Muffler advice needed

Belgian1979vette

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Here is the short story. When building up my car I had no idea about the HP of my engine, so I went with the mufflers I had lying around from a donor car and that were in reasonable condition : 2.25" turbo muffler, some 14" long.

Recently I blew up one of the mufflers. Never mind the reasons, but due to this and the fact that it was rather rusted from the inside and also has some smaller holes on the outside I decided to hunt for a SS muffler of the same size but this time with a 3" inlet/outlet since I found out my 2.25" was way to restrictive.

Via Summit I found a couple of possibilities among which a baffled type of which I didn't like the sound and the magnaflow 11229. Now this is a straight through type glaspack and I checked the sound via some soundclips on YouTube and it seemed to be ok.

So I ordered those.

I just tried one of them one my old dual exhaust pipes with an adapter to see how they do, but oh boy, they are way loud on my car.

Now, what's a possible solution ? A mid car muffler/resonator ?
 
My pipes are 2.5 with a H cross over behind the trans....and dual Magnaflow stainless muffs....I think they are 2.5 also....

but my engine is fairly mild, maybe 350 horse....

:eek::gurney:
 
You might be able to squeeze some resonators in between the transmission crossmember and the diff. Not sure how much it would help, but it would reduce the sound some. I've worked on some cars before where we pulled off the resonators to add some sound back to the factory exhaust, but we had no way of measuring the dB so I'm not much help for you there. The biggest obstacle I see is that a resonator for a 3" exhaust is going to be at least 4" in diameter, so packaging might be an issue and you would probably need to be double sure you have good insulation in the floor pans to keep from heating the already hot C3 cockpit.
 
Here is the short story. When building up my car I had no idea about the HP of my engine, so I went with the mufflers I had lying around from a donor car and that were in reasonable condition : 2.25" turbo muffler, some 14" long.

Recently I blew up one of the mufflers. Never mind the reasons, but due to this and the fact that it was rather rusted from the inside and also has some smaller holes on the outside I decided to hunt for a SS muffler of the same size but this time with a 3" inlet/outlet since I found out my 2.25" was way to restrictive.

Via Summit I found a couple of possibilities among which a baffled type of which I didn't like the sound and the magnaflow 11229. Now this is a straight through type glaspack and I checked the sound via some soundclips on YouTube and it seemed to be ok.

So I ordered those.

I just tried one of them one my old dual exhaust pipes with an adapter to see how they do, but oh boy, they are way loud on my car.

Now, what's a possible solution ? A mid car muffler/resonator ?

This probably won't totally cure your noise issue, but when I put my H pipe in, right at the header outlet/reducer, it noticeably quieted the exhaust harshness and volume.

I would expect a resonator to help some, but without knowing what the offending frequency is, it's going to be somewhat of a gamble.
 
I have been going over the internet to see how a magnaflow would perform with a resonator in the line from the headers, but I'm getting conflicting info.
 
I have been going over the internet to see how a magnaflow would perform with a resonator in the line from the headers, but I'm getting conflicting info.

This topic is SO subjective, because of tooooooo many variables, not just the machinery but the owner and their requirements, which depend on the GAL involved, should she be brave enough for a ride......:bump:
 
I'm not sure what it is but even the 2.25" and turbo mufflers had difficulty controlling the sound. Apart from that the turbo's were far too restrictive as was evident when the muffler came apart.
 
IF memory serves, I looked through the Maggies I have and saw some light and of course a ton of holes lined with fiberglass/packing and some stiff bends....so essentially lined pipe....I not hardly a muffler expert....:surrender:
 
I'm not sure what it is but even the 2.25" and turbo mufflers had difficulty controlling the sound. Apart from that the turbo's were far too restrictive as was evident when the muffler came apart.

I'm running 3" Dynomax turbo mufflers. They're pretty quiet and flow very well. Their site has the flow/pressure drop ratings for each model (Thanks, Larry). I put a pressure gauge in my exhaust to double check my system, and I'm happy with the results.
 
I will tell you this : when the muffler came apart, I had to drive some 20 kms to get home. So essentially this was with a practically open exhaust.

I took the plugs out to read them. Before the engine was pretty rich. After that episode the bank in which the muffler blew, was lean, really lean...

I have a maf on the engine because I was originally going to have it run on maf, but with the old exhaust it proved to have a lot of reversion. Somehow, I think the exhaust had a lot to do with it.

I need to get this sorted out. I'm inclined to go with an extra X-pipe and bullet style resonator, but the cost is prohibitive if this doesn't work...
 
I think an X pipe would help a lot. It splits the exhaust pulses and flow in half, so there is a more even flow and increased pipe area downstream of it. You can definitely hear and feel the difference at the tips between cars with and without one. Exhaust flow is more 'relaxed' and quieter.

I'm running Magnaflows on mine. I don't recall the part number, they are 10 years old. They have blown out a bit and are louder than when new, and they have a nice quiet burble at low RPM which opens up to a scream when floored. But they are not obnoxious at all. (Well, I should probably say I don't mind the cabin noise and none of the neighbors have complained!)

You can see my exhaust system on my dyno comparison thread.
 
Thanks Phill,

I think however that your cam is pretty mild compared to mine. The lca explains a lot of the exhaust noise produced as usually an increase in cam open duration and a lower number in Lca means the exhaust opens sooner, and with more pressure.
 
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