Question about LOP operation and HP %age

[Auburntsts]

If you've got some time, check out what I consider to be a pretty comprehensive article on LOP ops: http://www.avweb.com/news/pelican/182084-1.html

[lr172]

Originally Posted by alpinelakespilot2000

Larry,
Have you done a lean range test to figure out how lean each cylinder is running? Fuel distribution in an 0-320/360 can be REALLY screwy leaving one cylinder (or more) much leaner than the others and thus increasing that one cylinder's detonation potential, even when it appears that you are well ROP or LOP on the Dynon. I am in this situation so I am very careful about leaning unless I am absolutely certain I'm well below 75%. Am I being too conservative? I don't know what I don't know, so I don't know. Just something to check on yours if you haven't already. Hope this helps.

My peaks are well grouped. 1/2 together and 3/4 together. They end up about 30-40* apart in cruise; I get a better distribution at WOT. This is all somewhat moot for me, as I have purchased a Bendix FI setup that will be going in over the next couple of weeks and should be able to get my peaks pretty close after tuning.

[David-aviator]

Originally Posted by Toobuilder

A minor point in this particular instance, but any time you throttle the engine you are giving up VE. WOT is one of the keys to pulling good BSFC numbers.

...and a good reason to have a CS prop...

[Toobuilder]

Originally Posted by David-aviator

...and a good reason to have a CS prop...

Agree 100%.

[Jordan1976]

Originally Posted by David-aviator

Mathematically and no other factors considered, 23" MP is 76.87% power.

By that logic, you're at 100% power when on the ground and the engine is off.

RPM is a primary factor in power too. So you can just run 29" at 2,000 RPM which is 75% power as well.

In reality, 22" at 2,400 RPM is about 66% power so you're giving up quite a bit.

[hevansrv7a]

Originally Posted by lr172

My peaks are well grouped. 1/2 together and 3/4 together. They end up about 30-40* apart in cruise; I get a better distribution at WOT. This is all somewhat moot for me, as I have purchased a Bendix FI setup that will be going in over the next couple of weeks and should be able to get my peaks pretty close after tuning.

I'm rusty, but my recall says that the degrees EGT are not the correct way to know if they are peaking together. That's because each sensor's placement and the somewhat different characteristics of the pipe and even variations in the sensors can make this inaccurate. The recommended method as I understood it had to do with when they peak, not the EGT reading itself. There is lots of information about this from GAMI, Advanced Pilot and others.

I hope this helps.

[Carl Froehlich]

Recommend you contact Don Rivera at Airflow Performance and enroll in his engine balancing clinic: http://www.airflowperformance.com/ht...#privatenozzle

You will get the real gouge on LOP operations, and come away with a very efficient engine.

Carl

[tim2542]

Originally Posted by lr172

My peaks are well grouped. 1/2 together and 3/4 together. They end up about 30-40* apart in cruise; I get a better distribution at WOT. This is all somewhat moot for me, as I have purchased a Bendix FI setup that will be going in over the next couple of weeks and should be able to get my peaks pretty close after tuning.

Peak EGT at the same fuel flow is the goal, *NOT* matched EGT's. The actual EGT value isn't important and we don't care if they all read the same. You want them to peak (at what ever number) at the same time relative to fuel flow.
Once LOP, use fuel flow formula to determine power. Fuel Flow * 15.9 / rated HP for % power.
Tim Andres

[PCHunt]

Originally Posted by Auburntsts

If you've got some time, check out what I consider to be a pretty comprehensive article on LOP ops: http://www.avweb.com/news/pelican/182084-1.html

Great article, I try to read it about once a year! Written in 1999, still true today.

[N941WR]

Originally Posted by David-aviator

...and a good reason to have a CS prop...

I guess then I shouldn't be flying LOP with my O-360 fixed pitch prop.



As for how and when I run LOP, I only do it above 6500' DA and start leaning at 65% power, as indicated by the SkyView, and when down low I typically see it drop to about 55% power and less than 7 GPH, as seen in this photo: