From: Fred Moreno [mailto:fredmoreno@optusnet.com.au
]
Sent: Thursday, August 30, 2007 6:58 PM
To: John Barrett
Subject: FW: Engine efficiency
Hi John:
Please forward the note below to LML as it is rejecting my emails again after a brief run of acceptance.
Cheers,
Fred
___________________________________________________________________
"The
Continental engine manual doesn't seem relevant with the high compression.
On the other hand, I did get data from APS/GAMI on operation LOP. For 10:1
compression the HP = 16.6 x FF(gph). That is a significant jump from the
14.9 factor for the stock 8.5:1 compression."
I have difficulty believing 16.6 hr hour per gallon. Assuming 5.85 pounds per gallon (a GAMI figure)I calculate that this is equivalent to a specific fuel consumption of 0.352 pounds per horsepower hour which is into diesel territory.
I plotted some SFC data published by manufacturers including liquid cooled IOL-200 used on Voyager which had a compression ratio of 11.4. It suggested that the correct figure for a compression ratio of 10 is closer to 15 hp hr/gallon. The figure of
14.9 sounds too high for 8.5:1 compression as well. I would expect it to be about 6% lower efficiency based on charts of efficiency vs compression ratio, or about 14.1 HP hr/gallon at 8.5:1.
As usual, carefully collected data collected with calibrated instruments should tell the tale.
Fred Moreno
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