Stock Nismo exhaust with forced induction - power loss expected?

braydo25 · 02-16-2017, 02:45 PM

Hey guys,

I have a TT Nismo 370z making around 500whp on 7psi right now with a full 2.5" true dual straight pipe exhaust (No crossover). The only things in the exhaust are a resonator for each side of the exhaust.

The car is so loud lately that I can't drive it without getting a headache or wearing earplugs.

I'm planning on throwing just the stock '13 Nismo muffler back on the rear of the car so the system goes from each turbo -> 2.5" true dual straight pipe -> each pipe into it's own resonator -> a little more 2.5" piping towards the rear muffler -> each pipe into 1 of the inlets of the Nismo exhaust.

I've noticed the Nismo inlet piping diameter is 2.25", so I'll be using a concentric reducer from the 2.5" to 2.25".

My main concern is will adding the rear muffler inhibit spool / power delivery a noticeable amount? I'd assume no given the nature of the true dual system - each sides' 3 cylinders having at worst 2.25" diameter piping to flow through independently.

Also, would perhaps adding an H pipe into the exhaust configuration prior to the resonators (or after) make sense and help in exhaust flow for turbo application?

TopgunZ · 02-16-2017, 02:48 PM

It will cost you a little power and torque but you should also probably get it re-tuned because its going to go rich. Since you are at such a low psi I dont know how bad it will be but if you have an AFR gauge then just keep an eye on that to see if you require one. I am guessing you will. You will be adding a muffler to it which are the most restrictive components of an exhaust.

braydo25 · 02-16-2017, 02:53 PM

Quote:

Originally Posted by TopgunZ

It will cost you a little power and torque but you should also probably get it re-tuned because its going to go rich. Since you are at such a low psi I dont know how bad it will be but if you have an AFR gauge then just keep an eye on that to see if you require one. I am guessing you will. You will be adding a muffler to it which are the most restrictive components of an exhaust.

Good to know, the car is actually scheduled for a retune mid next week - which is after this install, so it should all come together nicely

Jayhovah · 02-16-2017, 02:59 PM

You are bound to lose something, how much I have no idea... I am interested in seeing your results though!

bcfromfl · 02-17-2017, 01:44 AM

Just out of curiosity, would you mind sharing which exhaust you're using that's too loud?

YzGyz · 02-17-2017, 04:10 AM

Actually, can you share his you got 500whp ? Must be a bad *** set up. I love all things turbo.

YzGyz

solidus · 02-17-2017, 08:39 AM

As much as I love the sound of my MXP exhaust, I suspect that it is too restrictive and holding up power. Being that I had to modify the exhaust for the BP setup (Basically cut the Y )

ChaseZ · 02-17-2017, 12:05 PM

Would adding restriction tend to create more backpressure ergo holding higher boost?

TopgunZ · 02-17-2017, 12:29 PM

Quote:

Originally Posted by ChaseZ

Would adding restriction tend to create more backpressure ergo holding higher boost?

Yes = Bad.

GTRphil · 03-09-2017, 08:46 PM

Made 600whp 12psi on TT 370 with stock NISMO cat back exhaust, no problems, but just removed it for a 3"FI and boost went up and had to adjust the tune calibration.

02-16-2017, 02:45 PM	#1 (permalink)
braydo25 Base Member Join Date: Apr 2012 Location: Tacoma Posts: 67 Drives: Nismo z34 Rep Power: 13	Stock Nismo exhaust with forced induction - power loss expected? Hey guys, I have a TT Nismo 370z making around 500whp on 7psi right now with a full 2.5" true dual straight pipe exhaust (No crossover). The only things in the exhaust are a resonator for each side of the exhaust. The car is so loud lately that I can't drive it without getting a headache or wearing earplugs. I'm planning on throwing just the stock '13 Nismo muffler back on the rear of the car so the system goes from each turbo -> 2.5" true dual straight pipe -> each pipe into it's own resonator -> a little more 2.5" piping towards the rear muffler -> each pipe into 1 of the inlets of the Nismo exhaust. I've noticed the Nismo inlet piping diameter is 2.25", so I'll be using a concentric reducer from the 2.5" to 2.25". My main concern is will adding the rear muffler inhibit spool / power delivery a noticeable amount? I'd assume no given the nature of the true dual system - each sides' 3 cylinders having at worst 2.25" diameter piping to flow through independently. Also, would perhaps adding an H pipe into the exhaust configuration prior to the resonators (or after) make sense and help in exhaust flow for turbo application?

02-16-2017, 02:48 PM	#2 (permalink)
TopgunZ A True Z Fanatic Join Date: Jun 2012 Location: Minneapolis Posts: 2,651 Drives: 06 350Z , 09 370Z MT Rep Power: 6833	It will cost you a little power and torque but you should also probably get it re-tuned because its going to go rich. Since you are at such a low psi I dont know how bad it will be but if you have an AFR gauge then just keep an eye on that to see if you require one. I am guessing you will. You will be adding a muffler to it which are the most restrictive components of an exhaust. __________________ ROTREX SUPERCHARGER TUNER KITS - $6799/ CUSTOM STILLEN AIR TO AIR KITS -$2100/ 700+ WHP!! WWW.TOPGUNSPEEDWORKS.COM Last edited by TopgunZ; 02-16-2017 at 02:51 PM.

02-17-2017, 04:10 AM	#6 (permalink)
YzGyz A True Z Fanatic Join Date: Jun 2013 Location: Houston Posts: 1,449 Drives: 2010 Nismo Rep Power: 62	Actually, can you share his you got 500whp ? Must be a bad *** set up. I love all things turbo. YzGyz __________________ http://www.the370z.com/members-370z-...gyzs-turn.html YzGyz

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02-17-2017, 01:44 AM	#5 (permalink)
bcfromfl Enthusiast Member Join Date: Nov 2016 Location: Youngstown, FL Posts: 256 Drives: 2015 PW Nismo 6MT Rep Power: 8	Just out of curiosity, would you mind sharing which exhaust you're using that's too loud?

02-17-2017, 08:39 AM	#7 (permalink)
solidus Track Member Join Date: Oct 2014 Location: Orlando, Florida Posts: 694 Drives: 15' Nismo Black 6MT Rep Power: 10080	As much as I love the sound of my MXP exhaust, I suspect that it is too restrictive and holding up power. Being that I had to modify the exhaust for the BP setup (Basically cut the Y )

02-17-2017, 12:05 PM	#8 (permalink)
ChaseZ A True Z Fanatic Join Date: May 2016 Location: Calgary Posts: 3,799 Drives: 16 370z Rep Power: 94682	Would adding restriction tend to create more backpressure ergo holding higher boost?

03-09-2017, 08:46 PM	#10 (permalink)
GTRphil Base Member Join Date: Nov 2016 Location: Orlando Posts: 6 Drives: Nissan Rep Power: 8	Made 600whp 12psi on TT 370 with stock NISMO cat back exhaust, no problems, but just removed it for a 3"FI and boost went up and had to adjust the tune calibration.