I think part of the problem folks have without a muffler is that they run the pipe as straight as possible. While that is good from the standpoint of getting rid of the exhaust it doesn't do it for noise. The bends cancel out noise and mufflers have some serious internal bends. I had the muffler shop run my 2 1/2" pipe in the same route as the factory exhaust except WITHOUT the muffler. This gives the bends for sound but makes the bends gently for better flow. I doubt that my truck as it is now is more than a db or two louder than stock.
I run a 3" mandrel bent exhaust with a muffler. It is quiet with a slight whistle. My mates HDJ80 with 3" mandrel bent exhaust runs with no muffler. Both of our exhausts follow the original pipe routing. His is about the same db as mine but with a deeper sounding rumble and slightly more whistle.
Another mate has a Nissan GQ ute. Her ute has a stainless steel 3" mandrel bent exhaust with only three bends in it. This truck has the coolest sounding exhaust I've ever heard. It whistles at idle and just gets better as the revs climb but it's noisy to travel any distance in.
I run a 3" mandrel bent exhaust with a muffler. It is quiet with a slight whistle. My mates HDJ80 with 3" mandrel bent exhaust runs with no muffler. Both of our exhausts follow the original pipe routing. His is about the same db as mine but with a deeper sounding rumble and slightly more whistle.
Another mate has a Nissan GQ ute. Her ute has a stainless steel 3" mandrel bent exhaust with only three bends in it. This truck has the coolest sounding exhaust I've ever heard. It whistles at idle and just gets better as the revs climb but it's noisy to travel any distance in.
That sounds like a good way to describe the way mine sounds too! Also kind of reinforces my thoughts as well. I'm sure any sound engineer would also agree on the quieting factor of a few more bends.
the whole idea is to disrupt as many of the sound waves as possible with out too much back pressure, right?
if you look inside a muffler you have baffles and in some the air flow runs down one side and then back and then down and out, coupled wioth the baffles it really quiets the exhaust system. the bneds in the pipe accomplish the same effect just not as well...
cheers
the whole idea is to disrupt as many of the sound waves as possible with out too much back pressure, right?
if you look inside a muffler you have baffles and in some the air flow runs down one side and then back and then down and out, coupled wioth the baffles it really quiets the exhaust system. the bneds in the pipe accomplish the same effect just not as well...
cheers
Actually Wayne, I dare say that with the stock routing (or any other routing with several bends) and the natural sound deadening of the turbo the bends in the pipe probably do a better job of reducing noise while not adding backpressure than a muffler does.
At least that's my theory and it seems to be borne out in my truck. My daughters truck is somewhat noisier but the pipe is also straighter (less bends).
And GoldBoy, back pressure robs you of potential power. There IS a reason why race cars don't have very effective sound control and that is to reduce backpressure. You NEED to read the book "Maximum Boost". It's a really good book on turbos and while it is mostly gas engine oriented it does go into the back pressure myths. No back pressure is best from the standpoint of power.
Actually Wayne, I dare say that with the stock routing (or any other routing with several bends) and the natural sound deadening of the turbo the bends in the pipe probably do a better job of reducing noise while not adding backpressure than a muffler does.
At least that's my theory and it seems to be borne out in my truck. My daughters truck is somewhat noisier but the pipe is also straighter (less bends).
And GoldBoy, back pressure robs you of potential power. There IS a reason why race cars don't have very effective sound control and that is to reduce backpressure. You NEED to read the book "Maximum Boost". It's a really good book on turbos and while it is mostly gas engine oriented it does go into the back pressure myths. No back pressure is best from the standpoint of power.
Actually Wayne, I dare say that with the stock routing (or any other routing with several bends) and the natural sound deadening of the turbo the bends in the pipe probably do a better job of reducing noise while not adding backpressure than a muffler does.
At least that's my theory and it seems to be borne out in my truck. My daughters truck is somewhat noisier but the pipe is also straighter (less bends).
And GoldBoy, back pressure robs you of potential power. There IS a reason why race cars don't have very effective sound control and that is to reduce backpressure. You NEED to read the book "Maximum Boost". It's a really good book on turbos and while it is mostly gas engine oriented it does go into the back pressure myths. No back pressure is best from the standpoint of power.
Where can I get a copy of this book. As i'm in Aust I'll probably need an author and maybe a publishers name to track it down. Can you help me out, sounds like an interesting read.
I bought the book on my initial install of the turbo so all I have to compare to is a naturally aspirated 3B and the turbo makes it a new truck! I figured since I was spending some serious coin on the AXT turbo, a few more dollars for a book is probably a good idea to get it right the first time.
Gold Boy, I'm sure you're familiar with the Coquihalla Connector and the hill out of Westbank. That WAS a 60kph hill in 3rd pre-turbo and became a 90kph hill in 4th after the turbo!
I bought the book on my initial install of the turbo so all I have to compare to is a naturally aspirated 3B and the turbo makes it a new truck! I figured since I was spending some serious coin on the AXT turbo, a few more dollars for a book is probably a good idea to get it right the first time.
Gold Boy, I'm sure you're familiar with the Coquihalla Connector and the hill out of Westbank. That WAS a 60kph hill in 3rd pre-turbo and became a 90kph hill in 4th after the turbo!
I think part of the problem folks have without a muffler is that they run the pipe as straight as possible. While that is good from the standpoint of getting rid of the exhaust it doesn't do it for noise. The bends cancel out noise and mufflers have some serious internal bends. I had the muffler shop run my 2 1/2" pipe in the same route as the factory exhaust except WITHOUT the muffler. This gives the bends for sound but makes the bends gently for better flow. I doubt that my truck as it is now is more than a db or two louder than stock.
I had a tractor muffler on my truck made for a massey ferguson tractor sounded nice, for 25 bucks at TSC it was pretty good, but now I have the ehaust dumped out the side just liek the pic above with 2 3/4 inch stainless and a cherry bomb style muffler, like Wayne said if you can live with the noise it saves you money on pipe (expecailly SS) and I think it will prolly help a bit with EGT's
mine seems to be alot better anyway, could have been that massey ferguson tractor muffle though, LOL
