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Old 08-04-2009, 03:18 PM   #1 (permalink)
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exhaust system: resonator

I have had the same models' cars for 12 years and am baffled (pun ) about resonators. It is simply an old subaru, 1781cc. Rather than a short hatchback, it is 14.6 feet to the back, with an up and over an axle like an older car design. My question is for little engine people and resonators. What is a good one? I got advice for a glasspack after the convertor, then a muffler, and I melted the innards of the glasspack. The restriction was just right, but it did not hold up. I exploded 3 factory versions, they are much too small, and hotter than a convertor! I may have even aided and abedded a complete belly pan failure with resonator. OE and 3 main boxers have been torture together as usual. My exhaust is simply 2 inch, straight midpipe, factory y-pipe with convertor and dynomax full chambered muffler. It is great right now, and passes inspections, but bad fuel and cold engine..there is a hint of a spuutering sputter in engine braking, I want it to go away forever.
I am guessing the honda category with the less than 2 liter engines have this same phenomona. they made a resonator universal and throw it at the market, never accounting for very very hot tiny stroke engines. I did find stainless steel, but it is not honeycomed, it is straight through. the straight through leaves a bassy rumble in the interior of my very hardened welded sube.
An acoustic mystery, as well as chemistry and heat to withstand oe convertor not far off...

Any suggestions on a real resonator to match a sube at 2 inch? non-straight through? restrictions are a must avoid..while going for cadillac silence..
Searches on web for hacked up echaust is like finding a mr.gasket plenum that bolted up to an 87 sube..it is never the front page of ebay ya know?

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Old 08-04-2009, 04:50 PM   #2 (permalink)
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Quote:
Originally Posted by bgd73 View Post
I have had the same models' cars for 12 years and am baffled (pun ) about resonators. It is simply an old subaru, 1781cc. Rather than a short hatchback, it is 14.6 feet to the back, with an up and over an axle like an older car design. My question is for little engine people and resonators. What is a good one? I got advice for a glasspack after the convertor, then a muffler, and I melted the innards of the glasspack. The restriction was just right, but it did not hold up. I exploded 3 factory versions, they are much too small, and hotter than a convertor! I may have even aided and abedded a complete belly pan failure with resonator. OE and 3 main boxers have been torture together as usual. My exhaust is simply 2 inch, straight midpipe, factory y-pipe with convertor and dynomax full chambered muffler. It is great right now, and passes inspections, but bad fuel and cold engine..there is a hint of a spuutering sputter in engine braking, I want it to go away forever.
I am guessing the honda category with the less than 2 liter engines have this same phenomona. they made a resonator universal and throw it at the market, never accounting for very very hot tiny stroke engines. I did find stainless steel, but it is not honeycomed, it is straight through. the straight through leaves a bassy rumble in the interior of my very hardened welded sube.
An acoustic mystery, as well as chemistry and heat to withstand oe convertor not far off...

Any suggestions on a real resonator to match a sube at 2 inch? non-straight through? restrictions are a must avoid..while going for cadillac silence..
Searches on web for hacked up echaust is like finding a mr.gasket plenum that bolted up to an 87 sube..it is never the front page of ebay ya know?
I've never heard of a Honda with this problem, but something I've done on small engines to use as a resonator is to gut the cat from a larger engine, and just place it inline after your OEM cat.

This allows the exhaust gasses to expand and helps to silence them.
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Old 08-04-2009, 05:57 PM   #3 (permalink)
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The "hint of a spuutering sputter in engine braking" you describe may be something else. Resonators are tuned to a specific exhaust system and muffler to help tune out the frequencies the muffler misses. Glasspacks take out the high frequency and let the low tones through and is what many resonators are. Some aftermarket chambered mufflers let some high frequency through and a short glasspack will 'clean up' the sound, unless of course you happen to like the sound.

So, is the spuutering sputter a high or low or mid frequency? Does it come from the end of the exhaust pipe, somewhere in the middle (leak), or the engine compartment (something else like air injection, or vibrating heat shield)?

Also a 2" exhaust on your 1781cc Sube seems pretty big. You'd likely gain back some torque if you went with a smaller diameter pipe with a free flowing muffler. If you want silent, stock is about as good as it gets.
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Old 08-05-2009, 10:46 AM   #4 (permalink)
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I had some problems like that a while back with my Civic, turned out it was solved by using math... exhaust systems are tuned with simaler math as musical instruments, but it sounds like your problem is that you have to large of an exhaust pipe, you can fix this in one of three ways, you can run your engine wide open all the time (red line it) to get enough flow to keep the momentum of your exhaust up, you can also get a larger engine that will have more exhaust flow, or you can get an exhaust that is tuned for your engine, as it is it's kind of like having a skinny little kid trying to play the tuba.

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