I've done a good amount of research, and now I am at the point where I'm trying to understand what exhausts are the best choice for a TT setup.

I know that AAM has a 3.0" exhaust which is perfect for what I am looking to do, but I believe that is only a catback.

What downpipe would be neccessary with the Greddy kit? Do they utilitze stock pipes or do they supply thier own downpipe?

How about the TN?

 

AAM now is making a 3" downpipe/test pipe

 

The GReddy Twin Turbo kit attaches to the factory cats.

With the GReddy Kit we have our 3" MaxFlow True Dual Exhaust & MaxFlow 3" Dual Downpipes that work very well. Here is a link for pics:

Exhaust: http://www.alteredatmosphere.com/mm5..._Code=350Z_EXH

We make a special version of the AAM 3" MaxFlow Exhaust that fits the Turbonetics Single Turbo kit for our Turbonetics customers.

Downpipes/Factory Cat Pipe Replacement: http://www.alteredatmosphere.com/mm5..._Code=350Z_EXH

The AAM MaxFlow Downpipes actually replace the housing GReddy supplies that goes between the turbocharger and factory cats. The MaxFlow Downpipes bolt directy to the back of the turbochargers for maximum flow.

Hope this helps,

 

I know that AAM has a 3.0" exhaust which is perfect for what I am looking to do, but I believe that is only a catback.

Our AAM-Max flow exhaust is a true, mandrel bent 3" exhaust. Our exhaust is in fact a cat-back exhaust with noticable gains and sound to match.

Quite a few pictures and details about the exhaust can be found here: http://www.alteredatmosphere.com/mm5..._Code=STRFRONT

What downpipe would be neccessary with the Greddy kit? Do they utilitze stock pipes or do they supply thier own downpipe?

The GReddy kit can be used in conjuction with a wide-array of pipes available today. For example we installed the following with GReddy twin turbo kits: AAM-2.5" Test-pipes, AAM-Hi-FLow metallic cats, the stock cats and most common our dual AAM-Max Flow 3" downpipes with open dumps. These allow a full 3" exhaust from the turbos back (there is approx. 1-3" of 2.5" piping used as step-up piping)
These can be seen here: http://www.alteredatmosphere.com/mm5..._Code=350Z_EXH

How about the TN?

We have had tremendous sucess with mating the supplied 3" pipe from the exhaust housing back(included with the t-netics kit) with our 3" AAM max flow single exhaust

 

Sounds good, still a little complicated. I guess when I order something I'll just tell you guys that i'm looking for a 3" turbo back for either a greddy or TN kit.

Thanks for the help!

 

check out the SVRTechnologies 3inch Exhaust. Comes with the downpipes already built into the exhaust, an X pipe, extra O2 bungs welded in for your Wide Band and exits straight out the back not at that angle. He also has wastegate relocators for the Greddy TT Kit. Excellent quality and one of the best out there as far as the 3inch goes.

You can PM the owner his name on the forums is overZealous1. He is a Forum Sponsor as well.


John

 

What would be the benefit of the X pipe opposed to individual piping?

 

the X-pipe helps even and flatten out torque and hp curves, and helps scavenging. the firing order of the VQ35 makes the X pipe extremely effiecient and work better than on a V-8 where the technology was originally derived. we saw a big difference in flattening the hp and torque curves on 350ZNV's car on the dyno. this doesn't reduce the peaks, but raises the areas around it to make the motor pull through a broader range.
the X pipe also helps aid in sound cancelation. the large dual 3" systems suffer from being loud due to the large piping. i have sat next to an aps dual 3" car and the SVRTech was quiter. i feel this is one of the quitest 3" duals available.
a sound clip is available on my site under the exhaust section. if the exhaust is going on a greddy tt car, we sell the exhaust and our w/g dumps as a kit. thanks

scott

 

From the basic fundamentals of turbocharged cars, wouldn't an x-pipe increase back pressure? I'm not doubting the potential, but I just don't understand how going from a 2-1-2 exhaust would be beneficial, it seems like it's just creating more back pressure.

On a NA applicaiton it'd be a wonderful idea, it just doesn't make sense to me in a FI application, but I'm sure there are a few things I'm overlooking. Could you please elaborate?

 

There are several choices, but it all comes down to personal preference.

 

Here at AAM our research and development on our in-house dyno reveled that a straight through design creates the least backpressure - just as APS most likely found with their designs. X-pipe designs DO function very well in a NA application but there is no such thing as scavenging in a turbo charged vehicle. There is a significant amount of backpressure prior to the turbo. Post turbo the only requirement of the exhaust is to evacuate the gases as quickly as possible. The super hot expanding gases must exit the small nozzle area of the turbo so that the additional gases trapped in the manifold can be utilized. Since the production of exhaust gases is exponential with increases in boost this evacuation is extremely important. Also, boost control is relative to the pressure differential between exhaust manifold pressure and exhaust backpressure.

The X-pipe or H-pipe design is likely to create more backpressure and turbulence because of the volume of exhaust gas that is being generated. As the two paths of exhaust intersect they are forced to mingle together. The X also creates a larger area of volume where the gas expands and slows down...then the X forces it to recompress. The net loss in velocity is high. In turn this lowers the HP potential and causes spool to occur later.

Firing order is disregarded in the case of a turbo charged vehicles becasue the turbo itself casues all the pulses to co-mingle. Even with an equal length turbo manifold this principal still applies.

