N1 exhaust vs. custom 240 muffler

[240Stilo]

I was messing around with some numbers and found that i can come up with good performance with a stock looking exhaust for my future turbo. To be exact, my custom exhaust would be everything before and after the muffler. I know by now you're saying "what a dumy....there's nothing after the muffler" well I'm refering to the tips. I was measuring the chrome tips on the muffler to see the area it could give me for exhaust flow if i welded it to the muffler after cutting holes to match. Each of the stock tips are at least 64mm from my not too accurate measurement. The N1 has a 90mm tip. After using the "area of a circle equation" i found that the stock chrome tips (without the middle pipe) would give me 71 cubic mm more area for flow. Now the only thing that I wonder if i should go with 3 inch piping from muffler to downpipe or use 3.75 and follow in the footsteps of the N1 which is already a good exhaust. My aim is for less noise so I'm leaning more towards 3 inches.

All this of course is assuming that the stock muffler is just an empty can that doesn't cause too much turbulence for the exhaust gases.

[andrave]

you know, the stock muffler is, well.. a muffler.
and the n1 is around 3 inches. The GT is the one that is closer to 3.75.
Anyway you will have hard time finding a shop to do anything but crush bent.
If you buy the 3" mandrel bends they can probably weld up a mandrel bent one.
I'd say 3" is plenty adequate for nearly any street car.
I don't know what you mean about the stock muffler...

[240Stilo]

Well for my 95 it's the big can at the end of the exhaust. I'm not sure if they're different from the previous years. And it's not for "any street car," it's for a turbo 240.

[andrave]

sorry, I thought it was for a street car.
If you are racing I'd just turn a pipe out right after the downpipe.
Really no point in having in go clear to the back of the car unless your sanctioning body requires it.
What kind of racing are you doing? drag? auto cross?
Then again, I just read in your original post that you want less noise, I'd say a 3" exhaust is still going to be loud as hell.
what is the DB limit at the track?

[andrave]

oh yeah, one more thing, you know the diameter of the tip has absolutely nothing to do with the performance of the exhaust or the muffler, right?

[240Stilo]

Really, so if i had an exhaust that consisted of 3.75 piping from the downpipe to a 2 inch can it wouldn't hinder the performance?

[Roly]

Or just do what I'm considering.... When you go turbo, use an electronic cut-out on the downpipe. Basically, when you're running on the street, it goes through the stock exhaust, and it's a quiet sleeper. When you go on the track or for a race, switch open the cut-out and it's a straight 3" dump off the downpipe.

[240Stilo]

Now that sounds cool. How exactly are you doing this?

[andrave]

lots of companies sell kits, or you could theoretically make your own from a y pipe with a flange welded on the end, and a block off plate to fit the flange.
for the above post, I just meant that you were comparing tip diameters, saying "this one offers this much surface area" well my exhaust has like a 4 or 5" tip but the exhaust itself is only 2.5 inch, and most aftermarket exhausts are similar.

[240Stilo]

Well if i'm understanding you, you're trying to say that although the tip is 4 or 5 inches wide the piping behind it is still 2.5. I'm just trying to think of a way to have a good exhaust for a turbo setup without having after market (shiny) exhaust tips. That's why I just thought of custom 3 inch piping and making bigger holes for it to flow better through the muffler.

Edit: I'm liking the switch exhaust idea more now. Good job Roly. (too bad there's no more thumbsup smiley)