D180 display: What causes ROP to shift to LOP

[alpinelakespilot20]

On a 4-cylinder engine, do all EGT's have to go over peak for the % power display to shift from "ROP" to "LOP" or is it possible that a "LOP" indication might show before one or more cylinders have yet peaked?  Put differently, can I rely on the "LOP" indication to tell that all four cylinders have peaked and that it's not just one, two, or three cylinders that have gone to the lean side?

Thanks.

 

[dynonsupport]

Are you taking about the ROP/LOP that shows right below the EGT graph or the one that shows next to % power?

 

[alpinelakespilot20]

My question was focused on the one that shows next to % power. That said, I'd love to know more about the one below the EGT graph as well and/or be directed someplace where I can go to learn about what those other indications truly represent. I looked through both my installation and operating manuals and didn't see much information. Thanks.

 

[dynonsupport]

The calculation of ROP, LOP, or PK next to % power is actually pretty independent of EGT. It's calculated in a unique way. You can actually turn on the EMS at 1300 degrees and it will know if that is ROP or LOP right away.

When you are first tuning the system, you need to use your EGT's to determine if it is finding the peak correctly. If it reads PK before you peak on EGT's, you need to adjust your HP number in setup so that it matches your real engine. The HP should be close to your rated HP, but can vary from the rated HP a bit.

Once you have it tuned, then the LOP/ROP indication should be very accurate when you are a bit away from the actual peak. It won't be specifically tied to a certain cylinder peaking or all of them peaking. If you're trying to use it right at peak it's not the right tool, although it does try and tell you PK when you are close.

The LOP/ROP at the bottom of the EGT graph is much simpler. Once one EGT peaks, it reads PK. When the last EGT peaks, it sees if you went up or down in fuel flow between the first and last one peaking, then it says LOP or ROP. However, this never updates once it determines LOP or ROP and requires you to go into leaning mode first.

 

[DBRV10]

The Dynon system is pretty well set up. If you know the fuel flow, MAP and RPM, for a given engine you can tell a lot.

But think of it like this, HP is determined essentially by the following;

ROP=Mass Airflow (MAPxRPM)

LOP= Fuel Flow.

For more education, I 100% recommend you sign up for this www.advancedpilot.com

 

[PRose]

When you are first tuning the system, you need to use your EGT's to determine if it is finding the peak correctly. If it reads PK before you peak on EGT's, you need to adjust your HP number in setup so that it matches your real engine. The HP should be close to your rated HP, but can vary from the rated HP a bit.

So if my first to peak is actually sooner than the indication next to the % power says peak, which way should the HP be adjusted, up or down?

I have 9:1 pistons in an O-320 and have guessed at 165 HP.  Never realized that this indication was independent of the the EGT numbers and would like to get it at close as possible to correct.

Thanks

 

[DBRV10]

9:1 pistons will screw up the tables a bit.

Ignore the ROP/PK/LOP indicator and just use the EGT readings as you would on a JPI or others.

HP when LOP your HP can be calculated by 15.47HP per USG of fuel flow.

When ROP either don't worry about being super accurate as a few % points dont matter that much or use this > When ROP, mass airflow determines HP, therefore, %Hp.
( %Hp = (100-(((Max RPM-RPM)/100)*2.5+(Max MAP-MAP)*3.5))/100


I suspect entering the HP of your engine, the Dynon will give you reasonably accurate ROP %'s as per the above. On the LOP side it will not, so you can work out LOP HP in your head, GPHx15.5

 

[dynonsupport]

If you are reading lean early, adjust the HP number down.

David,
The whole point of the HP number is that it tweaks everything so the LOP/PK/ROP is accurate. This can adjust for different compression ratio pretty effectively as well. It's easy to verify that the LOP/PK/ROP is accurate by checking it against EGT's, and I think you'll find when you do that you can trust it. It works just fine when ROP or LOP.

 

[DBRV10]

Hey mine works pretty well, it a bit vague in the peak indication but heck I really am splitting hairs there.

I am interested in knowing how you are tweaking for different compression ratio's. It has been a few years since I set ours up, but I do not recall the fields having any adjusting factor for compression ratio. I have all the LOP data for other ratio's, I can calculate them anywhere in-between, but I have not seen it in the D180.

So what is new that I missed?