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i was install 2 apexi WS muffler...it was damn silence...if i didn't cut off the cat...i can't even knew i got install that..
after few month, i was goin to do a 2'5 catback system...after tat i recognise when i gone to over 4000rpm then the sound of that muffler changed already...omg...the sound was like ...SHIT>>>>>> can some1 tell me is that muffler like that or i should call apexi distribuler to hav a cheak for it...
i shouldn't change to apexi ...don't i???
Ok, I'll try to break down what you are trying to say; :)
You installed Two Apexi WS Muffler, It was so damm quiet that if you didn't remove the Cat Con, you don't even know the Mufflers are there.
After a few months, you wanted to do a 2.5" Cat Back system but you realised that after revving past 4000RPM, the sound of the Mufflers changed and it sounded like S**T.
Can someone tell me if the Muffler is supposed to sound like that or I should give the Apexi Distributor a call and get them to check it?
I don't know how an Apexi WS Muffler sound like.... but......
My first question,
Do you still have the cat in the car? Did you remove it completely or you just hollowed out the honeycomb, I ask because it makes a difference to the sound.
Number 2,
A leak or a crack in the exhaust will cause the noise to change, and by revving higher, it creates a more vibration in the exhaust pulses. I think it could be a leak as what you are saying is that it happened after a few months.
I'd say it's best you go to your exhaust guy to have it checked if it is leaking..
CHEEEEEERS :)
the people say the muffler shouldn't hav problem cause if got problem then the stranged sound should come out when the engine started...but the car didn't hav any cat at the moment..i removed it already....
then the repair guys say hav to cheak for the piping after few week when he was free....so sad...
you dont have a cat? I'd get one quick smart - especially if your exhaust sounds unusual you might get pulled over by the cops and thats $10,000+ fine
hah, i was goin to put 1 in but the sales person said he is not free by the moment....i also heard from my fren say....
id love to help but i cant even understand what u are saying.
:( so sad...my english are very poor...forgive me.....ozhonda member...hehe
Driving without a catalytic convertor is illegal if a cop pulls you over and bothers to check you will be up for a massive fine. Put it back on. I was talking to a guy at an Autobarn once and he was fined $6000 dollars for removing his. And apart from that I have no idea what you were saying....
Peekay34 thankz for your commant...
I knew a guy who’s got an apexi exhaust system on his euro and the sound really is crap, it has to be one of the worse exhaust notes I have heard. So maybe that’s the kinda sound that apexi produces.
as long it doesnt sound like a lancer running on tomato sauce.. it fine then :D
Quote:
Originally Posted by Spoon-Accord
Could be BBQ sauce even worse... :D
usually u lose power if u take of the cat..... just put it back on ...
Huh? this is the first time I've heard that!Quote:
Originally Posted by preludacris
You lose the power to drive because the police take away your catless car! :)
Most tests I've seen generally indicate that there's not a lot of restriction in a cat anyway -- it's more the diameter of the exhaust in general and the muffler. Headers can just help the whole thing work more efficiently.
Of course, NA cars need a certain amount of back pressure anyhow -- the problem is reducing it without reducing it too much!
I can't remember the exact details, but I've always remembered it. My mechanic father-in-law explained it to me once and I've read about it somewhere on the Net. If anyone knows better, help me out... Something to do with pressure in the chamber and sucking in air???? Also, if you reduce the backpressure too much the engine isn't as efficient or something...
Forced aspiration cars (turbo and supercharged) you want as little backpressure as possible because the air is already being forced into the cylinders and you just want it to get out as fast as possible...
I'm open for help explaining, as I really can't remember the details -- or be proved wrong...
Tobs, what you're talking about is pulse alignment, not back pressure
when your exhaust valve opens the exhaust gases is pushed out into the header causing a high pressure wave effect. this is followed by a low pressurre area.
your stock header is designed so that at a lower rpm all the waves line up so they 'drag' the next wave along as the pipe meets. aftermarket headers are designed so that they meet most efficiently at a higher rpm. thats why headers can cause a poorer drivability at lower rpm... nothing to do with tuning, just volumetric efficiency at different rpm.
you never want back pressure. what their point is is that you should not have a 5in exhaust on your 1.6L car as the engine doesn't have the capacity to push that amount of air out of the pipes and hence it settles and cools, becoming denser and harder work for the engine to move it out. Smaller exhausts keep a higher flow velocity for the same flow rate and hence clears hot gases out faster. but if exhaust is too small, it reaches the maximum flow rate of the exhaust system before the engine reaches it full flow rate capacity.
Thank you! I found a similar explanation at
http://www.warnertechnology.com/Cars/backpressure.shtml (see below -- sorry for the length!)
I have a theory that (besides the nature of the engine and type of muffler) it's the too big pipe that makes so many 4-cylinders sound crap -- like a 1.5 Excel with a 3 inch exhaust: it literally is blowing really hard into too large a space and gives that farty sound. Chucking on the biggest pipe possible, isn't necessarily going to improve things -- and in some cases could be detrimental.
Quote:
Backpressure and Exhaust Pipe Size
Q. Why do engines need backpressure? Won’t a larger exhaust pipe give my 944’s naturally aspirated engine more power?
A. I’ve always understood that you want to keep the exhaust gases moving, even once you get them out of the cylinder. One thing that will cause the gas to slow down is a sudden decrease in temperature, which is one reason why auto makers don’t try to cool the exhaust manifold. The other thing that can cause a decrease in flow velocity is rapid expansion and turbulence, like going from a small passage (like the exhaust port in the head) to a 6-inch pipe. A smaller-diameter pipe geometry will tend to keep the flow rate up, but it will also lose heat more quickly (less exhaust gas per linear inch of pipe). However, a large pipe will slow the velocity due to expansion. Worse still, the exhaust is constantly cooling from the moment it leaves the cylinder, meaning it’s getting denser and slower. See the problem here? It’s all about compromises. The proper pipe size is going to be influenced by the flow rate (volume rate, which is related to RPM and engine displacement), exhaust velocity (again related to RPM), exhaust temperature (constantly changing, and as high as 2,000&Mac251;F, if I remember right), and undoubtedly an array of other factors. All of this is dependent on the application: is this a street car, a race car, or something in between? Where will the engine spend most of its time? Idle, full throttle, part throttle?
I’ve also heard the thing about back pressure, but I believe that they’re really talking about flow velocities. That is, if you can keep the exhaust gases moving in the exhaust pipe, they will cause a small reduced-pressure area behind the closed exhaust valve, in the exhaust. This happens because the gases have momentum. They move away from the valve, creating a localized reduction in pressure. When the exhaust valve opens, this reduced-pressure zone will help evacuate the burnt gases from the cylinder. Or so the theory goes, as I understand it (two disclaimers there).
The bottom line is that Porsche has probably already considered all this and other factors when sizing the exhaust on the 944. Unless you’re significantly increasing the flow rate, you’re likely to cause more harm than good.
although apexi WS model look nice but the sound not good...when done catback for that muffler...the sound was like chick....poor man.:)
i think hav to ask for my mecha. about should i put the converter back...