exhaust note

maxleng · Post by **maxleng** » Mon Oct 26, 2009 11:39 pm

yo, before flaming me i have searched and there were heaps of threads about exhuasts(apexi etc) but i couldnt find anything about what i want to know.

what do ftos sound like if you remove the rear muffler and just have straight pipes to the rear(with a tip) with no muffler? while everything else is stock. is this even legal (not because of how loud it is but because of emissions? etc.)

anyone done it? or heard one with it done, does it keep the stock note but just louder? or is it a droning sh*t sound

reason being i don't want to go all out on the exhaust now, and when i do it i want to do it properly, but just want something abit louder in the mean time.

thoughts?

SchumieFan · Post by **SchumieFan** » Tue Oct 27, 2009 12:52 am

no its not legal, ive heard one with the exhaust system ripped off from the headers...

sounded like a nascar

Post by **Bennoz** » Tue Oct 27, 2009 6:39 am

Or a top fueler. Unbearable.

Gholdwayne · Post by **Gholdwayne** » Tue Oct 27, 2009 8:56 am

if you take out the 6a12 mivec engine out and ignite it, it kind of sounds like theres a t-rex inside it roaring, theres a video in youtube that i favourited, i think you search for 6a12 mivec, cant link it now coz im at work and youtube is blocked. its basically the 6a12 being tested or something before being placed in the engine bay of another car.

SchumieFan · Post by **SchumieFan** » Tue Oct 27, 2009 9:30 am

kewl!

http://www.youtube.com/watch?v=tmt4tODirwI

bushido · Post by **bushido** » Tue Oct 27, 2009 11:02 am

For about a month or so I took off the rear muffler of my old exhaust system. It was 2.75 in stainless catback. Basically without the back box, (so the piping ends just before the rear wheels), it was VERY loud. I did still retain one resonator so it was bearable but nevertheless not something you want to have for a long time. From what I understand you to be saying you want to remove the back box and replace that space with just a straight pipe? This setup would be "quieter" than having the piping end before the rear wheel since the noise would be dissapated out the back of the car. Although loud, the noise is very nice, a true roar

.

I have heard aza's track setup which consisted of a straight pipe from the cat, one tiny resonator and ending just after the passenger door side. Could be heard easily from the other side of Wakefield.

If you want your car just a little louder, remove the resonator and replace that bit with a straight pipe. Cheaper than replacing the back box with one.

maxleng · Post by **maxleng** » Tue Oct 27, 2009 12:34 pm

hmm i see

that video of the 6a12 being tested is so awesome, the thing just growls

what/where exactly is the resonator? is it located inisde the back muffler box near the rear or is it located further up just after the cat or something?

i had a look under the car and after the cat the pipe is connected to some cylinder object that has a larger diameter and then reconnects to the normal pipe, and then one further down just before the muffler box.. im guessing these are the resonators? is the only purpose of them to lessen the sound, so removing them and replacing them with just straight pipes would make it louder? does any one know if you would get a deeper sound with resonators or without

nathan · Post by **nathan** » Tue Oct 27, 2009 12:56 pm

Gholdwayne wrote:if you take out the 6a12 mivec engine out and ignite it, it kind of sounds like theres a t-rex inside it roaring, theres a video in youtube that i favourited, i think you search for 6a12 mivec, cant link it now coz im at work and youtube is blocked. its basically the 6a12 being tested or something before being placed in the engine bay of another car.

mine has extractors and i removed the exhaust from there back and started it over a pit and HOLY sh*t

lol soooooo loud

bushido · Post by **bushido** » Tue Oct 27, 2009 4:50 pm

Those are the resonators. The first resonator is the large one and the second one is quite smaller. Removing these will make your note a lot deeper. Usually resonators cancel out a lot of the "burble" sound (ie noise below 3000rpm) your exhaust makes. Having said that I have never heard an FTO with a stock exhaust and no resonator. Also the resonators stop the sound from being raspy. So it goes a little like this;

1. No resonators = slightly deeper, not much louder at idle speeds, louder at MIVEC, little more raspy

2. No resonators + punched cat = Very raspy, similar sound at idle speeds, lot louder at MIVEC

3. No resonator + punched cat + no muffler = straight pipe = VERY loud everywhere.

maxleng · Post by **maxleng** » Tue Oct 27, 2009 6:21 pm

sweet, thanks for clearing that up.

