Tuned pipe or muffler with large 2-Strokes?

[ROBERT PASTORELLO]

There's a variety of perspectives on this question.  As a "tinkerer", I've chosen to use mufflers because of the reasons you identified.  With the OS 1.6, ST 1.4, and now the Webra 1.45, I've found them to be very solid with mufflers.
  Dealing with the "spool up" is a different situation, and I think that it is exacerbated by a sharply-tuned pipe.  If you have a broad peak, then I've been told it's easy to deal with.
  On my own setup, I've found the cure to be careful use of the Throttle Curve (function 18 on JR 10X) to solve the spool up.  It's a strange looking curve, sort of like reverse expo for the first third, then normal expo for the next third, then straight linear for the last part.  SO far, it works, and it's close.  Still tweaking.
  SO my answer is - pipe or muffler - play around with the throttle pushrod geometry and the curve to fix the ills....

Bob P.
faipatrn at msn.com
www.rcaerobats.net  

----- Original Message -----
From: Keith Black
Sent: Saturday, September 21, 2002 2:50 AM
To: discussion at nsrca.org
Subject: Tuned pipe or muffler with large 2-Strokes?

I'd like to hear some feedback on running tuned pipes vs. mufflers on the large 2-stroke engines such as the OS 1.40RX, Webra 1.45 and Bully 1.45.

What I've understood is that these large engines have plenty of power running just a muffler without a tuned pipe, and by not running a tuned pipe the throttle response should be smoother and not so "peaky". I'd think the smoother throttle response would make flying pattern much easier. Certainly one of the benefits of 4-strokes is the instant throttle response with no spin-up time. It seems as though using a pipe would just aggravate the spin-up issue with 2-strokes.

However, in reading some of the messages lately I see that people are still running tuned pipes on these engines. For example, under the "Webra Bragging" thread Matt indicated that he is running a Webra 1.45 with an OS/Hatori tuned pipe and it flies very well.

I'd really appreciate hearing everyone's experiences relating to this issue.

Thanks,
Keith Black
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