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Old Jan 18, 2003, 08:12 PM
ken ward
Guest
n/a Posts
Magnum Pro 45 break in Qs

I've mostly flown r/c gliders, but was recently given a nitro r/c
trainer; kind of a hand me down. One thing I noticed was that the
engine had recently been returned after warranty service. They replaced
the piston, and noted that it needed further break in. I did a search
of the r.m.r.a. archives, and found some partial procedures to get
started.

I built a little test stand and ran it under the folowing conditions:
throttle pinned full open
11 x 6 prop
new fox miracle plug
fresh, filtered 15% fuel
8 oz tank -> 8 minutes of running

1st run was with high speed mixture set at 4.0 turns out. I saw about
7000 rpm & a smokey exhaust. momentarily setting it at 3.0 turns raised
rpm to about 7500. ran the tank out, removing the fuel line just before
empty.

2nd run was at 3.0 turns out. I saw about 7500 rpm, smokey exhaust, and
momemtarily setting it at 2.0 turns raised the rpm to about 8500.

3rd run was at 2.0 turns out. I saw about 8500 rpm, smokey exhaust,
intermittently making 2 stroke noises; momemtarily setting it at 1.5
turns raised the rpm to about 11,100 and it really started sounding like
a 2 stroke.

here's my questions:

does it need more running in, at incrementally leaner mixture settings,
producing higher rpms? the manual says this engine ought to have a
range of 2,000 to 17,000 rpm. do you judge "lean enough" based on rpm,
sound, temperature, or what?

I observed a significant amount of fuel pooling around the rear of the
cylinder/head when running, and it looked like there were possibly
bubbles coming from the cylinder head joint. do those head bolts
typically get torqued to a specific value?

public or private suggestions would all be appreciated!

Best Regards,
Ken
San Jose, CA
Old Jan 18, 2003, 09:42 PM
Ted Campanelli
Guest
n/a Posts
Re: Magnum Pro 45 break in Qs

On 1/18/03 7:54 PM Ted shuffled out of his cave and grunted these great
(and sometimes not so great) words of knowledge:

3 - 5 tanks of fuel SHOULD be enough of a break in for an ABC/ABN
engine. If this is a ringed engine, it will most likely take a gallon
or 2. In either case, the engine should be broken in enough to fly.

The max rpm is, to a great extent, determined by the dia x pitch and the
nitro content of the fuel. The other factor is the engine will "unload"
in the air. This means the engine will speed up several hundred rpm.

How you want to "tune" the engine is as follows: Max the engine speed
out, then back off about 1/8 turn (300 - 400 rpm). Then pick the plane
up and stick its nose straight up, If there is no change in rpms go
fly. If there is a change in rpms, back off on the needle valve another
1/8 turn and try it again. Keep doing this until there is no change in
rpms.

Most 40 size engines will usually run at about 13,000 - 15,000 rpms with
a 10x6/11x5 APC prop.



> I've mostly flown r/c gliders, but was recently given a nitro r/c
> trainer; kind of a hand me down. One thing I noticed was that the
> engine had recently been returned after warranty service. They replaced
> the piston, and noted that it needed further break in. I did a search
> of the r.m.r.a. archives, and found some partial procedures to get
> started.
>
> I built a little test stand and ran it under the folowing conditions:
> throttle pinned full open
> 11 x 6 prop
> new fox miracle plug
> fresh, filtered 15% fuel
> 8 oz tank -> 8 minutes of running
>
> 1st run was with high speed mixture set at 4.0 turns out. I saw about
> 7000 rpm & a smokey exhaust. momentarily setting it at 3.0 turns raised
> rpm to about 7500. ran the tank out, removing the fuel line just before
> empty.
>
> 2nd run was at 3.0 turns out. I saw about 7500 rpm, smokey exhaust, and
> momemtarily setting it at 2.0 turns raised the rpm to about 8500.
>
> 3rd run was at 2.0 turns out. I saw about 8500 rpm, smokey exhaust,
> intermittently making 2 stroke noises; momemtarily setting it at 1.5
> turns raised the rpm to about 11,100 and it really started sounding like
> a 2 stroke.
>
> here's my questions:
>
> does it need more running in, at incrementally leaner mixture settings,
> producing higher rpms? the manual says this engine ought to have a
> range of 2,000 to 17,000 rpm. do you judge "lean enough" based on rpm,
> sound, temperature, or what?
>
> I observed a significant amount of fuel pooling around the rear of the
> cylinder/head when running, and it looked like there were possibly
> bubbles coming from the cylinder head joint. do those head bolts
> typically get torqued to a specific value?
>
> public or private suggestions would all be appreciated!
>
> Best Regards,
> Ken
> San Jose, CA


Old Jan 18, 2003, 10:22 PM
Dr1Driver
Guest
n/a Posts
Re: Magnum Pro 45 break in Qs

> I did a search
>of the r.m.r.a. archives, and found some partial procedures to get
>started.
>


The procedure you described is not good for an ABC engine. This type of engine
needs to get up to operating temperature to properly break in without wearing
out. It should be run in a SLIGHTLY rich setting. Also, the prop diameter is
a little large.

Run the engine further, using a 10-6 prop and the fuel and plug you described.
Run it in the previously mentioned 2-stroke mode. About 3 to 4 tanks of fuel
should see it ready to fly.


Dr.1 Driver
"There's a Hun in the sun!"
Old Jan 18, 2003, 11:42 PM
bear
Guest
n/a Posts
Re: Magnum Pro 45 break in Qs

Why do you say it should be run in a slightly rich setting? Just
curious, my knowledge is limited.

