davidc1

So, I just deleted my previous topic since nobody was staying on topic.

Here's the question.....

Has anybody ever tried welding in that "T-pipe" that is on the OEM exhaust to reduce drone if you have an aftermarket exhaust.

Please don't tell me your exhaust doesn't drone, that's not what I'm asking...thanks everyone!

jh4db536

That "t pipe" is a branch resonator and its engineered to work with the stock catalyst.

So when you spend the money to buy a spoon or asm catback with the branch resonator after the cat and you are using a testpipe, then you're defeating the purpose and the drone cancelling properties.

Most people who have aftermarket exhausts usually have hfcs or testpipes too.

If you're using the stock cat it might work. I believe testpipe setups drone the least in exhaust systems without the branch resonator and hfc are the worst.

Some exhausts for example the evs ssp70 are 70mm replicas of the asm siren circuit without the front branch resonator and a modified one near the muffler are designed to work with a testpipe rather than a cat.

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Thateguhate

Header wrap supposedly helps. I haven't tried it yet though...

davidc1

So, it's a branch resonator designed to be used with the stock cat.

So, if my skunk2 has it's own resonator, and I have a test pipe, what would be the likely effect of the branch resonator if I welded it in?

jh4db536

It probably won't do anything except make ur wallet lighter and ruin a perfectly intact catback.

mister x

That branch/helmholtz/donkey dong resonator affects a fairly narrow sound frequency range. You'll probably not reduce drone enough to make an annoying exhaust livable. I used a section of OEM midpipe (triangle flange to Y split) on my Toda 60mm cat-back and it reduced overall loudness slightly, more a function of the larger midpipe resonator IMO. It still droned although the tone seemed to have less "attack", kinda hard to explain but the sound was more of a "whoosh" instead of a "bark". Bottom line; sound tuning is a complicated and expensive endeavor, buy a Fujitsubo/Mugen/Tanabe for a sporty but mature sound.

s2000maniac

Also I think you lose some torque and HP with a resonator like OEM.

Gernby

The OEM resonator doesn't reduce power, but it does reduce midrange torque when you tune for a lower VTEC engagement.

You can achieve some reduction in drone with a properly sized branch duct (J Pipe), but it isn't as effective as a properly designed mid-pipe.

Here were a few J Pipes I tried out. They had to be about 30 inches long in order to attenuate drone at 3500 RPMs. As someone mentioned above, they aren't effective across a wide frequency range, and the drone frequency changes with temperature.

davidc1

That's really interesting Gemby, thanks for the info!

nlink720

Here's a post I made some time ago: My link https://www.s2ki.com/s2000/topic/510...t__p__20878738