Sandman
08-05-2009, 11:01 AM
http://jalopnik.com/5329935/the-25-most-useful-car-technologies/gallery/
#6 is pretty neat:
Name: Muffler Valves
What it does: Butterfly or plenum valves located in the muffler or nearby open at certain revs or throttle positions, reducing back pressure and increasing power and noise.
Extreme example: The 2010 Jaguar XKR I'm driving this week is whisper quiet in normal driving, yet roars like a banshee when you get on the throttle. It's glorious and, for now, legal.
Why it's useful: Pesky governments want to restrict our fun by limiting noise levels and emissions. These valves get around those laws by remaining closed in the conditions required to pass the test, then opening in other conditions to deliver the full effect.
#6 is pretty neat:
Name: Muffler Valves
What it does: Butterfly or plenum valves located in the muffler or nearby open at certain revs or throttle positions, reducing back pressure and increasing power and noise.
Extreme example: The 2010 Jaguar XKR I'm driving this week is whisper quiet in normal driving, yet roars like a banshee when you get on the throttle. It's glorious and, for now, legal.
Why it's useful: Pesky governments want to restrict our fun by limiting noise levels and emissions. These valves get around those laws by remaining closed in the conditions required to pass the test, then opening in other conditions to deliver the full effect.