Dr1Driver wrote:

>>I did a search
>>of the r.m.r.a. archives, and found some partial procedures to get
>>started.
>>
>>
>>

>
>The procedure you described is not good for an ABC engine. This type of engine
>needs to get up to operating temperature to properly break in without wearing
>out. It should be run in a SLIGHTLY rich setting. Also, the prop diameter is
>a little large.
>
>Run the engine further, using a 10-6 prop and the fuel and plug you described.
>Run it in the previously mentioned 2-stroke mode. About 3 to 4 tanks of fuel
>should see it ready to fly.
>
>
>Dr.1 Driver
>"There's a Hun in the sun!"
>
>



Old Jan 18, 2003, 11:53 PM
Brian Hampton
Guest
n/a Posts
Re: Magnum Pro 45 break in Qs

bear wrote:

> Why do you say it should be run in a slightly rich setting? Just
> curious, my knowledge is limited.
>
> Dr1Driver wrote:
>
>> It should be run in a SLIGHTLY rich setting. Also, the prop
>> diameter is
>> a little large.
>>

Slightly rich is very subjective. What's slightly rich to one person
could mean almost at the point of seizing to another. Even the best of
the manufacturer's instructions are vague on what they mean by rich. The
safest is the point where it's just broken into a clean 2 stroke sound
although I like to hear the occasional 4 stroke for an instant. Even a
beginner can detect the different sounds. This ensures that the engine
is up to temperature but still allows a good flow of oil through it
during the critical first runs.

Smaller than normal props are best for running in because this not only
reduces the load on the engine but allows it to run at closer to the
revs it'll eventually be flown at.

Old Jan 19, 2003, 02:02 PM
bear
Guest
n/a Posts
Re: Magnum Pro 45 break in Qs

Thanks for the information. I never thought about why you'd want to run
a smaller prop during run in, it makes sense.

Brian Hampton wrote:

>bear wrote:
>
>
>
>>Why do you say it should be run in a slightly rich setting? Just
>>curious, my knowledge is limited.
>>
>>Dr1Driver wrote:
>>
>>
>>
>>>It should be run in a SLIGHTLY rich setting. Also, the prop
>>>diameter is
>>>a little large.
>>>
>>>
>>>

>Slightly rich is very subjective. What's slightly rich to one person
>could mean almost at the point of seizing to another. Even the best of
>the manufacturer's instructions are vague on what they mean by rich. The
>safest is the point where it's just broken into a clean 2 stroke sound
>although I like to hear the occasional 4 stroke for an instant. Even a
>beginner can detect the different sounds. This ensures that the engine
>is up to temperature but still allows a good flow of oil through it
>during the critical first runs.
>
>Smaller than normal props are best for running in because this not only
>reduces the load on the engine but allows it to run at closer to the
>revs it'll eventually be flown at.
>
>
>



Old Jan 19, 2003, 02:12 PM
Dr1Driver
Guest
n/a Posts
Re: Magnum Pro 45 break in Qs

>Why do you say it should be run in a slightly rich setting? Just
>curious, my knowledge is limited.


The cylinder of an ABC engine is gorund with a slight taper (smaller diameter)
at the top. That's why they are usually very tight at the top when you turn
one over by hand. When the engine runs at, or close to, operating temperature,
the cylinder expands more than the piston, creating the proper clearance. If
it doesn't, the piston will wear out prematurely.
Dr.1 Driver
"There's a Hun in the sun!"
Old Jan 20, 2003, 08:42 AM
Mathew Kirsch
Guest
n/a Posts
Re: Magnum Pro 45 break in Qs

ken ward <kenward1000@hotmail.com> wrote in message news:<kenward1000-9636F0.16543618012003@newssvr17-ext.news.prodigy.com>...

> 3rd run was at 2.0 turns out. I saw about 8500 rpm, smokey exhaust,
> intermittently making 2 stroke noises; momemtarily setting it at 1.5
> turns raised the rpm to about 11,100 and it really started sounding like
> a 2 stroke.


Ugh, the first two runs were BAD for the engine. ABC engines need to
be run as you did in the third run, lean enough that they sound like a
2-stroke, but not at peak RPM. The piston liner is tapered so the top
is narrower than the bottom. When the engine gets to operating
temperature, the top of the piston liner expands, and the sides of the
liner become parallel. Running the engine slobbering rich like you did
in runs 1 and 2 does not allow the liner to expand properly. The
piston just wedges itself into the tapered liner over and over and
over, causing excessive wear. The idea is to get the engine up to
operating temperature ASAP.

> does it need more running in, at incrementally leaner mixture settings,
> producing higher rpms? the manual says this engine ought to have a
> range of 2,000 to 17,000 rpm. do you judge "lean enough" based on rpm,
> sound, temperature, or what?


Yes, the engine needs to be run in at increasingly leaner settings.
Usually, you can do this in the air after the first tank or two. Just
lean the needle valve out a click or two every few flights.

The engine will never spin at 17,000 with an 11x6 prop. I would expect
peak RPM to be in the 12,500 to 13,500 range. Most engine companies
are very liberal with the RPM estimates of their engines. To achieve
them, you would have to turn a very small diameter prop, producing
very little thrust.

> I observed a significant amount of fuel pooling around the rear of the
> cylinder/head when running, and it looked like there were possibly
> bubbles coming from the cylinder head joint. do those head bolts
> typically get torqued to a specific value?


Tighten them down. The exact torque is not critical, as long as all
the bolts are tightened equally.
 


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