LOP/ROP info

[aadamson]

I recommended this a couple of days ago to someone intersted in leaning. It's a very good read for fuel management *and* engine diagnostics using an engine monitor. While I'm sure it's written with EI products in mind, it should be pretty easy to translate to your specific Engine monitor. I also noticed that they will send you a "free paperback" version of it as well as being able to download the electronic version.

Enjoy...

http://www.buy-ei.com/The_Pilots_Manual_by_EI.htm

[mark manda]

can you give some broad strokes?

How do I lean at 7,500 ft?

I like that company, I think they're the one's I ordered connectors from. IIRC

[aadamson]

Originally Posted by mark manda

can you give some broad strokes?

How do I lean at 7,500 ft?

I like that company, I think they're the one's I ordered connectors from. IIRC

Mark, not sure what you are trying to do? If you want to see if you can run LOP, and you have an engine monitor with fuel flow and individual cyl values. I'd go do the "lean test" that is documented on www.gami.com. Fill in the spreadsheet and then let us know how it turned out.

The general premis, is that it's more healthy to run an engine LOP (if not in the "red box" - explained on the gami site), than it is to run it ROP, especially 50d ROP. All kinds of reasons, most covered in that booklet from EI and in reading Deakins info on Gami and Avweb (search for that name on Avweb).

In order to be able to run LOP, tho, you have to get your injectors matched. That's what the lean test is all about, it will show you your "spread". There are a couple of places that will "tweak" your injectors. Gami will, but they sell you certified version.

I think Mike - Kahuna did this to his Super 8 and used someone that can do it, but its doesn't cost you certified prices.

See here... http://www2.mstewart.net:8080/super8/nozzles/index.htm

Sorry, I can't be more specific, but not sure what "Broad strokes" you need? The "starter package" of them is to do the above.

[osxuser]

Airflow Performance will build up a non-certified balanced FI system. We were just talking about this (talking is putting it nicely) on the Socal list a few days ago.

[mark manda]

thanks-- earlier today I was on webtv and can't see the screen too well or go to websites etc. that's why I was asking for the gist of it.

we had a good tread going about this over on the socal group too.

the other night I was flying back to LA over the mountains so I started leaning and watching the CHT's, EGT's and GPH. I was around 9--10 GPH and started leaning, EGT's around 1300, CHT's all at 350--375. All of a sudden the CHT's all dropped 50 degrees. 325 deg. across the board. I didn't have enough info about LOP so, since I was over the mountains- i chickened out and got my CHT's back up to 375 by richening up. FWIW

I'll have to check out the info. thanks

[N916K]

Mark

I have a GRT 4000 in my 9 and I use it to lean most every flight. If you really are new to leaning your engine, give me a call the next time your are in the area and we can go flying again. It took me a while to get the balls to really lean my engine out but once I realized the fan wasn't going to stop I basically dropped at least a gallon an hour. Plus it helps on those flights from Tehachapi to Bakersfield to keep the CHT's up when I drop 6000 feet in a few minutes. Picking up Harmon Rocket parts in my RV is way more fun than driving down the hill.

[mark manda]

okay, I'll give you a call. I buzzed your field twice this week-- I mean I had to go missed twice this week-- didn't see you. and I figure they'll think I'm you anyway.

[aadamson]

Mark, you probably were into LOP. Hard to tell how far and if all cylinders were LOP.

The advantages of LOP are lower CHT's, lower internal cylinder pressures, better combustion (for example I've heard it said, that an oil change interval of all LOP flight, will product oil that is still clear, with little to no carbon in it that when run ROP usually turns it dark)

The best way to get to LOP is what is called the "big pull". You basically pull the mixture way back until you feel the the airplane slow down, now you are LOP and you find peak from there and lean back 50 degrees. Not very scientific, but those that try it say it works every time.

Some trade-offs of LOP

You'll most likely loose airspeed when LOP vs. the same ROP. However, it won't be much and you'll be burning at least 1 if not 2 gal/hr less.

You need to have balanced A/F mixtures across the cylinders in order for the engine to run smoothly.

You need to have a good/sound intake system - one that doesn't leak and you'll be suprised how leaking an intake system can be that runs perfectly fine ROP.

So, before you "go for it". Make sure you run the "lean test" on the gami.com site and establish your "lean spread". That will help you determine if it's even possible to run LOP with your current setup.

[BruceMe]

Since we're talking LOP...

My old RV-3 (O-320 carburated, not tuned, 150hp, climb-pitched wood prop, fuel-totalizer, no MP, 25g tank). I usually cruise at very low power settings (2,100-2,300 rpm and high altitudes 10k-12k). I did this for a couple reasons, I loved flying that plane, it's not all about getting there and I'm cheap. And the third reason, oh yah, I'm just cheap!

First I understand that at these power settings it's basically impossible to "hurt" the engine. Can't detonation/pre-ignite. So I played around with mixture a lot. One thing I found was that once you hit "rough" you where pretty much done withe red knob, nudge it in a couple MM and that's as good as it gets. If you continue leaning to the rough, you loose power, you can make up for it by increase MP, which in turn used more fuel. Net result: "in the rough" net fuel flow = airspeed. But typically I could reduce fuel flow by at least a GPH until rough and CHT/EGTs did all the things they are supposed to (increase).

I added FI to the RV-4 I'm building now specifically to tune the injectors and run LOP, cruise cooler and better. I'm interested to see how different it operates in this area. Can anyone describe "extreme lean" on a ballanced engine? Does it just "fade" without the roughness? I think in theory; continued leaning of a perfectly ballanced engine should just smoothly loose power till it stops running.

-Bruce

[dan]

Originally Posted by BruceMe

Can anyone describe "extreme lean" on a ballanced engine? Does it just "fade" without the roughness? I think in theory; continued leaning of a perfectly ballanced engine should just smoothly loose power till it stops running.

I can only speak to my own experience. On my engine, if you just continue leaning, as you get past about 40 LOP you feel the power drop off pretty rapidly, but it does so smoothly. And then there's literally a point where you pull the mixture a hair more and the engine stops. It lurks right there with no real warning other than the HP dropping. This is not a bad thing -- this is a very good thing imho.