Nismo Cat Back

Rooskey · 03-10-2011, 03:58 PM

Quote:

Originally Posted by 6spd

got a sound clip?

Nope. Its kinda raspy though. Im thinking I may take them off and use some header wrap on them to help out with the rasp. It makes good power though. I will be dynoing here in the next week or so. Ill post up the results on my dyno thread.

Nikkolai · 03-10-2011, 04:12 PM

That seems odd to me. I thought getting test pipes (non-resonated or even resonated) would cause a lot more rasp than hi flow cats. I was assuming more sound is being resonated in an actual catalytic converter.

chops · 03-10-2011, 04:44 PM

there is definitely rasp if you add test pipes (resonated or not) or high flow cats to the nismo exhaust. i believe the H pipe is the culprit here. the new cats/tp's go from 2.5" pipe to the 2.25" flex pipe flanges, which end at 2" to the midpipe/resonators.

a member in the nismo forum said he added a custom 2.5" x-pipe which got rid of all his rasp. im determined to go this route as well...as soon as someone makes one!

Nikkolai · 03-10-2011, 05:34 PM

Quote:

Originally Posted by chops

there is definitely rasp if you had test pipes (resonated or not) or high flow cats to the nismo exhaust. i believe the H pipe is the culprit here. the new cats/tp's go from 2.5" pipe to the 2" flex pipe flanges, which open upto 2.25" to the midpipe/resonators.

a member in the nismo forum said he added a custom 2.5" x-pipe which got rid of all his rasp. im determined to go this route as well...as soon as someone makes one!

What about those cheap Y-Pipes from Ebay coupled with the rest of the Nismo exhaust? I do not mind the rasp if it goes away upon warm up.

chops · 03-10-2011, 06:34 PM

Quote:

Originally Posted by Nikkolai

What about those cheap Y-Pipes from Ebay coupled with the rest of the Nismo exhaust? I do not mind the rasp if it goes away upon warm up.

a Y-pipe will not work..only the stock Z has 2 catalytic converters joined to a single pipe. nismo owners will require an X-pipe

Jessobear · 03-10-2011, 08:02 PM

Quote:

Originally Posted by chops

there is definitely rasp if you add test pipes (resonated or not) or high flow cats to the nismo exhaust. i believe the H pipe is the culprit here. the new cats/tp's go from 2.5" pipe to the 2.25" flex pipe flanges, which end at 2" to the midpipe/resonators.

a member in the nismo forum said he added a custom 2.5" x-pipe which got rid of all his rasp. im determined to go this route as well...as soon as someone makes one!

I have the Nismo OEM exhaust with FI resonated HFC's and I can definitely tell you that my car does not have any noticeable exhaust rasp.

I also find it funny that everyone really gets on the piping diameters of the H pipe. Having stepped piping sizes is actually totally normal and can actually aid in the scavenging effect of the exhaust system. Think about this in terms of total cross-sectional area: passing the exhaust through two 2" diameter pipes is a greater cross-sectional area than passing through a single X or Y pipe.

The advantage of an X pipe has nothing to do with cross sectional area. It has to do with easier flow between the two sides of the exhaust due to a smoother transition compared with an H pipe. An X pipe will also have the effect of making the exhaust quieter from noise cancellation due to the easier cross flow of the two legs. The H pipe configuration is not a bad design in essence, which is why people have only seen small gains from other exhaust systems.

Here's a decent link about putting an X pipe exhaust system on a car:

Exhaust System Installation H-Pipe, X-Pipe,- Car Craft Magazine

chops · 03-10-2011, 08:59 PM

Quote:

Originally Posted by Jessobear

I have the Nismo OEM exhaust with FI resonated HFC's and I can definitely tell you that my car does not have any noticeable exhaust rasp.

I also find it funny that everyone really gets on the piping diameters of the H pipe. Having stepped piping sizes is actually totally normal and can actually aid in the scavenging effect of the exhaust system. Think about this in terms of total cross-sectional area: passing the exhaust through two 2" diameter pipes is a greater cross-sectional area than passing through a single X or Y pipe.

