'06 Ram w/Diesel -- Doesn't 'hold' heat

Page 2 of 4  


Please explain to me exactly how the liquid within the block is going to do much of anything when the engine is not running and it is not moving? A V-8 would not have as much surface area as an I-6 or to put it much more accurately, not as much surface area in relation to total area.
--
If at first you don't succeed, you're not cut out for skydiving



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Doesn't liquid moving or motionless wick heat from metal?

I really don't know if that is correct or not. But, there are a heck of a lot more parts to hold heat in a V360 than in a I-6
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Wick it to where? The water is contained within the block so where is it going to send the heat? When the engine is running the water carries the heat to the radiator but when the engine is not...

Just looking at it you can see that it does. In an inline block, both sides of the cylinders are exposed to the outside air while in a V configuration, only one side of each bank are exposed not to mention all of the internal webbing that a V series has that simply doesn't exist with an inline block.
--
If at first you don't succeed, you're not cut out for skydiving



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Even if the engine is not running, natural convection will cause water currents to move within the engine thus transferring heat. Also, heat is transferred from hot to cold thus the cooling of the exterior of the engine will cause the heat to be transferred to the cooler exterior. If your previous statement were true, the interior of the engine would never cool off.
Mike

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

1) Heat moves through different substance at different speeds. I don't know the relative heat conduction of oil, water/coolant and cast iron. 2) Solids can only transfer heat via conduction or radiation, while liquids can also transfer heat via convection. I'd be willing to bet that some convection occurs inside an engine after shutdown.
It would require an engineer to calculate how fast any engine would cool down from normal operating temperature to any given ambient temperature because of a huge number of variables (many of which I probably wouldn't even think about). We could heat two trucks to normal temperature, then park then near each other, then measure the time it takes to cool down. But, where do we measure the temperature - the thermostat, the oil pan, the location of the temperature gauge sending unit, the side of the block, the geometeric center of the engine?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

First, congrats on the most reasoned approach to the vexing problem of the rapidly cooling Cummins. This thread appears to be getting a tad <ahem> out of hand!

The property you are referring to is thermal conductivity which is conventionally expressed as "k". "k" is = Btu/h/ft2/degreesF/ft. The "k" of materials varies greatly, for example the "k" of water is .343 @ 32 degrees F while the "k" of wrought iron is 34.9 @ ~60-212 degrees F. Interestingly, with the exception of most metals, the "k" varies with temperature, increasing as temperature rises. The reverse is true in crystalline materials.

Not exactly true as solids can indeed transfer heat via convection. Conduction is the transfer of heat from one part of a body to another part or to another body by short range interaction of molecules and/or electrons. Convection is the transfer of heat by the combined mechanism of fluid mixing and conduction. A good example is a forced air electric furnace. The heat from the electric coil is transferred to the air via convection. Radiation is the transfer of heat in the form of electromagnetic waves. All bodies above absolute zero radiate. I'd be willing to bet that some

Actually, all three are occuring simulataneously!

Any engineer who attempt to calculate this is sending himself on a fools errand. As you correctly observed, there are simply too many variables to accurately predict what will happen. I remember years ago in one of my engineering classes the professor gave us a drawing of a table with four legs. On the table were stacked randomly a series of books. The weight of each book was given and the relative placement of each stack was accurately represented. Our challenge was to "determine" the amount of weight (or load) each table leg was bearing. We were given one hour to solve the problem. Off we went with slide rules and formulae to calculate the load on each leg. At the end of the hour we each presented our results and the methodology. All of us were wrong! How then could the load be determined, we asked? He said that you simply picked up the table and weighed each leg on a scale. A lesson in practical engineering I remember to this day!
We could heat two trucks to normal temperature, then

Now yer talkin'!

A good point! Where, indeed? Since each engine is different, what do you use as you reference point? Probably the most logical is the geometric center, then both engines must be heated to the same temperature and then record the time each engine takes to reach equillibrium with ambient. That would be my guess...
Mike

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Fastinating. Questions... 1) From your equation, it looks like a higher "k" value mean faster heat transfer. Is that correct? 2) What is "h" in the above equation? 3) What is the "k" of water at say 75F or 212F? If one where to plot the "k" of water vs. the temperature of water, would that be a straight line, a logarithmic line, or would there be peeks and valleys? 4) Does pressure affect the "k" of water at different temperatures?

Whoa, I'm a little lost on this one. I would think that the heat would be transfered to the air at the solid coil/fluid air interface via conduction and radiation, then the fluid air would transfere it primarily via convection. In other words convection would be occuring at the solid/fluid interface, which means...I had to think this one through while typing my response, but I think see it now.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes
Hours
The "k" of water is relatively stable until the phase change occurs. For example the "k" of water @ 140 degrees F is .377. Once the phase change to ice occurs, the "k" increases to 1.26. A phase change to steam @ 200 degrees F results in a "k" of .0132.

Only after the phase change to steam.

