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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › question on engine power due to worned out ring
04-08-2010 05:00 PM  8 years agoPost 1
Git

rrVeteran

Brunei

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i have an os91hz which i feel is losing pop. can any rrmasters/rr profs/ math geniuses pls help me calculate roughly how much power im losing?

i have taken the ring out and measured the thickness.. it's 0.9mm

a new ring is 1.1mm.. so i already lost 0.2mm on the old one.

how much power/compression loss does that equate to just for the sake of my knowledge?

Alees Rush 750

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04-08-2010 06:29 PM  8 years agoPost 2
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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Well it’s intuitively obvious to the most casual observer that through the process of elimination you have lost .2mm of new ring mass thickness or 18.18181818181818181 percent.

Now if we assume that the molecular substructure is still integral with the surrounding nanostructure and completely, entirely, and in all other ways unharmed, and that the blowback from the loss of compression is non-linearly homogenous, unvarying, uniform and not causing any interference with the flux capacitor, then I clearly can’t choose the wine in front of me. Wait a minute, I digress.

Obviously from this mathematical uncertainty, and since today is Thursday, we can postulate with a probable certainty of 37% that you are losing roughly 0.18181818181 times Pi * R2 or 1.21 gigawatts of dense dark matter energy, which roughly equates to 0.3141592654 hp for a 0.91 in3 nitromethane engine.

My recommendation is to put a new ring in it, break it in correctly, and have fun!

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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04-08-2010 06:42 PM  8 years agoPost 3
Randog

rrApprentice

Santa Clarita,California,U SA

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Holly Cow!, I am not sure what professor Rock is saying but I am tending to agree with him. I think.

Professor Rock. Where did you get your credentials.

As a dumb construction worker I say who cares. Change the ring and fly!

Cheers

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04-08-2010 06:43 PM  8 years agoPost 4
USNAviationjay

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Houston Tx USA

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DING DING! We have a winner!

lol.. nice post Rock..
yeh replace the ring and be done with it.

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04-08-2010 06:44 PM  8 years agoPost 5
nivlek

rrProfessor

Norfolk England

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If you can tell it's down on power , then you've lost too much . That's all you need to know .

At the end of the day , it gets dark .

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04-08-2010 06:50 PM  8 years agoPost 6
jackheli

rrProfessor

Vancouver - Canada

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31.3452%

It's easy to find an excuse to do wrong. Hard is not to find an excuse to do right.

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04-08-2010 07:07 PM  8 years agoPost 7
inkspot1967

rrProfessor

Cranston Ri

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ok Rock you know im only a truck driver can i get the english version of what the heck you said.......lol

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04-08-2010 07:07 PM  8 years agoPost 8
rotormonkey

rrKey Veteran

Ottawa, ON - Canada

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Am I wrong in saying it shouldn't matter how thick the ring is? I mean as long as it seals the gap between the piston, and sleeve if it's all wearing evenly, it shouldn't matter right? Only if there's scoring of some kind does air get through which causes loss of compression.

Or am I missing something?

I'm of the school of thought, if it ain't broke, don't fix it. I know you said you don't have the power you think you should, but I don't get how it can be related to the ring thickness.

If my thinking is wrong, please educate me.

If it can't hover, it ain't worth flying.

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04-08-2010 07:10 PM  8 years agoPost 9
dkshema

rrMaster

Cedar Rapids, IA

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Thickness -- as in from top to bottom? That would be kind of weird to have that kind of wear in a ring.

The real test is to remove the ring from the piston without breaking it, then put it in the cylinder, use the piston to square it up in the cylinder, then measure the ring end gap.

Repeat the process with a new ring, measure ITs end gap.

Compare the two.

That would tell you how much wear you really have on the ring.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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04-08-2010 07:21 PM  8 years agoPost 10
LonR

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Macomb,Mi

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https://rc.runryder.com/t579326p1/ .

600LE,OS55,OS PowerBoost pipe,Align 610's,Spartan

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04-08-2010 07:28 PM  8 years agoPost 11
Git

rrVeteran

Brunei

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rock: will you be attending the next star trek convention? *lol*

rotormonkey: i wud assume, the tighter the ring pushes against the liner, the stronger the compression hence more power.

dkshema: sorry, forgot to mention, thickness from id to od. i used the knife edge of a vernier caliper to measure so it cant be out by much.

the rest: definitely loss of compression for sure.. coz i realised i dont get hydro lock anymore and i can even twist the starter coupling easily with my fingers when the engine is cold.

Alees Rush 750

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04-08-2010 07:30 PM  8 years agoPost 12
Git

rrVeteran

Brunei

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btw, i changed it already.. i just wanted the peace of mind that im doing the right thing

Alees Rush 750

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04-08-2010 07:36 PM  8 years agoPost 13
rotormonkey

rrKey Veteran

Ottawa, ON - Canada

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I guess that makes sense. You do have to compress the ring to get it in usually though, so it should press against the cylinder sleeve no matter what. But I guess if it's less worn, it's compressed in more, therefore pushing harder on the sleeve, and thus a tighter tolerance? Makes sense.

If it can't hover, it ain't worth flying.

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04-08-2010 07:40 PM  8 years agoPost 14
baddynergy

rrElite Veteran

sierra madre, ca- usa

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Like DKShema says, the only proper way to measure wear is endgap. A piston ring is a spring and will always push against the cylinder.

**Unattended children will be givin a shot of espresso and a puppy**

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04-08-2010 09:02 PM  8 years agoPost 15
QuantumPSI

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Atlanta, GA

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Rocko's post had me DYING!

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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04-08-2010 09:08 PM  8 years agoPost 16
BLUETHUNDER

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Glass City

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One thing about a piston ring
It's either wearing in (break In)
Or it's wearing out from use.

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04-08-2010 09:27 PM  8 years agoPost 17
nickt919

rrVeteran

New Orleans, Louisiana

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The real test is to remove the ring from the piston without breaking it, then put it in the cylinder, use the piston to square it up in the cylinder, then measure the ring end gap.
Repeat the process with a new ring, measure ITs end gap.
Compare the two.
That would tell you how much wear you really have on the ring.
There you have it...It's the widening of the ring gap that obviously lowers compression. ....Bigger hole lets more air squeeze through faster....

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04-08-2010 09:43 PM  8 years agoPost 18
BLUETHUNDER

rrVeteran

Glass City

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The best way to check for a worn out ring or rings is to use a
compression gage. compare your engine to a fresh engine.

http://www.rcplanet.com/Dynamite_Co...e_p/dyn2514.htm

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04-08-2010 10:08 PM  8 years agoPost 19
heli-cuzz

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Pittston, Pa. USA

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The best way to check for a worn out ring or rings is to use a
compression gage. compare your engine to a fresh engine.
+1

I have that same guage. Not sure what the 91 is but a brand new hyper is about 145 to 150 psi.
When the compression drops to 50% of the original reading, then its time to change the ring.
I've been averaging about 40 to 50 gallons on the hyper50 ring before replacing it with a new one.

Fury 55 NIB Furion6 CGY750 fbl helicopter-Frenzy CGY750 fbl nitro-Frenzy fbl NOBAR90

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04-08-2010 10:52 PM  8 years agoPost 20
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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Rocko's post had me DYING!

Glad you were entertained!

I was having fun and got on a roll..................

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › question on engine power due to worned out ring
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