The advantage of an X pipe has nothing to do with cross sectional area. It has to do with easier flow between the two sides of the exhaust due to a smoother transition compared with an H pipe. An X pipe will also have the effect of making the exhaust quieter from noise cancellation due to the easier cross flow of the two legs. The H pipe configuration is not a bad design in essence, which is why people have only seen small gains from other exhaust systems.

Here's a decent link about putting an X pipe exhaust system on a car:

Exhaust System Installation H-Pipe, X-Pipe,- Car Craft Magazine

Quote:

For any performance exhaust system, some type of crossover connecting the two sides of a dual exhaust system is important because it acts to balance the two banks of the engine. The common H-style crossover is good at balancing sound pulses between the two halves, but does little to promote scavenging because the exhaust gases tend to follow the path of least resistance, which is straight through each pipe rather than taking the 90-degree turn through the H-pipe into the other half of the system. In an X-pipe system, however, where the two sides of the system intersect, the gasses have no choice but to intermingle as they pass through the junction. This promotes improved scavenging effects by smoothing out uneven exhaust pulses from the engine’s firing order. It also helps quiet down the exhaust, resulting in a mellower, less raspy tone. According to Magnaflow, the faster acceleration of the gasses through an X-pipe causes them to flow in a linear fashion parallel to the walls of the tubing rather than tumbling. This “laminar” flowing gas is much quieter than tumbling gas, resulting in an exhaust tone up to 8 decibels quieter than a traditional H-pipe.

this is fine by me! more power, less rasp, cant go wrong with the X-pipe..

Nikkolai · 03-10-2011, 11:22 PM

Quote:

Originally Posted by chops

a Y-pipe will not work..only the stock Z has 2 catalytic converters joined to a single pipe. nismo owners will require an X-pipe

Yes, that is my fault. It was totally obvious. I guess the late shifts I had this week is taking a toll on my brain, lol.

Jessobear · 03-11-2011, 08:38 AM

Quote:

Originally Posted by chops

this is fine by me! more power, less rasp, cant go wrong with the X-pipe..

Which is why if I were to recommend an aftermarket exhaust, it would be the Fast Intentions (even though I really hate the look of having the visible polished/angled mufflers under the car). All I'm saying is that even with the H-pipe in my OEM Nismo exhaust, I'm not getting any raspiness. This may be because of my resonated HFC's, which as far as I can tell I'm one of two people on this forum to own, the other guy being in Australia. Perhaps removing either the cat part or the resonator part (which would describe the setup that 99% of the people here have) induces some raspiness that I'm not getting.

chops · 03-11-2011, 01:45 PM

Quote:

Originally Posted by Jessobear

Which is why if I were to recommend an aftermarket exhaust, it would be the Fast Intentions (even though I really hate the look of having the visible polished/angled mufflers under the car). All I'm saying is that even with the H-pipe in my OEM Nismo exhaust, I'm not getting any raspiness. This may be because of my resonated HFC's, which as far as I can tell I'm one of two people on this forum to own, the other guy being in Australia. Perhaps removing either the cat part or the resonator part (which would describe the setup that 99% of the people here have) induces some raspiness that I'm not getting.

yea..ive already approached fast intentions in hopes that they will create an X-pipe for us nismo owners

ArtVandaleigh · 03-11-2011, 02:01 PM

I had the Nismo S-tune exhaust with both stock and Berk cats for about 10k miles. It's a well made piece, but overall I was disappointed with it. Sound wise it's just barely louder than stock, a tad deeper only when it warms up. I was mostly let down when I went to the Berk cats though, power improved a bit but the sound level was still far too quiet... I'd say the same type of sound level increase from stock to S-tune. I must say when I switched to the FI exhaust I had an immediate noticable power increase. When you sit the OEM and S-tune exhausts side by side, the S-tune is essentially just a polished version of stock, with "slightly" larger piping. Good for those who would want a shiny muffler and some bling, but no way worth the 1500+ they ask. Considering I ran almost every Nismo part for my old 350Z, the current 370Z line parts are a let down. The 350Z S-tune exhaust was far superior in performance/sound/cost IMO.

