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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › Will 30% Shorten the life over 15%
09-04-2013 11:37 PM  4 years agoPost 1
shinysideUP

rrApprentice

USA NJ, NY

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I have a 91HZR, I fly 3D and "smack" and currently run 15%, will moving to 30% shorten my motors life considerably?

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09-05-2013 12:53 AM  4 years agoPost 2
unclejane

rrElite Veteran

santa fe, NM, USA

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It will make the motor work harder, so there will definitely be some negative impact on its lifetime. How much shorter that lifetime will be, though, I couldn't really say. But the general rule of thumb is, the more work you extract from a piece of metal of a given size, the faster it's going to wear out.

Most of our nitro engines die from crash damage or rotting away in closets etc. long before we ever actually wear them out, though, so it's probably going to last quite as long as you'll ever need even on 30%.

OTOH, I would imagine tuning mistakes like running too lean will be less forgiving at those higher power outputs.

So hard to say, other than yes it will wear out faster by some unknown amount .

LS

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09-05-2013 01:13 AM  4 years agoPost 3
KevinB

rrKey Veteran

Saskatoon, Saskatchewan, Canada

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You could also argue the other way......Running 30% you can run the engine a little richer/cooler and still get the same power as running 15% and leaning it to the limit. That would be easier on the engine, not harder. However, you must resist the little voice telling you to take the 30% to the limit or yes....it will be working the engine harder.

KevinB

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09-05-2013 02:20 AM  4 years agoPost 4
dkshema

rrMaster

Cedar Rapids, IA

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Properly tuned, it shouldn't be a problem. Remember that there are countless people who have easily fried their motors running 15% nitro, just due to bad tuning. It's not the nitro that is the problem, it's how you use it.

-----
Dave

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

Team Heliproz

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09-05-2013 03:02 AM  4 years agoPost 5
Tyler

rrElite Veteran

Chicagoland area

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30% is more forgiving and makes more power at a richer tune. I hurt more engines on 15 because the needles are more critical and I wanted the power others found with 30%. lower nitro does cost less and flies longer per ounce with leaner needles.

20% is a great middle ground with benefits of both camps.

Enjoy things that money can buy IF you don't lose the things money can't buy.

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09-08-2013 04:24 AM  4 years agoPost 6
shinysideUP

rrApprentice

USA NJ, NY

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These are the Optimal setting that Scott Grey uses with 30% on his STOCK 91HZ with a 0.012" shim
• SZ / C-Spec 0.012" head shimming; HZ stock head shim only
• OS#8 or new OS#7 Glow plug (medium to medium hot heat range)
• High volume, close fitted cooling shroud system
• 8:1 gear ratio
• 15,500 - 16,000 Max Engine RPM (1950-2000RPM Main Rotor)
• 3D Fuel - Cool Power 30% Heli fuel
• F3C Fuel - Cool Power 30%/15% 1:1 Mix Multi Viscosity fuel combination

OS Engines benefit and run best with lower viscosity oils at higher contents in fuel.

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09-08-2013 01:18 PM  4 years agoPost 7
unclejane

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santa fe, NM, USA

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I'm skeptical only about the higher oil content being needed. I ran my last .91 HZ-R for about 50 hours mostly on 15% CP multi vis at 18% oil content. I only took it out of its last heli to put a 1.05 in it - the only wear it had at removal was a shiny spot just starting to form on the piston under the ring land at the exhaust port. Still had normal compression, running and power.

An engine's worst enemy is always it's owner/operator; I think the "tuners" are the ones propagating this idea that 1/4 of the fuel jug has to be oil else it'll burn up lol.

I don't disagree the higher oil content helps buy you a little time if you're running too lean, but the running too lean is the problem, not the fuel, in my experience. If you set the mixture correctly, the extra oil doesn't really buy you anything. You can practically run whatever fuel you can find in stock without troubles that way. Long as it's 18% or more, OS doesn't have a problem with it as far as I know.

And having run a couple OS's out at this point, even old-school airplane fuel seems to be just fine (unless you really need to push the engine to the max).

LS

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09-12-2013 11:53 PM  4 years agoPost 8
shinysideUP

rrApprentice

USA NJ, NY

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Can someone chime in here, the stock gasket on my 91hzr is .14mm. I removed a gasket from a second 91hzr and was the same .14-.15mm. Well i put both together on my digi. caliper and it adds up to .3mm. I am now running both thin shims but wondered if the single .2mm will yield more performance with 30% in NY weather?

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09-13-2013 12:32 AM  4 years agoPost 9
ICUR1-2

rrElite Veteran

Ottawa, Ontario

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Will 30% Shorten the life over 15%
it's not the nitro content that matters it's the tune and oil content.

spending time, paying attention

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09-13-2013 07:14 AM  4 years agoPost 10
TMoore

rrMaster

Cookeville, TN

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I have a 91HZR, I fly 3D and "smack" and currently run 15%, will moving to 30% shorten my motors life considerably?
No. You can run the engine richer and still make more power than 15%.

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