av8tor1977

My Feedback: (6)

Hi,

How much rpm gain can a person expect to see on a .61 size ringed engine after break in? About how much running does it take to see a gain?

Thanks,

AV8TOR

DarZeelon

Av8tor1977,

Since peak RPM is NEVER measured on a new, unused, ringed engine, there is really no way to know.

Some prominent ABC engines, like Jett, Nelson, MVVS Q-500, are tached before they are shipped out of the factory.
Since such an engine must retain the TDC pinch, to be considered in good condition, and since the needed break-in is only about 20-30 minutes, it will be close to its maximum performance potential.

It will not sustain any damage from this test run, unlike a ringed engine, which potentially will be damaged.


If you tach the engine after completing a good, correct break-in, it will unleash 100-300 RPM more, by the time it collects about 30 hours.

Sincerely,

av8tor1977

My Feedback: (6)

Thanks.

The reason I ask, is because I have a new Fox Eagle .61. It has about 6 tanks or so run through it, fairly rich. This is a ringed engine. After the 6 tanks, when I would lean it in briefly, it would only tach about 10500 with an APC 12 x 7. (I'm at sea level, and using 15% nitro.) This is 500, if not 1000 less than I expected.

In the review/engine shoot out done recently by MAN magazine, they got 11500 with a Fox Eagle .61 on an APC 12 X 7, WITH ONLY 5% nitro. The 15% I'm using seems about right, as there is just a tiny drop in rpms when I remove the glow heat.


Thanks again,
AV8TOR

PatinIdaho.

My Feedback: (3)

This is a little of topic but ummm NICE avatar av8tor1977

DarZeelon

Av8tor1977,

About what I wrote as to RPM gain from break-in; it still goes.

Ringed engines must be broken-in very rich, for the first 30 minutes, or so; that is blubbery, four-cycle rich.
The next 20 minutes should be rich two-cycle. You can fly it by then. Afterward a few clicks richer than normal for another hour, or two. If you did it so, your engine is most likely in good shape

If I remember correctly, newer Fox engines are set to run on 0-5% nitro, without problems. If I recall correctly, the Fox was the only one of the 10 engines, tested with 5% nitro (22% oil ) fuel, while all the rest were fed 10% nitro juice. The Fox has a higher compression ratio and using hotter fuel in it, forces you to run it richer, to prevent pre-ignition and overheating. This may in turn reduce power.

With nitro, more is not always better. If your engine doesn't need it, it can even be worse.

Try running the engine on fresh, 5% nitro fuel and taking readings then. Dave Gierke's engine from the shootout, did not have more time on it than yours. Their performance should be about the same.

If it still lags by more than 200-300 RPM, you can ask Fox (although I couldn't find their direct support forum in RCU), or ask Dave Gierke.

BTW, if the glow plug is right, loss should be 0-100 RPM at low revs. At high RPM it should be very close to zero, unless you are too rich, that is...

Sincerely,

Flypaper 2

No two engines are exactly alike. A loose fitting new engine will show less RPM gain than a tightly fitted engine when broken in.

av8tor1977

My Feedback: (6)

I always thought that if the rpm's sagged on removing the glow heat, that you could use more nitro. I've always run my Fox engines on 15% with good luck. (I know changing to a hotter plug can help this as well.)

Also, is there that much power difference between ABC and ringed engines? The MAN test used an ABC Fox .61, and mine is ringed. That's why I was thinking that perhaps my ringed engine needed to break in further to match their readings, or at least come closer.

Thanks,
AV8TOR

DarZeelon

Av8tor,

Ringed engines need a richer, more prolonged break-in procedure, compared with ABC engines. I had to see the MAN shootout to realize you are not comparing the same engines. Before I just heard about it from friends and from the forum.

BTW, the Fox and the Tower are the winning candidates.

Most small displacement model engines, which produce high levels of power, are ABC engines (C for Chromium, not Composite). Larger displacements don't even exist in ABC, unless there is a ring included in the name (and in the engine) like some Super Tigres and others.

I suppose the Fox ringed version may produce slightly less power, than the ABC version tested by MAN.

Sincerely,

Matt Kirsch

My Feedback: (21)

It means your low speed needle could stand to be set leaner. The reason more nitro helps is because the extra nitro displaces the methanol, making the mixture leaner.

Sport_Pilot

Fox makes this engine in both ABC and ringed versions. Once broken in the ringed engine should be just as powerfull. But Fox ringed engines take a long time to break in, may take a couple of gallons of fuel to react max power. I agree you should get more power from 5% fuel.

Ernie Misner

[QUOTE]Originally posted by av8tor1977
[B]I always thought that if the rpm's sagged on removing the glow heat, that you could use more nitro.

A hotter plug is what I would try first.

Ernie

Hobbsy

My Feedback: (102)

AV8, your Eagle .60 should turn a 12x8 at 11,000 on 5% nitro, a hotter plug will only make it worse. My .60 turns a 12x8 at 11,000 and my .74 turns the same prop at 11,200. I use Fox 5% nitro fuel that is 20%-50/50 lube and Fox GoldPost idle bar plugs.

Razor-RCU

My Feedback: (50)

I have to ask- How on earth do you know soo- much about engines?

You and W8YE should go into business!

17 years in the hobby and I just don't seem to know much at all...

Seriously, I/we appreciate all your advice so keep it comin'!

Later,
james

av8tor1977

My Feedback: (6)

My Fox is turning an APC 12 x 7 at 10500 on 15% fuel at sea level and about 75 degrees. I think it should do better, but maybe it will with more running time. It only has about 5 or 6 tanks through it at this point.

Thanks
AV8TOR

Rudeboy

Why? These guys are "motor-heads"....

DarZeelon

Razor, Rudeboy,

There are some people who are not in this forum (some are not with us) at this time. Among them; Peter Chinn, Harry Higley, George Aldrich, Clarence Lee, Gerry Yarish, Dub Jett, Dave Gierke.

Those people are real gurus, when it comes to engines.
I read much of the material they published and learned enough from it to even point out slight oversights and mistakes they also, as humans, occasionally make.
Besides, I myself have a 23 year experience in engines, model and full size, repairing, overhauling, hot-rodding, adjusting and just tinkering with them.

I also learned my physical mechanics and materials well enough to gain a profound understanding of what is happening inside and outside an engine, a tuned-pipe, props and carburettors.
It is quite natural to me and mechanical knowhow is a gift I have.

I am a software testing engineer and an economist by trade.
I am just waiting for a good offer to go into business in models and engines; my hobby. I also fly R/C planes, BTW.

Sincerely,