Do you really need a thermostat on a new build?

[N/A Camry Sleeper]

OK I have another theory:

Why should ANYONE use a thermostat in a fresh motor? Here's my reasoning...

When a motor is new the tolerances are tighter - the rings have less clearance to the cylinder walls, the piston fits tighter in the bore, valves fit tighter inside valve guides - you get the picture...

Adding heat to this system causes all parts to expand which makes the tolerances even tighter right? With me so far? So operating a new motor at the usual temperature between 180-210*F depending on your tstat there will be more friction initially until the rings wear away the bore a little bit - the crank bearings will go through the same process - there will be initial wear - that's why almost all builders and dealerships recommend an oil change 100 miles up to 1000 miles after initial break in; again, depends on who builds your motor - Toyota or a machine shop.

I read an article about 10 years ago where Motor Trend (I think) road tested a new Porsche 944 or 928 - one of the faster versions but not a supercar. They drove the car for 40,000 miles and tested acceleration, fuel economy, and a few other things IIRC. The results of the test were that after 40,000 miles the car was something like .3 seconds faster 0-60 and almost .6 sec faster in the 1/4 mile. Fuel economy was markedly better as well; something like 5-6 MPG overall improved. They took into consideration tire wear, track elevation above sea level, and a few other variables - it was a very scientific test and I commend Motor Trend for conducting such a controlled experiment - nowadays it seems a little different with marketing and such...

I've been thinking on my N/A build to go without a thermostat for several reasons - and anyone feel free to chime in with input here!

1. Heat is the enemy of any machine - it is quite simply wasted energy not going to the wheels
2. Keeping the engine as cool as possible keeps the incoming air cool and dense - which equals more available oxygen which equals more power
3. In a new build it is my belief that keeping thermal expansion down to the absolute minimum is vital to producing the most power since friction is reduced.
4. I will use 0W-30 oil which is very thin - a cooler-running engine will need a thinner grade of oil. As heat increases, most oil thickens to an extent causing more friction
5. Using a V6 radiator in the 5SFE largely because of the 12.5:1 compression ratio - try this out in winter first. Have to see what summer with the A/C running will do...
6. The sludge issue of running an engine too cool has been discussed in some Ford forums - but I think this can be corrected by using the right oil and changed at the right intervals
7. Also been thinking of using CO2 spray before runs to chill the intake and head which will further densify the incoming air. A cooler engine will transfer less heat to the chilled parts DURING the run
8. The ECU can be tricked into thinking that it's at operating temp with a few resistors here and there. The IAT sensor can be "dimmed" much like a MAP sensor enhancer works
9. Jet hot coating on the exhaust manifold
10. Everything I've ever removed the tstat from in the past had plenty of heat in the winter time down to about 0*F.

What do you think?

Keeping a tstat on an engine that's broken in already makes sense since it is used to that operating temp. When a normal engine is started, you get more blowby and lost energy since the metal parts are a little loose and not at operating temp

But I say, never get it that hot to start with and let the metal get accustomed to running at 120-140*F. Tighter tolerances, less friction, better piston sealing, etc.

Oh, and MORE POWER! (theoretically, of course)

[Dave's]

I'm not an engineer. I guess they should send out all new cars without t-stats. They could install them after a suitable break-in period or as part of a scheduled maintenance. Would that make sense as well?

[Luckynumber5]

I don't like it.

[rusty9]

Just get a lower temp thermostat.

[awisniewski]

I'm saying this in a friendly tone.... I can't sum up my exact words but I don't think its as simple as you presume. The thermostat is designed to keep the engine temperature within a certain range, you want the engine to get to that range as quickly as possible and stabilize. I could understand the idea if you only keep the car in some climate that always was very hot outside, like out west, etc. If I had to guess I would imagine the thermostat has most of its useful purpose while our engines are warming up from a cold start (unless we are in a very cold climate). Without the thermostat the engine would take longer to warm up and in theory more engine wear occurs during the initial warm up period so extending that warm up period by a few minutes or more wouldn't be good for engine life (wear) and wouldn't be good for more power down the road. Now with what I said I'm thinking of a none rebuilt engine, one that already has miles, but I don't see how that would be different for a fresh engine.

I saw you said that you've operated a car without a thermostat in the past and had no issues with heat. That's funny you say that because when I bought my 1998 Camry I had terrible heat output in the cabin. I noticed the temp gauge in the console took a long time to move up and never seemed to quite get into the center. Long story short someone took apart the engine thermostat and reinstall just the shell. Now the temprature where I live doesn't get to cold in the winter, its Nashville TN and it had an effect on the warm up time and heat output (Even after driving for 20+ minutes). This was with a 4cyl engine by the way. Anyways my experience is different then yours.

Well...let me know what you think

[RichieRichJP]

Originally Posted by rusty9

Just get a lower temp thermostat.

5SFE doesn't have a low temp t-stat, unless you want to try the 4AGE one and give us confirmation!

[fenixus]

no thermostat = longer warm up = more engine wear & more fuel used up (richer mixture in warm up phase)

I don't like the idea if you ask me.

[BMR]

Read up on the Carnot cycle. It's what's going on in an internal combustion engine. Hotter combustion chamber temperatures are better. Running without a 'stat would be counter productive to that, unless you've done something to increase combustion chamber temperatures that drive you to do that, to protect the engine from melt-down.

Wiki link to the following info:

"The efficiency of the cycle is the ratio of the white area (work) divided by the sum of the white and red areas (heat absorbed from the hot reservoir)."

Edit: Combustion chamber temperatures are limited by the materials used. That's why you'll find articles about using ceramic coated piston crowns, ceramic pistons, carbon, etc., etc.. The higher the combustion chamber temps can be driven, the more efficiency the engine will have in extracting power from the fuel it's burning.

[Zembonez]

Engines are designed and built to operate at a prescribed temperature. The thermostat ensures that the warmup is quick and a semi-constant temp is maintained. You can put as much scientific thought into this as you want, but it doesn't change the fact that a thermostat is a big part of the design.

I see no reason to try and reinvent the wheel here.

[JimBowNut]

I've never heard about oils thickening at higher temps ?.........have to think about that ? Maybe at really high burn-off type temps ?

And If you are going to try to avoid wear I would go with Amsoil 0w20 ......google all those wear tests and see what you think, one test I remember reading about is that 4-ball wear test.....if I recall Royal Purple had double the wear as Amsoil....

j