quadman20

Clutch no offense here neither just stating my experience and what I have seen. In my life theory is great but reality holds real truth. Can't tell you how many engineers or architects I've had that discussion with and they just can't see why I think like I do. They say it added up on paper so it should be true. That what great about this site we can agree to disagree.

.boB

The thermostat only controls minimum temp. That's all it does. Once it's open, the coolant flows "freely", and the rest of the cooling system does it's job.

During light duty operation (Driving around in town empty) you will see that the operating temp is lower. Of course it is, the cooling system is doing it's job. The cooling system is so good on a Cummins that you are not putting any strain on it. So it stays at 180*'ish. That's what's supposed to happen.

Now, pull a 12K# trailer west out of Denver and I bet it won't stay at 180*.

The question is: is there any benifit? The answer is: I don't know, but I suspect not.

Last winter I did some testing in WY. What I found out was that as the water temps rose, so did fuel mileage. Which leads me to believe that a diesel will be more efficient the hotter it gets (to a point, of course). With that thought in mind, I'd want to install a 195-200* thermostat to see what happens. I never tow 12K#, so I don't have to worry about it.

In smog controlled gas engines, the stock stat is usually 195*. That's the temp where the emissions are best. Has nothing to do with power or economy, it's all about emisssions. In years past, you could simply swap in a 180* stat, and the engine ran great. Some engines actually made more power, but most did not. But car guys were happy to install the lower stat, because we felt better seeing a lower temp. There was a gauge with a needle that we could look at and say, "See! It helped!" Much better than the Butt-O-Meter.

Now we're talking about computer controlled engines. The computer tries to run the engine where it gets the lowest emissions. Many times, if you simply swapped in a lower stat, the computer thinks it is still in warm up mode. I tried it on my '01 Dodge 5.9L gas engine. It enriched the fuel curve and retarded the timing. The engine ran terrible and got poor mileage. In order to go with a lower stat, you had to reprogram the computer to accept it.

But you still have to question the value of running the engine cooler. A cooler, denser air charge makes more power. Any racer will tell you that. But, does making the coolant temp 10* lower give you a cooler denser air charge, and therefore more power? No one has tested the theory, but I suspect the answer is no, it does not.

I'm not a diesel engineer by a long shot (but, not many here are, either). From my limited education, I would think a hot engine with a cold intake charge would be the most efficient. Efficiency makes power and conserves fuel.


Can you "hurt" an engine with a cooler operating temp? Yes, you can. Sometimes you can get away with it, and sometimes you can't. And temps below 160* have been shown to increase cylinder and ring wear.

Dodgezilla

The way I've always looked at it is that heat kills. It's bad for all the underhood components and eventually it will weaken the steel that the engine is made of. Of course that will take a long time to happen though. I'm sure your point is valid and I have been hearing the exact same thing since I started driving. My brain, however, cannot accept it and keeps telling me to run cooler stats. I guess it's my loss.....

Ace

An open 180 stat flows the same amount of water as an open 190 stat.

Dodgezilla

Well apparently my system is flowing perfectly because opening it sooner is keeping the temps down.....

quadman20

Ace thats pretty much my point. Like I said earlier GM uses a 192 stat but the run 200-210 which is normal. So it's open all the time as well. Also as said 10 degrees is not that big of a gap. Now a 160 would be considerable to a 190. Also stated about computer using temp to change emission. Well those with say a Smarty doing the controls does it really affect it as a factory program.
Where's the Ram/Cummins engineers now when we need them.

Ace

Combustion efficiency is generally proportional to temperature, within a certain narrow optimal range for a given engine and tune.

I don't know what the numbers for that range are but 190 is probably a good target. I know the newer trucks seem to run hotter, at least mine does. Steady state under load is what I would be worried about. It only goes up from there towing and hauling. If you are using it as a DD/grocery getter I would think a hotter stat would be better.

Just a hunch.