AlfonsoTan

Hey all,

I'm a new guy on the forum (first post!). I'm not sure if I'll be a regular since I'm still shopping around for a car, but I was hoping I could get some information out of you guys.

I've been trying to research the stock G37 exhaust and not getting very far. Someone told me that the exhaust manifold length to the Y-Pipe is used to create a scavenging effect by bouncing exhaust pulses back and forth under certain conditions. Does anyone have any more information on this? I'm trying to figure out Nissan's design theory behind this. Does anyone have any drawings / pictures, detailed technical information, dimensions, and dyno plots vs. the OEM G35 exhaust? Any information is helpful. Thanks!

DiamondGCoupe

iTrader: (4)

Can't help you on the exhaust but welcome to the forums, congrats for posting in the right place!

G-WIZ KID

Sorry if I ask, but where ru trying to go with this?

AlfonsoTan

I just want to see how it works, wondering if the design is something that can be used on other cars. I'm coming from the Honda world, and also a former Formula SAE guy, and haven't heard of this before, but think it'd be sweet to see it implemented elsewhere.

solopresident

use the search function on the forums.

AlfonsoTan

First thing I tried sir. Got any information?

wheelsun

iTrader: (1)

i hope no one ever figures this out. because i am selfish and greedy.

oh. that and hearing eclipses and civics with my exhaust tone

Sirhc7897

I know in the 2 stroke world they do just what you have described....Expansion chambers are acoustically designed to generate a scavenging affect and effictively pull exhaust gas out of the combustion chamber...Minor changes to exhaust temp (through water injection into the pipes...more water simulates a longer pipe which builds power up top whereas less water simulates a shorter pipe improving bottom end hit) makes for substantial differences (more bottom end vs more top end)...

Now in the 4 stroke world I'm not sure how this applies...I know up to a certain point changing your exhaust runners (and other factors like timing retard/advance on the combustion and intake side) affects where the flame kernel is...This would be part of the reason equal length primaries into the collector on a exhaust system are usually a good first mod (ie going to longtubes headers over the log header found on most autos for cost reasons)...The same thing doesn't really apply in the forced induction world because there it's all about just getting the exhaust moved through since you're force-feeding the combustion chamber...It can help but usually doesn't happen until you start talking significant power levels...

Don't see why it wouldn't be possible though...Although IMO it would seem something of overkill (if even beneficial) considering the variable valves should be performing somewhat the same optimization of combustion and scavenging through valve opening modulation?

I could be in left field though...In the end it's really all about moving air...especially in a N/A vehicle...Anything you can do to flow more air is usually a good thing as long as you can keep the intake velocities up and the fuel poured to it to combust...More air is more power (hence why Nitrous and forced induction are such great power adders)...

AlfonsoTan

NOTHING to do with exhaust tone at all. I'm just interested in dimensions and the like.

...Did I really come to the right place? Or is every response I get going to be like this? EDIT - it looks like someone knowledgeable posted right above me, I'll read when I get home from work & school. Keep the helpful posts coming... thank you.

wheelsun

iTrader: (1)

oh i apologize for misunderstanding then and i have no clue about the exhausts myself, hopefully someone can help you out!

UNV-IT46

iTrader: (3)

The bouncing term is a little incorrect. Normal exhaust systems dont really bounce the sound. They absorb a lot of the sound into the metal. Now Full Titanium exhaust's dont absorb the sound. Ti doesn's absorb sound vibrations. It just bounces the sounds down the whole length of the exhaust which is why Ti exhaust are always louder. If you have two exhaust of the exact same design one Ti the Ti will be a good amount louder because of the bouncing effect

AlfonsoTan

I don't care about the sound AT ALL. I want to know what performance gains are to be had by doing what the G37 exhaust does over the G35 one. Apparently there was a lot of torque picked up low-end by making some changes to the system... this is why dyno's would be helpful.

UNV-IT46

iTrader: (3)

the fact that they went from a 3.5 to a 3.7 is the main reason for more tq....

AlfonsoTan

Right... that's why I'm having trouble separating the variables here. It couldn't have all be attributed to the bump in displacement, right? In the same article that pops up way to much on google searches, it says that there's an equal-length manifold involved, but I'm hoping to find more to the story.

mal_TX

In their marketing, Infiniti claims it was VVEL that delivered the increased torque.