160° thermostat question

[teamjnz]

What does a 160° thermostat do to increase performance? So the engine runs cooler…

 

With the engine running cooler does it effect the emissions? I live in California and we a have strict emission program on all cars and trucks.

 

teamjnz

[dewfpo]

A cooler running engine will run richer, potentially making a little more power at the expense of engine wear, poorer emisions and less mpg.

 

I wouldn't do it on a modern, computer controlled engine unless it was desigined to run at that temp. You're tailpipe emissons will suffer and you may not pass the emissions test in CA.

 

DEWFPO

[100R1]

Also to take full advantage of a 160 degree thermo you will need to add external cooling fans with a adjustable switch in order for the fans to kick in at the new lower temperature you will be running.

 

If you just stick in a 160 degree thermostat without doing any other cooling mods you take the risk of overheating in city driving as the thermostat will stay open all of the time and not "cycle"

 

 

I would start with a 180 - 185 degree stat. better chance of passing local emissions and will keep the engine closer to the factory intended operating temperature.

[Yukon04]

100R1 and dewfpo,

 

I am a little confused about this string...wouldn't cooler air equal a leaner fuel condition? (Pending any PCM adjustments) more O2 per in^2... Also, 160 thermostat would keep the engine at a lower temperature (by circulating coolant at this temp instead of ~210) and the fans are controlled by the coolant temp sensor. So why would the vehicle overheat?

 

AND, even if the engine were to run richer, where would the excessive engine wear come from. Generally speaking, rich fuel conditions do not cause engine wear. Lean conditions do.

 

The only thing that does make sense (to me) here is that rich fuel conditions will cause bad emissions.

 

Please double check your advise and as Father Guido says "Splain' to me"....

[builderpaul]

100R1 and dewfpo,

 

I am a little confused about this string...wouldn't cooler air equal a leaner fuel condition?  (Pending any PCM adjustments) more O2 per in^2...  Also, 160 thermostat would keep the engine at a lower temperature (by circulating coolant at this temp instead of ~210) and the fans are controlled by the coolant temp sensor.  So why would the vehicle overheat? 

 

AND, even if the engine were to run richer, where would the excessive engine wear come from.  Generally speaking, rich fuel conditions do not cause engine wear.  Lean conditions do.

 

The only thing that does make sense (to me) here is that rich fuel conditions will cause bad emissions.

 

Please double check your advise and as Father Guido says "Splain' to me"....

 

<{POST_SNAPBACK}>

 

 

 

Yes cooler air makes more power but that is different from a cooler engine. Once the air is in the engine you want it to heat as fast as possable. Hot air atomizes the fuel better so it burns better. Cooler engines don't burn the fuel as effecint so unburned fuel can wash oil off the cylinder walls. It will also be sent out the exhaust and cause problems with the cat converter.

 

I think the point of the fans is this. The engine may generate enough heat that without the fan it would not cool to 160. The 160 stat will be open longer than the 190. This means coolent won't be in the radiator as long. If your fans don't kick in till 180 than coolent may never cool to 160. If you are going to try to run 160 you will need to reporgram the fan turn on lower. I don't know how it will overheat.

 

Leave the temp where the engine was designed to run.

[d-dog]

Interesting, but I've got to disagree on a few points. The Hypertech reprogrammer recomemnds the 160 thermo which I installed. The theory is the cooler air contains more oxygen molecules. And, yes, the warmer air does help atomize the fuel, but at a cost. There's a point of diminishing returns there. The air warms up plenty as it enters the plenum, so there's not a lot of gain having the motor up around 220 vs 160. Also, if it's been reprogrammed, you shouldn't have a problem with running too lean. And yes, the mileage may suffer a bit, only because the system will add more fuel to make up for the cooler, more dense air. Think about it - aircraft engines have used a water injection systems for years. Water is injected at the intake to cool the air at the low pressure fans, causing the air to cool and be more dense. In the 70s is was a big thing to put a water injection on your car, but for whatever reason, seemed to lose favor. The high temp thermos is mainly for emissions - keeps the nox down.

[Bish]

IMO, running a low temp t-stat won't do much by itself. It does, however, allow you to use a programmer to advance the timing (along with premium fuel) without getting detonation and thus theoretically giving more power.

 

I'm running a 180 year round in Chicago.

[Yukon04]

Builderpaul,

How will fuel "wash oil off the cylinder walls"? If this was true, which makes no sense to me, wouldn't the combustion process "burn" the oil off the cylinder walls? Fuel and oil are not designed to mix, otherwise our gas powered trucks would smoke like diesels. I agree that the cylinder walls do contain trace amounts of oil in the metal molecules, but raw fuel should not disturb this.

The atomization of the fuel is mostly due to the intake process and heat does add energy. But, the difference between ~200 and 160 could be negligible. Without PCM influence, cooler fuel will produce more Hp than warmer fuel, that is fact. In my opinion, the 160 t-stat shines the most by lowering underhood temperatures. I see no arguements or data here that will cause engine damage.

 

Please advise if I'm off track....

