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In a message dated 12/13/00 0:24:38 AM EST, lancair.list [at] 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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