I was at the track yesterday and coming out of a turn I noticed the car sounded wrong. I found that the 8 inch pipe that sticks out of the main pipe behind the muffler was gone and now there is a big hole in the exhaust. What was that pipe? Can I fix that hole or do I need a whole new system? It was a MG Racing exhaust. If its not for back pressure I would rather fix it, so any info would help. thanks

 

It's called a hemholtz resonator, it's there to cancel out some of the resonance. You can either have it welded back on, or have a muffler shop patch the big hole. I wouldn't replace the entire exhaust.

 

Slows2K is right. I used to call on the exhaust design engineers at several domestic auto companies and exhaust manufacturers, and it's fascinating how they're designed. There has to be enough total volume in the exhaust system to reduce the noise volume and the geometry has to be tuned so that the entire system doesn't resonate - like a tuning fork.

Because the redline is so high, Honda had to design the exhaust system so that it will not resonate at any frequency (engine RPM) seen by the vehicle. If you've ever had a car with a modified exhaust system that didn't compensate for resonance, you know what I'm talking about. The exhaust gets real loud at a particular RPM, but is much quieter at higher and lower RPMs.

So an easy way to design an exhaust system that works is to break up long sections of pipe (through the location of the cat, muffler, etc.) and have resonators located in strategic locations. The Helmholtz resonator is a nice idea, because Honda was able to build the exhaust system with this pipe sticking out and adjust the length of the pipe to determine the optimum geometry to minimize resonance and noise level. Once they determine the optimum length, they can mass produce it for the car. An alternative would be to tweak the diameter of the exhaust tubing 'till you get it right. This would be expensive and time consuming to develop and would force Honda to use non-standard tubing sizes for a low production vehicle. This would drive the cost of production up significantly.

So if you just patch up the hole, you might experience higher noise levels and possibly have a really loud exhaust at some particular RPM.

 

Thanks guys!! Im just going to patch it up.

 

does the car sound different once patched up? I'm looking to increase the tone of the stock exhaust a bit!

TIA

 

Cut out the canister resonator if you want that.

 

Do you know if anyone has a video clip? I've tried searching but no luck!

Thanks!

 

I have to cut out my Spugen resonator since its got something making noise in it. It only happens around 4800 rpm