Possible exhaust leak?

Labcoatguy

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I had a muffler shop custom install an Infiniti G35 coupe exhaust onto my MR2. Looks great, sounded great, at least for the first day. Now it sounds like the retarded offspring of a F1 car, and not in a good way, with a metallic rasp that borders on ricey. It still has a great growl with the windows up, but I'm almost embarassed to open them. I took it to the shop last week and they couldn't find anything wrong with it. Does this sound like it could be an exhaust leak?

http://www.duke.edu/~yt10/pics/MVI_4864.AVI
 

Z Draci

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This is what happens when you put a muffler designed for a 3.5 litre V6 and put it on a car that has a 2.0 litre inline 4. Nissan did a really fancy job when designing the exhaust for the 350Z/G35. In order to get that "unique" (for a lack of a better word) on the 350Z/G35 they used a resonator--a metal reed that vibrates and plays musical notes like a reed instrument. This metal reed was designed specifically to sound the way it does with the exhaust volume and pressure of the 3.5 litre V6. The muffler is also designed to work with the rest of the exhaust system to achieve that exact exhaust note.

For musicians, it would be like putting a contrabassoon reed on a clarinet. It requires a custom fit but it still won't make it sound right. You need to find the specific application that best suits your instrument. Your MR2 doesn't have a big tenor saxophone. A small 4 cylinder engine is more like a flute. So don't expect anything low and growly.

Your car does sound like a 2.0 litre class race car now. But it sounds a bit too "Honda Civicy." I would check MR2 forums and see what kind of muffler options they suggest. Somebody may have already found what you're looking for. Or maybe even a solution to the muffler you have on there right now.

Remember that auto companies have entire departments dedicated to the engineering of exhaust sounds! Ferrari's exhaust department is one of the most prized in the business. It's not as easy as it seems to get the perfect exhaust note.
 

Redliner

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Well, I liked it....I prefer that metallic rasp instead of growly, low exhaust notes.
 

Mally Dangerous

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I have nothing to add to this thread other you had me laughing when you got out of the car and pointed. Or was that the remote for the cam? Either way, it looked like you were pointing :lol:
 

Labcoatguy

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Mally Dangerous said:
I have nothing to add to this thread other you had me laughing when you got out of the car and pointed. Or was that the remote for the cam? Either way, it looked like you were pointing :lol:
Yeah, that was the remote, and it didn't work that time, stupid infrared transmitter.

Z Draci, I get what you mean; the problem is that right after the muffler was installed, it wasn't this Civic-y and raspy, and it did sound pretty good, even if nowhere near the sound of a G35. I'm just confused as to how the sound deteriorated so quickly.
 

Z Draci

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How used was the G35 muffler? All mufflers get "broken in" after you drive it for a while. The heat and carbon build up inside the muffler can cause the exhaust note to change dramatically over a course of time.

Are your catalysts still installed? There's a lot of smoke in that video.
My guess is that the carbon buildup caused the change in tone.
 

Labcoatguy

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Buildup could be the culprit. The G35 muffler had fairly low miles on it, and since my car runs "naturally" rich, it probably dumped a load of carbon into the muffler can. I replaced my manifold and cat with a set of heat-wrapped headers, but there is an aftermarket catalytic converter right upstream of the muffler, which would take longer to reach operating temperatures than the stock one, which was right after the collection point in the manifold. I'm going to take it to a shop somewhere to get a professional opinion; at this point, it sounds a lot like the leak I had about a month ago.
 
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