[SEL] The McVickerish Engine

[Best, George]

Larry,

Interesting experiment.

I'd never really thought about engines governing against compression that the expanding of the compressed air does return some of the energy used to compress it so it is not a total loss.

Although I'm not sure your experiment is a good comparison between governing against compression and the common method of holding the exhaust valve open.  If your compression release is a much smaller opening that that provided by an open exhaust valve, then I wouldn't have the same effect.

Your experiment did show that keeping the valves closed does take longer for the engine to come to a complete stop.

George

-----Original Message-----
From: sel-bounces at lists.stationary-engine.com [mailto:sel-bounces at lists.stationary-engine.com] On Behalf Of Larry Evans
Sent: Tuesday, March 23, 2010 9:51 AM
To: The SEL email discussion list
Subject: Re: [SEL] The McVickerish Engine

Elden:

This reminds me of an experiment I ran a while back with the 50 hp. 
Fairbanks Morse spark ignited engine at the Mount Wilson Observatory.  What 
I did was run the engine up to its regulated speed of 290 rpm. and then 
killed the ignition and fuel to shut it down.  It took 2 minutes and 45 
seconds to come to a complete stop.  I then did the exact same thing but 
also opened the compression releases at shut down.  It took just 2 minutes 
to come to a stop which indicates to me that governing against compression 
probably is a little more efficient than not.

Larry



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