Yeah, I think you got it! Radiation in this example plays a very minor role since radiation doe a poor job of heating air since air is mainly made up of empty space. You can take a radiant heat source in a cool room and stand some distance away and "feel" the warmth impinging on your body, but the air temp between you and the heat source remains relatively unchanged. That's why space between us and the sun remains quite cold... there's nuthin' to heat!
To elaborate (a little) on the convection example above, there are really two forms of convention, natural and forced.
I hope this clarifies it for you.
Mike

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That kinda sounds like the difference between an over-paid Detroit enginneer and a mechanic with common sense..........
<VBG>
Denny
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Denny wrote:

And what if the weight problem your engineer needed to solve was 1000 miles away? Going to fly him out there?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You must be an enginneer with this thinking.... How about telephones...pictures....internet....
Denny
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Denny wrote:

So your "practical" engineer can build a duplicate of the problem in his shop, and then weigh it?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Why in the fuck would I "want" to weigh a patio deck????? What in the hell happened to all the common sense in this world??? I'm starting to think you ain't got the brains to pound sand in a rathole....
Denny
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote in message >I'm starting to think you

It would seem, my floppy eared friend, that you just might of hit on it.
Roy
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Denny wrote:

Exactly, you wouldn't. Especially with a jacuzzi tub positioned at (60,20)

Good. A start is good.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Given the way you addressed me, that's kind of funny. However, no where did the OP ask about it compared any engine configuration, other than gasoline. He doesn't mention V-8 or I-6, except that we know he has an I-6.
Furthermore, I'm not sure about Beryl's assumption that an I-6 has more surface area than a V-8. After all, a V-8 has two cylinder heads sticking out in the air, which implies more surface area because there are 2 more sides to account for. And usually a V-8 has more displacement that an I-6. It's far to general a statement. One can compare specific engines, for instance the Cummins 5.9L and the Magnum 5.9L
I don't know what the surface area of a Cummins 5.9 is compared to a Magnum 5.9, but the Cummins has a bore of 4.02" and a stroke of 4.72" where as the Magnum has a bore of 4" and a stroke of 3.58" which means that the surface area of the cylinder which the piston travels past is actually larger on the Magnum by about 2 square inches. Of course the actual surface area of the cylinder walls in both engines is larger and that's no way to measure the outside surface area of the engine, but it's interesting to note. Does anyone here know the surface area of the Cummins engine, and/or a the Magnum 5.9?
Also, the surface area is only one part of the equation. How about thermal mass? I don't know the weight of the Cummins engine, or the Magnum, but I understand those Cummins are pretty heavy. That implies more thermal mass, which will hold the temperature longer.
Finally, I can't speak from experience about the Cummins cool down time, but my Duramax 6.6L V-8 diesel cools down at about the same rate as the OP's. I don't know the surface area, weight, or thermal mass of that engine either, but anecdotally, it doesn't support Beryl's claim.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The way that I addressed you???? Give me a break. You are really grasping at straws here. As for the engine configuration, while the OP did not ask for a comparison between different types, the inline configuration of the Cummins is a factor in how fast it loses heat.

Then I guess that you never really looked at an inline engine.

That would be true if it wern't complete BS. There is almost the same amount of surface area between the two. While the V series has two heads, they are about half as long so where is the gain. The only gain is in the added area from the two added endpoints which really doesn't add up to all that much.

Really??? Since you have just claimed that the Cummins has a slightly larger bore and a much longer stroke (which would make sense since it has two less cylinders and the same displacement), how exactly does the Magnum have a LARGER surface area per cylinder??????

What exactly does "the actual surface area of the cylinder walls in both engines is larger" even mean? Larger than what??? This is not a wise crack, I really don't understand what you are trying to say here.

More thermal mass means that it can store more heat energy, not necessarily that it can hold temp longer. Thermal transfer rates and the surface area exposed has a lot of influence on how quikly that heat is pulled from that mass.

That would be valid only if your and his truck were exposed to the same temp and have the same or similar under hood conditions. I don't know if that is the case or not and neither do you. I am not saying that Beryl is correct in this theory, only that it was on point with the OP's question and was a valid theory.
--
If at first you don't succeed, you're not cut out for skydiving



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Correction, "_total_ the surface area of the cylinder_s_ which the piston_s_ travel past..." The Magnum has a smaller surface area through which the piston travels per cylinder, but the surface area for all the cylinders is slightly greater in the Magnum. I made a linquistic mistake and if I posted the formulas below this probably wouldn't be an issue.
Magnum 5.9 surface area for the piston travel = 4" x Pi x 3.58" x 8 = 359.7 square inches. Cummins 5.9 surface area for the piston travel = 4.02" x Pi x 4.72 x 6 357.5 square inches.

The cylinders walls have to extend below the top of the pistons so that the pistons will remain in the cylinders. Therefore, the actual surface area of the cylinder walls is larger than what I calculated.

conditons outside of the hood that need to be the same for a meaningfull comparison.
I mis-represented myself in my haste to post (dang, I should've been a poet) and caught it only after I clicked the send button. What I should have said is that my 6.6L Duramax cools faster than my 5.9 Magnum in approximately the same conditions. Those conditions - since I bought the Duramax - have been such that, after sitting for about an hour, no matter what the ambient tempurature is, the DMax engine has to run for about the same amount of time for the tempurature gauge to read above it's low of 180F as compared to the amount of time required heat it up at sunrise after sitting all night. This is anecdotal as I haven't actually sat with a stop watch and a thermometer, but I believe it to be true.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Edith:

It isn't anecdotal to you, Edith, whether or not you used a stopwatch and thermometer. It is anecdotal to the rest of us. Whether or not you used a stopwatch and thermometer.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Edith:

...
Your issues go beyond linquistic mistakes, you moron.

Now that you've explained what you were talking about, no, this isn't interesting to note.

Combustion chamber surface area has nothing to do with however much cylinder sleeve extends below. Including the cylinder heads would have made some sense. But you didn't, of course, so I have to tell you.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.