 

the exhaust pulses do not mingle, if they did you would not hear individual cylinders firing and the car would have a constant tone rather than being able to hear the cylinders fire.
even with backpressure in the manifold, the piston forcing the spent gases is creating the pressure. point being, equal pressure in=equal pressure out. meaning that is the reason you still hear nearly the same exhaust note as you would from an n/a car, minus the sound of the turbos spooling. with the VQ35 firing opposite banks constantly, you are never forcing 2 pulses at the same time regardless of manifold backpressures.
i heard someone say they tried it on a high hp supra with no results. an inline motor would not react the same unless a very extravagant header was made to take advantage of the firing order hence the reason no results.
i completely understand what you are saying, and yes i'm sure the turbos have an effect, but not enough to cancel out the benefits created.
this is a fairily new concept in the import world. but as shown on mikes car, he still gained 35rwhp at only 14psi from his other dual, and torque only dropped a small amount with a very noticeable flattening of the torque and hp curves, only one way to explain it really.
now the X pipe is not supposed to give the car rocket like super powers, but just a small gain. even 5-10rwhp is worth the price. let alone the ability to help quite the system, for that reason alone it is worth having it in the system!

 

i would actually like to have someone prove me wrong on a dyno with the X pipe. i could knock a bunch of money of the price of the exhaust and get them out alot quicker, hahhaha. they are truely a pain to make.

 

Scott I say you make a exhaust without a X pipe and one with. Im all for the X pipe but some just dont get it yet and for those you should offer another choice. I know the X pipe is a pain to make anyway so knock off 100.00 off your system without a X pipe. AAM is going trip a bit cause your exhaust is the same price as theirs and offers much more, Built in 3in test pipes and extra bungs welded in.

 

I mean Scott is a great guy he's very knowledgable and has already helped me out a couple times, and the products he offers look to be excellent quality, but I just don't understand how that x pipe would be a better solution on a turbocharged vehicle. Maybe if we had side by side dyno comparisons it'd be easier to actually determine the difference.

 

lol, didn't know i made it so apparent where is was heading with that .

 

thanks. pm sent.

 

Although the principal is correct the actual application should be considered completely. All current turbo kits use log (unequal length) manifolds except for possibly the SFR/SSR kits. Equal length is the key to the concept of scavenging as was mentioned with the example of the Supra and an extreme manifold design. For scavenging to occur there is a need to precisely time the exhaust pulses to occur one right after the other. This is why equal length manifolds are heralded as the absolute best design in NA and Turbo applications. X designs depend on velocity to function, the turbo has stolen all that velocity to generate additional air flow, hence the idea of "free power". In regards to turbulence, why have open dumps and not recirculate it? The idea of noise control came up in the discussion, open dumps are extremely loud.

The AAM Spec design incorporates dual straight through Ultra Quiet in-line mufflers and Dual Straight through Mufflers that provide more then enough noise suppression. We use our exhaust on NA applications (with pending turbo upgrades) all the time with no complaint. Normally we get the comment "Wow this sounds really good! Very distinct!”

16 Gauge (some of the thickest in the industry) and 304 Stainless materials are something that we demand for our customers. Thinner gauges and lower quality steel are less expensive, but we feel that our customers deserve the best.

 

i understand completely what you are saying. yes, properly designed headers need to be equal length to gain their scavenging effects into the collector or merges that can be placed before the collector. that is based on a time and volume function to work the best. so primarily timing of the pulses and which pulses are merged determines the effectiveness. this is why i feel the X pipe is perfect for the Z. firing order of 1-2-3-4-5-6 makes it so the pulse is coming from one side to the other, constantly and at all rpm's. distance from the turbo's is near perfect before the X pipe, and true it will merge the exhaust gases together in the manifold before the X pipe, but for the input pulse, it does not matter which piston is firing, it just needs to be the back and forth pulse for the X pipe to gain it's strengths. now lets say that when pressure builds before the turbo, the force from the piston pushing out the spent fuel, will out put an equal force past the turbo. hence, you are still seeing a pulse and not just a constant airflow.
our X pipe is roughly 3.5"+ through the center of it, which is still hardly a restriction, but only one solid pulse at a time can possibly run through it. right after that, the exhaust has 2 paths now to choose, doubling the size of the exhaust and also the efficientcy of the mufflers and resonators. ok, actual tests have effientcy go up roughly 75% and not a full 100%, but you see what i am getting at.
now, exhausts are actually kind of stupid, they can't really think for themselves. they have no idea if they are flowing behind a turbo or n/a or a supercharger. so with the same pulse output being sent through the exhaust system, the theory behind the X pipe would be the same for n/a or f/i.
for guys that think they do not work for high hp. do a search for nascar, the most competitve auto sport ever, and look at the exhaust systems. i know that is n/a, but they have to yank every single last hp they can with all the restrictions.
i feel the X pipe to be a very good addition, and we have already seen it flatten the curves on a tt car. the flat curves make this a better street car, which is how 95% of the cars here are driven. after 14 psi, we watched the torque jump from 600, to 690 with only 2 more psi!! that starts to show that the X pipe is getting very effiecient in that flow area. this was on jim wolfs dyno with jim wolf running it. from what i hear he was very skeptical at first also. i also heard he was very impressed with the numbers the exhaust actually put out, and the curves.
don't get me wrong, i know you guys have a nice system also. just want to explain what i feel to be of realistic value to the 3" turbo market.