% Power and LOP

bjb3013 · #1 03-15-2007, 09:15 PM

I have an IO360 with a FP prop. When I pull the mixture to go lean of peak I loose RPM and power. My fixed pitch prop prevents me from increasing MP or power . It is easy to end up with 50% power or less.
With the understanding of staying out of the red box, how can I run higher power settings.
Should I go LOP at 75% power and below to make do with 50% power or start at 80-90+ % power and end up at 75% power LOP.
All the info I can find is based on a constant speed prop so I end up with different results.

Thanks
BB

Bryan Wood · #2 03-15-2007, 09:32 PM

You can try searching the old posts for this, and for the life of me I can't remember the general consensus on this from peoples responses. A friend told me that the Cessna owners groups go full throttle and then go to full carb heat. This is supposed to drop manifold pressure and rpm and then they can lean to offset everything.

Edit... here's the link to the other thread
http://www.vansairforce.com/communit...ight=carb+heat

Good luck

N79PT · #3 03-15-2007, 11:25 PM

I'm running a 180hp fixed pitch with the Ellison TBI in my RV6. I know this a different setup than yours but it does present another FP data point. I can get about 67% power at 20-40d LOP at 7gph and 160kts. The RPM is about 2450 and I always fly above 8500ft. At 75% power I can't get more than 20d LOP. The numbers are pretty similar as tested up to 10500ft. The RPM does creap back a little and I stop leaning due to roughness or desire to maintain RPM. I hope this helps.

bjb3013 · #4 03-17-2007, 07:26 AM

I guess the question is -should I pull LOP power at 75% and end up with 50% power Or can I start the pull at 90% power and use the mixture to go LOP and use this power loss to stay in the 75% power range LOP

I want to run LOP at 75% power and a I can not turn up the manifold press once LOP with a FP prop

dan · #5 03-17-2007, 07:43 AM

Quote:

Originally Posted by bjb3013

I guess the question is -should I pull LOP power at 75% and end up with 50% power Or can I start the pull at 90% power and use the mixture to go LOP and use this power loss to stay in the 75% power range LOP

I want to run LOP at 75% power and a I can not turn up the manifold press once LOP with a FP prop

Push the throttle in! Or are you really saying you'll select your CRUISING ALTITUDE so as to give you 75% at LOP full throttle?