Nissan 370Z Forum  

Trying to understand the cumulative effect of breathing mods

OK, so I understand that with an aftermarket exhaust on the Nismo, you sacrifice some of your low and mid range power for power in the higher rev band. Conversely,

Go Back   Nissan 370Z Forum > Nissan 370Z Tech Area > Engine & Drivetrain > Intake/Exhaust

Like Tree4Likes
  • 1 Post By TeamARK
  • 3 Post By jcosta79

Reply
 
LinkBack Thread Tools Display Modes
Old 01-22-2013, 07:43 PM   #1 (permalink)
Base Member
 
Join Date: Jun 2012
Location: Redmond, WA
Posts: 180
Drives: 2012 Nismo 370Z
Rep Power: 9
KingJoseph is on a distinguished road
Default Trying to understand the cumulative effect of breathing mods

OK, so I understand that with an aftermarket exhaust on the Nismo, you sacrifice some of your low and mid range power for power in the higher rev band. Conversely, with the M370 intake manifold mod from Motordyne, it seems you gain in the low to mid range and lose a little top end.

Something tells me the two mods together don't necessarily offset the losses in a simple arithmetic type of way for an overall gain. Can anybody explain what to expect from the combination of two mods of this type either from a seat of the pants perspective or with dyno charts?

Further, I have high flow cats. At what point does this car have too LITTLE backpressure? If ever?

Thanks in advance.
KingJoseph is offline   Reply With Quote
Old 01-22-2013, 08:20 PM   #2 (permalink)
A True Z Fanatic
 
Megan370z's Avatar
 
Join Date: Oct 2009
Location: Canada
Posts: 1,156
Drives: 370z
Rep Power: 20
Megan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond reputeMegan370z has a reputation beyond repute
Default

Quote:
Originally Posted by KingJoseph View Post
OK, so I understand that with an aftermarket exhaust on the Nismo, you sacrifice some of your low and mid range power for power in the higher rev band. Conversely, with the M370 intake manifold mod from Motordyne, it seems you gain in the low to mid range and lose a little top end.

Something tells me the two mods together don't necessarily offset the losses in a simple arithmetic type of way for an overall gain. Can anybody explain what to expect from the combination of two mods of this type either from a seat of the pants perspective or with dyno charts?

Further, I have high flow cats. At what point does this car have too LITTLE backpressure? If ever?

Thanks in advance.
saying it short and simple.


it all come down to optimizing the airflow capabilities of your mods.

bigger doesnt always mean better ,
doesnt mean its big and it will result in less restriction,

an exemple for this is your exhaust ,,,
too big of an exhaust, your airflow will slow down considerably before it leave the tailpipe. this also create backpressure
which you want to avoid as much as possible if you are staying N/A and want the most power in the higher powerband.

once you have a good flowing exhaust you have to find where is the bottle-neck. which will surely be on your intake side.
__________________
Megan Journal *Click Me* ....................One Man Team Motorsport *Click Me*
Megan370z is offline   Reply With Quote
Old 01-24-2013, 01:00 PM   #3 (permalink)
Track Member
 
Join Date: Jul 2009
Location: CHINO
Posts: 957
Drives: Black 350z/370z
Rep Power: 13
TeamARK is on a distinguished road
Default

Note that you simply cannot put one and one together with mods. It comes down to how compatible each parts are with each other. Sometimes its hard to measure this because of how gases are released. They blow out in pulses not a constant streams of air fuel and gas.

In order to make your mods work at its optimal level, a good tune is necessary.
roy'sz likes this.
TeamARK is offline   Reply With Quote
Old 01-25-2013, 04:31 PM   #4 (permalink)
A True Z Fanatic
 
jcosta79's Avatar
 
Join Date: Jul 2012
Location: N/A
Posts: 1,430
Drives: N/A
Rep Power: 11
jcosta79 is a name known to alljcosta79 is a name known to alljcosta79 is a name known to alljcosta79 is a name known to alljcosta79 is a name known to alljcosta79 is a name known to all
Default

You don't want back pressure. What you want (and what most people mistake back pressure for) is velocity. In broad, general terms, the smaller the piping diameter, the faster the exhaust gasses will flow.

