180 Thermostat Results (With Towing Data)

[Jon A]

Jon, given the assistance the fan has on keeping temps lower, would an engine driven fan, like the big clutch fans of earlier models provide more margin? They have many times the air moving capability of electric fans.

 

Yes, absolutely. I haven't kept up with the latest, but my understanding is the HD's still come with mechanical fans as do most real "trucks." They just can't be beaten for ultimate cooling performance, it's not even close. Electric fans have gotten a lot better in recent years but they can still only move a fraction of the air a big mechanical fan can.

 

Of course the mechanical fans have some big drawbacks. Mainly they suck down a whole bunch of gas. On any vehicle where you're counting the hundreths of a MPG in the EPA testing, you'd want to avoid one of these. They're hard to control precisely with the computer. They first tried the electro-hydraulic clutch on the Trailblazer 15 years ago and it was a disaster. Many TSB's, etc, until they replaced it with the old fashioned type. It just never worked reliably. I assume the ones on the current HD's work better than that one did, but compared with an electric fan they're going to be slow to react and very inefficient.

 

As with most things, everything's a compromise. Pick the performance parameters that matter most for the application and deal with the consequences.

[Jon A]

My post says that MOST calibrations will disable fans at speed. That includes all trucks with fan control from 1998 to 2013 (as verified this evening). I don't have a 2014 in front of me to verify as well, so I will take your word on that until I do.

 

What speed exactly? 45, 50 MPH that many find themselves at towing up a big hill on the highway? I'm sure I am missing some tables for the 2014's but the "VSS Low" value in the fan section is set at 124 MPH. I'll conceed, at 124 MPH the fans are doing very little. The last time I was towing some horses up a mountain I was not quite able to maintain such a speed....

 

Density is density.

 

Clearly it's not or you wouldn't need different timing. The idea an engine will produce exactly the same amount of power under an infinite combination of environmental conditions as long as the intake density ends up in the same place is just silly. Yes, there is a pretty decent range in which they'll be close, but when you're at a temperature at which the OEM calibrators decided they had to pull huge amounts of timing to stave off detonation, you just may be a bit out of the engine's "happy zone."

 

There is a reason SAE J1349 specs are set to a specific temperature and pressure and not a single density number. They also specify limits--you can't vary the IAT more than 10 degrees C from the standard temp your test is not valid. Why do you think those silly Engineers made all these rules if none of it matters?

 

But here we are again, arguing about meaningless minutia that has nothing to do with the purpose of this thread. And it looks like it has successfully destroyed this thread.

 

Congratulations.

Edited August 11, 2015 by Jon A

[Spurshot]

 

...

As with most things, everything's a compromise. Pick the performance parameters that matter most for the application and deal with the consequences.

 

Granted, we are talking about a specific task in this thread. My brother (a Mech Eng major, off to a different line of work) and I had a similar discussion years ago about fan capabilities. Those big ol clutch fans took some HP to turn, but moved massive amounts of air. My 2008 had a snout on the water pump that could still accommodate the fan, although it had electrics. I'm not sure these Gen Vs could be fitted, with their offset pumps.

Edited August 11, 2015 by spurshot

[Spurshot]

Guys, please keep it polite and respectful.

[kstruckcountry]

I'm not sure about the claim that a clutch fan moves more air. Everything I've seen seems to suggest electric fans are superior in every way.

[Spurshot]

I'm not sure about the claim that a clutch fan moves more air. Everything I've seen seems to suggest electric fans are superior in every way.

 

Dan,

The electrics have motors with less than 1 hp. A clutch fan of old can consume something like 15 hp turning those big blades. Electrics are easily programmed to come on when they are needed most. Not so easy with mechanical fans.

Edited August 11, 2015 by spurshot

[kstruckcountry]

That's true, but the electric fans are capable of 100% output when the engine isn't putting out 100% power. I know there are other variables at play, but it seems like vehicles with electric fans are good at maintaining the temp at all operating conditions, where vehicles with a mechanical fan are usually optimized for one condition, for example a tractor.

[.justin.]

