exhaust noise levels

[grumpyvette]

HEY GRUMPYVETTE
Just as a point of discussion...
Given the same length of pipe in the system, is an exhaust system louder when the muffler is closer to the header or closer to the tailpipe outlet? OR, doesn't it make any difference?

think it thru, the further the exhaust pulse from the exhaust port in the cylinder head needs to travel, and the larger the internal volume of the pipe its traveling thru, the more it disipates its energy in and the less sound energy the mufflers internal baffles need to disipate, Length AND internal volume dissapate pulse velocity and energy but adding an (X) as close to the collectors as possiable will tend to both split the pulse volume and almost double the internal exhaust path voluum, there by disipating energy faster still and allowing the pulse strength to be reduced a bit more effectively.

viewtopic.php?f=79&t=497

OK ILL try this way,
SORRY IT THAT WAS NOT CLEARLY STATED, we ALL screw things up on occasion.(I SURE DO!)
IDEALLY youll place the mufflers as far away from the engine as you can and install an (X) as close to the header collectors as space permits, and if your really concerned you can install these

http://www.spiralturbobaffles.com/

http://www.spiralturbobaffles.com/images/IMG_9889.JPG

or weld up your own versions
inside the pipes after the (X) and before the mufflers interance to further disrupt sound waves, but read the linked info and the muffler test, but selecting the correct mufflers not the cheapest or the chrome ones that look best goes a long ways toward getting the sound reduction under control! :biggrin:

viewtopic.php?f=56&t=495

 

[grumpyvette]

first keep in mind SOUND is the result of both vibration intensity and FREQUENCY, and how well you isolate the exhaust components from the cars interior, you can REDUCE the INTENSITY if you install an (X) pipe as close to the header collectors as you can due to clearance issues and theres not a darn thing preventing you from installing a second (H) or (X) pipe just in front of the muffler entrance too further dissipate the sound producing pulse intensity, further busting up or separating the pulse strength before the mufflers need to start breaking down the sound waves and breaking up the resulting frequency they produce. Rubber exhaust hangers and insulating heat resistant pads can do a great deal to reduce transmitted sound, and theres no reason you can,t get creative and experiment.
distance from the pulse source and internal pipe volume and a tuned length all can help or hinder the break up of the exhaust pulse strength and duration.
next keep in mind you want to keep the minimum diam. exhaust pipe that won,t prove to be a restriction to flow in the intended rpm range your engine makes its power in, to maximize scavenging but without inducing any significant back pressure that will reduce flow and power as a result.
there are plenty of well designed exhaust systems available , but before you go throwing big buck$ into an exhaust think about how long youll own the car, if you think it will be over about 5 years you might want to think STAINLESS steel because although its significantly more expensive its also a material that lasts far longer., than aluminized steel, that's commonly used.
In many cases its clearance issues under the car, cost and parts availability that will dictate the choices, especially if you don,t have ready access to a lift and decent welder.
http://www.flowmastermufflers.com/faq.html

http://www.summitracing.com/search/?keyword=exhaust cones&dds=1

IF your trying to reduce noise levels, you can buy or fabricate these cones that tend to break up and reduce exhaust noise, once installed in the exhaust, without producing much of a restriction since the total surface area of the mini holes is greater the the pipes cross sectional area
the tabs can be tack welded or sheet metal screw attached, and adding an (X) pipe near the collectors and an additional (H) near the muffler entrance point tends to mellow the tone