Thermostat Delete?

[TexasBlownV8]

I was curious, for hot summer months where you're not worried about heater operation (nor emissions): is there any harm or reason to not run with a thermostat? (i.e., delete the thermostat.) There should be higher flow through/to the radiator, instead of the puny little opening a thermosat opens in relation to the hose size.
This is with a '07+ 4.6L, and the single upper hose crossover.

 

[RocketcarX]

You could knock out the center and use the thermostat as a restrictor plate. It will be fine

 

[Laga]

The only reason to ever remove a thermostat, is when it is struck closed.

 

[FredB66]

I'd be interested to see some actual data on this. The idea of deleting the thermostat for better cooing has been around for as long as I can remember. From a fluid mechanics point of view, a thermostat is a flow restriction and therefore reduces fluid velocity and consequently heat transfer efficiency. It may be insignificant, may not, but I would think a mythbuster out there has studied it at some point.

 

[Dino Dino Bambino]

I was curious, for hot summer months where you're not worried about heater operation (nor emissions): is there any harm or reason to not run with a thermostat? (i.e., delete the thermostat.) There should be higher flow through/to the radiator, instead of the puny little opening a thermosat opens in relation to the hose size.
This is with a '07+ 4.6L, and the single upper hose crossover.

It depends on the ambient temperature. On a 90*F day it won't matter but at night time and outside of the summer months when it's a lot cooler, the engine will take longer to warm up and may run cooler than normal. I'd certainly throw the thermostat back in once the ambient temperature drops below 70*F.

 

[WJBertrand]

On cars (and motorcycles) I’ve owned, failed open thermostats typically cause the engine to fail reaching operating temperature, even in warm weather. So far I’ve never suffered a failed closed one. In the case of EFI cars and motorcycles, gas mileage suffers as the computer thinks the engine is still trying to warm up and feeds in extra fuel. In cars, the heater doesn’t provide proper heat (not a problem in summer I suppose). I also experienced an error code being set because the computer never sees the expected operating temperature. I can’t think of any rational reason to run with no thermostat.


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[TexasBlownV8]

So, let's add a little more information to my question:
- in the 05/06 crossover style, the return hose to the radiator, from the passenger side, is open and unrestricted, and same size large (2" or so); the thermostat is on driver side hanging in front of engine. Flow is a little different of course, but if the lower-placed thermostat prevents flow from radiator to the block, that would be similar to blocking flow from the top end.

- without a thermostat, would the flow be too high, too fast, through the radiator and engine, and not slow enough through the system to collect [from the engine] and dissipate heat [in radiator]?

 

[07 Boss]

Removing the thermostat will not effect the upper range of your cooling system, it will only make it take longer to get there.

Exactly what kind of issues are you seeing during the summer? My car runs the same temps all year round. If you are having issues in warmer weather there is something wrong with your cooling system which means fixing, not modifying.

 

[JC SSP]

Living in S. FL I have always ran a 160 degree thermostat up until around 1996... introduction of OBD2. Then switched to a more computer compliant 170 (in my 05 & 06 GT's) and 180 (5.7 Hemi) degree thermostats.

I still run a 140 degree thermostat from a MerCruiser in my little fox 5.0L, but that's another story.... LOL

In reality I have only seen restrictors or complete removal of thermostat on drag cars, where an electric pump circulates coolant while cooling off in the pits...

 

[Pentalab]

The T stat in my 2010 GT is an oem 190 F unit. Once up to temp, the in dash heat gauge is a little less than 1/2.

Somebody posted a cylinder wall...... (wear vs eng temp graph), a few years ago. It was an eye opener to say the least.

 

[TexasBlownV8]

I'm not having overheating issues, but I was somewhat surprised when I looked closer at the opening hole that a thermostat makes when open (as I'm changing to the '07+ setup from an '05/06 setup), and in how much smaller the opening is compared to the radiator hose itself and compared to the radiator inlet/outlet ports. Just seems like a natural moderate restriction.

FWIW, I use an electric water pump that I can control with a switch as needed, in addition to key on/off relayed power; and that's been a great mod. Upgraded radiator and gt500 cooling fan, and 170* thermostat that I'll be using.

 

[brasil]

leave the thermostat where it belongs. IN your car. If you remove the thermostat...your engine will suffer ... the engine needs to reach a certain operating temperature of around 190-195 deg F ( water temp ) so the engine oil also goes up to the same temp....
a good idea is to use 5w30 weight... instead of 5w20.

 

[brasil]

forgot to say... without the thermostat, the milage goes south. Because the ECM is permanently in the " cold start mode ". not so good.

 

[Laga]

- without a thermostat, would the flow be too high, too fast, through the radiator and engine, and not slow enough through the system to collect [from the engine] and dissipate heat [in radiator]?

Another myth that won’t die. It also is against the laws of physics and thermal dynamics.
The faster you move a fluid across a surface, either liquid or gas, the more heat it will carry away. Ever hear of wind chill factor?

 

[DieHarder]

Another myth that won’t die. It also is against the laws of physics and thermal dynamics.
The faster you move a fluid across a surface, either liquid or gas, the more heat it will carry away. Ever hear of wind chill factor?

What you say about physics/thermodynamics is absolutely true. The issue for me however is what do our cars need in the way of heat to operate efficiently? During the initial install of my DOB kit the thermostat I bought wasn't seated fully and allowed about a 1/16" of clearance coolant flow around the outer edge. You might not think that's much but during a winter trip (~400 mi) my temps went down so far the dash gauge wouldn't register anymore but the car kept running so though concerned I kept going. After I got back I went to a local hardware store and finally found an O-ring that would fit. Later I added some standalone gauges to monitor Water/Volts/Oil Pressure/Oil Temp. I like things to run cool as well so I'm using a 170 which works fine in winter and summer though I note that my summer readings can run as high as 210 - 220 (measured at the upper radiator hose) before the fan kicks in and cools things down to ~200. The idiot gauge in the instrument cluster never registers higher that 1/2 scale but does work so I'm good. That said, my understanding is (heard somewhere) our cars need to be around 200 to operate effectively. Others?

 

[JC SSP]

If you have a tuner you can adjust the high and low fan settings. I did this when I installed the 170.

 

[Laga]

That’s why I stated early not to remove the thermostat.
For the record, the myth that removing the thermostat and fast moving water doesn’t cool, is that SOME engines can develop a laminar flow of coolant through the block. This prevents the coolant from going completely around the cylinder water jackets and just by them. This creates hot spots. The thermostat, or washers, creates back pressure and turbulence within the block that ensures coolant touches all parts of the engine.
I used to run a 160°F thermostat in the summer and a 190°F in the winter. It made no difference in the operating temperature of the engine. It is 195°F to 200°F year round. Unless I’m at a track day.

 

[moooosestang]

The biggest restriction has to be the radiator so i don't think removing the thermostat will do anything. remove the ac condensor and you'll get better air flow to the radiator for better cooling.

 

[WJBertrand]

Another myth that won’t die. It also is against the laws of physics and thermal dynamics.
The faster you move a fluid across a surface, either liquid or gas, the more heat it will carry away. Ever hear of wind chill factor?

Specifically it’s known as a boundary layer phenomenon. The faster the flow, the thinner the stagnant boundary layer is at the surfaces you want to cool, and the better the heat transfer.


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