MicWeb_xA
12-29-2004, 10:16 PM
Long Day’s Journey into Mufflers
I have played with mufflers before and come to realize that there is no free lunch…you can have relative quiet, with some flow restriction, or you can put on a freer flowing muffler and maybe pick up some power (some real power, plus that subjective jolt that comes from being able to rev more freely- where pulling to the redline seems easy instead of stifled). I’ve never been a fan of "sports car" sound, quite the opposite, I think it's true genius to have maximum power PLUS ultra quiet.
Anyway, the one big negative about the stock Scion xA with a stick shift, is that at today's typical freeway speeds (75-80 mph) the engine is turning over at a whopping 4150 rpm (or higher, I can't see the tach that clearly). Now, the engine is ultra smooth and well balanced, so in a way it purrs at 75-80, but there is also a little bit of droning that seems to come in around 65 mph and doesn't depart until 80 mph. Which motivates me to kick it up to 80 mph to get past the drone, which isn't a good thing.
In hindsight, I wish I'd ignored the drone, but I'd had recent success with an Echo by putting on a Dynomax 17709, now discontinued, which was a 7" round, 18" long, 2.25" inlet/outlet muffler. On the Echo, it was very quiet, but seemed to flow much better than stock. Keep in mind that the Echo, which was an automatic, had a much lower rpm at freeway speeds than the heavier, stick shift xA (even the xA automatic has much lower rpm).
By the time I got the xA, the 17709 had been discontinued, but I managed to get a Dynomax 17710, identical in all respects except for 2.5" inlet/outlet. Well, the increased diameter coupled with the increased rpm meant a world of difference, and the first replacement muffler I tried was too loud, with a large drone in the cabin.
The next muffler I tried was a Magnaflow 13650. That is a nice 6" round (much easier to fit, only 1" over the stock 5" diameter), with a 2" inlet/outlet (much closer to the 1.75" stock tubing) but with an 18" body (about 4" longer than stock). I figured, at that time, that a longer body would be quieter because there would be more muffler to quiet things down. This was the Magnaflow XL which is a three chambered, turbo (perforated interior tubing) design compared to the more usual Magnaflow straight through glass-packs. I figured the more conventional design would be quieter, certainly quieter than the Dynomax. WRONG! This was the loudest muffler I tried. Great sound, though, and if I never went over 35mph on the street, the one I'd keep. At freeway speed, though, it was really, really loud. Gave the most power, though.
Although I had saved the stock factory muffler, instead of going back to stock, I decided to try a 1.75" inlet/outlet Walker Quiet flow, same body size as the late lamented Magnaflow. This was definitely quieter, but the least powerful.
Finally, one muffler shop told me 1) don’t go up in tube size more than a 1/4 inch over stock, our you actually lose power; 2) don’t get a much larger (length or diameter) muffler, it can’t do its job right. So I ordered a Dynomax 17742, which is 6" round, but only a 14" body, and has 2" inlet outlet.
This final muffler seems to do the trick. It has a nice sports car sound, especially in parking structures, but is very quiet at freeway speed, unless you are going uphill or get on the accelerator. I think it is actually noisier at all speeds than the stock muffler (or the Walker I tried) based on the radio volume levels I use, but doesn’t have the drone I was trying to get rid of before. Although it is a little louder at all speeds, the tone is very good, it lacks the "drone" peak, and wind and tire noise are still louder than the muffler on the freeway (the muffler isn't the biggest source of noise). On the other hand, the payback in performance and “sportability" is very great. I don't feel the motor is struggling to get past 4,000 rpm. It doesn't seem to "complain" in the last portion of the power band. (It is, however, a lot louder in this last section of the power band and this increase is relatively greater than the much more moderate increase in cruising loudness).
In short the Dynomax 17742 seems to deliver what the TRD design does, at a fraction of the price. True, it's a weld on (instead of bolt-on, like the TRD) part, but the installation only ran me $30 with the welding and hanger fabrication, and the muffler itself only cost $39.95 from Summit Racing with free shipping. It's hard to beat that pricing.
The xA feels like a little sports car with it's new muffler, I even find myself taking some curves faster, because I can hold it in lower gear longer without feeling like I am in the "forbidden zone" of rpm.
I do wonder if throwing a downshift going around a corner is going to get more police attention, but I figure nowadays radar is what gets you, not subjective reaction. And I am still way far away from fitting any tuner profile (this isn't a "rice can" muffler and it has the stock tip).
