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...Macaw...
..let my quote Albert Einstein...
..if you can't explain it simply, you don't understand it well enough...with that out of the way let me try..
A "combustion engine" is a device which converts the chemical energy stored in a fuel into heat energy, and then converts a portion of that heat energy into mechanical work.
It is a known fact that a piston engine does a rather inefficient job of converting fuel energy into power. The rule of thumb approximation is that nearly 1/3 of the fuel energy goes out the exhaust pipe as lost heat, approximately 1/3 of the fuel energy is lost to the cooling system (coolant, oil and surrounding airflow), leaving roughly 1/3 of the energy (best case) available for power output. Some of that power is lost to making the pistons go up and down, driving accessories (oil pump, coolant pump, alternator, vacuum pump, hydraulic pump, etc.), losses from pumping air through the engine, thrashing the oil in the crankcase, and friction in various forms.
hot air is less dense than cold air...less dense air within the cylinder will give less temperature, less pressure and less velocity when the A/F mixture is ignited and the combustion process begins...the thermal efficiency of an engine..
for a given throttle position (a 1/8 throttle) on a hot day probably will not get you out of the garage due to the poor thermal efficiency of the engine to produce work so more throttle is required to get going so more fuel...on a cold day with the same throttle position (1/8) you'll be flying down the road..
Sorry Albert...I guess I don't understand it well enough either..
The inside cabin air is pretty stagnant compared to the air coming in from the side scoop. The objective is to push in as much fresh air into the engine. In order to do this from the inside cabin, you would need some sort of a blower to blow air into the engine. The blower from the A/c unit does not have enough CFM to properly supply air into the engine.
if you put your hand over the exhaust, you will get an idea of how much new air you will be drawing into the cabin while sucking it out for the engine. it will be very hard for the AC to keep up with the volume of air.
However, you could use it for short bursts, turn off the AC, open the interior valve, suck all the nice cool air out of the car, get on the Freeway, then drive super economically while the engine works to cool the car again.
...Macaw...
..let my quote Albert Einstein...
..if you can't explain it simply, you don't understand it well enough...with that out of the way let me try..
A "combustion engine" is a device which converts the chemical energy stored in a fuel into heat energy, and then converts a portion of that heat energy into mechanical work.
It is a known fact that a piston engine does a rather inefficient job of converting fuel energy into power. The rule of thumb approximation is that nearly 1/3 of the fuel energy goes out the exhaust pipe as lost heat, approximately 1/3 of the fuel energy is lost to the cooling system (coolant, oil and surrounding airflow), leaving roughly 1/3 of the energy (best case) available for power output. Some of that power is lost to making the pistons go up and down, driving accessories (oil pump, coolant pump, alternator, vacuum pump, hydraulic pump, etc.), losses from pumping air through the engine, thrashing the oil in the crankcase, and friction in various forms.
hot air is less dense than cold air...less dense air within the cylinder will give less temperature, less pressure and less velocity when the A/F mixture is ignited and the combustion process begins...the thermal efficiency of an engine..
for a given throttle position (a 1/8 throttle) on a hot day probably will not get you out of the garage due to the poor thermal efficiency of the engine to produce work so more throttle is required to get going so more fuel...on a cold day with the same throttle position (1/8) you'll be flying down the road..
Sorry Albert...I guess I don't understand it well enough either..
jetfuel
That I understand but with a modern computer controlled fuel injection will not a warmer intake (within reason) run a leaner fuel mixture with better mpg's vrs a cooler intake running a richer mixture? Not debating overall hp increase....
Carbon monoxide and noise. I wouldn't do it. Also typically the air inside the car may only be 10-20 degrees cooler in the summer, otherwise in the winter the air would be warmer!!!
That I understand but with a modern computer controlled fuel injection will not a warmer intake (within reason) run a leaner fuel mixture with better mpg's vrs a cooler intake running a richer mixture? Not debating overall hp increase....
Rewind to 1973. Intaking hot air was how the genius's in Detroit tried to improve emissions...... it didn't work. Driveability were at an all time worst.
That I understand but with a modern computer controlled fuel injection will not a warmer intake (within reason) run a leaner fuel mixture with better mpg's vrs a cooler intake running a richer mixture? Not debating overall hp increase....
...ring the bells...you hit the nail..
...the computer will do his job to maintain the stoichiometric A/F ratio..in today's engine that's 14.7:1..air:fuel...
it's possible to run an engine at leaner mixtures like 16:1 or more at part throttle to gain mileage...the difficulty with this is that driveability and throttle response suffers at these ratios...engine response is lazy and stumbles are commonplace.
...Lean mixtures produce hotter combustion gases than does a stoichiometric mixture, so much so that pistons can melt as a result...$$$
...Rich mixtures produces cooler combustion gases than does a stoichiometric mixture...the extra fuel caries heat out...
....stoichiometric mixtures are only used at idle and under light load conditions... for acceleration and high load conditions, a richer mixture (lower air-fuel ratio) is used to produce cooler combustion products and thereby prevent detonation and overheating of the cylinder head.
clear as mud...right?...
jetfuel...in Naples FL
Last edited by jetfuel; 06-30-2009 at 05:52 PM..
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