Think of blowing air out of your mouth with your mouth wide open, versus blowing out of a straw. Not much velocity to the air coming out of a wide open mouth, but from the straw it's quite different.

So what happens when you slap on a larger diameter exhaust system is that you lose velocity (and with it, low to mid-range torque) until the engine is moving enough air to properly use the larger diameter piping.

Tuning an exhaust system properly is quite difficult. Just look at how many updates F1 teams make to their exhausts. Bigger is usually NOT better, especially if you are not adding some sort of forced induction.

What you typically want to look for in an aftermarket exhaust is smooth bends and transitions, as well as smooth welds on the inside of the piping. Anything on the inside of the piping that can cause turbulence will hurt performance because air running through a tube travels along the walls, not the "empty space" on the inside.

As a (very) general rule of thumb, smaller diameter piping (and long header primaries) will help improve low to mid range torque, while larger diameter piping (and short header primaries) will help improve top end power. Unless you are drag racing, you want a system that favors low to mid-range torque because that's where you are spending the majority of your time. As much as we would like to think that we are speed demons that drive everywhere at WOT, very little time is actually spent at redline.

Hope that helps somewhat.
DEpointfive0, Hotrodz and Sorrovv like this.
__________________
2012 PW NISMO #0559 - GT Spec Brace Kit - Swift Springs - ARK TP & Invidia CBE K&N Intake - UpRev Tune - 15mm Z1 Spacers & Studs - StopTech Slotted Rotors & SS Lines - ZSpeed CMAK with Stage 2 Clutch and Lightweight Flywheel
jcosta79 is offline   Reply With Quote
Old 01-25-2013, 06:24 PM   #5 (permalink)
Premium Member
 
SS_Firehawk's Avatar
 
Join Date: Oct 2011
Location: Tampa
Posts: 4,102
Drives: 13' Magma Red Nismo
Rep Power: 7058
SS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond repute
Default

Jcosta79 did a great job explaining it. Regarding that M370 intake manifold, the reason why it improves low, mid, and mid high rpm's is because the intake runners are longer, this improves torque. The shorter runners on the stock manifold benefit high in the rpm range. Even at our engines power band, the shorter runners don't have much benefit in high rpm power over the longer intake runners when both are properly tuned. The concept is very similar to headers.
__________________
Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI
New Car: Under Construction

SS_Firehawk is offline   Reply With Quote
Old 01-25-2013, 06:31 PM   #6 (permalink)
Track Member
 
Coon-azz's Avatar
 
Join Date: Mar 2012
Location: Fredericksburg,VA
Posts: 689
Drives: '12 370z Sport DD
Rep Power: 10
Coon-azz will become famous soon enough
Default

Quote:
Originally Posted by jcosta79 View Post
You don't want back pressure. What you want (and what most people mistake back pressure for) is velocity. In broad, general terms, the smaller the piping diameter, the faster the exhaust gasses will flow.

Think of blowing air out of your mouth with your mouth wide open, versus blowing out of a straw. Not much velocity to the air coming out of a wide open mouth, but from the straw it's quite different.

So what happens when you slap on a larger diameter exhaust system is that you lose velocity (and with it, low to mid-range torque) until the engine is moving enough air to properly use the larger diameter piping.

Tuning an exhaust system properly is quite difficult. Just look at how many updates F1 teams make to their exhausts. Bigger is usually NOT better, especially if you are not adding some sort of forced induction.

What you typically want to look for in an aftermarket exhaust is smooth bends and transitions, as well as smooth welds on the inside of the piping. Anything on the inside of the piping that can cause turbulence will hurt performance because air running through a tube travels along the walls, not the "empty space" on the inside.

As a (very) general rule of thumb, smaller diameter piping (and long header primaries) will help improve low to mid range torque, while larger diameter piping (and short header primaries) will help improve top end power. Unless you are drag racing, you want a system that favors low to mid-range torque because that's where you are spending the majority of your time. As much as we would like to think that we are speed demons that drive everywhere at WOT, very little time is actually spent at redline.

