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Muffler Technology and DIY
http://www.ozdat.com.au/forum/viewtopic.php?t=34413
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Author:  RJB510 [ Sun Jan 29, 2017 12:35 am ]
Post subject:  Re: Muffler Technology and DIY

Unfortunately the twin loop design just won't fit neatly with the limited space. I had looked into that one already. Not only does it pass the sound twice through the mufflers, the proper ones should have the sound waves re-entering the chamber 180 deg out of phase to the ones coming into the muffler for the first time. They will effectively collide with each other and cancel each other out.

Author:  MangaNOID [ Sun Jan 29, 2017 2:01 am ]
Post subject:  Re: Muffler Technology and DIY

as long as it meets legal noise limits when open it would be.

Author:  skitzone [ Sun Jan 29, 2017 4:19 pm ]
Post subject:  Re: Muffler Technology and DIY

Try a aero chamber muffler. I put a small 9" long one in my Mrs ute with a cammed l67 and it sounds pretty blood stock lol. They reduce volume A LOT.

Author:  SR20Datsun [ Mon Jan 30, 2017 8:58 am ]
Post subject:  Re: Muffler Technology and DIY

Did you notice any power decrease?
Are they straight through?

Author:  260DET [ Mon Jan 30, 2017 10:13 am ]
Post subject:  Re: Muffler Technology and DIY

Makes your Datto sound like a V8 lol.
https://www.youtube.com/watch?v=k67iEZZg0g0

Author:  Coz22a [ Mon Jan 30, 2017 10:32 pm ]
Post subject:  Re: Muffler Technology and DIY

Looks cool and sounds nice too but, what's a tuning tube? Is it adjustable/tuneable and how does it cancel amplitude?

Author:  SR20Datsun [ Tue Jan 31, 2017 2:36 pm ]
Post subject:  Re: Muffler Technology and DIY

I've always wondered how these work with different capacity engines with different cylinders with different revs.
I assume there is a small Helmholtz resonator somewhere in there
Helmholtz resonators work with only specific frequencies and the associated harmonics. It's just a way of absorbing the energy using the existing energy out of phase.

Author:  RJB510 [ Tue Jan 31, 2017 2:47 pm ]
Post subject:  Re: Muffler Technology and DIY

That's pretty much what i want to create within a standard muffler. Calculating the size needed isn't as simple as a 1/4 wave resonator though!

Author:  Stoney [ Fri Feb 03, 2017 5:21 pm ]
Post subject:  Re: Muffler Technology and DIY

I am running a twin 2.5" in/out Varex muffler on my XR8 ute, pity they're not legal, but it works perfectly, quiet over the whole rev range with it closed apart from a deep idle, loud as hell with it open.

Author:  gtirdat [ Sun Apr 09, 2017 7:25 pm ]
Post subject:  Re: Muffler Technology and DIY

I have made my sr20 1600 exhaust front to back with the intention of it being as quiet as possible at lower revs or idle. It is a full 3 inch with a 24 inch hotdog down the center and the biggest muffler I could possibly fit out the back. I bought a dynomax VT from the states as the configuration I was after wasn't sold locally. The difference with these mufflers is they have a light spring loaded valve on the exit. It is the quietest modified datsun I have heard at idle but sounds like a straight through muffler at full noise. The only thing I haven't tested yet is how it effects turbo response but it's a pretty light spring so I can't see it being much.

Author:  SR20Datsun [ Mon Apr 10, 2017 10:15 am ]
Post subject:  Re: Muffler Technology and DIY

Good information to know.
I'm google searching the muffler as I type this!

Author:  gtirdat [ Tue Apr 11, 2017 8:43 pm ]
Post subject:  Re: Muffler Technology and DIY

It can sound a little fluffy at idle due to the valve but it reminds me of a stock 1600.

If your interested enough I can chuck a clip up of it on my YouTube channel.

Author:  RJB510 [ Wed Apr 12, 2017 9:13 am ]
Post subject:  Re: Muffler Technology and DIY

I think a sound clip would be good. Very surprised that you managed to fit a 600mm long hot dog in the middle. I built one that big and it was a very tight fit. I want happy with it so i cut it back out. My exhaust is tucked up very high.

Author:  gtirdat [ Wed Apr 12, 2017 7:01 pm ]
Post subject:  Re: Muffler Technology and DIY

I have the Datsport solid gearbox crossmember with the exhaust provision which gave me a bit of extra room.

Here is the you tube link https://youtu.be/3iUsG9yzIHI

Now before anyone flames me I am well aware of how unreliable the phone db meters are but it is hard to gauge how quiet it is just with the video of it.

Author:  RJB510 [ Wed Apr 12, 2017 9:00 pm ]
Post subject:  Re: Muffler Technology and DIY

I have my own gearbox cross member. But it would need to sit between the prop shaft and the floor behind the gearbox. Thanks for the vid.
Does sound quiet at idle. What's the in cabin noise like when accelerating and cruising?

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