 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
dcaofak(at)acsalaska.net
Guest
|
 Posted: Mon Oct 16, 2006 12:43 pm Post subject: 582 W/ chopped muffler |
 |
|
DeWayne,
I have a 'chopped' exhaust system on my Model III with a 582. I did this to fit the exhaust entirely on the right side of the engine. This allowed my simplified fuel system to occupy the left side of the firewall and be well separated from the exhaust system heat.
Changing the curvature of the exhaust elbow or the tapered pipe leading to the muffler will not alter the engine performance IF the changes in angles are relatively small (less than 15 degrees per bend) AND the centerline length of the exhaust system remains unchanged. If you need more than 15 degrees of change use multiple 'bends'.
A good way to make a bend is to carefully mark a wedge to be cut from the inside of the bend, the sharp ends of the wedge must be exactly on the opposite centers of the tube. Cut a straight line from the side opposite the removed wedge to withis 1/16 inch of the tip of removed wedge. Bend the tube along these tiny 'hinges' and the removed wedge should perfectly fill the new open wedge on the outside of the bend.
This of course takes a little practice to get it right. You can make tapered tubes from sheet stock and practice on them.
There is a good narrative with illustrations of this technique in the expansion chamber section of "Two-stroke Tuner's Handbook" by Gordon Jennings. If you go to the extreme and design and build your own exhaust system from scratch using this manual be aware that there are some errors in the math examples, always do your own math to double check the text.
Regards,
John Stoner
KFIII, 582
Alaska
[quote][b]
| | - The Matronics Kitfox-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:
http://www.matronics.com/Navigator?Kitfox-List |
|
|
|
| Back to top |
|
 |
Malcolmbru(at)aol.com
Guest
|
| Posted: Mon Oct 16, 2006 2:18 pm Post subject: 582 W/ chopped muffler |
|
|
So the manafold and the muffler has 1/2 and 3/4 cut off them so the center line is shorter? ,the elbow is wedged out a little bit did I loose any power ? what causes the need to rejet ?
[quote][b]
| | - The Matronics Kitfox-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:
http://www.matronics.com/Navigator?Kitfox-List |
|
|
|
| Back to top |
|
|
dave
Joined: 22 Sep 2006
Posts: 1382
|
| Posted: Mon Oct 16, 2006 2:26 pm Post subject: 582 W/ chopped muffler |
|
|
John , great write up on the Kitfox chopped exhaust. I was always under the impression that the 582 is a bit less that 64 HP in the Kitfox as the exhaust length is a bit different than a stock rotax exhaust. I had a new manifold here and compared it to the Kitfox Y pipe and the Kitfox one was about 1" to 1 1/2 " shorter than the brand new one. Now I know the cone is altered after the elbow and measuring through the centreline it seemed to be the same length as the new one in total.
What did you find on your workings with this ? Right now we have a great comprise between wider power band and you don;t have to be on the pipe at a narrow rpm range to get the torque.
That being said if you wanted to lose some reliability and use more gas , I am sure you could get 100 hp ++ out of the 582..... but if would not be nearly as flyable as it is now. Would be good for a show off plane for super quick take offs and climb outs..........
Dave
[quote] ---
| | - The Matronics Kitfox-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:
http://www.matronics.com/Navigator?Kitfox-List |
|
_________________
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/user/kitfoxflyer
Hundreds of Kitfox Movies
Most viewed Kitfox on youtube
Most popular on youtube
Highest rated on youtube |
|
| Back to top |
|
|
dcaofak(at)acsalaska.net
Guest
|
| Posted: Mon Oct 16, 2006 3:33 pm Post subject: 582 W/ chopped muffler |
|
|
Malcolm,
The shorter centerline length of your exhaust most likely made the power band slightly narrower and makes peak power at a little higher rpm. This change would also likely reduce the exhaust scavenging at the cylinder exhaust port, which would require a richer mixture, hence the larger jets. Poorer scavenging will reduce power output. Bear in mind also that the jetting is air temperature and density dependant. Up here in Alaska I routinely switch to larger jets about this time of year when our temp rarely go above 40 degrees (F).
