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<< Lancair Builders' Mail List >>
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In a message dated 12/13/00 0:24:38 AM EST, lancair.list@olsusa.com writes:
<< Number 3 cylinder (IO-360 B1F) runs consistently hotter than the rest by 30
degrees or so >>
Ed -
Per your post, you have concentrated on the cooling of this cylinder.
Perhaps the problem isn't insufficient cooling but more heat generation
within the cylinder. Do you have an EGT gauge on all cylinders? You might
have enough of a mixture difference on cylinder #3 to get a higher
temperature on that one due to cylinder-to-cylinder variations in mixture
ratio.
The GAMIjector people have an interesting graph that shows
cylinder-to-cyinder variations. They have you set a fuel flow and measure
EGT and CHT on each cylinder after a one minute stabilization period. Then
you increase the fuel flow by about 0.2 gallons per hour (constant RPM - you
change the mixture) and get another set of data points. You then plot out
the EGT/CHT for each cylinder as a function of total fuel flow, from about 12
GPH to about 15 GPH. Presumably the EGT will peak at the same fuel/air ratio
on each cylinder, and this test shows you where this occurs for each cylinder
individually. If you find that you're running the engine at "best power" and
cylinder #3 is closer to the hottest fuel/air ratio than the others at this
total fuel flow, then your solution is to change the fuel flow to #3 to make
it match the others. This is what the GAMIjectors do, but you might be able
to get just one injector resized than buy their $700 package.
Hey, if nothing else, it gives you something to do during the 40 hour test
phase. And it's a good excuse to take up a buddy as a required flight test
crewmember.
Then again, maybe the problem is baffling sealing around the cylinder and you
can solve it with a glob of RTV. Here's hoping, anyway.
Good luck.
- Rob Wolf
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Please send your photos and drawings to marvkaye@olsusa.com.
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