inside ansa quad exhaust
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Dr.Jeff
True Classic
I've explored other Ansa mufflers before (not X1/9 application). They are like a standard "glass pack" design, with fiber insulation packing material wrapped around a perforated core to absorb the sound. And the packing deteriorates, dramatically changing the sound quality and dB level. Unfortunately they are a bit difficult to dissect so it isn't easy to try and repack one, but it could be done. You will need to cut it open, remove what's left inside, repack it, and reweld it shut. I'd use stainless steel wool for the new packing. The insides also tend to rust as the packing material holds water, so if you do open it up check for corrosion.
Dr.Jeff
True Classic
Reminds me of a lot of modern high-tech race engines. At idle or other no load (i.e. steady state) modes they are actually rather quiet. But once the throttle is opened and a load is applied the noise level goes WAY up. I remember back at my first live MotoGP event, standing next to the bikes at idle warming up in the pit area they struck me as very quiet. But a little later I was standing by the starting grid and when the lights went out it was like a huge explosion of unbearable noise. It was so sudden and so loud I instinctively recoiled in a "fight or flight" response.
JNewm
True Classic
This is super interesting--can I ask a dumb question: why do there seem to be two pipes coming in/going out of one side, but only one pipe on the other side? I thought the X was just single in, single out.
Dr.Jeff
True Classic
The extra pipes inside are why the stock muffler doesn't have any packing. Two different approaches to "muffling" the sound. Packing acts to sort of "absorb" the waves, while "baffling chambers" (those extra internal pipes and dividers) bounce the waves back and forth to lose energy. But that's why the stock style is more restrictive. The sound waves must pass through those little holes in one pipe, go across the chamber (isolated by walls that don't show well in that pic - look at the spot welds on the outer skin), through the holes in the other pipe, then out of that chamber...plus the other chamber on the other half of the muffler.
JNewm
True Classic
That makes more sense; thank you! That said, I'll admit I'm still at a bit of a loss. (Monday morning, still on my first cup of coffee, brain is accordingly even slower than usual...)
I'm still left wondering why three perforated pipes instead of two? The little arrows/question marks may help to illustrate my confusion. This looks like a later US-style muffler, which (I think) has just one inlet and one outlet. Put another way, this would make total sense if the X had a fake dual exhaust--i.e., one inlet pipe and two outlet pipes. But it doesn't--just one in, one out.
Alternatively, something like this could make sense (depending on what those wall/baffles look like)... but only if the X had the inlet and outlet on the same side, which at least mine does not.
I'm still left wondering why three perforated pipes instead of two? The little arrows/question marks may help to illustrate my confusion. This looks like a later US-style muffler, which (I think) has just one inlet and one outlet. Put another way, this would make total sense if the X had a fake dual exhaust--i.e., one inlet pipe and two outlet pipes. But it doesn't--just one in, one out.
Alternatively, something like this could make sense (depending on what those wall/baffles look like)... but only if the X had the inlet and outlet on the same side, which at least mine does not.
Dr.Jeff
True Classic
To be honest I would have to look at the stock muffler again to remember exactly where the inlet and exit tubes are located on the ends. But consider the following possibility to at least get an idea how this might work with three tubes. Assume the single inlet is on the left and single outlet is on the right, and both are located in the very middle/center of those end plates. The black lines indicate blocked areas (no gas passage), the green ovals are open passages, and the red arrows the gas flow path:
![IMG_0249[1].JPG](https://xwebforums.com/forum/index.php?attachments/img_0249-1-jpg.43881/ "IMG_0249[1].JPG")
JNewm
True Classic
That makes total sense. Thanks again! Interesting how much of the sound must be absorbed into/resonate out of the muffler walls. As you noted above, it functions very differently from a glasspack.
Given the way it works, I wonder whether you could reduce the dreaded "highway drone" by wrapping the whole thing in insulation? Something like this: https://www.zoro.com/unitherm-ceramic-fiber-insulation-8-cu-ftlb-1-wall-cf8-1-24x60in/i/G9205701/.
It'd be ugly as hell, of course....
