Lycoming O-320 power settings for break in
 

I am nearing time for my first flight in a 9A with a new O-320 Lycoming engine and a fixed pitch Sensenich with a pitch of 81 in. I will need to run my engine at 75% power for the first 30 minutes but I can't find a simple way to determine this power setting. I plan to do this break in at 3000 ft. I have a manifold pressure gauge on an EIS. I would also like to know what power settings for 65% power for the period when I am to alternate between 65% and 75% power.
It would be great if I could just worry about the RPM's as I did in my little Cherokee 140 when I broke in an overhauled Lycoming O320. Would it be safe to assume that 2500 RPM would be close enough? I have never used a manifold pressure before.
BTW: I don't have a fuel flow monitor. I am not a very cerebral person so please keep it simple.

Hello Cleve
 

On my Cessna 172 with a new engine I did the following:
First 30 minutes - full throttle, don't lean, stay under 8000 ft.
Next 1.5 hours vary the rpm between 2500 and 2700, stay under 8000 ft and don't lean.
Until I had 10 hours on the engine I didn't do much leaning and not to much slow flight.

Have fun.

Kent

simple enough?
 

Run it with as much throttle as possible without over-temping the cylinders.

-Geoff

I have an RV-4 with O-320 and fixed Sensenich. At 3,000' it runs fairly 'square' i.e. 22"MP gives 2200 RPM and 24" 2400RPM.

75% will be close to 24"MP and 2400RPM, so 2400 RPM or higher and mixture rich should put you in the right region. Its best to stick to lower altitudes to keep the MP and hence the engine internal pressure (BMEP) high.

Worth a read of the Lycoming article here, if you haven't already done so.

Ignore MP....
 

......for now Cleve, since you really don't need one for a FP prop anyway. 2500 RPM is close to 75% for 320's and 360's.

Regards,

Thanks all. I hope to fly in a couple of weeks and will probably run between 2400 and 2500 for the 75% at 3000 feet.

MAP gauge is for fixed prop planes as well.
 

Mr. Thompson if you have a fixed prop, it's a great you have a MAP gauge. I lifted a couple of charts for example. Although for the Lyc 360, percent wise it is close to the Lyc 320.

See the two pwr charts below. The first chart formate is more for fixed prop. The the second chart is more for c/s pitch prop. You see differences, and that is from different props, airplane and installation (scoop/airbox). (click thumb nails below)


(example only check against Lyc engine manual)

You say you want to fly at only 3,000 feet (or 3,500 feet VFR better) you need MAP of 23" or less @ 2,400 rpm.
I like Kent's suggestion above. You should try to run wide open throttle (WOT) or near WOT. That means a climb to about 8,500 feet. May be slit the difference and fly at 5,500' or 6,500'. (3,000' or 8,000' as you know are "hard altitudes", IFR pilots use, who may not be looking out for you.)

Not sure why you want to be at 3,000 feet to break-in. You can break in at any altitude, but flying higher is good for emergency, giving you more glide. Not sure if break-in is better at WOT and higher RPM or partially closed throttle and lower RPM? Probably does not make a difference.

Once you break-in the engine and have time to do some flight test you can make charts like the ones above (either one as you like).

The reason factory planes with fixed props don't have a MAP are two fold:

1) the FAR's say it does not need it.

2) The factory does extensive flight testing (with a MAP gauge) and makes power charts for all kinds of conditions, standard day or hot or cold.....etc.

An example chart and DA
 

Here is an example of the Power Performance chart for my Grumman Tiger (fixed pitch prop., O-360 engine). I made it into a spreadsheet and added mpg... note that mpg and knots are both used in the table.

http://home.earthlink.net/~gilalex/T...ce%20chart.xls

I also used Density Altitude. All of the above discussions should actually be referenced to DA... especially for those of us in the hot SW...:)

When I broke in my Tiger cylinders in June, I flew for an hour at 1500 ft above our 3000 ft airport at 7:00 am. I was pushing 7000 ft DA, and needed over 2650 rpm to reach the requested 75% power...

Higher is not better in summer if you want 75% + power...:)

gil A

Fuel Burn
 

Expect a very high fuel burn during the break in. I was shocked to see 12 gph on my O320E2D while breaking in after overhaul. Have fun, Joe Hesano

Keep the gear leg fairing and wheel pants off.
 

While I can not speak for a 9A with an 0320, I know on my IO360 RV6 75% put me right at the start of the yellow arc. I was able to run hard even when it was bumpy, which it was most of the 10 hours I used for my break in period.
More drag is better at this stage of the game. You dont want to have to reduce power for bumps.