80 Operating Temperature per FSM

[ShottsUZJ100]

Thanks guys. I have new coolant. I'll grab a cap and look at the clutch stuff. How much is a new clutch if I need one? I might just get it.

 

[Romer]

Thanks guys. I have new coolant. I'll grab a cap and look at the clutch stuff. How much is a new clutch if I need one? I might just get it.

1-800-cruiserdan

 

[SUMOTOY]

I don't see where running with the thermostat partially closed automatically means the clutch is engaged and wasting energy. The clutch is controlled by the air temp that is in front of it. And if that air is cooled to the pioint where the clutch won't come on then it will have no ill effect. This is often true when driving along where ram air provides sufficient cooling.

Well it's technically never disengaged, so it is wasting energy, just a lot less than fully engaged. Ram air is a variable to thermostat closed loop cooling capacity. I don't read into any post that a thermostat partially closed *automatically* means the clutch is engaged and wasting energy. However, you would be wasting energy if the thermostat is partially closed and the VC is locking up.

In my specific case I was running extremely hot during weather that exceeded 85* and towing. The cooling system needed help which I gave it.

What is "extemely hot"? What 'help' was that exactly Rick? And how does it compare to the 203F equilibrium temperature?

Just because my truck is running at 185* now in 70* weather doesn't mean if I removed my clutch entirely that the temp would increase.

Not sure I understand this statement. Simply stated your temp would increase if the total cooling capacity is less than engine thermal load. If it specifically didn't increase, then you have a lot of overcapacity. It dosn't matter what you do, take the fan out, take out the VC, direct drive the fan, block the radiator, increase ram air....

Given a stock thermostat
If engine thermal load = cooling capacity then engine temp = 203F

Rick, try adding cardboard to the front of the radiator until engine operating temps are 200F. What do you observe? Is the fan 'more' locked up than at 185 operating temp? That's the problem. Your thermostat isn't fully open.

I personally believe if you are running at 185, your thermostat isn't even in closed loop yet. It's effectively closed. That much cooling overcapacity, isn't good heat management.

SJ

 

[landtank]

Extremely hot, was with a modified OEM temp gauge it was pegged over the red zone. The red zone begins at 217* and full tilt is well over 230*

The help I gave it was to advance the clutch timing as it was never locking up regardless of how hot it got.

Idling and driving around the truck's temp was maybe around 210*. But as you said there is always some drive there.

In todays weather I am quite sure I could remove the clutch and drive the truck without any issues and maintain 185* while moving. Idilng would be a different story obviously.

If this whole thread was to point out that there is a parasitic loss when running a Viscous clutch you could have just stated the obvious from the begining and got no arguement from anyone I think.

 

[Darwood]

Extremely hot, was with a modified OEM temp gauge it was pegged over the red zone. The red zone begins at 217* and full tilt is well over 230*

By in the red zone do you mean top of needle touching the bottom of the red zone or bottom of needle touching the bottom line of the red zone. In the former the truck is at 212F and in the later 217F. Just making sure you are aware of this.

 

[landtank]

By in the red zone do you mean top of needle touching the bottom of the red zone or bottom of needle touching the bottom line of the red zone. In the former the truck is at 212F and in the later 217F. Just making sure you are aware of this.

It was just as a reference of how the gauge is setup as there have now been a few iterations of the mod. But during my overheating experience the needle had no more room to move hotter on the dial, it was pegged all the way up and could have easily been well beyond the limits of the gauge.

 

[SUMOTOY]

The help I gave it was to advance the clutch timing as it was never locking up regardless of how hot it got.

If this whole thread was to point out that there is a parasitic loss when running a Viscous clutch you could have just stated the obvious from the begining and got no arguement from anyone I think.

The very first post in this thread, really has to do with identifying the point at which engine thermal load = Cooling Capacity = 203F

Specific to your help by "advance the clutch timing", advancing it to engage before 203F would casuse the secondary fan open loop circuit to fight the primary thermostat closed loop circuit.

Parasitic draw from a partially closed thermostat during fan clutch lockup results in unnecessary engine draw (fuel consumption). The thermostat creates a false switch condition for VC fan lockup.