I have played with mufflers before and come to realize that there is no free lunch…you can have relative quiet, with some flow restriction, or you can put on a freer flowing muffler and maybe pick up some power (some real power, plus that subjective jolt that comes from being able to rev more freely- where pulling to the redline seems easy instead of stifled). I’ve never been a fan of "sports car" sound, quite the opposite, I think it's true genius to have maximum power PLUS ultra quiet.
Anyway, the one big negative about the stock Scion xA with a stick shift, is that at today's typical freeway speeds (75-80 mph) the engine is turning over at a whopping 4150 rpm (or higher, I can't see the tach that clearly). Now, the engine is ultra smooth and well balanced, so in a way it purrs at 75-80, but there is also a little bit of droning that seems to come in around 65 mph and doesn't depart until 80 mph. Which motivates me to kick it up to 80 mph to get past the drone, which isn't a good thing.
In hindsight, I wish I'd ignored the drone, but I'd had recent success with an Echo by putting on a Dynomax 17709, now discontinued, which was a 7" round, 18" long, 2.25" inlet/outlet muffler. On the Echo, it was very quiet, but seemed to flow much better than stock. Keep in mind that the Echo, which was an automatic, had a much lower rpm at freeway speeds than the heavier, stick shift xA (even the xA automatic has much lower rpm).
By the time I got the xA, the 17709 had been discontinued, but I managed to get a Dynomax 17710, identical in all respects except for 2.5" inlet/outlet. Well, the increased diameter coupled with the increased rpm meant a world of difference, and the first replacement muffler I tried was too loud, with a large drone in the cabin.
The next muffler I tried was a Magnaflow 13650. That is a nice 6" round (much easier to fit, only 1" over the stock 5" diameter), with a 2" inlet/outlet (much closer to the 1.75" stock tubing) but with an 18" body (about 4" longer than stock). I figured, at that time, that a longer body would be quieter because there would be more muffler to quiet things down. This was the Magnaflow XL which is a three chambered, turbo (perforated interior tubing) design compared to the more usual Magnaflow straight through glass-packs. I figured the more conventional design would be quieter, certainly quieter than the Dynomax. WRONG! This was the loudest muffler I tried. Great sound, though, and if I never went over 35mph on the street, the one I'd keep. At freeway speed, though, it was really, really loud. Gave the most power, though.
Although I had saved the stock factory muffler, instead of going back to stock, I decided to try a 1.75" inlet/outlet Walker Quiet flow, same body size as the late lamented Magnaflow. This was definitely quieter, but the least powerful.
Finally, one muffler shop told me 1) don’t go up in tube size more than a 1/4 inch over stock, our you actually lose power; 2) don’t get a much larger (length or diameter) muffler, it can’t do its job right. So I ordered a Dynomax 17742, which is 6" round, but only a 14" body, and has 2" inlet outlet.
This final muffler seems to do the trick. It has a nice sports car sound, especially in parking structures, but is very quiet at freeway speed, unless you are going uphill or get on the accelerator. I think it is actually noisier at all speeds than the stock muffler (or the Walker I tried) based on the radio volume levels I use, but doesn’t have the drone I was trying to get rid of before. Although it is a little louder at all speeds, the tone is very good, it lacks the "drone" peak, and wind and tire noise are still louder than the muffler on the freeway (the muffler isn't the biggest source of noise). On the other hand, the payback in performance and “sportability" is very great. I don't feel the motor is struggling to get past 4,000 rpm. It doesn't seem to "complain" in the last portion of the power band. (It is, however, a lot louder in this last section of the power band and this increase is relatively greater than the much more moderate increase in cruising loudness).
In short the Dynomax 17742 seems to deliver what the TRD design does, at a fraction of the price. True, it's a weld on (instead of bolt-on, like the TRD) part, but the installation only ran me $30 with the welding and hanger fabrication, and the muffler itself only cost $39.95 from Summit Racing with free shipping. It's hard to beat that pricing.
The xA feels like a little sports car with it's new muffler, I even find myself taking some curves faster, because I can hold it in lower gear longer without feeling like I am in the "forbidden zone" of rpm.
I do wonder if throwing a downshift going around a corner is going to get more police attention, but I figure nowadays radar is what gets you, not subjective reaction. And I am still way far away from fitting any tuner profile (this isn't a "rice can" muffler and it has the stock tip).