Given the way it works, I wonder whether you could reduce the dreaded "highway drone" by wrapping the whole thing in insulation? Something like this: https://www.zoro.com/unitherm-ceramic-fiber-insulation-8-cu-ftlb-1-wall-cf8-1-24x60in/i/G9205701/.
It'd be ugly as hell, of course....
Dr.Jeff
True Classic
I know there are standard type mufflers with double outer walls for this very reason. Looking at those stock X1/9 muffler "cutaway" pics posted earlier it does not look like it has a double wall. So it might help to cover it. But honestly I'd look at replacing the entire muffler with a better unit; one with less restriction but better noise control. There are a few approaches to sound reduction in mufflers - more than we've discussed so far. Some are quite good at controlling the sound but also offer great flow. And before you ask, sorry I don't have any recommendations to offer. There is way too much individual difference in what is considered "loud" or "good" or other factors that go into the choice. Therefore any preference I might have would not be good input for your personal decision. Sadly it often comes down to trying one and seeing if you like it.
Dr.Jeff
True Classic
I saw a article about exhaust system design that reminded me of this thread. The article described some tests they did to evaluate the difference in engine performance between various types of mufflers and diameters of pipes and mufflers (exhaust size).
The engine (not Fiat) was mounted on a engine dyno and the various exhaust system configurations were made to be as close as possible to one another, but with the different diameters and muffler types. Therefore the results are not directly applicable to our SOHC engines, but the general findings support what many previous tests have shown and offer some insight to what we should expect.
Basically the two types of mufflers tested were like the ones we've been discussing; a "straight through" design like the ANSA muffler, and a "baffled" design like the stock X muffler. The two sizes (diameters) of systems tested were one that's typical of most aftermarket systems (for that particular engine) and one larger than that. The stock X exhaust system and the ANSA system are similar diameters, with the ANSA being only slightly larger. Therefore the comparison made in these tests might be more like comparing the ANSA with a custom one that is even larger diameter. But there may be some similar results found between the stock system diameter and the ANSA diameter.
The results are really not surprising. The straight through muffler outperformed the baffled muffler significantly. And the larger diameter slightly outperformed the smaller one. But here is the interesting part. The type of muffler made so much more improvement in overall output (torque and HP, across the RPM range) that a smaller diameter system with a straight through muffler made considerably greater output than the larger diameter system with a baffled muffler. So basically design matters more than size.
As I said, these tests are not directly applicable to the X. There are lots of factors that influence the correct size of pipes (diameter and length) for any given application and use. But the general findings about muffler type will be the same for pretty much any application; less restriction is better.
No, they did not measure sound levels or comment on sound quality. This was only a performance test. So naturally that's another consideration. But the difference in performance due to the muffler type was so significant that it is worth consideration. If sound levels are a real concern then perhaps a aftermarket muffler with better noise control than a straight through design, but less restriction than a stock muffler design may be the answer.
The engine (not Fiat) was mounted on a engine dyno and the various exhaust system configurations were made to be as close as possible to one another, but with the different diameters and muffler types. Therefore the results are not directly applicable to our SOHC engines, but the general findings support what many previous tests have shown and offer some insight to what we should expect.
Basically the two types of mufflers tested were like the ones we've been discussing; a "straight through" design like the ANSA muffler, and a "baffled" design like the stock X muffler. The two sizes (diameters) of systems tested were one that's typical of most aftermarket systems (for that particular engine) and one larger than that. The stock X exhaust system and the ANSA system are similar diameters, with the ANSA being only slightly larger. Therefore the comparison made in these tests might be more like comparing the ANSA with a custom one that is even larger diameter. But there may be some similar results found between the stock system diameter and the ANSA diameter.
The results are really not surprising. The straight through muffler outperformed the baffled muffler significantly. And the larger diameter slightly outperformed the smaller one. But here is the interesting part. The type of muffler made so much more improvement in overall output (torque and HP, across the RPM range) that a smaller diameter system with a straight through muffler made considerably greater output than the larger diameter system with a baffled muffler. So basically design matters more than size.
As I said, these tests are not directly applicable to the X. There are lots of factors that influence the correct size of pipes (diameter and length) for any given application and use. But the general findings about muffler type will be the same for pretty much any application; less restriction is better.
