High RPMs...thick or thin?

[Shannow]

Originally Posted by OilUzer

How about let's say a car with manual trans. going 35mph on flats or slight down hill @ 2300 rpm vs. doing the same rpm & gear going uphill or slight uphill?
will the heat from the bearings be the same since the same rpm? The temperature in cylinders (combustion) will obviously be much higher going uphill.


OilUzer...I had a caprice (Oz RWD) with the L67.

Using a type K thermocouple down the dipstick hole, I could measure the oil temperature right where the oil all drained back....method was to drive at 100km/h, drop it into neutral and turn the engine off and pull to the kerb. pop the bonnet and drop the T/C down the dipstick tube to the point measured the same as the "add" on the dipstick.

In drive, at 100km (15 km highway speed), 1,800RPM the oil read 95C regularly.
Drop it into 2, same speed, road, but nearly 4,000RPM...same road load, same "road friction" (I hear it's higher in some places and makes a difference), same pull over point, I saw 129-135C oil temperatures...with ILSAC 5W30s, or A3/B4 5W30s.

Only difference at all was the engine speed...road load, aero, all the same.

 

[OilUzer]

Originally Posted by Shannow
Originally Posted by OilUzer

How about let's say a car with manual trans. going 35mph on flats or slight down hill @ 2300 rpm vs. doing the same rpm & gear going uphill or slight uphill?
will the heat from the bearings be the same since the same rpm? The temperature in cylinders (combustion) will obviously be much higher going uphill.


OilUzer...I had a caprice (Oz RWD) with the L67.

Using a type K thermocouple down the dipstick hole, I could measure the oil temperature right where the oil all drained back....method was to drive at 100km/h, drop it into neutral and turn the engine off and pull to the kerb. pop the bonnet and drop the T/C down the dipstick tube to the point measured the same as the "add" on the dipstick.

In drive, at 100km (15 km highway speed), 1,800RPM the oil read 95C regularly.
Drop it into 2, same speed, road, but nearly 4,000RPM...same road load, same "road friction" (I hear it's higher in some places and makes a difference), same pull over point, I saw 129-135C oil temperatures...with ILSAC 5W30s, or A3/B4 5W30s.

Only difference at all was the engine speed...road load, aero, all the same.



intetesting, Almost %42 increase in oil temperature due to higher rpm! I had a small car iirc was 1.8 or 1.6 L and after going fast or going uphill for a while at speed limit, I could feel the heat difference if i popped the hood. Was like getting out of Vegas casinos in the summer and the sudden heat wave !

My car om says something like "use thicker oil (one with higher number lol) for high speed driving or high load ..." It may result in even more heat but it will protect the engine!

 

[Gokhan]

Originally Posted by Shannow
Cool, now 80,000lb trucks on an 8% grade are pertinent to passenger car engine oils and thin/thick and RPM...

And I get accused of diverting threads.

When you see this in your rear-view mirror, all of a sudden, it becomes very pertinent.

 

[ZeeOSix]

This was an interesting graph showing that engine RPM is the main factor in raising the oil temperature. The engine load does have a small effect, and that effect is greater at low RPM than it is at high RPM.

 

[ZeeOSix]

Originally Posted by Gokhan
Originally Posted by Shannow
Cool, now 80,000lb trucks on an 8% grade are pertinent to passenger car engine oils and thin/thick and RPM...

And I get accused of diverting threads.

When you see this in your rear-view mirror, all of a sudden, it becomes very pertinent.

Only if you're both going down the 8% grade and that truck lost its brakes.

 

[Shannow]

Originally Posted by ZeeOSix
This was an interesting graph showing that engine RPM is the main factor in raising the oil temperature. The engine load does have a small effect, and that effect is greater at low RPM than it is at high RPM.


Yeah, I know...I introduced that chart to the board...but clearly, RPM is the bigger of the variables...note I have never said that load is not a varaiable, but RPM is more of an influence.

Same with the warmup one that I've posted before...and verified by quite a few members that holding 2,500RPM early in their trip more rapidly brings the engine up to temperature.

 

[OilUzer]

Shannow,
You had a nice chart showing the impact of heat from combustion on the engine oil or engine block.
It was an older chart. I have it on my computer. It was like blocks or slice of heat going this way or that way ...

I think the high load results in additional combustion heat and small part of it transfers back to engine block. Your pie/block chart was showing that as well.

 

[Shannow]

These ???

 

[OilUzer]

Yes, there was one more. See if I can find it. I'm on my little tablet. I saved it on my laptop.

It was called energy flow diagram for an IC engine. I found it but with tablet i can't do much.
That's it, showing not much combustion heat going back to the sump!

