Quote:
Originally Posted by t vago
You're describing pumping loss. And, yes, vacuum creation will always be associated with pumping loss.
Sure. All of these will reduce pumping loss, and will likely reduce throttling loss as well. However, I am primarily focusing on reducing throttling loss right at the throttle body.
|
I guess I wasn't clear but I am in the camp that throttle losses are irrelevant for a fuel economy problem. As long as we are dealing with a part throttle condition its not an airflow problem. The engine doesn't feel drag from the pressure drop at the throttle, the engine feels drag from the vacuum at the piston tops. As long as we are in the part throttle region the engine only cares that it sees the % of cylinder filling it needs to meet the torque demands at that steady state condition.
To illustrate my earlier point, imagine that all of the cylinder filling occurs during only one degree of the 180 degrees of the intake stroke. Would you rather have all that filling at the start so the vacuum is near zero (or more likely positive pressure, but lets assume zero vacuum for multiple degrees) at the start and slowly increases for the length or the stroke OR a perfect vacuum for 179 degrees and full filling at the end. There may be minuscule gains fiddling with throttle shapes and port configurations but if you are truly chasing the elimination of this loss the real way to do it is advance the intake lobe on the cam.