[mwebb]

Originally Posted by mort

Hello mwebb,
You are confusing pumping losses with throttling. They aren't the same. Your graph dosen't show any information about pumping losses.
-mort

above is a brief overveiw of what i was showing a trace of in the earlier screen cap , it is combustion chamber pressure over time culled from a large capture with a pressure transducer and a hi res scope . the positive peaks occur at TDC 0 and 720 degrees of crankshaft rotation ----
running compression test
------------------------------
i can take one cylinder out of the equation by disconnecting spark and injector
same conditions

calculated load delta becomes the measurement of the pumping loss and frictional loss of the non contributing cylinder
in percent

compare calculated load , not absolute calculated load but calculated load , now one cylinder is nothing but pumping and frictional loss
the difference exceeds 5% every time
do not take my word for it

do it your self
post your results

KISS

the discussion around thermodynamic efficiency may work real well in the lab and in computer models - so EGR which degrades thermodynamic efficiency should also degrade FE
but
it (EGR when in use )
improves FE ,
by reducing suction throttling losses / pumping losses and by reducing the amount of air fuel mixture per combustion event

i had not considered the difference between pumping and throttling loss - for the purposes of this discussion
is there a difference ?

real world 5% is not the value

I posted some stuff in a thread Doug Miller started about efficiency.
To sum up. Pumping losses are less than 5% of shaft hp upto WOT, where they go toward zero. The loss of efficiency is simply thermodynamics. For an engine throttled down to 20% and a compression ratio of 8.5 the effective CR is 1.7:1. So at full throttle the maximum (Carnot) efficiency would be about 57% but throttled about 20%