hmm may go option 1 it wouldn't be that expensive would it?

what is a punched cat? is that an aftermarket cat or something else

just to clarify, no muffler box + resonators would be much louder than no resonators + stock muffler box ? or would the difference just be in the exhaust note, as you said deeper and raspy with the no resonators as opposed to a loud scream with no muffler.. am i on the right track with that?

from some googling i got this:

resonators create a band-pass filter that eliminates problem frequencies - so they tune it for a specific loud spot in engine operation. It targets only a small range of frequencies.

so im guessing with the fto one resonator blocks out the frequencies at idle or low revs and the other one blocks out some of the frequencies around mivec point?

nathan · Post by **nathan** » Tue Oct 27, 2009 6:58 pm

punched cat

hmm well inside the cat is like a honeycomb textured baffle inside it and it REALLY restricts airflow, and to puch it out or bash it, is to hollow it out, like remove the baffle

bushido · Post by **bushido** » Tue Oct 27, 2009 7:42 pm

No muffler + resonator would definately be louder than just removing the resonators. And when i say raspiness I mean the sound in that video when the guy revs it then backs off the throttle. Thats raspiness and it is very present with a punched (read gutted) cat. Take all this info in like a grain of salk though. best to ask an exhaust shop for more specific questions

maxleng · Post by **maxleng** » Tue Oct 27, 2009 8:06 pm

ic, yeah im gona go down to an exhaust shop once my exams are over and sus sh*t out, just wanted to know exactly what was what in the exhuast system.

im thinking il get the cat punched or whatever, and replace resonators with just straight pipes. see how that sounds and then maybe down the track replace the muffler with a new high flow one or something.

re: punched cat, is this as simple as removing the cat taking out the baffle and reconnecting it? or do you need to replace the baffle with something.

cheers for the responses

Post by **Supplanter** » Tue Oct 27, 2009 8:35 pm

Just keep in mind that a punched cat is defectable

Post by **aza013** » Tue Oct 27, 2009 8:54 pm

Here is one for you

http://www.youtube.com/watch?v=P8HYp00BLew
the track set up I drop the cat and everthing behined it out off the car and put a 2.5" manderel bend pipe in as said comes out just befor the back wheel and it spits flames too

maxleng · Post by **maxleng** » Tue Oct 27, 2009 9:27 pm

hells yeah

that sounds insane. man the fto just sling shots out of that corner, golf has nothing on it hehe

bas · Post by **bas** » Wed Oct 28, 2009 9:56 pm

hey nice vid azza watched your other one too "chasing down a golf" golf wasnt as good a driver though. hehe

ye any way, wanted to ask bout this exhaust stuff too. i wanted to know how to get the exact same note as stock just louder. i realy dont admire the deep tuner sound nd was happy with the note atm just not loud enough though

bushido · Post by **bushido** » Thu Oct 29, 2009 7:42 am

cat is easy to punch out. undo the four bolts, detach the o2 sensor, get a long ass screw driver, hammer and away you go. make sure you wear gloves and a face mask would help too. It took me 15 minutes of bashing to get everything out.

Just make sure you dont get busted for it.

Post by **Bennoz** » Thu Oct 29, 2009 8:33 am

^This

A deliberately altered cat can attract fines of up to $10,000 plus jail time!

But..... the internals of cats do deteriorate over time & get blown out the exhaust..... catch my drift?

maxleng · Post by **maxleng** » Thu Oct 29, 2009 8:42 am

was reading a thread on nissansilvia about punched cats, apparently only the work shop can be fined $10000 if they are caught doing it, if you are caught it is just a normal defect.

Its a defect if your caught with a punched out cat. (depending on the cop its a $200 fine or just a piece of paper saying 'get it fixed')

If your caught without a Cat at all in your exhaust system ( i.e: Straight through pipe, not even the shell of a cat ) its a $5,500 fine.

If your a workshop or licensed mechanic and you are caught red handed in the middle of punching out a cat - its a $10,000 fine.

Cat's fail all the time, over time they melt and eventually shoot out the end of the exhaust.

http://www.nissansilvia.com/forums/inde ... 36022&st=0