The elbow being wedged out a little may or may not effect the power output. If it looks like the smooth flow of exhaust is comprimised, it almost certainly is, and will reduce power output. If the elbow looks like it still allows smooth flow throughout the length of the bend and into the next segment of the system, it probably does not contribute to power reduction.
The welds as they are seen from inside the tubes can also be detrimental to flow. Rough welds that protrude into the flow path can cause turbulene in the flow, thus reducing power. The smaller the diameter where the welds are the more significant the potential problem.
The proper execution of a good exhaust on two stroke engines is a combination of science and art. The physics can speak for themselves, certain dimensions, tapers, etc. are either right or wrong for the goals of power band width and rpm at peak power. The art is making it look like it will flow smoothly with minimum turbulence as seen from the exhaust gas perspective.
Regards,
John Stoner
KFIII, 582
Alaska
From: ([email]Malcolmbru(at)aol.com?subject=Re:%20Re:%20582%20W/%20chopped%20muffler&replyto=cc9.5506fb.32655ea5(at)aol.com[/email])Malcolmbru(at)aol.com ([email]Malcolmbru(at)aol.com?subject=Re:%20Re:%20582%20W/%20chopped%20muffler&replyto=cc9.5506fb.32655ea5(at)aol.com[/email]) Date: [b]Mon Oct 16 - 3:18 PM[/b] [quote] | Quote: | So the manafold and the muffler has 1/2 and 3/4 cut off them so the center
line is shorter? ,the elbow is wedged out a little bit did I loose any power
? what causes the need to rejet ?
|
[b]
| | - The Matronics Kitfox-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:
http://www.matronics.com/Navigator?Kitfox-List |
|
|
|
| Back to top |
|
|
dcaofak(at)acsalaska.net
Guest
|
| Posted: Mon Oct 16, 2006 3:50 pm Post subject: 582 W/ chopped muffler |
|
|
Dave,
It would be very easy to get 100 hp or more from a 582. This could be done with only exhaust system changes. The biggest argument against doing this (IMHO) is not overstressing the connecting rod small end bearings.
The horsepower our engines make in flight is continuous, that is a steady all the time 48 hp (at 75 % cruise for example). In other applications like snow machines, they claim a higher horsepower rating from the almost identical engine. But, they only operate at that high horsepower setting for a few seconds at a time, their cruise output is likely in the 25 to 30 hp range.
One of the main differences between the 583 snow machine engine and the 582 aircraft enging is the rod small end bearings. Caged bearings in the 583, easier to install, and adequate for the power levels they see on a continuous basis. Loose needle bearings in the 582 provide more surface contact and better heat dissipation at the higher continuous loads.
As I understand it, this is the main reason that Rotax discourages putting a 'higher' output 583 in an aircraft.
Regards,
John Stoner
KFIII, 582
Alaska
Subject: Re: Re: 582 W/ chopped muffler From: Dave (dave(at)cfisher.com ([email]dave(at)cfisher.com?subject=Re:%20Re:%20582%20W/%20chopped%20muffler&replyto=017601c6f171$6501a8c0(at)leroy[/email])) Date: [b]Mon Oct 16 - 3:26 PM[/b] [quote] | Quote: | <<<
, I am sure you could get 100 hp ++ out of the 582..... but if would
not be nearly as flyable as it is now. Would be good for a show off
plane for super quick take offs and climb outs..........
Dave |
[b]
| | - The Matronics Kitfox-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:
http://www.matronics.com/Navigator?Kitfox-List |
|
|
|
| Back to top |
|
|
dave
Joined: 22 Sep 2006
Posts: 1382
|
| Posted: Mon Oct 16, 2006 4:00 pm Post subject: 582 W/ chopped muffler |
|
|
Sounds right to me ......... and also a 582 fuel burn will go up considerably with a better exhaust. But with a better exhaust comes alot of screwing around with jetting and you will always have issues as the temps and climate changes............so imo bestd to leave it alone.........
---
| | - The Matronics Kitfox-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:
http://www.matronics.com/Navigator?Kitfox-List |
|
_________________
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/user/kitfoxflyer
Hundreds of Kitfox Movies
Most viewed Kitfox on youtube
Most popular on youtube
Highest rated on youtube |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
