[SPAM] Re: Webra 145 pump pressure ?

[Paul Horan]

Randy,
    When I first ran this engine with the 17x12 I got about 7900 with BLACK oil in the exhaust.
I have deliberately lengthened the pipe a bunch to drop the rpm where engine stress should be less.  So far I  only have 1.5 gallons 
through the engine.
Even at 72-7300 I have enough power for the intermediate pattern.
Thanks,
Paul
----- Original Message ----- 
From: "Randy" <randy10926 at comcast.net>
To: <discussion at nsrca.org>
Sent: Thursday, April 07, 2005 12:51 PM
Subject: Re: Webra 145 pump pressure ?


>I got more RPMS than this with a 17X12 on this motor with a greeve pipe.  I seem to remember around 8K.
> Randy
>
> ----- Original Message ----- 
> From: "Grow Pattern" <pattern4u at comcast.net>
> To: <discussion at nsrca.org>
> Sent: Wednesday, April 06, 2005 11:53 PM
> Subject: Re: Webra 145 pump pressure ?
>
>
>> Paul,
>>           I have been thinking about your Webra problem. Your rpm seems too low for that prop.  I was wondering which MAC pipe 
>> you are running? I have found the 145 to be a bit fussy in the mid range if the pipe volume is not big enough. It also needs a 
>> good taper at the front of the pipe to get a good transition. Your pipe could be partially blocked?
>>
>> The OS 1.40 pipe, and/or ES CF clone pipe, has proven to be a good pipe for this motor.
>>
>> I believe that you are right about the pump but it is also related to tank position. The pump does not deliver quite enough fuel 
>> in the mid range which might be why it is getting hot on sustained 1/2 throttle. You can help your pump perform by moving the 
>> tank forward a bit.  If the back of the tank is on the CG it does not seem to mess much with the flight CG as it drains fuel.
>>
>> Quite a few folks have richened up the pump with good results. I would try the above external changes first before you start 
>> messing with it.
>>
>> A big "no!" to Castor content. Just fit the new BOCA stainless steel bearing. I would also soak the liner, ring and piston parts 
>> in an Acetone/Lacquer-thinner mix to remove any shellac build up.
>>
>> Regards,
>>
>> Eric.
>>
>>
>>
>>    My Webra has a good top and bottom end. Only about a gallon and a half through it so far.
>>  The top end is nice and smokey, idle is solid, but the mid range is very little smoke.
>>  It is on a Prophecy running a 16.5 x 12 at 7300 rpm with the Macs pipe at 27  inches.
>>
>>  Most of my flight is at roughly 1/2 throttle. When I land the oil residue on the coupler and
>> fuselage is medium brown - fuel is a mix of 20 % synthetic and 5 % synthetic.  Main needle is open 1.5 turns.
>>  am wondering if I should increase the pump pressure to richen up  the midrange.
>> Or am I just being too fussy ?
>> Thanks,
>> Paul Horan
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