Hope that helps somewhat.
I agree here.
__________________
I don't care how slow you want to drive; I encourage it. JUST GET THE HELL OUT OF THE PASSING LANE YOU TUCK FARD!!!
Coon-azz is offline   Reply With Quote
Old 01-27-2013, 01:52 PM   #7 (permalink)
Base Member
 
Join Date: Oct 2012
Location: TX
Posts: 11
Drives: 2012 Golf R
Rep Power: 9
tylerk is on a distinguished road
Default

Quote:
Originally Posted by jcosta79 View Post
You don't want back pressure. What you want (and what most people mistake back pressure for) is velocity. In broad, general terms, the smaller the piping diameter, the faster the exhaust gasses will flow.

Think of blowing air out of your mouth with your mouth wide open, versus blowing out of a straw. Not much velocity to the air coming out of a wide open mouth, but from the straw it's quite different.

So what happens when you slap on a larger diameter exhaust system is that you lose velocity (and with it, low to mid-range torque) until the engine is moving enough air to properly use the larger diameter piping.

Tuning an exhaust system properly is quite difficult. Just look at how many updates F1 teams make to their exhausts. Bigger is usually NOT better, especially if you are not adding some sort of forced induction.

What you typically want to look for in an aftermarket exhaust is smooth bends and transitions, as well as smooth welds on the inside of the piping. Anything on the inside of the piping that can cause turbulence will hurt performance because air running through a tube travels along the walls, not the "empty space" on the inside.

As a (very) general rule of thumb, smaller diameter piping (and long header primaries) will help improve low to mid range torque, while larger diameter piping (and short header primaries) will help improve top end power. Unless you are drag racing, you want a system that favors low to mid-range torque because that's where you are spending the majority of your time. As much as we would like to think that we are speed demons that drive everywhere at WOT, very little time is actually spent at redline.

Hope that helps somewhat.
So are you saying that for a DD, you would recommend keeping the stock exhaust (non-nismo touring sport) as apposed to upgrading to say a Fast Intentions CBE?

I'm not disagreeing with your post, just curious why everyone raves on performance gains from this particular product. Maybe it's the aesthetics that everyone likes with this mod?
tylerk is offline   Reply With Quote
Old 01-27-2013, 02:16 PM   #8 (permalink)
Premium Member
 
SS_Firehawk's Avatar
 
Join Date: Oct 2011
Location: Tampa
Posts: 4,102
Drives: 13' Magma Red Nismo
Rep Power: 7058
SS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond repute
Default

Quote:
Originally Posted by tylerk View Post
So are you saying that for a DD, you would recommend keeping the stock exhaust (non-nismo touring sport) as apposed to upgrading to say a Fast Intentions CBE?

I'm not disagreeing with your post, just curious why everyone raves on performance gains from this particular product. Maybe it's the aesthetics that everyone likes with this mod?
What Jcosta was eluding to was being naturally aspirated, 2.5" is the best size for the car. 3" is best for forced induction applications making 650+ bhp.

Example: Our car's stock exhaust is a coffee straw. 2.5" exhaust is a regular straw, and a 3" exhaust is a water hose. Blow through the coffee straw and sure you get velocity, but there is a lot of back pressure. Blow through the regular straw and we still have very good velocity, but we also have much less back pressure. Blow through a water hose, the size of the hose is so large, there is very little velocity and no back pressure. It's too big to be efficient for the application.
__________________
Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI
New Car: Under Construction

SS_Firehawk is offline   Reply With Quote
Old 01-28-2013, 11:17 AM   #9 (permalink)
A True Z Fanatic
 
jcosta79's Avatar
 
Join Date: Jul 2012
Location: N/A
Posts: 1,430
Drives: N/A
Rep Power: 11
jcosta79 is a name known to alljcosta79 is a name known to alljcosta79 is a name known to alljcosta79 is a name known to alljcosta79 is a name known to alljcosta79 is a name known to all
Default

Quote:
Originally Posted by tylerk View Post
So are you saying that for a DD, you would recommend keeping the stock exhaust (non-nismo touring sport) as apposed to upgrading to say a Fast Intentions CBE?

I'm not disagreeing with your post, just curious why everyone raves on performance gains from this particular product. Maybe it's the aesthetics that everyone likes with this mod?
Quote:
Originally Posted by SS_Firehawk View Post
What Jcosta was eluding to was being naturally aspirated, 2.5" is the best size for the car. 3" is best for forced induction applications making 650+ bhp.

