Quote:
Originally Posted by drmiller100
...Lets say we take a multi port fuel injection engine.
And we take the throttle body and wire it wide open.
Then we tell the computer to read a fly by wire throttle plate. And we shut off the injectors 98 percent of the time, but every once in a while we give a specific cylinder the "right" amount of fuel to run at WOT.
But most of the time the cylinders are not getting any fuel.
Then we determine "once in a while" to be decided by the throttle pedal - the more we push on the throttle, the more often a cylinder gets a shot of gasoline.
No pumping losses. Full efficiency of the cylinder. The engine can run at very efficient loads, and we can use the air pumping through the engine to be a pseudo carnot cycle.
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Sounds essentially like a diesel with a spark plug. I'd be interested in hearing some educated opinions as to why we don't do this. Emissions? I find it interesting that this system could potentially do-away with an O2 sensor.
Honda (and probably others) has tackled this with variable valve timing. Their newest Civic engines don't have a throttle plate, but instead leave the intake valves open into the compression stroke and close when the right amount of air is left in the cylinder to combust @ their ideal AFR, which solves to problems at once - no pumping losses, and vastly improved emissions.
I know there are also engines (Honda V6's?) that shut off 3 cylinders and leave both intake and exhaust valves closed when driving under low load conditions. This additionally reduces the energy lost pushing air through those cylinders.