running lower oil temps?

[zharzhay]

Hello,
I am engineering some modifications that utilize engine oil to heat alternative fuels. Because of this heat exchange, the engine oil will probably run about 20-30 degrees (farenheit) cooler. So, if the average oil temp is about 220-240, mine will be around 190-220. Will this be a problem in the long run?
I realize this will delay warmup... if I plan to use it in a more temperate climate (southeast), where temps are rarely below freezing, what will the implications be? What if I was to use it in colder climates (northeast).
I can give more info if you're interested.
Thanks for your input,
Erik

[pod]

your engine should run longer due to the fact that in cold weather the cyl shrinks more than the block

[MustangRoadRacer]

cooler oil is good.
good for engine life and more horsepower actually.
some high performance cars, and Diesel trucks actually use engine oil coolers (looks like a radiator only smaller) to cool the oil.

It most likely will not affect the car too much on startup, because when the oil is cold, it is harder to take heat away from it using whatever methods you plan on using.

[SaabJohan]

Why don't use engine coolant instead? It warms up more quickly and the heat exchanger can easily be mounted on the tubes to the radiator.

Many cars use oilcoolers but they are often shut off when the oil is cool, much like the coolant flow to the radiator is stopped. Some oilcoolers are also cooled by the coolant, this speed up the warm up and they have no need of any valves that shut the flow off.

When the engine is started the oil should heat up fast as this keeps the wear and oilpump losses to a minimum. After that the oil can be a little cooler (use a little thinner oil with that).

[ivymike1031]

Originally Posted by pod

your engine should run longer due to the fact that in cold weather the cyl shrinks more than the block

Huh?

[ivymike1031]

Originally Posted by MustangRoadRacer

cooler oil is good.
good for ... more horsepower

What??

[zharzhay]

hello all, thanks for the responses...

SaabJohan, I would like to use the engine oil because it runs much hotter (230-240F) than the coolant (170-180F). This extra heat would simplify the rest of my design. However, if the heat exchange will significantly increase the time it takes for my oil to warm up to a functional temp, then I would have to add a switch to bypass the exchange system until the engine is warmed up... yes?

ivymike1031, do you have any advice?

Thanks again,
Erik

[ivymike1031]

I don't have enough information about what you're doing to make any sensible suggestions at this time.
The first questions that come to mind are:
* What is the fuel, and what is the goal of heating the fuel? Ease of pumping? Improved combustion?
* What are the detrimental effects of not heating the fuel, for both short (startup) and long (sub-zero operation) durations?

I would recommend that you drop in on the yahoo highefficiencyvehicles discussion group, as you may be able to find some helpful information there.

http://groups.yahoo.com/group/highefficiencyvehicles

[pod]

Originally Posted by ivymike1031

Huh?

when a cyl is as cold as a block it shrinks more than the block can compansate for

[ivymike1031]

Originally Posted by pod

when a cyl is as cold as a block it shrinks more than the block can compansate for

I guess that by "cyl" you mean cylinder liner, since the "cyl" in a parent-metal configuration technically IS the block. Are you talking about a cast iron liner in an aluminum block (in which case you'd be wrong), a cast-iron liner in an iron block (in which case you may or may not be right, but the difference is small), or something else?

Since it turns out that this discussion is in regard to an international turbo diesel engine, probably a powerstroke, we might be able to come up with the actual engine configuration in question. I'm not completely sure what configuration the powerstroke engine uses, but I'd guess (top of my head) that it's a floating iron liner in an iron block, and that the thermal expansion coefficients are approximately equal.

[ivymike1031]

Originally Posted by ivymike1031

Since it turns out that this discussion is in regard to an international turbo diesel engine, probably a powerstroke, we might be able to come up with the actual engine configuration in question. I'm not completely sure what configuration the powerstroke engine uses, but I'd guess (top of my head) that it's a floating iron liner in an iron block, and that the thermal expansion coefficients are approximately equal.

strike that, I just checked with one of our mechanics, who tells me that the powerstroke v8 uses a parent-metal bore in an iron block. So the cylinder is just a hole in the block, and the metal expands and contracts at the same rate vs temperature. The cylinder should be hotter than or as hot as the rest of the block under all operating conditions that come to mind...

[SaabJohan]

Originally Posted by zharzhay

hello all, thanks for the responses...

SaabJohan, I would like to use the engine oil because it runs much hotter (230-240F) than the coolant (170-180F). This extra heat would simplify the rest of my design. However, if the heat exchange will significantly increase the time it takes for my oil to warm up to a functional temp, then I would have to add a switch to bypass the exchange system until the engine is warmed up... yes?

ivymike1031, do you have any advice?

Thanks again,
Erik

The oil temperature isn't that much higher than the coolant temperature. Coolant temperature is often around 90 degrees C (194 F), maximum temperature around 130 degrees C (266 F). Oiltemperature is in general 10 degrees C higher than the coolant temperature (depends on where you take the oil, but usually from the oil filter) so it's just above 100 degrees C (212 F) or so under normal conditions. A normal oilcooler is usually fully open at 180 degrees F.

The coolant is also much likely to contain more energy than the oil so unless you must up to temperatures above 180 F (the efficiency of the heat exchanger will likely be under 100%) or so there is no reason to use the oil.

[ivymike1031]

you know, one thing that might be worth looking into, depending on what kind of veg oil you're thinking about using is whether it would be suitable for use as an engine lubricant (castor bean?), . The concept I have in mind is drawing the oil from the fuel tank into the sump while the engine is running, then drawing it from the sump into the fuel circuit. You could eliminate oil changes that way - the oil would constantly be changing as you drove. One problem that comes to mind is what to do if you ever run short of veg oil - I don't suppose standard diesel fuel would work very well in this sort of application.

[MustangRoadRacer]

well, cooler oil helps keep the engine cooler which nets more power. This is only true up to a point of course, as a cold engine will not perform as well as one in normal operating temps.
but the effect is most noticeable in the cylinder heads which, when cooled, help to keep the incoming air/fuel mixture cool for more power.
That's all I meant.

[ivymike1031]

Originally Posted by MustangRoadRacer

well, cooler oil helps keep the engine cooler which nets more power. This is only true up to a point of course, as a cold engine will not perform as well as one in normal operating temps.
but the effect is most noticeable in the cylinder heads which, when cooled, help to keep the incoming air/fuel mixture cool for more power.
That's all I meant.

Yeah, a cooler intake charge is more dense and will result in greater power output. I wouldn't expect 20deg cooler oil to have a noticeable effect on charge air temps, especially if that heat is intentionally redirected to the intake charge (heated fuel). On the other hand, cooler oil is more viscous, and significantly increases friction losses within the engine. As such, running the engine oil hotter is commonly cited as a way to improve power output through reduced friction.