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HelicopterEngines Plugs Mufflers Fuel › Webra 91 max RPM and gearing?
12-21-2003 06:45 PM  13 years agoPost 1
iachia

rrVeteran

Milan, Italy

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Hi there, does anyone know what is the max rpm of the webra 91? I can't find that info anywhere...
Also I'd like to know what gearing is mostly used with this engine.
I use 7.91:1 but not really happy with it. Would you suggest something else like 8.18?
thanks
p.s.
I use 10% nitro 18% oil in a raptor 90

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Synergy N9

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12-22-2003 05:41 AM  13 years agoPost 2
sharam

rrElite Veteran

Northern California - Fly at Morgan Hill Field

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Do a search on RR. I have posted extensively on this and I know that others have as well.

It sems that the Webra 91's power range is in the 14,000 to 15,000 range.

My experience is that it can run at 16,000 without much trouble.

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12-22-2003 10:43 AM  13 years agoPost 3
iachia

rrVeteran

Milan, Italy

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Thanks sharam I'll search your posts.
What gear ratio do you think that works best with this engine?

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Synergy N9

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12-22-2003 05:39 PM  13 years agoPost 4
sharam

rrElite Veteran

Northern California - Fly at Morgan Hill Field

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I guess you need to decide what headspeed you want and work from there.

I fly my Cuatro (Webra 91, 800mm blades) with a headspeed of 1650 max. With an 8.89 gear ratio, the engine rpm is 14,668 which is right in power band.

If you want a head speed of 1800, then assuming an engine rpm of 14,500, your gear ratio ought to be around 8.06 or thereabouts.

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12-22-2003 06:58 PM  13 years agoPost 5
thierry

rrApprentice

Paris FRANCE

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hello sharam
what paddle are you using on your cuatro ?
are they ok for roll ?
what is the speed roll ?
thanks

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12-22-2003 07:07 PM  13 years agoPost 6
sharam

rrElite Veteran

Northern California - Fly at Morgan Hill Field

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Bonjour Thierry,

I am using the stock paddles. The roll and flip rates are slow. I will probably experiment with lighter paddles soon.

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12-22-2003 09:05 PM  13 years agoPost 7
vagpas

rrApprentice

Thessaloniki-Greece

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iachia

Keep your ratio. It is correct if you are aiming at around 1900 head speed.

I use 7.86 and i`m turning at 1950. I have tried higher and lower than that.

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12-23-2003 03:10 AM  13 years agoPost 8
iachia

rrVeteran

Milan, Italy

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I use 1800 and at that speed it's fine but if I try to go 1850 with the gv1 it seems that it's too much for the engine and I don't get good performance.
I was also thinking to upgrade to a MP2.
what do you think about this pipe on the Webra?

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Synergy N9

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12-23-2003 06:40 AM  13 years agoPost 9
Jarno

rrVeteran

Finland

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I've been using the MP2 with the Webra 91 for a long time with great results. It may not be as quiet as the Funtech HN-90 type-F muffler, but the engine runs smooth and with good power.

As for the gear ratio, I use 7.75 for FAI flying and I'm happy with that. Low gearing means pretty high head speed on fff, but it suits my flying style and my Freya very well..

Just my thoughts..

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06-26-2004 09:18 PM  13 years agoPost 10
ROTORVETERAN

rrNovice

Belgium Europe

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I use the Webra 91 P5 AAR for some time now , but modified the engine with the new 3 needle carb. from Webra.The engine is running fine between 14500 and 15500 rpm , lots of power ,

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08-21-2004 08:41 PM  13 years agoPost 11
Matthew

rrApprentice

Christiansburg, VA

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What % of nitro are you all running in your 91's. Also any of you have a perry pump on it?

Raptor 70 V2 MPII 9C

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08-22-2004 08:40 AM  13 years agoPost 12
Jarno

rrVeteran

Finland

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CP 10% works just great for me. I'm using the Ultramix carb. wich is a bit over sensitive on "higher nitro" like 10-15%, but if you know how to tune it then it's fine.

You don't need any perry pump with Webra. It runs well without it. Just make sure that you have good muffler pressure and no leak with tubing.

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08-22-2004 10:02 AM  13 years agoPost 13
G.Man

rrProfessor

Bristol

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8.3:1 was what i used

Don't Email me as I wont reply - PM Only (spam countermeasures)

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08-22-2004 01:03 PM  13 years agoPost 14
Matthew

rrApprentice

Christiansburg, VA

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Jarno,

Thanks for the reply. Mine came with the pump and the 3 needle carb. It s the read head Webra 91. I have a pic of it someplace have to post it. Also my carb didn't come with instructions and i looked at webra site. Where is the hight middle and low needles. I figure the low is in the throttle arm. and the hight is closes to the carb. So it leaves the middle closes to the fuel line. Little help?

Raptor 70 V2 MPII 9C

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