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lcottrell
Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or
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 Posted: Wed Oct 12, 2016 5:33 pm Post subject: Fwd: HKS question |
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HKS Engine Interference Questions
---------- Forwarded message ----------
This thread started me thinking about a different exhaust system, so I wrote to Jerry (at)Green Sky to see if the engine actually needed a muffler. Below is his answer.
For me one of the good things about the HKS was that it is quieter than a 503. I hate loud noise and do all I can to protect my hearing, even using protection when mowing my lawn. So Bill, how about becoming a real test pilot and let us know how bad the noise level is when flying the darn thing without a muffler.
If I was doing it I would bring both pipes together right behind the back end of the cage and down about 3/4 of the way to the boom tube with perhaps a bend back towards the prop. It would of course be nice to keep it away from the prop, so perhaps coming alongside the boom tube straight down. It should be easy to brace the pipe using the upright tubes on the cage. I'm pretty sure you would have your own ideas. The wings folded might cause problems with a tube alongside the boom tube.
Larry
From: <mail(at)greenskyadventures.com (mail(at)greenskyadventures.com)>
Date: Wed, Oct 12, 2016 at 5:26 PM
Subject: Re: HKS question
To: Larry Cottrell <lcottrell1020(at)gmail.com (lcottrell1020(at)gmail.com)>
Hi Larry,
You might loose a little HP, but a little his hard to quantify. I recently started test running dual pipes with a resonator in each one for sound dampening. I though my exhaust was too quiet. Now it sounds like a 750 norton P11 scrambler. I like it, but it might be too noisy in closed cockpit. If I was doing a kolb for myself, that is probably what I would do unless there were lots of noise complaints.
Regards,
Jerry
Quoting Larry Cottrell <lcottrell1020(at)gmail.com (lcottrell1020(at)gmail.com)>:
| Quote: | Does this engine require a muffler? There is some talk of making an exhaust
manifold that would go down the back of the cage and thus out of the stream
flow. This of course would be a good thing as the location of the muffler
causes a bunch of problems with heat, dirtied air flow etc. Any thoughts?
Thanks
Larry
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*The older I get, the less tolerant I am of those who are intolerant of
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*If you forward this email, or any part of it, please remove my email
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The older I get, the less tolerant I am of those who are intolerant of others.
If you forward this email, or any part of it, please remove my email address before sending.
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stuart(at)harnerfarm.net
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| Posted: Wed Oct 12, 2016 6:53 pm Post subject: Fwd: HKS question |
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At OSH one year I was looking at a BackYard Flyer with a Generac engine on it. The exhaust was two tubes wrapping around the front of the engine (tractor setup) and if I remember right they used a slip joint to join them.
There was no open end on the tube but a series of small holes aprox. 1/8” diameter drilled in the underside of the tube. This allowed for dispersion of the exhaust gasses to keep the heat down and did a good job of controlling the noise.
I have searched for pictures but have found none in my albums.
Perhaps something like this could be done with the HKS on the FS.
My thought process for experimenting would go something like this.
Get a scale that you can tie to the plane and a solid object to measure thrust.
Start with the existing exhaust since you already have that. Dial the prop in for the proper full throttle static RPM and measure thrust.
Remove exhaust and re-measure thrust. Now you have a couple of baselines to work from.
Install a “mock-up” version welded out of standard automotive exhaust pipe. (cheap and easy to work with). Drill holes of a quantity and diameter that you think would be a minimum required.
Test for static RPM and thrust again and judge the noise made.
Drill more or larger holes as needed to get a design that works for you.
Once all the bugs are worked out to your satisfaction, then take the prototype to a place that can make up a nice one from more durable and hopefully lighter weight material. I understand titanium is wonderful for this kind of thing. 
It might take some time dialing it in, but it shouldn’t cost too much to try it.
Just a suggestion, do with it what you wish.
Stuart
From: owner-kolb-list-server(at)matronics.com [mailto:owner-kolb-list-server(at)matronics.com] On Behalf Of Larry Cottrell
Sent: Wednesday, October 12, 2016 8:33 PM
To: kolb-list(at)matronics.com
Subject: Fwd: HKS question
HKS Engine Interference Questions
---------- Forwarded message ----------
This thread started me thinking about a different exhaust system, so I wrote to Jerry (at)Green Sky to see if the engine actually needed a muffler. Below is his answer.
For me one of the good things about the HKS was that it is quieter than a 503. I hate loud noise and do all I can to protect my hearing, even using protection when mowing my lawn. So Bill, how about becoming a real test pilot and let us know how bad the noise level is when flying the darn thing without a muffler.
If I was doing it I would bring both pipes together right behind the back end of the cage and down about 3/4 of the way to the boom tube with perhaps a bend back towards the prop. It would of course be nice to keep it away from the prop, so perhaps coming alongside the boom tube straight down. It should be easy to brace the pipe using the upright tubes on the cage. I'm pretty sure you would have your own ideas. The wings folded might cause problems with a tube alongside the boom tube.
Larry
From: <mail(at)greenskyadventures.com (mail(at)greenskyadventures.com)>
Date: Wed, Oct 12, 2016 at 5:26 PM
Subject: Re: HKS question
To: Larry Cottrell <lcottrell1020(at)gmail.com (lcottrell1020(at)gmail.com)>
Hi Larry,
You might loose a little HP, but a little his hard to quantify. I recently started test running dual pipes with a resonator in each one for sound dampening. I though my exhaust was too quiet. Now it sounds like a 750 norton P11 scrambler. I like it, but it might be too noisy in closed cockpit. If I was doing a kolb for myself, that is probably what I would do unless there were lots of noise complaints.
Regards,
Jerry
Quoting Larry Cottrell <lcottrell1020(at)gmail.com (lcottrell1020(at)gmail.com)>:
Does this engine require a muffler? There is some talk of making an exhaust
manifold that would go down the back of the cage and thus out of the stream
flow. This of course would be a good thing as the location of the muffler
causes a bunch of problems with heat, dirtied air flow etc. Any thoughts?
Thanks
Larry
--
*The older I get, the less tolerant I am of those who are intolerant of
others.*
*If you forward this email, or any part of it, please remove my email
address before sending.*
--
The older I get, the less tolerant I am of those who are intolerant of others.
If you forward this email, or any part of it, please remove my email address before sending.
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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Richard Pike
Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee
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| Posted: Thu Oct 13, 2016 5:32 am Post subject: Re: Fwd: HKS question |
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Reminds me of this picture in Tony Bingelis' book "Firewall Forward."
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_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing. |
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