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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Baffle placement question /cgi-bin/YaBB.pl?num=1358700313 Message started by Greg on 01/20/13 at 08:45:13 |
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Title: Baffle placement question Post by Greg on 01/20/13 at 08:45:13 So I did a little searching and found a thread with a great deal of information (http://suzukisavage.com/cgi-bin/YaBB.pl?num=1302216606 but I have a question. einheit13 (who was last seen on Sep 10th, 2011 so I can't ask him) stated that the baffle should be no closer than 2" to the end of the straight pipe. Could it be placed in the pipe where the pipe and header attach? How about in the end of the header itself? Is there a sound or performance difference between the 2 locations? |
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Title: Re: Baffle placement question Post by Cavi Mike on 01/20/13 at 10:32:34 No matter what you do - anything in the exhaust is going to reduce performance and change its sound. There's no way around it. "Tuning" an exhaust is really just trying to make sure those losses are somewhere outside of the useable powerband. As far as needing to be 'no closer than 2" from the end of the straight-pipe(header)' that's a load of bollocks. The farther away from the exhaust port you can put the baffle - the better. Why? Because the exhaust has had more of a chance to smooth out so instead of being short quick bursts of air that are easily restricted, it's a slower moving smooth stream and will restrict the movement of the piston less. It has nothing to do with its placement in relation to the end of the header because headers are all different lengths and designs. It matters how far away you are from the exhaust port and the farther the better. |
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Title: Re: Baffle placement question Post by Greg on 01/20/13 at 13:48:11 Thanks man! |
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Title: Re: Baffle placement question Post by spacepirates on 01/21/13 at 11:39:47 4F4A4D46414B280 wrote:
I think it was Diamond Jim that had a thread about this a long while back. What he did was attached a handle to the end of the baffle, and while the bike was running held the baffle in the pipe and slid it around to different locations to hear how the sound changed, then later he bolted the baffle in place. I'd also argue against Cavi Mike's statement that "anything in the exhaust will reduce performance," as exhausts need back pressure. There is a ton of science behind exhausts, so nothing is clear-cut though. Running without a baffle tunes your engine for a very high RPM that our engines can't hit, so while in racing applications you might not want a baffle since you're sitting on a hotrod engine at 10k rpm, on our bikes you are much more likely to be sitting at 3k rpm, so you want the torque curve of your exhaust to peak at 3k rather than 10k. |
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Title: Re: Baffle placement question Post by WD on 01/21/13 at 15:15:37 What kind of baffle... quiet it down or so it passes the "night stick" test? Used to be if the police could shove a night stick more than a few (3-5) inches up the pipe you had an illegal exhaust, regardless of the decibel output. On my fishtail pipe I dropped the "stick stopper" in at the front end of the pipe, slid it back to where round tubing flares out for the fishtail, and welded it in. Still sets off car alarms, but... technically legal since it isn't a straight pipe. Your results may vary... I tend to name drop and get out of local issues. ;) |
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Title: Re: Baffle placement question Post by Cavi Mike on 01/21/13 at 20:18:25 No engine "needs backpressure" not even 2-strokes. It's a complete myth that backpressure makes an engine run better. All backpressure does is physically slow down the piston on the exhaust stroke. You get a "smoother" idle with more backpressure because the engine would be spinning a lot faster if it wasn't being restricted. Your smooth 500rpm idle with backpressure is really a restricted 1,000rpm idle. The "more torque at low rpm" is your engine trying to force out more air than you're allowing it to. You're moving your torque curve lower in the range and limiting its top-end power. Other than tuned-pipes on 2-strokes, the best exhaust is no exhaust. The only reason top-fuel rail cars have headers is to protect the exhaust valves and that's it. They're not performance pieces. |
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Title: Re: Baffle placement question Post by verslagen1 on 01/21/13 at 21:42:36 well that's a load of bs cavi. 2 stokes benefit from back pressure by a carefully timed reverse flow to push back the fresh charge that's gone thru the combustion chamber into the pipe. this supercharges the camber. when a 2 stroke is on the pipe, it takes off like a rocket. same thing happens to a 4 stroke just not as much cause there's not much over lap on the valve timing. this doesn't lend over to supercharged engines because the intake is mechanically pressurized. |
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Title: Re: Baffle placement question Post by Greg on 01/22/13 at 04:58:47 697A3E0 wrote:
The fishtail is exactly what I am planning on doing. I would use the type that I have inserted at the bottom. How in the world would you weld it at the fishtail end? http://ecx.images-amazon.com/images/I/31b7MWIgJQL._SL500_AA300_.jpg |
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Title: Re: Baffle placement question Post by Routy on 01/22/13 at 06:24:23 Quote: the best exhaust is no exhaust. --------------------------------- Is that the same as "bigger is always better" ?? Is that why "small tubing headers" can perform better than large tubing ? |
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Title: Re: Baffle placement question Post by WD on 01/22/13 at 07:29:04 Wire feed welder, go in through the fishtail. It's big enough. It will pretty much cook off the chrome at the weld line. I run the double flared 8" version like in your pic. Less chance for vibration to break the welds as the second flare holds the back end relatively stable. My exhaust has a 12" glass pack with no packing, just a bare core, and the stick stopper in the end of the pipe. Sounds like a L.O.A.C.H. instead of a UH-1 Huey. I had to delete the airbox door and go up a size or 2 on the jets. I went a little fat with the jetting, so it runs a bit too rich, need to step them down a size since I'm only at 400' or so elevation now. Smokes like a 70s big rig until it warms up... :o |
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Title: Re: Baffle placement question Post by Greg on 01/22/13 at 10:57:54 Cool. Then it can be done! I am going with the black straight pipe extension. Since it can be welded near the rear, I can always add something else up front if it's too loud. Thanks! |
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Title: Re: Baffle placement question Post by Cavi Mike on 01/22/13 at 22:51:27 2D3E2928373A3C3E356A5B0 wrote:
That's not backpressure, that's a tuned sound wave, and it's still not "needed" for a 2-stroke engine to run - it just bumps power in a small portion of the power band. A 2-stroke engine will run just fine without a tuned pipe or a muffler. |
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Title: Re: Baffle placement question Post by Coaxial on 01/22/13 at 23:29:17 Is this relevant to this topic: http://www.youtube.com/watch?v=KjKUKhHQLHg |
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Title: Re: Baffle placement question Post by Greg on 01/23/13 at 04:45:22 200C021B0A020F630 wrote:
Very informative. Thanks. |
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Title: Re: Baffle placement question Post by Charon on 01/23/13 at 06:22:31 Some years ago I took a course in Diesel engines. There was a chapter on exhaust systems, in which these sorts of effects were mentioned. Remember that Diesels do not have carburetors, so jetting isn't available as a tool. One example cited was that of a truck with an overall exhaust system about twenty feet long. The experiment involved putting the muffler at different places in the pipe, those distances probably chosen by the length of the pipe segments. Five locations were tried, and the engine was dyno tested at the same speed (about 2000 rpm, from memory) with all systems. Each location produced different power levels and different noise levels. This, with the same muffler and piping. They postulated that the results would have been different had the engine speed been varied, because of differing pulse reflections. |
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Title: Re: Baffle placement question Post by teabowl13 on 01/23/13 at 07:33:37 604C425B4A424F230 wrote:
THANKS COAX!! I've seen a couple of these guy's other videos. Very good explanation that makes sense even to me, and I don't know Shi* from Shinola about these matters! ;D |
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