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I have the small rectangular opening in front of #5.
Steve -----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
Jeffrey Liegner, MD
Sent: Monday, October 19, 2009 6:19 AM
To: lml@lancaironline.net
Subject: [LML] Re: LOP MP setting for TSIO-550E
13.7 hp/gph for TSIO-550E
17.5 gph
240 HP = 68% (roughly)
At 20gph ROP, you were sending 2.5 gallons per hour of 100LL out the exhaust
manifold (unused). 14% greater carbon footprint without any benefit.
Now try 34" 2500 18.0gph which is where I run often.
Notice cyl 5 is hottest. Ususally it's cyl 2. Do you have the small
rectangular cut opening in front of cyl 5?
Jeff L
LIVP
In the original email, i asked what MP one should use when running LOP. George Braly suggested i go out and find out for myself. So I did.
Here are two runs, both LOP at 2500 RPM and 17.5 GPH lean of peak:
30" MAP
EGT 1558 1558 1576 1563 1528 1484 CHT 330 328 332 328 340 324 TIT 1593 / 1634
31.6 MAP
EGT 1542 1544 1556 1540 1514 1472 CHT 326 322 326 324 326 314 TIT 1578 / 1611
The IAS in both cases was the same, so the horsepower must have been the same. As one can see, higher MP means cooler temperatures.
Which makes sense, since the mixture is leaner. I think I'm concluding that one sets the fuel flow to pick the horsepower desired, and then adjusts the MP to get the temperature desired (within reason).
I thought 17.5 LOP would be about 75% power. So I went ROP and reduced MP until i got the same IAS as the LOP runs above. It took 27" MAP and 20 GPH to match the IAS, which I think is about 65% power (don't know why it isn't 75%...)
-isaac
N7842K ES-P
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