 

Clearly it's not or you wouldn't need different timing. The idea an engine will produce exactly the same amount of power under an infinite combination of environmental conditions as long as the intake density ends up in the same place is just silly. Yes, there is a pretty decent range in which they'll be close, but when you're at a temperature at which the OEM calibrators decided they had to pull huge amounts of timing to stave off detonation, you just may be a bit out of the engine's "happy zone."

 

There is a reason SAE J1349 specs are set to a specific temperature and pressure and not a single density number. They also specify limits--you can't vary the IAT more than 10 degrees C from the standard temp your test is not valid. Why do you think those silly Engineers made all these rules if none of it matters?

 

That is the same J1349 (and J607) test conditions that dyno manufacturers standardize power output to. If the timing was a factor outside of accounting for differences in flame front propagation, there would be no way to actually standardize output to specific operating conditions and weather stations become a moot point. Just to be clear here, the density component is ultimately what determines cylinder air mass, since mass = density / volume and volume is fixed.

 

I've appreciated the lively discussion! Hope you all have a wonderful day.

[nando87]

My truck is the one that has had the "High Oil Temp" warning and telling me to pull over and idle the engine when pulling a steep grade when towing.

 

During that grade and on other grades I'm not a full throttle depending on the gear the tranny goes into, if the truck down shifts into 2nd ( I think ) I can only be about 3/4 throttle most of the climb because the revs will get close to redline and it wants to go into 3rd and then I'm in trouble with bogging. Pulling steady around 60mph my revs are around 5k and the temps rise like crazy, usually by 3/4 the way up the grades I'm at full throttle as the power seems to really drop off when the temps climb higher.

 

Just recently we put a mild tune on the truck and had the fans kick in at 212deg, I pulled a smaller trailer over some small grades the other weekend and noticed that the fans did help keep temps in check. The temps did climb like but not as fast, probably due to a lighter load and less grade, but what I did notice was how fast the temps went back to normal after climbing once cruising on flat ground

[Spurshot]

That's true, but the electric fans are capable of 100% output when the engine isn't putting out 100% power. I know there are other variables at play, but it seems like vehicles with electric fans are good at maintaining the temp at all operating conditions, where vehicles with a mechanical fan are usually optimized for one condition, for example a tractor.

Generally a truism and Jon pointed that out above. But the clutch fan and flex fans were efforts to provide more diverse efficiency. Later the electronically programmable clutch fan was a further endeavor down the path to provide more diverse efficiency. Frankly, I think a hybrid system is going to be the most capable. But cooling capability can be gained in other ways. So we may not see a hybrid fan developed unless someone can show an advantage over other ways to achieve cooling capacity, either economic or functional.

[redwngr]

 

 

Incorrect. Maybe after I've explained it for the 1000th time the lightbulbls will come on.... The cooling systems are operating at the same capacity once the thermostats are wide open and the fans are running full speed. This occurs at 244 degrees with the stock system. At every temperature below that, the modified system is operating at a higher capacity. If 244 degrees is never reached, the modified cooling system has been superior 100% of the time. Being vastly superior for a range of 40 degrees before 244 degrees means the likelyhood of ever reaching 244 degrees is greatly reduced.

So now you're trying to tell use that the thermostats are't open until 244???

[iCryWheniGoPoop]

So now you're trying to tell use that the thermostats are't open until 244???

That great big bold print should be bigger and bolder I guess, lol!

 

Let me rephrase it... Your stock calibration doesn't command 100% cooling capacity until it reaches 244*. Thermostat opens much earlier but fans don't reach max until that point.

Edited August 12, 2015 by TDT

[TJay74]

Correct, under the stock calibration GM does not command 100% fan speed until around the 244° point. Even under AC the system is only at around 40% fan speed.

[RobZ71LM7]

Any updates on thermo availability?

[iCryWheniGoPoop]

Any updates on thermo availability?

From what I'm reading, the Gates 34198 thermostat fits these trucks and I have found them for $8. https://www.carpartsdiscount.com/catalog/chevrolet~corvette~2014.html?3593=431151

 

UPDATE- There are a couple web-sights posting this thermostat for our motors but it can't be right because it fits other LS motors and I'm almost positive ours is different

 

 

Sent from Off Driller Side

Edited August 16, 2015 by TDT