Dynon EMS Percent of Power display

Another thread that mentioned displaying percent of engine power caused me to refer back to my DYNON EMS manual. I have an O-320 with a Sensenich prop which has a redline limit of 2600 rpm. When I configured the DYNON EMS tachometer alarms I set the redline to 2600 and a warning from 2580-2600. This has worked fine for me but I just read in the DYNON manual that the percent of engine power display uses the tachometer redline setting to calculate power and that value should be set to 2700 in order for an accurate percent of power to be calculated and displayed. As I now see it perhaps the best compromise for me would be a yellow warning starting at 2580 and continuing to 2700. So, I?m curious how others have set up their DYNON EMS with an O-320 and Sensenich prop.

Its scemantics

you have a 180hp engine IF it can rev to 2700RPM..If you can't get there with the FP prop then your 100% won't be 180HP.

I'd leave it as is..so you see 85% on TO at sea level say and then for leaning etc just go with whatever the number tells you because that will be calculated on the true 100% of the rated power.

So no leaning above 75% for example..when you see 75% thats the number you use because it will be 75% of 180hp.

Put it this way..I have a C/S prop..How often do I look at the % power number?..About never..

Frank

frankh said:

Put it this way..I have a C/S prop..How often do I look at the % power number?..About never..

Click to expand...

The original question posted was with regard to when to run LOP. If you're never supposed to run LOP above a certain % of power, then this is simple. I always use it during the climb in order to not lean too aggressively above 75% power (which is where detonation can occur).

Frank,

I have a 160 HP O-320 Lycoming (new). The rated 160 HP is obtained at 2700 RPM according to engine manual. The Sensenich prop has a 2600 RPM redline because of harmonic issues so anyone running an 320 with this fixed pitch prop must limit their RPMs to under 2600. I can redline the prop all the way up to 8500 MSL and maybe even higher so I need to be aware of that RPM limit via the alarm provided by the EMS. The problem is that if I set the EMS redline and alarm to 2600 RPM because of the prop limit, the percent power display of the EMS will not be correct since the EMS uses the redline value in it's calculations as the RPM at which the engine generates full power.

Joe, It seems to me that you have two options here. You can either set your red line at 2700 rpm and set your warning for 2580-2700 like you said. Or you can set your red line at 2600 and input your rated hp as 155. I'm pretty sure that your engine is rated a 155 hp at 2600. Either of these methods should give you the proper numbers.
I think I would do the latter.

Thanks Mel!

I thought maybe I wasn't stating my question clearly but your answer sounds good to me, I'll configure the HP rating to 155 and see how that affects the engine percent power reading on the EMS.

If you go with that method, just remember that the 75% you are looking for will be 75% of 155, not 75% of 160.

Oh.... I'm starting to get a headache. I think I may do the 2580 - 2700 yellow warning/alert and set the redline to 2700 then. I would like the percent power indication to be as accurate as possible for the 160 HP engine (for bragging purposes). Actually I'll try them both and see which one works best for me.

Thanks Again!

Sorry Joe

I didn't see the redline for the prop at 2600.

I would still use the % power based on the engine at 2700 and just remember not to exceed the 260..Or you can go with Mel's suggestion of using the 2600RPM power number from the graph.

Frank

Joe,
I have same setup and have been using with the 2600 redline, but I use ~77% power when leaning agressively. ~77.4% of 155hp is 120hp which is the same as the 75% power of 160hp. That way you get the very important 2600rpm redline warning and can still lean as you wish. And if you still wish to use the75% power that just gives you an extra margin of safety. IMHO I would keep it the way you have it as the over speed is much more critical than the leaning issue.

From out in left field

My O-290-D2 has a red line of 2800 RPM but can only run up there for five minutes.

Otherwise the continuous limit is 2600 RPM.

Thus I set my red line at 2800 and yellow at 2600 RPM. My climb prop limits me to 64% power on the 2600 RPM limit.

Anyone interested in DYNON implementing a propeller redline alarm separate from the engine redline alarm should visit the DYNON forum and add your comment to the topic New Feature Request: Propeller Redline Alarm