Everyone seems to be going with X pipes and from the discussions I've read it seems that when people switch from their stock H to an X (either catted or not) that is when they start getting the drone (as opposed to when they install the cat-back). So, are there any good catted H pipes out there? Is there really any difference in performance between a good H pipe vs a good X pipe or are X pipes just the "in thing" right now?
Any good catted H pipes?
- Thread starter Voice of Reason
- Start date
drone has more to do with mufflers than anything else
the drone sound is resonating of the 2 mufflers. Without getting too technical the mufflers sound at 2000ish rpms start to resenate off each others sound (constructive interference) the stock mufflers are different sizes from one another so they dont have this interaction since they have diff resonate freq from each other. Thats the drone.
It just is more aparent with hi flow cats or offroads because its louder thats all.
the drone sound is resonating of the 2 mufflers. Without getting too technical the mufflers sound at 2000ish rpms start to resenate off each others sound (constructive interference) the stock mufflers are different sizes from one another so they dont have this interaction since they have diff resonate freq from each other. Thats the drone.
It just is more aparent with hi flow cats or offroads because its louder thats all.
Hmm, so if it is being caused by the mufflers resonating off eachother why wouldn't aftermarket companies just make a system with two slightly different sized mufflers?
I've had the drone with stock H and aftermarket catback. The system acts as a resonant tube...
The following example is for a car with a drone at 2000rpm and is very simplistic, but it makes a point...I think?!?
Resonant freq = 2000 rpm (4 pulses per revolution) ( 1/60 minute per second) = 133 Hz
Wavelength (@133 Hz) = approx 1077 feet per second / 133 Hz = approx 8 feet
Therefore an 8 foot pipe will resonate at 133Hz (and integer multiple thereof).
Would you like to guess the length a typical tailpipe is from the "X" or "H" to the tip??
For those that would be inclined to pick this example apart, yes I did not account for the high temperature of the exhaust or the acoustical obstruction presented by the mufflers, or....etc.
The following example is for a car with a drone at 2000rpm and is very simplistic, but it makes a point...I think?!?
Resonant freq = 2000 rpm (4 pulses per revolution) ( 1/60 minute per second) = 133 Hz
Wavelength (@133 Hz) = approx 1077 feet per second / 133 Hz = approx 8 feet
Therefore an 8 foot pipe will resonate at 133Hz (and integer multiple thereof).
Would you like to guess the length a typical tailpipe is from the "X" or "H" to the tip??
For those that would be inclined to pick this example apart, yes I did not account for the high temperature of the exhaust or the acoustical obstruction presented by the mufflers, or....etc.
This is why the stock mufflers on my 91 were slightly different sizes - I don't know if the 03's are or not, but I would bet they are slightly different somehow. I have been wondering why the aftermarket doesn't do the same thing. You also might be able to connect the two mufflers to each other with a tube and the resonance might go away.
As I have been reading, the after market mid pipes
only give you another 5 horsepower.They are expensive
as well.You lose back pressure also.It will be a catback
only for me.
only give you another 5 horsepower.They are expensive
as well.You lose back pressure also.It will be a catback
only for me.
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