Dynon percent power

I know that the Dynon unit bases it's percent power calculations on 8.5 to 1 pistons. I seem to recall reading that if you have 9 to 1's the calc.'s are still valid. In my case I have an ECI OX-360 A1A w/9-1 pistons, ECI says it's 188 HP. I'm wondering if I should input 188 instead of 180 in the Dynon D180.
To early to call Dynon.

I believe there is a way to set the compression ratio somewhere in the config screens...

For percent of HP it shouldn't matter what compression the pistons are should it? Just set the max MP and RPM, and Max HP...

When we first did % power, we didn't know as much as we do now. All the tables we had were for 8.5:1 engines, so we played it safe.

Turns out compression ratio doesn't matter. The tables for a 8.5:1 and a 9.0:1 engine are the same. What really matters is the redline RPM.

If you still have SW that says 8.5:1, you should update to software 4.0 or newer. This will just say "Lyc/Cont" and will ask you the redline of your engine.

HP is used for auto detection of ROP vs. LOP operation (something nobody else does). Set this number to 188 in the beginning, but don't be surprised if you need to tweak it to something like 180 or 170 to get your LOP/ROP to match your manual leaning. If you set it lower, it just means your engine is more efficent.

And just as a comment, % HP is way more complex than just MP and RPM. There's a reason all the Lycoming tables have altitude and OAT on them. Technically max HP doesn't matter at all either, since we're displaying % of max HP, not actual HP.

Dynon,

What about those of us with low compression engines, such as my O-290-D2 (7.5 to 1) and engines where we don't know the actual HP?

While I'm at it...

My engine has a 2600 RPM (135 HP) continuous power redline and a 2800 RPM (140 HP) limit for five minutes.

I would think it should be set for 135 as that is what I'm basing my 75% power on.

Any compression ratio is fine. Every Lycoming table I have looked at is the same, from CR's in the high 6's to the 9's.

I would assume you'd set it to 2600 RPM too, but that's a personal preference. We will display above 100% if you are achieving that.

dynonsupport said:

Any compression ratio is fine. Every Lycoming table I have looked at is the same, from CR's in the high 6's to the 9's.

I would assume you'd set it to 2600 RPM too, but that's a personal preference. We will display above 100% if you are achieving that.

Click to expand...

Thanks, that's what I thought.

FYI - With the climb prop I have, I can spin it up well past 2800 RPM so that will be interesting to see.

Oh, and yes, it should be 135 as a starting point for the LOP/ROP baseline.