har-vey

Hi All

I need some help with regards to my current exhaust set up. I've got a skunk2 mega power dual exhaust and as you all know its rather on the loud side. I've been reading up that 60mm systems are not as loud as 70mm systems which gets me thinking. Is there any implication if I replace my 70mm centre section with a 60mm section as it will still splits off into two further 60mm pipes?

Sorry for being a noob but I don't know anything about the science of exhaust flow.

Harvey

DaGou

is the only engine mod an exhaust? Did you ever have the car tuned with that exhaust? Most aftermarket exhaust do nothing for performance over stock, some are even worse. Unless you have a turbo bigger is not better just louder.

And member Gernby is THE exhaust guru. PM him and ask nicely.

iDomN8U

I'll give you advice before I answer that question.

Sell the exhaust and buy another system. By the time you factor in the $$ you make on the exhaust and spend it on another exhaust, you'll be ahead.

Consider the Tanabe Medallion touring, subtle.

Answer your question: It will help slightly but not enough to really make a difference. You're still using can's as mufflers (not much packing). If you're using a OEM Cat, consider switching to a Test pipe as it should remove a good portion of the drone (will make the exhaust louder though)

DaGou

Tanabe Medallion

Manga_Spawn

Take this advise. Sell the skunk 2 and buy something quieter or go back to stock. Changing the piping will likely just change the sound of the exhaust not nessecarily make it quieter.

Chuck S

Tanabe Medalion Touring registers right at 94dBA behind a Berk high flow cat on my 2006 S2000. Gentlemanly. Adult. With a K&N FIPK the car recorded 221 bhp on a Mustang Dyno (which are reputedly conservative) after a Gernby tune.

Changing exhaust diameters several times between the under 60mm manifold and the tip generates turbulence and creates inefficiencies.

-- Chuck

Szoylent Green

Yes, you definitely do NOT want to change diameters back and forth in the exhaust, its not necessarily that it creates turbulence, but rather, going from a small and abruptly to a big pipe creates whats called a standing wave in the upstream section, and these usually interfere with the exhaust pulses.

After the collector, you want to keep it the same diameter all the way down. However, and this is a big however, you can design an expansion chamber like the exhausts on 2 stroke engines. This is essentially what the Gernpipe is, and these are notoriously hard to design.

On another note, have any of you guys actually heard the T1R EM 70mm duals. I've heard a bunch of should clips on youtube, and I really like the tone and sound of them, I'm just not sure exactly how loud they are. I want something that has a bit more sound than the stock, but I definitely don't want something too loud and obnoxious.

I'm currently thinking about either the HKS SSM, or the T1R 70mm EM dual. I think they both have good sound, again, just don't want something thats too loud, and I live in the middle of nowhere, so its not like I can just go down to the nearest tuner had hear a bunch of exhausts in person.

har-vey

Thanks All, I got the skunk for next to nothing and I have a friend who is an exhaust fabricator so it wont really cost me much to have any modifications done.

I'm actually interested to try this anyway, the money part doesn't bother me. Ill have a new centre section made so if it fails I can always bolt the standard skunk section back in.

From your responses i guess increasing from one single 60mm to a dual 60mm isn't a good idea so i may look to just go down the route of adding additional silencers to the system and see how this works.

Thanks for all your help

iDomN8U

All the good exhaust go from a large pipe to two smaller pipe diameter. The reason for this is two smaller diameter pipes will outflow 1 larger one (This is based on reading some article Asura exhaust posted many moons ago, and might not be 100% fact, however to me it makes sense).

If you're buddy is custom fabricator, just build a custom exhaust.

Even though you got the exhaust for next to nothing, it's worth something to someone else, so if you could get $400 bucks for it, that's $400 less you'd spend on a quality exhaust. Chop it up and it's worth nothing.

s2000Junky

Yep I agree, sell it and start over with something custom or better to start with.

My understanding on the smaller exit with a dual, is the smaller pipe is meant to maintain flow through scavenging the smaller and less forceful pulse width by the time it reaches that length. Wile the residual of that is increased flow. A larger pipe diameter at the end of the system would end up creating turbulence, because the pulse strength has diminished and would start to defuse inside the pipe create turbulence and actually create less flow. In other words, there is more exhaust gas pressure at the first part of the exhaust system then there is at the back half. A smaller pipe maintains the pressure differential. With a turbo set up, the turbo itself is the exhaust restriction, therefore anything aft of this will reduce flow further so no exhaust system performs the best. Completely different strategy's here, but just to show both ends of the spectrum. A supercharger works off the same basic principals as NA.