Oil temp calcs?, Approx. Btu/hr based on rpm? Options

[Teutonic Speedra...]

Anybody know a real rough estimate or calculation from an engine book on how many btu/hr are introduced to engine oil based on rpm? I may just make something up, but we are trying to figure this out for a project for class.
:stupid:

[slowTA]

I would use the amount of heat generated by the fuel as an absolute maximum. Then just for good measure I would take 80% (IMG:http://www.frrax.com/rrforum/style_emoticons/default/unsure.gif)

You can always get the car warmed up then make a few quick blasts around the block, measure the before and after temps. Figure out how long the engine was at what RPM for WOT, get the total number of revolutions. If you have scanning capability you can find the injector pulse width and find the flow rate if you know the fuel pressure. You know the approximate mass of oil, if you don't have an oil cooler then you MIGHT be able ignore most of the convection running across the oil pan. If you have an oil cooler you can find out the ambient temperature and use a simple air to water heat exchanger problem. The speed of the air is just the vehicle speed. The thermal properties of fuel might be available online, but for a basic example I just did the internal combustion lab at school. I found the fuel values to be: specific gravity=.731, higher heating value=20,400 BTU/lb, density of fuel=45.62lb/ft^3, with an API of 62.

An extremely simple problem really (IMG:http://www.frrax.com/rrforum/style_emoticons/default/rotf.gif)

[felton316]

Only thing I can find is: 1 horsepower is 2,545 BTU/hr.

[94bird]

Just going from memory, try JR's value for HP --> Btu/hr and assume that the coolant losses (including oil) are about equal to the actual engine power output at the flywheel. Now, assume the oil only takes maybe 30% of the heat away and the radiator coolant takes the other approx. 70% away.

It's a starting point, but these are all VERY rough numbers. They can change rapidly based on engine rpm, CR, fluid temps, etc.

[94bird]

I took a look at thermal survey results from 2 engines at work today. One was a turbo 4 cylinder and another was a n/a V8. Both use piston oil squirters so they might have a little additional heat put into the oil than most engines, but the amount of heat rejected to the oil was only about 10% of the peak power number.

[Teutonic Speedra...]

I took a look at thermal survey results from 2 engines at work today. One was a turbo 4 cylinder and another was a n/a V8. Both use piston oil squirters so they might have a little additional heat put into the oil than most engines, but the amount of heat rejected to the oil was only about 10% of the peak power number.

Thanks for the info!

[slowTA]

When I go to work on Monday I'll take note of the oil and water temperatures versus the exhaust temp, I didn't think of it that way before Mike mentioned it. On the plus side we're using a bunch of LS1's. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/thumbup.gif) But in the negative column we run the engines with almost no timing in order to increase the exhast temps. The oil, water, and dynos are run through liquid to liquid heat exchangers so I'm not sure how much my numbers will help you. I do remember that our exhaust temps range from 850 to 1000 *C, so 10% sounds like a better number than the 80% I said last time. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/huh.gif)

[Teutonic Speedra...]

When I go to work on Monday I'll take note of the oil and water temperatures versus the exhaust temp, I didn't think of it that way before Mike mentioned it. On the plus side we're using a bunch of LS1's. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/thumbup.gif) But in the negative column we run the engines with almost no timing in order to increase the exhast temps. The oil, water, and dynos are run through liquid to liquid heat exchangers so I'm not sure how much my numbers will help you. I do remember that our exhaust temps range from 850 to 1000 *C, so 10% sounds like a better number than the 80% I said last time. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/huh.gif)

Where do you work?

[slowTA]

www.engelhard.com/

If you can't tell from the website we test catalytic converters (IMG:http://www.frrax.com/rrforum/style_emoticons/default/wink.gif) The engine lab is in Union. Don't get jealous, by the time they’re done with any of the engines they’re well toasted, not worth much at all, and would need a complete rebuild. The company is pretty big and has thier hands in everything, that's why they have other things on their website.