[mcreyaufmiller]

Run the stock thermo, it was deisgned for this. If you are installing a new PCM, and it calls for the 160, put it in.

[Bish]

I have to agree with the cooler underhood temps Yukon04 mentioned. I noticed a big improvement during the summer just by running the 180. With the complete intake and manifold running cooler, the intake charge will also be cooler. Not to what extent that provided more HP...I'm sure it provides some but is it .5HP ot 5HP or more?? WHo knows?

[builderpaul]

If you put your faith in tests and graphs you may find this intersting.

 

thermostats

 

Without seeing all the test conditions and results I am sceptical of most. So much "snake oil" is sold with tests specifically made to show a products greatness.

Remember slick50, tornados, throttle body spacers, high flow air filters. But those are another thread altogether.

[Butch 02 Denali]

Builderpaul,

    How will fuel "wash oil off the cylinder walls"?  If this was true, which makes no sense to me, wouldn't the combustion process "burn" the oil off the cylinder walls?  Fuel and oil are not designed to mix, otherwise our gas powered trucks would smoke like diesels.  I agree that the cylinder walls do contain trace amounts of oil in the metal molecules, but raw fuel should not disturb this. 

The atomization of the fuel is mostly due to the intake process and heat does add energy.  But, the difference between ~200 and 160 could be negligible.  Without PCM influence, cooler fuel will produce more Hp than warmer fuel, that is fact.  In my opinion, the 160 t-stat shines the most by lowering underhood temperatures.  I see no arguements or data here that will cause engine damage.

 

Please advise if I'm off track....

 

<{POST_SNAPBACK}>

 

 

 

Builderpaul is 100% correct Yukon04!

The additional fuel the computer adds because it thinks the engine is still warming up will wash the oil off the cylinder walls, it will soak right past the rings and dilute the oil film on the cylinder walls. No the oil doesn't burn, the film layer is so thin and coated on the cylinder wall. The "burn" is so quick, the oil doesn't get to it's flash point because of it's contact with the cylinder walls. The extra fuel will also dilute the engine oil, not a good thing. You can see the oil get dirtier much faster with a 160, because the extra fuel washes the combustion residue past the rings.

[Yukon04]

Good to know....

[d-dog]

Well, it sounds like this is a debatable area. I agree in "concept" on the washing of the walls, but.... that's a term that is leftover from carburated motors. With carbs, the fuel metering wasn't nearly as precise, and a choke was used to restrict the air. In that case, washing the walls was always a problem. However, with injected motors, this hasn't been a problem. Remember when your old car was warming up and all that black smoke was there? Injected motors don't do that, even when at their coldest because the metering is so much more precise. However, I do agree that the 160 thermo by itself would be problematic because the computer thinks the motor isn't warm and the mixture wouldn't be optimum. I'm assuming no one would run one without recalibration of the sytem. I've been running the 160 (with Hypertech reprogrammer) and couldn't be happier. The summer temps here easily get to 105 and even higher. With the stock thermo, I could see the gage climb quite a bit when towing my boat. That 160 gives a heck of a lot more room when the weather is extreme.

[Bish]

Builderpaul,

    How will fuel "wash oil off the cylinder walls"?  If this was true, which makes no sense to me, wouldn't the combustion process "burn" the oil off the cylinder walls?  Fuel and oil are not designed to mix, otherwise our gas powered trucks would smoke like diesels.  I agree that the cylinder walls do contain trace amounts of oil in the metal molecules, but raw fuel should not disturb this. 

The atomization of the fuel is mostly due to the intake process and heat does add energy.  But, the difference between ~200 and 160 could be negligible.  Without PCM influence, cooler fuel will produce more Hp than warmer fuel, that is fact.  In my opinion, the 160 t-stat shines the most by lowering underhood temperatures.  I see no arguements or data here that will cause engine damage.

 

Please advise if I'm off track....

 

<{POST_SNAPBACK}>

 

 

 

Builderpaul is 100% correct Yukon04!

The additional fuel the computer adds because it thinks the engine is still warming up will wash the oil off the cylinder walls, it will soak right past the rings and dilute the oil film on the cylinder walls. No the oil doesn't burn, the film layer is so thin and coated on the cylinder wall. The "burn" is so quick, the oil doesn't get to it's flash point because of it's contact with the cylinder walls. The extra fuel will also dilute the engine oil, not a good thing. You can see the oil get dirtier much faster with a 160, because the extra fuel washes the combustion residue past the rings.

 

<{POST_SNAPBACK}>

 

 

 

 

 

Agreed! If you run so cool that it never goes into "closed loop" operation, it will run rich all the time and it will dirty the oil much more quickly partly due to the fuel/oil wash and partly because the oil won't get hot enough to burn off the moisture and other chemical byproducts of combustion in the oil. Same reason a vehicle driven only on short trips (under 10 munites) will require much shorter oil change intervals.

 

That's the reason I chose a 180. If you are in the south where it is hot most of the year, I think you can get away with a 160 but anywhere it gets cool and/or cold it's not such a good idea IMO.