Fuel consumption increases

SJ

 

[cary]

More specifically, water flow is a constant and it's placement doesn't have to favor the front cylinders in cooling. Expect to see dual water system as the next step. 100C block temps for wear and combustion, and much less in head temps to reduce detonation.

SJ

Actually, in BMW's case, they are varying the flow with the electric motor, allowing for full flow at low RPM and reduced flow at higher rpm lighter loads. I agree the application expansion will be a big step forward when we can control head temps much better.

 

[cary]

As I understand it the viscosity does not effect the temperature at which the clutch activates, it increases the ammount of "drive" at any given temperature.

I second (third this). It seems to me that slightly thicker fluid is the way to go. By using the thicker fluid, you don't cause the clutch to engage early, potentially causing additional drag on the engine, but when it does engage, you get more airflow and more cooling.

 

[landtank]

Parasitic draw from a partially closed thermostat during fan clutch lockup results in unnecessary engine draw (fuel consumption).

While looking at this single element I would agree, however my personal experience with my 80 has been when you run the engine over 185* your performance drops and fuel consumption increases. This was also noted by another member.

 

[SWCruiser]

Swcruiser

The last few posts or summaries have been great guys and has really enlightened me as to the balance between radiator and clutch. Thanks! I do have one question though- Do you have any idea why 3000cst was used as opposed to 6000cst or even 10000 if these would have helped to keep temperatures at the 203 mark?

 

[SUMOTOY]

Actually, in BMW's case, they are varying the flow with the electric motor, allowing for full flow at low RPM and reduced flow at higher rpm lighter loads. I agree the application expansion will be a big step forward when we can control head temps much better.

Absolutely my understanding as well cary, bad choice of words. Equilibrium might be a better term, my meaning was constant in terms of coolant capacity vs thermal load. The water pump is creating only enough capacity to equal thermal load. BMW also doesn't run the water pump during the warm up phase, so again coolant capacity vs thermal load is as close to constant as possible.

As BMW touts this as a 1.3% fuel improvement, they are going after every last ounce of fuel efficiency. Sure seems to me that a possible 10-20% in our 80 would be 'massive' in comparison

SJ

 

[SUMOTOY]

While looking at this single element I would agree, however my personal experience with my 80 has been when you run the engine over 185* your performance drops and fuel consumption increases. This was also noted by another member.

Could it be because your fan is now locking up causing more engine load, negating the known thermal efficiency gain?

I personally think a 185* operating temp at 85F ambient means you should be testing the "help" you provided the cooling system. The only way I could see 185* temps '11 months' of the year, is if the VC fan mod you did is providing that (dis)service.

Might be an interesting test, that cardboard.

SJ

 

[SUMOTOY]

I second (third this). It seems to me that slightly thicker fluid is the way to go. By using the thicker fluid, you don't cause the clutch to engage early, potentially causing additional drag on the engine, but when it does engage, you get more airflow and more cooling.

The problem I have with this thinking is that a known property of VC Fans is that 'disengaged' is a percentage of lockup. The universal standard of disengaged VC fan speed iis 45% of lockup, which means that a thicker fluid will have more lockup below engaged temp than a lighter fluid. Could certainly explain Landtank's 185temps, regardless of his 'timing' targetted lockup temp.

Rereading this thread, I'd encourage those looking to go the VC fluid route to work some cardboard into the equation (partially block radiator vs accurate guage temps). This should take the timing and production/age variance out of coupling testing.

SJ

 

[landtank]

Could it be because your fan is now locking up causing more engine load, negating the known thermal efficiency gain?

The test was towing the trailer to the Cape and back, about a 100 miles each way. I live on the Merimac river 10 miles up river from the ocean and the spot at the cape was on the canal so the start and end elivations were very close. On the way down the truck ran 2 needlewidths above horizontal (which I now have confirmed through the ECU that horizontal to be 185*) during heavy loads. On the way back after further advancing the clutch I ran at horizontal the entire trip.

So on the trip down the engine ran warmer and the clutch was on less.

