine temps (maybe 4-5 degrees...) in hot, stop-n-go driving.
By reducing the temp under the hood, you allow the engine and radiator to give off more heat in the same period of time, because the diff between their temp and the air temp around them is greater. A cowl hood (or louvers, or whatever) can also help with this.


Again just my .02, hope some of it helps.
Dave-