my exhaust is too loud

[apzak]

Last weekend I lost the silencer to my OBX B3 b0mber. It's 2.25in. mineake bent pipe, and it's preaty straight. Without the silencer I'm setting off car alarms. Will a high flow cat quiet things down, and will it work as well if not better than the silencer? The silencer didn't realy make the exhaust alot quieter, it just took some bass out so it wasn't deep enough to trigger alarms. Anything else I could do other than getting a new exhaust? My friends love it, but I drive alot and it can get annoying on long trips. The high flow cat would also be a plus because I could pass emissions, and costs a lot less then a brand name HKS catback system which wouldn't improve horsepower, but probably make things alot quieter.

[240marcuSX]

i dont think a high flow cat will quiet anything down, wouldnt it make it louder? maybe you can call up obx and buy another silencer.

[:: orion ::]

High flow cat will smooth out the saound, but will not quiet it down much. You need a resonator...

Ever notice that the high-quality, name-brand japanese exhausts always have a smaller muffler right before the differential...?

You can get a Magnaflow straight thru, perforated core muffler for $80-100, and have it added to your current exhaust system. It will add a minimal amount of restriction if it's a perforated core...

Get that, and the sound will be better, smoother, and quieter. You won't be disapointed...

Later - Brian

[apzak]

For a while now I've been having my gasket leak where the dummy cat meets the HS headers. The dummy cat has a drilled out thread because a baked screw had to be cut off. As time goes on the exhaust slides and is no longer aligned with the header because I'm guessing the screw has no threads to grab onto. Anyway, if I get a highflow cat that will fix this gasket leak which will make it a little quieter, and the cat will smooth out the exhaust sound, which is similar to what the silencer did. I'll get a high flow cat first (150 at enjukuracing.com right?) and see how that changes things. If it's still too loud for me I guess I better save money, get something like an HKS with the resinator and sell this one to someone that's looking for a loud inexpensive system. It did add alot of horsepower I guess because it's so straight, and has very little restriction, but I'm willing to loose an hp or two for something more quiet. A high flow cat will also give me some backpressure right? Even though this is 2.25inch, I miss the backpressure I had with the stock exhaust.

[:: orion ::]

Even though this is 2.25inch, I miss the backpressure I had with the stock exhaust.

AHHHHHHHhhhhhhhhhhh...

Pet peeve of mine: "The Backpressure Myth"

Why does this set me off?

Because backpressure is an effect, not a cause. Backpressure is bad, no matter how you slice it. You want as little backpressure as possible, at all time, for any motor - N/A or turbo.

But what you want is velocity - High exhaust gas velocity adds to scavenging in high RPMs, creates power.

But to attain velocity, you need smaller piping...which creates some amount of backpressure.

So velocity is what you want, and backpressure comes along with velocity.

(Velocity is the cause, backpressure is the effect...)

The key is to find the ideal pipe size for the motor that lends to a high velocity, but can flow the needed amount of gas.

2.25" is OK for a KA24 with mild mods (say, up to 145rwhp). 2.5" or 60mm is OK until 155-160rwhp I'd say...and then at 160rwhp or more you need bigger...IMO.

So...sorry for the rant.

Later - Brian

[chino]

It may have been a rant to you, but it was velocity/backpressure..class 101 for me...thanks for the info.It will come in handy for me too!

[C-Kwik]

Here's an SCC article that goes into some really good detail.

http://www.sportcompactcarweb....art2/