CAMARO6 - View Single Post - NPP power difference between stealth and track

bluerayone · 09-07-2016, 04:06 PM

Parish8 thanks for posting your dyno results. One question though, what was the difference between open runs 1 and 3 (in other words, why the third pull, what were you testing there or trying to bring out).

I am surprised it was not more restrictive with the cutouts closed. In my other post in the camaro5 forum (link to that post in the beginning of this tread) I posted a cutout of Gen 6 NPP muffler

If I were to guess how an NPP muffler was designed I would have thought the inlet would have emptied into the muffler with equal access to both pipes exiting the muffler. Instead the gen 6 NPP cutout diagram reveals the inlet empties directly into the cutout pipe and bypass only occurs only when valve is closed and exhaust is forced through perforations in cut out pipe to reach the inner pipe.

I would have thought that design would be inherently restrictive,however, given your dyno results, guess its not. Apparently engineers have included enough perforations in the cut out pipe to feed the exhaust capacity of 2 1/2 in inner pipe without restricting too much.

All posters on this thread predicting a marginal HP difference (if any) were right. Apparently NPP is more of a noise maker (that I appreciate once in awhile), giving a panacea effect of more power akin to sticking a card in the spokes of your bicycle when you were a kid.

Good to know. Thank you for your post.

09-07-2016, 04:06 PM	#20
bluerayone Drives: 2015 Camaro 2SS/RS Join Date: May 2016 Location: Buffalo, New York Posts: 23	Parish8 thanks for posting your dyno results. One question though, what was the difference between open runs 1 and 3 (in other words, why the third pull, what were you testing there or trying to bring out). I am surprised it was not more restrictive with the cutouts closed. In my other post in the camaro5 forum (link to that post in the beginning of this tread) I posted a cutout of Gen 6 NPP muffler If I were to guess how an NPP muffler was designed I would have thought the inlet would have emptied into the muffler with equal access to both pipes exiting the muffler. Instead the gen 6 NPP cutout diagram reveals the inlet empties directly into the cutout pipe and bypass only occurs only when valve is closed and exhaust is forced through perforations in cut out pipe to reach the inner pipe. I would have thought that design would be inherently restrictive,however, given your dyno results, guess its not. Apparently engineers have included enough perforations in the cut out pipe to feed the exhaust capacity of 2 1/2 in inner pipe without restricting too much. All posters on this thread predicting a marginal HP difference (if any) were right. Apparently NPP is more of a noise maker (that I appreciate once in awhile), giving a panacea effect of more power akin to sticking a card in the spokes of your bicycle when you were a kid. Good to know. Thank you for your post.