Engine basics > Engine set up tips

Tune pipe

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Mike Scholtes:
Larry and I both have new RoJett BSE 61s to go into Thundergazer-ish models. Is the Hattori an aluminum pipe, or is Brett referring literally to just the end of the tailpipe, where the grey rubber deflector normally goes? And, is the Hattori pipe (if that is what Brett is referring to) available these days? Are they made by Hattori Hanzo of "Kill Bill" fame? Failing a Hanzo pipe, what would those in the know suggest in a CF pipe from Randy Smith or Brian Eather or any other maker, as to overall length, baffle placement, and other critical features? Thanks in advance.

Brett Buck:

--- Quote from: Mike Scholtes on October 14, 2020, 06:27:53 PM ---Larry and I both have new RoJett BSE 61s to go into Thundergazer-ish models. Is the Hattori an aluminum pipe, or is Brett referring literally to just the end of the tailpipe, where the grey rubber deflector normally goes? And, is the Hattori pipe (if that is what Brett is referring to) available these days? Are they made by Hattori Hanzo of "Kill Bill" fame? Failing a Hanzo pipe, what would those in the know suggest in a CF pipe from Randy Smith or Brian Eather or any other maker, as to overall length, baffle placement, and other critical features? Thanks in advance.

--- End quote ---

   I was assuming that Larry meant the rubber exhaust deflector. As far as which pipe to use, the ones I have are long since out-of-production, although Randy says he has an equivalent product (that is slightly too big around to fit in my airplane). Either that, or ask Dennis Nunes which one he has - seems to work pretty good. You can try it on your current 40/46VF-sized pipes, but I would expect it to have a significant effect on the power.

    Brett

Dennis Nunes:
Hi Mike,

For my RO-Jett BSE 61 setup I'm using a Rich Oliver pipe that was purchased through Dub Jett. Attach is a PDF with some pictures of this setup. Also included is pictures of the Randy Smith "Slimline" pipe that I haven't used.

BTW, I will be at the Napa flying site tomorrow (Thursday) morning. If you would like to try this pipe, come by site if you can and pick it up. If not, we can make other arrangements to get it to you. Just let me know.


Dennis

John Leidle:
  Several decades ago my neighbor was an AMA GP  racer he rode Yamaha 250 , 350 twin cylinder 2 smokes. I don't remember his name but he knew all the guys ,, he would tell me about tuning & using the expansion chambers , etc why I mention  this is he found when you make the stinger longer  the rpms  increase,,, have no idea if it applies here.
            John L.

Brett Buck:

--- Quote from: Lauri Malila on October 15, 2020, 10:06:07 AM ---Well, think of the stinger as one acoustic element that has a certain volume. Acoustics is all about volume.
By varying the volume (lenght) you can tune it (like a minipipe) to have either positive or negative backpressure, or to be neutral. Whatever suits you the best.
So it doesn't mean that longer is allways better, you've got to optimize it.
But if you want to test things, I'd recommend something stiffer than silicone hose. L

--- End quote ---

   Generally he idea is to either getting more boost by the reflecting cone larger by having a smaller outlet, or more flow and less boost with a bigger outlet which makes the reflecting cone surface area smaller.

   The practical length for stingers probably puts it at far too high a frequency for any useful additional boost. And, you *don't need more boost" if the intent was to (selectively) kill power in the first place.

    Brett

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