Chooned pipe for a GMS 47
09-19-2007 | 05:57 AM
#1
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From: Cape TownWestern Cape, SOUTH AFRICA
Chooned pipe for a GMS 47
Am about to install the 47 on a Diamond Dust and am looking for advice on tuned pipes. I am looking for maximum revs and that classic tuned pipe sound. Will any pipe designed for a 40 - 50 size motor work? What brands and size should I avoid, if any. The reason I ask is because a friend has a piped OS160 and it sounds worse than an unmuffled chainsaw.
09-19-2007 | 07:10 AM
#2
Senior Member
RE: Chooned pipe for a GMS 47
Spoiler,
You can get a [link=http://macspro.com/tunedpipes.asp]Macs[/link] tuned-pipe, but the cost is humongous...
Of the pipes offered by Macs, in your particular installation, there are several choices:
Quiet pipes
7.5cc (.40-.50) 16½" 3.4 oz 77.95 1040
8.5cc (.45-.60) 16¾" 4.0 oz 92.95 1050
Tuned pipes
7.5cc (.40-.50) 12¼" 2.0 oz 47.95 1140
8.5cc (.45-.60) 12¾" 2.0 oz 52.95 1150
And Muffled tuned pipes
6.5cc (.35-.45) 14¼" 3.4 oz 65.95 1230
7.5cc (.40-.50) 15¼" 3.6 oz 66.95 1240
8.5cc (.45-.60) 16¾" 4.2 oz 75.95 1250
For a Diamond Dust you would want the maximum RPM, so the shortest pipes are in order.
The 1140 will give you the highest possible performance, but believe me, you don't want to hear it...
You can get a [link=http://macspro.com/tunedpipes.asp]Macs[/link] tuned-pipe, but the cost is humongous...
Of the pipes offered by Macs, in your particular installation, there are several choices:
Quiet pipes
7.5cc (.40-.50) 16½" 3.4 oz 77.95 1040
8.5cc (.45-.60) 16¾" 4.0 oz 92.95 1050
Tuned pipes
7.5cc (.40-.50) 12¼" 2.0 oz 47.95 1140
8.5cc (.45-.60) 12¾" 2.0 oz 52.95 1150
And Muffled tuned pipes
6.5cc (.35-.45) 14¼" 3.4 oz 65.95 1230
7.5cc (.40-.50) 15¼" 3.6 oz 66.95 1240
8.5cc (.45-.60) 16¾" 4.2 oz 75.95 1250
For a Diamond Dust you would want the maximum RPM, so the shortest pipes are in order.
The 1140 will give you the highest possible performance, but believe me, you don't want to hear it...
09-19-2007 | 07:14 AM
#3
Senior Member
RE: Chooned pipe for a GMS 47
Alternatively,
You can get a high-RPM tuned silencer (MVVS #3246 from 17K RPM northward), but you will need a suitable header to fit your engine.
The cost will be a fraction of the Macs pipes. Performance will be several hundred RPM lower.
You can get a high-RPM tuned silencer (MVVS #3246 from 17K RPM northward), but you will need a suitable header to fit your engine.
The cost will be a fraction of the Macs pipes. Performance will be several hundred RPM lower.
09-19-2007 | 10:56 AM
#4
Senior Member
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RE: Chooned pipe for a GMS 47
If you hate the two-stroke sound, you have nothing to worry about, once the model is airborne. <G>
The wing's surface will direct most of the sound upwards.
A small, unmuffled tuned pipe made for a .39 to .55 size engine would serve you well. I don't know of any that should be avoided, except for weight considerations.
Frankly, these days I buy all of my tuned pipes from eBay sellers. Pipes that would normally cost me $60 (USD) can be had for as little as $15. Just be sure to ask the seller about dents and cracks first. Also ask how much the pipe was shortened to "tune" it. Yes, I've heard of folks shortening the pipe instead of the header.
Don't forget to lower the compression a bit by adding head shims. If you don't do this, you will go through glow plugs very, very quickly.
Ed Cregger
The wing's surface will direct most of the sound upwards.
A small, unmuffled tuned pipe made for a .39 to .55 size engine would serve you well. I don't know of any that should be avoided, except for weight considerations.
Frankly, these days I buy all of my tuned pipes from eBay sellers. Pipes that would normally cost me $60 (USD) can be had for as little as $15. Just be sure to ask the seller about dents and cracks first. Also ask how much the pipe was shortened to "tune" it. Yes, I've heard of folks shortening the pipe instead of the header.
Don't forget to lower the compression a bit by adding head shims. If you don't do this, you will go through glow plugs very, very quickly.
Ed Cregger
