running lower oil temps?

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

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

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.

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).

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

Huh?

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


What??

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

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

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

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.

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...

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.

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.

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.

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.

thanks for all the ongoing input...

ivymike, it's great idea to run the veg fuel through the sump, lube the engine, and then into the fuel system... but there would be a few problems:
1) it is nearly impossible to start an engine on veg fuel, as the fuel needs to be heated up to 170F before it gets thin enough to go through the injectors and atomize/mix with air properly for combustion. This could theoretically be achieved by an electrical heater, but the common way to do it is by engine heat - so the engine is started on petrol diesel, then once things get hot we switch to veg. So, we'd have to bypass the sump during this warmup, and then at shutdown we'd have to make sure the sump is filled to appropriate level with veg fuel again.
2) If we could solve the above, then we'd have to run the veg fuel out of the engine (it was lube) and through the fuel filter, then into the injectors... I wonder if this would kill the fuel filter quickly... particles from the engine?

Can anyone else speak to saabjohan's post on the temps of oil vs coolant? I found a study at http://aigproducts.com/temperature_chart_recorder/Case_studies/case_auto.PDF which shows the engine oil to be much hotter (50-70F) than the coolant. Does anyone know more?

Thanks again,
Erik

Can anyone else speak to saabjohan's post on the temps of oil vs coolant? I found a study at http://aigproducts.com/temperature_chart_recorder/Case_studies/case_auto.PDF which shows the engine oil to be much hotter (50-70F) than the coolant. Does anyone know more?

Thanks again,
Erik

100C to 115C is about right for engine oil in the sump, in a medium-duty diesel application, with 135C being a bit on the extreme side, but achievable.
82C to 100C is about right for coolant, 120C is about the limit.

If I remember correctly, SJ said that there was about 20degC difference, which matches my expectations fairly well.

Automotive gasoline applications tend to run the oil hotter, with 150degC being the upper limit. Coolant is still in the same range.

90-130 degC (89+-2 to 131) is Saabs spec on their B205/B235 engines, the first number is the thermostat opening temperature and the last is the system boiling point. Cooling fans (lowspeed) are activated at 100 degC so this should mean that the operating temperature is normally 90 degC or a little above.

For the oiltemperature a have a chart from a turbocharged engine (no specs but probably a gasoline engine) and some specs on where some oilcoolers are opened which can be from 80 to around 110 degC; this should inticate that the oiltemperature isn't much higher than that under normal operation. The oil on some places can however have a higher temp, for example the oil in a turbocharger is normally 140 degC or so (can climb up to 300 degC after shutdown with a hot turbo).

The average temperature here:
http://aigproducts.com/temperature_...s/case_auto.PDF
seems to be around 115 degC but I wonder if a 1995 Pontiac Bonneville has a oilcooler, the ambient temperature was quite high.

In general there is no problem if the oil temp of a warm engine is a bit cooler as long it doesn't get below 60 degC since at this point the water in the oil will have it difficult to vaporise.

Some other ideas:
- A heat exchanger could possibly be built into the sump. This shouldn't be that hard to do and there is no reason to worry about oilflow.
Perhaps it can be used together with an electric oil heater to reduce warm up time. Some engines have had oilcoolers built into the cooling passages in a similar way.

- Exhausts could be used to heat up the fuel. This is more difficult to build and one must be careful not to overheat the fuel. The advantage is that we have a lot of heat and that it gets warm very quickly.