3" Dual exhaust system UPDATE Dyno Graph, Group Buy link inside...

http://www.s2ki.com/forums/index.php?showtopic=556974

I'm sure the sound clips will be available shortly.

Great news. Streetable high flow exhaust .

never did get clarification on this.


My guess is that it is a 3"OD before and after the split with a reducing piece from 3" to 2.5" to feed each of the mufflers with the mufflers having a 2.5" perforated straight through core.


Asura not to suggest you try or change your design at this point (looks like you have a good system) however did you try a Magnaflow Muffler that is a 3" core.

http://www.magnaflow.com/02product/shopexd...one=main&id=791

It has a similar volume and should have similar sound dissipation properties assuming the packing materials are the same.

Using the Magnaflow mufflers would make this a true dual all the way out to the tips.

Depending on how it sounds and your clarification on the 2.5 or 3" mufflers is it possible to get the exhaust with out the mufflers attached so I can supply my own mufflers?

I had the privilege to ride in this car and I have to say...the exhaust barely droned. it had more of a crisp sound than any other duals out there.

good stuff asura and thanks for the ride!

Anytime Tommy

Just to let you know, the day I saw you the belt was loose and the car wasn't holding boost past 7500 RPM.
It's significantly faster after I tuned it yesterday. I can't stop driving it

Probably my favorite S2000 SCed Street Car that I have driven.

^ this sounds good, i'm hoping a gb would be in the works asura?? Any information on your single FI exhaust? Would it perform better than a dual?

Curious as to how N/A Applications could benefit from the exhaust as well

sound clips yet?

I have them but no time to work with them until tomorrow afternoon.

bump for sound clip wasssssup ASura

I doubt a 3" would be beneficial to an N/A S2000 as i was udner the impression that the 2.75 exhaust like J's are the best size for an N/A application.

can't wait to hear the clips

It made power, if someone in SoCal wants to dyno on their NA car (2004-2005 AP2 with F22C preferred) vs a stock exhaust and has an EMS on the car already, I would be willing to have this independently verified.

We did a few low speed idle cruises followed by a flyby on PCH

Be patient, Sideways got it on camera, I swear I had nothing to do it

Our proprietary mufflers are quieter than 3" Magnaflow. Magnaflow makes nice mufflers, it was just not the exhaust note we were looking for on this system.

We do incorporate a 3" from the mid-pipe that is split after the center resonator into two mandrel bent 2.5"

You can see it here somewhat.

Any benefit from going to a 2.5" split rather then staying 3" all the way?

Maybe because it makes the car A LOT more streetable by keeping the db levels low.

there is more to it then just sound

Maximize exhaust velocity (constant speed) down the entire length from start to finish while mimizing back pressure.

However there is a inversely proportional relationship between induced backpressure due to pipe diameters and exhaust velocity.


Exhaust velocity is what you are looking for when trying to maximize exhaust gas scavenging.
However to get an increase in exhaust velocity (with a fixed amount of mass flow) one must decrease the pipe diameter to get more speed (ignoring the effects of increases mass due to gas cooling as it travels down the pipe) mass flow in must = mass flow out…

So with fixed mass flow
Smaller pipe faster velocity but greater back pressure
Big pipe slower velocity but less back pressure.


So there is a dual relationship that fights each other in the quest for more power out of a NA/ supercharged engine.

Exhaust velocity is good because it creates a bit of negative pressure at the exhaust valve when the piston is at TCD and the cams are in a position of overlap.

This negative pressure helps pull in a bit more Air/Fuel into the cylinder before the piston starts on its downward motion.

And as everybody knows more air +more fuel = more power.


For Turbo application the theory is a bit different.
Post turbo exhaust velocity is not even looked at; you want the minimal amount of backpressure to get the turbo to spool quickly.

another way to say what I just said


The ideal goal of an exhaust system is have a high delta pressure and induce exhaust scavenging. When a cylinder fires it sends a pulse of exhaust gas down the piping that has a high pressure and directly following it is a low pressure which then helps to pull the next pressure wave behind it thus the exhaust diameter is picked so it has the greatest delta pressure where you want the most power. If the pipe is too small you will have too much backpressure and lose power and if the pipe is too large you will have low delta pressure and lose power.


spliting to a 2.5" instead of a 3" is one way to maximize this effect.

Can this be built with the stock 04+ tips on the back? I'm considering something a bit more stealthy than what I have now. Thanks.

Tim

+1 for
seeing if the 04 tip will go on with out effecting the power gain.

http://videos.streetfire.net/video/bf9f5e6...a2a0105b9bd.htm

http://videos.streetfire.net/video/e5a6850...a2a010a8faa.htm

Don't get car sick watching it. I was holding the camera and my hat flew off.

^ i love the sound

if we get my car straight with the issues I have been having i'll definately pick up this exhaust.

Asura FTW

That is very quiet, almost too quiet.
Is the video accurate? Or is there more sound volume that the camera didn’t catch?

The camera does have an automatic sound reduction feature. It is fairly close to reality in the clips. Notice how loud the supercharger is in the first clip until he goes by.