Mixture at full throttle, 8000' DA

[rightrudder]

I have been reading the engine manual for my IO-320-D1A and various threads on engine leaning and I can't seem to find the best procedure for a full-throttle run at altitude. I don't plan on doing this often, but I want the best procedure to avoid harming the engine for a few brief WOT runs at approximately 8000' DA. Normally, I'm doing "performance cruise" at 2300-2400 rpm with mixture slightly LOP.

My thoughts are full rich initially, but can I lean to peak rpm or 50 degrees ROP once the throttle is fully in? The engine should be producing less than 75 percent power at this DA.

Sorry for the noob-ish question, but most of my flying in rental planes to date has been at 3000 to 4000 ft, and now my practice area is in SoCal's high desert.

[Dbro172]

Doesn't your efis give you a % power readout? Technically you should be at 8500' since your VFR and that engine would be hard pressed to make much over 75% at 8500'. Giver heck! Like I've mentioned before though, with that prop, ,mine would easily spin up to 2800 rpm at peak, or 50 ROP at 8500'

[aerhed]

At 8000 DA you can do anything you want with the mixture and you can't hurt it (unless you manage some backfires). If you're trying for max power available with a fixed prop, just lean to peak RPM.

[bruceh]

Doug,

At this point in the engine's life, run WOT as much as you can. Only back off if the CHT's are getting too hot (400-425). Cruise climb at 115-120Kts to keep them cooled. Watch your EGT's in the climb and keep them consistent to where they would be at 100 degree ROP. At altitude, lean it out to LOP until it is rough, then back off a bit. Done.

LOP will keep the CHT's low and the power should be somewhere under 70%. This isn't hurting the engine at all.

[rightrudder]

Thanks, guys! As always, I really appreciate the help.

Yes, I'm diligently observing the VFR west/east cruising altitudes...8000' DA could be 7500' MSL and so forth. I'll start a Phase 1 update thread in a couple days (9A model forum) and post some TAS and peak rpm numbers. Next flight will be with the wheel pants on for the first time, so I'm curious to see the improvement. I think I'll do some additional ASI calibration runs a little closer to top speed too. As it stands, I did the calculations for 80, 100 and 120 KIAS, and on average, the ASI was reading 10 percent low.

[brad walton]

Run it hard to get a good break in. That means at least 75% power which is wide open at about 8000 ft density altitude. Keep it about 100 to 150 degrees rich of peak. Leave the lean of peak operation until later when you have an opportunity to calibrate your injection nozzles. Now is time to get good break in. Most of us have a tendency to want to baby the engine when we should be running it like we stold it. Not sure about an IO320, but a 180 hp engine makes 75% ROP power at about 10 to 11 gallons per hour. A 160 hp engine should burn about 10 gph at 75% ROP.

[Rupester]

Just like Derek, my IO-320 with Catto 3-blade will also spin to 2700+ at full throttle at 8000MSL. I have to back off the throttle just a smidge (technical term) to stay under 2700.

[rightrudder]

Thank you for the input. The consensus is: More throttle! So I'm happy to oblige. Should get a flight in tomorrow.

Oil consumption has only been a little over a quart in 11.3 hours. Even if it doesn't improve, it would still be acceptable. But I expect it to improve.

I'm fully expecting to see 2750 (Catto's number) to 2800 rpm flat-out, but I'll only maintain this for a minute or so. Top speed is more a curiousity than anything else... I just want to be able to cruise between 2300 and 2500 rpm. I have to say, 2400 is a real sweet spot in terms of low noise/vibration. 2200 is kinda loud. I guess my birthday present to myself will be an ANR headset!

[Rupester]

IMO, a good ANR headset significantly improves the RV flying experience ... at least in Sevens and Nines. Once I got out of my flyoff period, I ordered a pair of Zulu 2s for moi and the Spousal Unit. Way more better.