On the return trip the clutch was engaging sooner and it was confirmed by lower operating temps.

So according to these papers my MPG on the return trip should have taken a double hit, 1- loss in thermal efficency and 2- higher parasitic loads from the clutch.

I did record MPG both ways and saw an increase on the return trip as well as less downshifting to maintain speed.

My only thought is that the cooler engine allowed for a cooler air intake temp and a cooler head helping to avoid pre-ignition pinging. Quite a few have noticed this pinging on their trucks. Both these conditions will rob an engine of power quickly as I'm sure you know.

I'm not interested in doing any cardboard testing. Next season I might look into insulating the filter canister as I saw a nice drop in air temps and it negated the need for cutting holes in the hood. After that I'll see if I can retard the clutch timing and see how that effects the MPG.

This will happen after evaluating the MPG change this winter. I've historically see 16.4 MPG rolling down the freeway at 75-80 MPH. That was recorded last year after my injection swap.

 

[SUMOTOY]

So according to these papers my MPG on the return trip should have taken a double hit, 1- loss in thermal efficency and 2- higher parasitic loads from the clutch.

I did record MPG both ways and saw an increase on the return trip as well as less downshifting to maintain speed.

My only thought is that the cooler engine allowed for a cooler air intake temp and a cooler head helping to avoid pre-ignition pinging. Quite a few have noticed this pinging on their trucks. Both these conditions will rob an engine of power quickly as I'm sure you know.

I'm not sure I buy cooler engine temps causing a meausrable cooler IAT with no other changes. I would expect more radiator heat exchange to cause higher IAT. Do you have the coolant circuit hooked up to the tbody? Since I deleted that circuit, I have experienced no pinging, even with the supercharger. I do however, use premium gasoline in my rig.

To really attribute this gas mileage to cooler operating temps, some better methods might be in order. Under the same conditions, run a 200F operating temp. And isolate the fan VC mod to a temperature.

IIRC you saw a .5mpg increase above, which really is tough to attribute to *any* change Rick. A 10% gain due to lower fuel consumption at 203FF, and more gain by putting the fan engagement back to something over 203F should yield you something in the 'hood of a couple mpg, IMO.

That has significance you can isolate via road testing. .5mpg would require a dyno and possibly a lot of calculations.

My thinking is to run a dyno baseline with radiator fan locked up, then one with no radiator fan at all. I suspect that mongo fan Mr. T puts in there moves a lot of air at the expense of a lot of engine power.



Scott Justusson

 

[landtank]

Scott, I'm not selling anything.

It is what it is and two of have seen the same thing.

The .5MPG represents a 5% increase.

Just some real world info and a little speculatiion thrown in, nothing scientific.

A 10% gain due to lower fuel consumption at 203FF, and more gain by putting the fan engagement back to something over 203F should yield you something in the 'hood of a couple mpg, IMO.

I'm not sure what you are missing here but the truck ran like crap when it was in that range. I've had my ass in that chair for the last 160,000 miles and this is something you can bank on.

 

[SUMOTOY]

I'm not sure what you are missing here but the truck ran like crap when it was in that range. I've had my ass in that chair for the last 160,000 miles and this is something you can bank on.

Something *you* can bank on. IME running these temps with a supercharger and without, my truck runs like crap when *underhood* temps are high (and if my oil is getting near service, bad idle). At A/C cutout temps and steam out the radiator, I'd get a WOT stumble. I knew it was coming when the vent temps started to climb.

I, er tested this overheat (steam baseline) 6 times. My real world observation says whatever the vents do, my VC lockup is less, and I haven't had any underhood stumbles regardless of operating temp.

My calculator shows 16.4 up .5mpg to 16.9 = 3%

We need to watch out, the data sharks are sensing blood!



Scott Justusson

 

[SpenserAK]

.

 

[Dusten]

The OEM thermostat is 180 degrees.
The operating temp should hover around 18

Temps should creep slow around 170 as the thermostat prepares to open and begins to allow coolant to cycle.

I bet closed loop is closer to 160 or 170

My lightning is a 185 t-stat and closed loop is 170.