No, they did not measure sound levels or comment on sound quality. This was only a performance test. So naturally that's another consideration. But the difference in performance due to the muffler type was so significant that it is worth consideration. If sound levels are a real concern then perhaps a aftermarket muffler with better noise control than a straight through design, but less restriction than a stock muffler design may be the answer.
JNewm
True Classic
This is all very interesting reading--I'm very much enjoying it while taking a break from doing battle with old/rusty fuel lines. Ugh.
Another odd finding to add to the mix: somewhere on here I came across a super old thread in which (Mark?) Allison relayed the dyno results from his header design for the X. It performed quite well, as I recall. But the really odd part was that he seemed to indicate that a dyno run *with the catalytic converter installed* yielded higher numbers than a dyno run without the cat. That seems counterintuitive to me, but it does seem to fit with the overall sense that you'd really need to play around with various configurations, dyno-testing each, to figure out what works best for a given engine. (And, of course, "best" is contingent.)
My thought is that the single best way to reduce highway-speed engine noise would probably be to remove the back glass window to promote airflow through the cabin. The back glass just seems to act like a big bucket for catching air, allowing the sound waves from the engine to come toward the front instead of being "blown" backwards, away from the cabin. Having ridden a motorcycle with straight pipes, it can be earsplitting at a stoplight but almost "silent" to the rider at highway speeds.
Another odd finding to add to the mix: somewhere on here I came across a super old thread in which (Mark?) Allison relayed the dyno results from his header design for the X. It performed quite well, as I recall. But the really odd part was that he seemed to indicate that a dyno run *with the catalytic converter installed* yielded higher numbers than a dyno run without the cat. That seems counterintuitive to me, but it does seem to fit with the overall sense that you'd really need to play around with various configurations, dyno-testing each, to figure out what works best for a given engine. (And, of course, "best" is contingent.)
My thought is that the single best way to reduce highway-speed engine noise would probably be to remove the back glass window to promote airflow through the cabin. The back glass just seems to act like a big bucket for catching air, allowing the sound waves from the engine to come toward the front instead of being "blown" backwards, away from the cabin. Having ridden a motorcycle with straight pipes, it can be earsplitting at a stoplight but almost "silent" to the rider at highway speeds.
Dr.Jeff
True Classic
You might look at adding better sound (and heat) insulation to the entire firewall between the cabin and engine bay. The stock insulation on the engine side of that wall isn't very effective, and there is basically none on the interior side. Using a modern insulating material like they do for high end stereo installations would help a lot. You could even add it to the underside of the engine cover. Like @carl said, the exhaust isn't the only source of noise. It will also work well on the rest of the interior to reduce road noise. Plus add some on the rear firewall between the engine and trunk, as well as the trunk floor, to help isolate the exhaust noise from the chassis/body.
I think removing the rear glass would create more problems than benefits. But I get what you mean.
I think removing the rear glass would create more problems than benefits. But I get what you mean.
carl
True Classic
Noise and packaging are two big issues with Xs. I went with a turbo muffler as it's quite effective in reducing noise while taking up a relatively small space. Single glass packs are too loud and I didn't want to snake multiple mufflers in the muffler bay to quiet down the exhaust.
I saw the Engine Masters episode on the Motor Trend channel last night and the turbo muffler did not perform as well as the straight through mufflers. This was a 400hp V8 on the dyno and they sort of admitted the turbo may not have been big enough for this application.
I have run several after market cat back systems on my Miatas and in every case I went back to stock as the after market systems droned terribly, which of course everyone on the Miata forum knows. Xs are severely limited in after market options. Probably the most glorious sounding X exhaust is on Erwin's (Art basement) X and while it sounded great outside the car I bet Erwin is probably deaf after a drive.
I saw the Engine Masters episode on the Motor Trend channel last night and the turbo muffler did not perform as well as the straight through mufflers. This was a 400hp V8 on the dyno and they sort of admitted the turbo may not have been big enough for this application.
I have run several after market cat back systems on my Miatas and in every case I went back to stock as the after market systems droned terribly, which of course everyone on the Miata forum knows. Xs are severely limited in after market options. Probably the most glorious sounding X exhaust is on Erwin's (Art basement) X and while it sounded great outside the car I bet Erwin is probably deaf after a drive.