Nikkolai · 03-11-2011, 02:44 PM

Quote:

Originally Posted by ArtVandaleigh

I had the Nismo S-tune exhaust with both stock and Berk cats for about 10k miles. It's a well made piece, but overall I was disappointed with it. Sound wise it's just barely louder than stock, a tad deeper only when it warms up. I was mostly let down when I went to the Berk cats though, power improved a bit but the sound level was still far too quiet... I'd say the same type of sound level increase from stock to S-tune. I must say when I switched to the FI exhaust I had an immediate noticable power increase. When you sit the OEM and S-tune exhausts side by side, the S-tune is essentially just a polished version of stock, with "slightly" larger piping. Good for those who would want a shiny muffler and some bling, but no way worth the 1500+ they ask. Considering I ran almost every Nismo part for my old 350Z, the current 370Z line parts are a let down. The 350Z S-tune exhaust was far superior in performance/sound/cost IMO.

When you say "immediate noticable power increase" did you run it on a dyno and verify?

6spd · 03-11-2011, 03:57 PM

Ive gotta disagree on the piping size, the s-tune is much larger that stock, especially at the y-pipe choke points and flex pipes.

GZ3 · 03-11-2011, 04:10 PM

^^ true it is larger

Rooskey · 03-12-2011, 01:46 AM

Quote:

Originally Posted by chops

this is fine by me! more power, less rasp, cant go wrong with the X-pipe..

Actually an X pipe works as a vacuum on the exhaust side. The crossover helps pull the exhaust out. Kinda like using vacuum on the intake side to run power brakes or opening up throttle bodies. It helps helps pull the oxygen through the engine. (Add's power)

03-10-2011, 04:44 PM	#18 (permalink)
chops A True Z Fanatic Join Date: Oct 2010 Location: NA Posts: 1,732 Drives: NA Rep Power: 21	there is definitely rasp if you add test pipes (resonated or not) or high flow cats to the nismo exhaust. i believe the H pipe is the culprit here. the new cats/tp's go from 2.5" pipe to the 2.25" flex pipe flanges, which end at 2" to the midpipe/resonators. a member in the nismo forum said he added a custom 2.5" x-pipe which got rid of all his rasp. im determined to go this route as well...as soon as someone makes one! Last edited by chops; 03-10-2011 at 06:35 PM.

03-11-2011, 03:57 PM	#28 (permalink)
6spd A True Z Fanatic Join Date: Aug 2009 Location: South Florida Posts: 3,001 Drives: Q50RS Rep Power: 24	Ive gotta disagree on the piping size, the s-tune is much larger that stock, especially at the y-pipe choke points and flex pipes. __________________ -Jay- jonathanjamesphotographer.com

03-11-2011, 04:10 PM	#29 (permalink)
GZ3 A True Z Fanatic Join Date: Dec 2009 Location: SATX Posts: 3,296 Drives: Z Rep Power: 21	^^ true it is larger __________________ 09 GT-R 12' 370Z 7AT HANDED DOWN 12'+13' 5.0 SOLD

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03-10-2011, 04:12 PM	#17 (permalink)
Nikkolai Base Member Join Date: Jun 2010 Location: DFW Posts: 238 Drives: Boss 302, Frontier Rep Power: 14	That seems odd to me. I thought getting test pipes (non-resonated or even resonated) would cause a lot more rasp than hi flow cats. I was assuming more sound is being resonated in an actual catalytic converter.

03-11-2011, 02:01 PM	#26 (permalink)
ArtVandaleigh Base Member Join Date: Jan 2009 Location: NE Ohio Posts: 227 Drives: 09 PW 370Z Rep Power: 675	I had the Nismo S-tune exhaust with both stock and Berk cats for about 10k miles. It's a well made piece, but overall I was disappointed with it. Sound wise it's just barely louder than stock, a tad deeper only when it warms up. I was mostly let down when I went to the Berk cats though, power improved a bit but the sound level was still far too quiet... I'd say the same type of sound level increase from stock to S-tune. I must say when I switched to the FI exhaust I had an immediate noticable power increase. When you sit the OEM and S-tune exhausts side by side, the S-tune is essentially just a polished version of stock, with "slightly" larger piping. Good for those who would want a shiny muffler and some bling, but no way worth the 1500+ they ask. Considering I ran almost every Nismo part for my old 350Z, the current 370Z line parts are a let down. The 350Z S-tune exhaust was far superior in performance/sound/cost IMO.