Webra 1.45 tuning length?

[David Lockhart]

Ryan,

The Asano setup is designed for the OS140 which has different port timing than the 145 - the stock setup is about 24" (610 mm) exhaust flange to tuning baffle.

The recommended tune length from Webra for the 145 using the tuned muffler (Horizon part # 1100/260, I believe also sold by Piedmont) is 780mm (30.75"), from the exhaust flange to the flat end of the pipe before the exhaust stinger.  800m for the 160 - which is interesting because the 160 is a lower timed engine which typically will utilize a shorter tune length.  I believe Webra is specifying these tune lengths for approx 8100 RPM.

I am running the 160s and find that the 1100/260 at 31" ( 787 mm) to the flat end (24" to the tuning baffle) and the Asano at 23.785" run similarly at about 7700 RPM.

More RPM = shorter pipe.  If the pipe is too short, the main needle will be sensitive and the midrange will be less linear.

Less RPM = longer pipe.  If the pipe is too long, the boost of the pipe will be limited, and the engine will be very "friendly".

Anywhere between 25-27" should work, best length will depend on prop and flying style.

Regards,

Dave

----- Original Message ----- 
  From: Rcmaster199 at aol.com 
  To: discussion at nsrca.org 
  Sent: Thursday, January 06, 2005 10:48 PM
  Subject: Re: Webra 1.45 tuning length?


  I am still flying the 145 blackhead  too. I use the Hatori/os140  pipe with the macs header. The first reflector is set at 24inches from the plug, straight line. I don't know how the Asano is setup inside so use the first reflector distance as a good place to start.

  MattK

  In a message dated 1/6/2005 10:06:30 PM Eastern Standard Time, Acroman300 at aol.com writes:
    Hello guys,

    I would like to know the tuning lengths that you all are running with the Webra 1.45. I have the blackhead version and am running an Asano pipe. I was running the flex header combo with it, but it broke and really didn't seem that it was tuned as well as it could be, as it was a pretuned system. Any input is greatly appreciated.

    Ryan Smith

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20050107/76ad36a5/attachment.html