 

[OilUzer]

Here is your flow diagram:

 

[PimTac]

Originally Posted by ZeeOSix
Originally Posted by Gokhan
You're overlooking the fact that you can't climb a steep grade in overdrive. It's going to be high RPM and high load.


You don't have to down shift and rev the engine to 6000 RPM unless the car has about 50 HP max. I can drive over mountain passes on cruise control and never have to downshift. It all depends on how much low end torque (and hence low end HP) the engine makes and the gearing.





Zee, it would depend on the pass and some passes are very easy. Snoqualmie is a good example. That's is basically a bump.

I drove a Mitsubishi 1.8 4 cylinder a few times over the Siskyous. That is a much more demanding pass. It had a 4 speed Auto with a button to lock out the 4th gear overdrive. I had to use that for most of the crossing so my rpms were up there. There was no oil temp gauge so I had no idea how that was but I assumed it got a good workout.

 

[CR94]

Originally Posted by Shannow
Cool, now 80,000lb trucks on an 8% grade are pertinent to passenger car engine oils and thin/thick and RPM...
Exactly as pertinent as a Corvette. The principles are the same, whether power/mass ratio is high, low, or moderate.

 

[PeterPolyol]

Originally Posted by Shannow
These ???

There's the stuff. Check out that exponential rise in heat conversion in just 2K RPM. Imagine 9K in an F20C or a 6+ cyl at 8500... the last thing anyone would want is to pump hundreds of additional Watts (if not KWs in some engines/viscosities) precisely into the highest shear points during the most severe operation..

 

[ZeeOSix]

Originally Posted by PimTac
Originally Posted by ZeeOSix
Originally Posted by Gokhan
You're overlooking the fact that you can't climb a steep grade in overdrive. It's going to be high RPM and high load.

You don't have to down shift and rev the engine to 6000 RPM unless the car has about 50 HP max. I can drive over mountain passes on cruise control and never have to downshift. It all depends on how much low end torque (and hence low end HP) the engine makes and the gearing.

Zee, it would depend on the pass and some passes are very easy. Snoqualmie is a good example. That's is basically a bump.

I drove a Mitsubishi 1.8 4 cylinder a few times over the Siskyous. That is a much more demanding pass. It had a 4 speed Auto with a button to lock out the 4th gear overdrive. I had to use that for most of the crossing so my rpms were up there. There was no oil temp gauge so I had no idea how that was but I assumed it got a good workout.


Guess I'm use to driving a 3100 lb car with 400+ HP. Sure if a car has low HP you're going to have to shift down to get some needed power to climb steep grades. My example with the Z06 showed it needs 57 more HP to climb an 8% grade at 80 MPH then it does cruising at 80 MPH on a flat road. If a car only puts out 150 HP max, it's obviously going to have issues maintaining good speed going up an 8% grade.

 

[Gokhan]

Originally Posted by ZeeOSix
Originally Posted by Gokhan
Originally Posted by Shannow
Cool, now 80,000lb trucks on an 8% grade are pertinent to passenger car engine oils and thin/thick and RPM...

And I get accused of diverting threads.

When you see this in your rear-view mirror, all of a sudden, it becomes very pertinent.

Only if you're both going down the 8% grade and that truck lost its brakes.

The Plymouth Valiant was no match to it.

 

[PimTac]

I remember that movie. All those idiot lights on the Valiant were flashing like crazy yet it kept going.

Great movie.

 

[ZeeOSix]

Originally Posted by Gokhan
The Plymouth Valiant was no match to it.



It was a movie (realism suffers for the drama factor). A syco in a semi tying to kill citizens in passenger cars, rattle snakes and tarantulas ... what more could a great movie have?

I think those license plates on the front bumper are his "kill counts" ... like on the side of an old WWII fighter plane.

Maybe the semi had a 2000 HP diesel so he could run down cars, or maybe the guy in the Valiant was running 0W-20 with a low oil level and the engine was spinning bearings from too much oil break down and losing power ...

 

[02SE]

Originally Posted by Gokhan

The Plymouth Valiant was no match to it.



How dare you blaspheme the slant 6. There have been recent topics on the leaning tower of power...

 

[53' Stude]

Originally Posted by PimTac
I remember that movie. All those idiot lights on the Valiant were flashing like crazy yet it kept going.

Great movie.


I want to know if the trailer behind the peterbilt is a fuel trailer or....

 

[demarpaint]

Originally Posted by 53' Stude
Originally Posted by PimTac
I remember that movie. All those idiot lights on the Valiant were flashing like crazy yet it kept going.

Great movie.


I want to know if the trailer behind the peterbilt is a fuel trailer or....


Septic system cleaner tank.........................