NPP question
Thread Starter
Racer
Joined: Oct 2007
Posts: 269
Likes: 0
From: Westfield MA
NPP question
I was washing my o8 Vert yesterday with the engine running and the M2W switch on "loud." The sound was very good! I was surprised that while at th rear of the car the sound wasn't as loud as I expected. I have been around other cars with nomufflers and I recall them being much louder. Does the NPP sytem only let a fraction of the exhaust bypass the mufflers?
Burning Brakes
Joined: Apr 2007
Posts: 1,084
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From: Santa Clarita California
Even though when open the pipe runs straight through the muffler, it will have perforations in the pipe that will allow for the tone to change. It's not like running no muffler at all.
Race Director
Joined: Jan 2005
Posts: 13,656
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From: Bay Shore, NY 11706 MILD2WILD (M2W)
St. Jude Donor '06-'07
I was washing my o8 Vert yesterday with the engine running and the M2W switch on "loud." The sound was very good! I was surprised that while at th rear of the car the sound wasn't as loud as I expected. I have been around other cars with nomufflers and I recall them being much louder. Does the NPP sytem only let a fraction of the exhaust bypass the mufflers?
Team Owner
Joined: Jan 2007
Posts: 22,136
Likes: 23
From: In the woods looking for my thrown putter.
St. Jude Donor '13, '15
"Path of least resistance." At idle there isn't as much pressure in the system (or volume) so the exhaust doesn't meet as much resistance passing through the fiberglass packing(non valve side of NPP). Therefore more of the exhaust gets routed through the packing than it would at WOT. However, at WOT when the pressure and volume increases, it is takes an exponential amount of pressure to push increasing amounts of volume throught the fiberglass packing. The exhaust will always look for the path of least resistance, which is through the straight pipe of the NPP muffler. In other words, the higher the volume in a given amount of time(pressure) the harder it is for the gas to travel through the fiberglass, therefore as the volume increases(WOT), so does the resistance forcing more gas through the straight pipe increasing the noise. At a low pressure(idle), it doesn't meet as much resistance from the fiberglass allowing more to travel through it, decreasing the noise.
Note: The above is a complete guess but sounds good to me.
Note: The above is a complete guess but sounds good to me.
Last edited by Silverspeed; Jan 10, 2008 at 05:25 PM.
Thread Starter
Racer
Joined: Oct 2007
Posts: 269
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From: Westfield MA
Wow,
I knew that I asked my question to the right folks! This forum is great. Now for why was the car runing while I was washing it. I lve in the frozen Northeast and the car was put away dirty. The weather here was in mid 60s tht day. I rad somewhere on the forum that the car should be run once in awhile. Also I loved hearing it run. My buddy and I took turns standing behind th car while the other one did some minor reving! Love that M2w
Silverspeed gave a great explaation, can't tell if its true, but I bought it!Now can someone tell me when the roads will be clear around here?!
I knew that I asked my question to the right folks! This forum is great. Now for why was the car runing while I was washing it. I lve in the frozen Northeast and the car was put away dirty. The weather here was in mid 60s tht day. I rad somewhere on the forum that the car should be run once in awhile. Also I loved hearing it run. My buddy and I took turns standing behind th car while the other one did some minor reving! Love that M2w
Silverspeed gave a great explaation, can't tell if its true, but I bought it!Now can someone tell me when the roads will be clear around here?!
