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Thread: Exhaust system....I need your ideas?

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Posts: 41-50 of 61
2010-08-06 14:23:45
Eh guess I didn't give it enough thought. Needless to say turbos do operate on both principles. But I still think my conclusion is still correct.
2010-08-06 14:24:51
Originally Posted by Viprdude
RedDragun, how long did you have the system on your car? And was it stainless steel or aluminum?

It's been on there for a couple of years now, maybe a little less. It's whatever material a Chevy 2500HD Duramax truck uses =P. I think they use stainless.
2010-08-07 03:51:20
Excellent Ben, thank you!
2010-08-10 14:38:45
Originally Posted by Bull
OK, after travelling up to Crail Raceway on Sunday (a round trip of 150 miles), the one thing that bugged the s**t out of me was the drone from the exhaust.

Having the side exit exhaust as pictured below, is excellent for producing maximum power, but the noise on long distance driving is just too much. It also attracts the attention of the Police, and I just don't need the hassle to be honest.

My neighbours also don't think much of the noise, so I need something new and improved.

What I am thinking of doing before I make the long trip down to Shakesphere County Raceway (5 hours drive away) is going with the biggest possible downpipe (probably an initial bend of 3.5" like I had on the Micra before the crash, as the alternator is very close) then going up to a 4" system, or going with a dual 3" system.

I would be using multiple silencers as I do not want the noise anymore, but still want to retain the power. I recon with 4" piping or twin 3" systems that the back pressure will still be kept to a minimum and the power will not suffer.

But will it fit under the car and over the rear axle...that is the question!

My car (the N15) uses virtually the same chassis and floorplan layout as the B14 SE-R.

Please give me your opinions.



In my testings I have found that a well done 3 turbo back is more than ok for over 600whp I have put 3,5 and 4 Dp vs 3 dP and I have found just a cuple of hp 3-5 and just a little better spool up 50 rpm??
Do a good 3 turbo back and the race pipe just for the track.
2010-08-10 14:55:39
I think everyone is missing the picture here.

Everyone is debating flow, yet they all seem to be missing the very first point:
Originally Posted by Bull

...the one thing that bugged the s**t out of me was the drone from the exhaust.

There's no way in hell you're going to get a 4" exhaust to be super quiet compared to a side dump exhaust, unless you resonate the hell out of it, and use at least a twin loop muffler.

My suggestion (and also the cheapest IMO), is to run a close to stock exhaust, with an actuated cut-out to divert the flow to the side exit when needed.

Do you use the power under the hood every minute of your day? If you say no, then why run a supersized exhaust that's still going to be loud as all hell, when you don't really need it!?!
2010-08-10 21:14:58
Sorry for missing the point on this and going off topic also

. I have to make note that the flow calculator won't work with car exhausts. I asked the creator of the calculator if the calc could take in all the variables of everything going on in the turbo cars exhaust and here was some of his reply. I wish it was that simple, I really want to find out the right person to ask and what really is best now.

"Flow through car exhaust is by no means stationary - it is oscillating with time very much so that flow calculator can not be used with high accuracy. How this oscillation is effected with pipe diameter and how to achieve resonance between flow and pressure oscillation with pipe diameter is question for somebody else."

He also said "My opinion is the best solution is to have no car exhaust pipe at all if you want highest power" That is something we can all agree on that is right.

Bull GTi I think you should use the front fender side exhaust with a cut out and a rear exit exhaust at the same time. I was planning on doing just that myself until recently ( found out a rule book won't allow for it )

My cut out plan was to make a custom divorced downpipe and have the cut out right around where your side exit is. With a "Y" pipe before forwards of the oil pan just under the turbo.
The rear exit exhaust after the downpipe would just be the stock or the equivalent. "I can take some pics of basically what the pipe would look like if you are interested.)
2010-08-10 21:35:11
For clarity I only use that calculator example to show that cooler fluids flow more volume and mass through a pipe than hotter fluids. It opened my eyes when I went searching for "the truth" months ago. I previously believed that hotter (more energized) fluid would flow no better and no worse than colder fluid through a pipe. And people shouldn't take it at face value that hotter fluids flow more (colder, denser fluids being a "stall" in the system) for whatever reason people seem to latch onto that idea.
2010-08-15 21:09:28
Well today was the day that I started with my new 4" exhaust build, so I'll run you guys through what I have achieved so far.

Here's what we had before with the 3" side exit setup...

The first problem, as I found, was clearing the alternator.

After taking a number of measuremennts, I figured the only way to clear the alternator was to go with a tight, yet high flowing 4" bend and then to blend the v-band flange to the piping.

It ended up looking something like this...

Please ignore the welding, as this was only the first stage, before blending the weld to the piping and polishing it.

So with the intial elbow done, I had to remove the exhaust, which was simple enough and here's what it looked like for those interested...

Once that was done, I had to convert the original GT 4 bolt to 3" V-band adapter, to accept the flange for a 4" V-band setup. This is where things turned nasty as there is just no access and exhaust nuts are a fudge packing nightmare. Anyways after about an hour swearing and many a scraped knuckle, I managed to remove the flange.

Here you can see how awkward access was, especially for the one nearest the radiator...

So after removing the adapter, I proceeded to weld the 4" V-band flange to the original adapter...

After refitting the newly made flange, I attached the elbow and luckily it cleared the alternator...

I will continue the build next weekend.


2010-08-15 22:05:06
LOL you are crazy take your radiator out so you can reach that stuff
2010-08-16 19:07:24
^ Yeah, I would have pulled that radiator out. I absolutely hate working in tight spaces.

Looks cool though. I'm interested to see the final product. And hear it.
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