Example: Our car's stock exhaust is a coffee straw. 2.5" exhaust is a regular straw, and a 3" exhaust is a water hose. Blow through the coffee straw and sure you get velocity, but there is a lot of back pressure. Blow through the regular straw and we still have very good velocity, but we also have much less back pressure. Blow through a water hose, the size of the hose is so large, there is very little velocity and no back pressure. It's too big to be efficient for the application.
I'm not sure what diameter piping FI uses for their CBE, but if it's 3" it's likely too large for N/A applications. I had 3" exhaust piping on my 517 RWHP Corvette, so it's a good bet that on a 370Z it's way overkill.

The power gain you are going to get by replacing the stock exhaust is in the muffler section. OE mufflers tend to be very restrictive because they have multiple baffles inside slowing down and quieting the exhaust. Aftermarket mufflers are typically less restrictive and offer a more "straight through" exhaust flow.

Hope that helps.
__________________
2012 PW NISMO #0559 - GT Spec Brace Kit - Swift Springs - ARK TP & Invidia CBE K&N Intake - UpRev Tune - 15mm Z1 Spacers & Studs - StopTech Slotted Rotors & SS Lines - ZSpeed CMAK with Stage 2 Clutch and Lightweight Flywheel
jcosta79 is offline   Reply With Quote
Old 01-28-2013, 02:49 PM   #10 (permalink)
Premium Member
 
SS_Firehawk's Avatar
 
Join Date: Oct 2011
Location: Tampa
Posts: 4,102
Drives: 13' Magma Red Nismo
Rep Power: 7058
SS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond reputeSS_Firehawk has a reputation beyond repute
Default

F.I. makes 2.5" standard and 3" nonresonated turbo exhaust.
__________________
Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI
New Car: Under Construction

SS_Firehawk is offline   Reply With Quote
Old 01-28-2013, 03:47 PM   #11 (permalink)
Track Member
 
Join Date: Jul 2009
Location: CHINO
Posts: 957
Drives: Black 350z/370z
Rep Power: 13
TeamARK is on a distinguished road
Default

Unless your going FI, 3" exhaust system is not unnecessary. I know that there are 2.75" in the market but thats pushing it. Bigger is not always better.
TeamARK is offline   Reply With Quote
Old 01-31-2013, 12:42 PM   #12 (permalink)
Track Member
 
chknhawk's Avatar
 
Join Date: May 2012
Location: Kentucky
Posts: 541
Drives: Like a batouttahell!
Rep Power: 10
chknhawk will become famous soon enough
Send a message via Skype™ to chknhawk
Default

The Greddy application (TI-C) is 2.75. That coupled with a test pipe or HFC should be ok for NA I think... Based on everything said here so far. I feel like I get a little more power to the wheels through the power band and not just high end. That is just seat of the pants and not so much tune/dyno. I do howerver know this. Once my Z realized that I was not taking the aftermarket bolt ons off it is over correcting the A/F mix and now the car idles at 1000 rather than the 6or700 it was at without the CEL. (Also CAI on the intake side for a little less congested airflow).

I like my setup and I think it works pretty good for this little car. Without spending 8000 - 10000 on a FI kit I have a little bit more HP and I can at least keep up with the NISMOs out there>

__________________
| AEM | INVIDIA | GREDDY | STANCE | NISMO | SETRAB | STOPTECH | HAWK | TOYO | HANKOOK | BRIDE (wishlist) |
chknhawk is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
I need help to understand this!!! Ricardo2.0 Exterior & Interior 13 09-28-2011 01:21 PM
Trying to understand zfromfl Wheels & Tires 3 10-21-2010 12:50 PM
K&N Press Release Infiniti G37 & Nissan 370Z Gets More Breathing Room! DriveLineEric DriveLine Motoring 0 05-20-2010 05:20 PM
Need an answer that I can understand. LONDON2012 Wheels & Tires 2 04-02-2010 05:29 PM
I just dont understand this one bit! SophiaZ Nissan 370Z General Discussions 18 01-07-2010 08:25 PM


All times are GMT -5. The time now is 09:25 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0 PL2