Tips for lowering dB? (Tomei expreme Ti)
 

Does anyone have tips on how to quiet this exhaust down? NCM has a 103dB limit at 50 feet and I doubt installing the silencer do much to help meet this level especially since the installation of test pipes.

Are there any products (baffles, turn downs) that can be easily adapted to the exhaust? Or will a custom solution be needed so I can run at NCM?

Thanks in advance for any advice.

probably going to need to do something custom. This is the reason I got rid of my Tomei. they did however just come out with a v2 silencer you can find on Z1's site that *may* work. But the tomei is just so loud I doubt it

Thanks for the heads up, I wasn't aware of the v2 silencer. Maybe if I have a turn down added to it as well as some baffles on the inside I can reach my dB goal... I refuse to give up my Tomei lol.

There is a product called a spiral silencer which I use on my race car. I don't have a US reference but you might want to check Spintech Mufflers who are US based. Google should help out

If you know what side of car the meter will be on. You can add turn downs that point away from that side. I've seen guys do that.

found a promo video for the tomei silencer

https://www.youtube.com/watch?v=emHA...ature=youtu.be

the last one sounds about as loud as a cat fart. may be your best option.

This comes to mind. :icon17:

While I can't give you a link to one, I've seen inserts that go in the end of the muffler that are designed to reduce the sound.

Also the turndown idea works pretty well. Even just pointing the turn down at the ground can make a big difference. Not sure the diameter of the tomei muffler tip but I've commonly seen autoxers use a HVAC duct elbow as a turn down with just a hose clamp holding it on.

Is that for a full muffler? I was hoping for something to add to my silencer and be able to take on and off.

Left side coming out of turn 2b onto a straight... I've thought about a turndown to the ground but maybe pointing it away from them will work better?

Will the HVAC duct hold its shape at track speeds?

It's only an elbow piece I'm talking about so I would think so. I know they do just fine at speeds approaching 90 mph. No knowledge beyond that but I wouldn't see any reason they would deform.

Something like this?

https://www.amazon.com/Duct-Elbow-De.../dp/B00BLUA5Z8

I think that could actually work. I just hope it's enough. Does anyone know of any cheap decibel meters I can use to test?

Free iphone app? Or search Amazon.

Bingo.

Here's a link to a picture of a 350z using one

Any thoughts on resonated test pipes being quieter than a non-resonated one? Or is that just to help with rasp?

My experience is that they change the tone but don't get much quieter.

Thanks for the info. I guess I will save money on resonated tp's then.

These are 15" long "hot-dog" style silencers.

My race car (5-litre V8, 14.2:1 on E85) runs 1.75" primaries into 3" collector into one of these mufflers (3" in and out) each side of the car and that is the ONLY muffler on the car and it is 93 Dba on 30metre drive-by test.

I have a pair of these on each side of my 370Z (one under the seats and the other at the rear) with motorsport cats (100cpi) and it passes the 75Dba drive-by on the track but still sounds "fat".

If you want your car to be "loud" on the street and you are being forced to be "quiet" on the track, the 65 y.o. in me thinks you might be a bit anti-social, but that's just an aside.

It can be loud at some tracks. I was just looking at ways to get to other tracks that have a dB limit. I'm gonna see if some baffles in the silencer and a turn down will be enough :ugh2:

I notice a difference in DB with my Z1 headers and F.I. RTP's compared to F.I.'s headers to F.I. exhaust if that helps. Both exhausts are F.I. 12" carbon fiber.

Always thought "Laguna Seca" mufflers were funny

https://www.google.com/search?q=lagu...=1966&bih=1012

Heard of some stock exhaust cars getting black flagged there. :eek:

I actually got some ideas from that link... thanks!!!

You could probably fart and get black flagged there lol

Hmm... I was considering some resonated tp’s but I wasn’t sure if it would make a noticeable difference.

I actually got black flagged and kicked off the track for exceeding db level. Under power I was well beneath the limit but when I would up shift the car backfires under load and it sent the decibel meter through the roof...121 lol!

Outstanding report Mr. Bob :xmastup:

:hohoho::hohoho::hohoho:

Not sure if this would need a new thread or not, but I'll add it here. The silencer I got for my exhaust says to never drive the car hard with it installed. What kind of issues will excessive back pressure cause? I would expect less power and higher temps due to trapped heat, but is there a possibility of catastrophic failure from running too much back pressure?

The silencer popping out is the only thing I can think of

I am adding 2 more bolts to the silencer to help prevent this. Any thoughts on this affecting the tune?

some safety wire would also be a good idea. did the silencer bring the noise down as much as expected?

I haven't had a chance to install the silencer yet. I just got a dB meter to get some baselines. If I have time this weekend I hope to get the silencer installed.

I ended up buying the tomei myself. I think my exhaust would have been fine but my girlfriend hated it (lol). The car is stock quiet but I sense a dip in power.
https://youtu.be/T6KhavX3H9A

Nice! I bought a cheap-o decibel meter and I'm going to do a comparison video when I get some free time. I'm not worried about the dip in power as long as it won't cause any issues from excessive back pressure on the track.

Right on. Same, I'd rather loose the power but get to race on a given day.

Or lose almost $200 for the because you get black flagged and not allowed to run!

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I found these on line and I think I have them or similar on cars at the track.

https://www.ebay.com/itm/Removable-S...-/301178319010

I have the tomei v2 like Brendan does. I'm just worried about what the excessive back pressure will do to the car during a HPDE day. The instructions that come with the v2 silencer say to never do high RPM stuff with it installed...

Yeah, that's not gonna work! I'm frequently on the rev limiter! I guess you could drill some holes it lol!

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