Quote:
Originally Posted by teoman
Assuming the car at 2000 rpm consumes 10 liters of fuel at 100km/h. That makes 10 liters per hour...
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This is a good and reasonable assumption, and I'm seeing similar figures with my Magnum.
So... Using this figure, and assuming a 14.7:1 mass ratio of air to fuel, I come up with 1.51 m^3/minute of air being ingested into the engine.
Quote:
Originally Posted by teoman
Lets assume that i am cruising at 2000 rpm with my 3.7L engine.
I do not have a turbo and i am assuming volumetric efficiency of 100. To redo my calculations yourself you can use this site that calculates airflow, and you can plug in your boost pressures etc... :
Engine Air Amount Calculator
So at 2000 rpm, my engine consumes 4.6m^3 of air per minute. |
4.6 is about 3 times that of 1.51. This is because that linked website assumes wide open throttle. That's good for base turbocharger calculations, but bad for calculating part-throttle cruise. Remember, there's a vacuum in the intake manifold, which is necessary for gasoline engines because the vacuum performs the oxygen metering.
Let's go through the rest of the calculations here - I've bolded all the numbers that would change as a result of the revised volumetric flow rate.
Quote:
Originally Posted by teoman
239 * 1.51 = 360.9 calories to heat it up by 1 deg (per minute).
Lets assume that the outside air is at 20 degs C and i want to bring it up to 80 deg C.
60 deg C temp difference so:
21653 calories are needed per minute. ( I have calories so:
Divide that by 540 we get 40.1 grams of water vapor are needed.
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Just to check feasibility, that would roughly make: 2.40 liters of water per hour.
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That makes your water to fuel ratio 2.4/10, or 24%. Seems much better than 70%.