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Sound Control Exhausts

scotty nm35
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scotty nm35 Grand Master

scotty nm35

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Posted

I have fitted a few Varex mufflers recently and was impressed enough to give a 3.5 inch one a go. I didn't really want the whole loud/quiet thing going on so I was going to buy their optional rev actuated setup, unfortunately it has been discontinued. Anyway, I was hoping I could actuate the motor off the ecu via a load controlled output but decided to go the easy way. What do you think?

http://www.xforce.com.au/about-varex-remote-control-sports-muffler.php

The actuator is a little firm meaning I need around 30psi to open it fully, (10psi is enough to partially open it.) luckily that's no problem. Just have to run some thin airline to the muffler.

It should be quiet running around town and snap open when boost kicks in. I have another 3.5 inch mid-muffler to fit also. :cheers:

post-63525-0-60077700-1331260852_thumb.jpg

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Commsman Veteran

Commsman

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Posted

That's really cool Scott. :thumbsup:

I guess it's possible to change how much boost is required to open the exhaust up by changing the leverage point. That would make it a viable option for guys running less boost than you.

Let us know your experience after using it for a while. I wonder if you will find it a little bit restrictive before you get up to full boost, or if you won't notice it at all....

scotty nm35 Grand Master

scotty nm35

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I will find out soon, it goes on this weekend hopefully. If I lose a little midrange I don't mind, as long as it's not laggy.

I can change where it comes in by getting a 4psi actuator or making my own perhaps. I can also change the closed position so it flows a little better. See how it goes I guess. I can always weld the motor back on if I dont like it.

Commsman Veteran

Commsman

Posted
Posted

Hey Scott, in your 3rd pic where the 2 pipes join, it's partially blocked from the pipe underneath. What's the science behind that? Is that to help the gas flows combine with least interference or was that a pic of work in progress & there's more to cut out?

scotty nm35 Grand Master

scotty nm35

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As I'm running stupid boost the wastegate is almost there for looks. (well for tuning anyway) That pipe is 2 inch and the hole is less than half blocked so its more than big enough. It will promote better gas flow and make the 3 inch turbo pipe the dominant one into the 3.5 inch. I can always cut it open if it boost spikes but I have the opposite problem at the moment, boost still dropping off at the top end.

Should have it finished today. :cheers:

scotty nm35 Grand Master

scotty nm35

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Just got back from the test drive, no rattles or bangs. :thumbsup:

It seems about the same noise at idle but its much quieter in the midrange and even the top end, though I cant be sure its opening properly yet. Boost seems to come on quicker and I can really hear the turbo spooling now.

scotty nm35 Grand Master

scotty nm35

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As a follow up, I am very happy with the exhaust, I changed the spring in the actuator by cutting it apart, now it opens at around 2-3psi and turns from a quiet street system into a loud race setup as boost hits. I'm planning on adding an external spring to fine tune the actuator next.

Hopefully I will be getting it tuned this weekend to see what gains there are, if any. The turbo definitely feels more responsive down low with the added back pressure.

Daleo Grand Master

Daleo

Posted
Posted

Nice work as always Scotty.:thumbsup:

How stealthy have you been able to make the actuator on the muffler?

I'm assuming you guys have the same problem in Vic that we have here in NSW; the filth know (or think they do) what a Varex looks like and they just target them because they're essentially illegal.

Yours will obviously do fine in a roadside noise test (no boost; no noise) which is quite clever, but is the baffle easily seen if you look up the pipe?

Cheers, Dale.

scotty nm35 Grand Master

scotty nm35

Posted
  • Author
Posted

Nice work as always Scotty.:thumbsup:

How stealthy have you been able to make the actuator on the muffler?

I'm assuming you guys have the same problem in Vic that we have here in NSW; the filth know (or think they do) what a Varex looks like and they just target them because they're essentially illegal.

Yours will obviously do fine in a roadside noise test (no boost; no noise) which is quite clever, but is the baffle easily seen if you look up the pipe?

Cheers, Dale.

You cant see the actuator unless you're laying on the ground or have it on a hoist, even then would they know what it does? Its all hidden on top of the muffler next to the spare wheel. I could put the heat shield back on and hide it completely if I had to.

You can look up the muffler and plainly see the valve, I was thinking a tip that dumps down would fix that. No way they would get their knees dirty. lol.

As long as it seems stock from the outside, that will lower my chances of being singled out. If they pop the bonnet i'm probably screwed.

Jetwreck Grand Master

Jetwreck

Posted
Posted

You cant see the actuator unless you're laying on the ground or have it on a hoist, even then would they know what it does? Its all hidden on top of the muffler next to the spare wheel. I could put the heat shield back on and hide it completely if I had to.

You can look up the muffler and plainly see the valve, I was thinking a tip that dumps down would fix that. No way they would get their knees dirty. lol.

As long as it seems stock from the outside, that will lower my chances of being singled out. If they pop the bonnet i'm ............ screwed.

^^^^^corrected!

Daleo Grand Master

Daleo

Posted
Posted

You cant see the actuator unless you're laying on the ground or have it on a hoist, even then would they know what it does? Its all hidden on top of the muffler next to the spare wheel. I could put the heat shield back on and hide it completely if I had to.

You can look up the muffler and plainly see the valve, I was thinking a tip that dumps down would fix that. No way they would get their knees dirty. lol.

As long as it seems stock from the outside, that will lower my chances of being singled out. If they pop the bonnet i'm probably screwed.

Yeah, as I was saying; they seem to be well clued up on them over here, and they're really starting to target them.

A nice burnished 45deg Stainless mandrel would make it a lot harder to see in; and also provide additional attenuation, as it directs sound down. On my old 48mm Weber fed 2.4 stroker 180B SSS; a 45 deg downward facing tip made a huge difference.

As you say; if you don't attract the attention to begin with; that's half the battle won.:thumbsup:

Good luck with the tune; any plans for a run down the quarter in the near future?

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