B6 Exhaust Piping?

[drddan]

I am swapping to a B6, and I was wondering about exhaust tube diameter.
I need new exhaust/muffler anyway, so my question is:

What is a good size diameter tube to use with a N/A SOHC B6?

The stock Festiva size is awfully small. :p

[Bert]

First clue I got about exhaust performance was when exhaust manifold downpipes for manual transmissions were discontinued and all you could get was the one for autos. And the auto versions were way bigger diameter so that business was an instant no-brainer.

Find out what diameter pipe the OEM auto B6s were using and then go from there. You don't want this thing too wide open and you'll want to try to adapt readily available pipes, cat and mufflers that are in keeping with space that's available under the car.

[Movin]

at least get aluminized steel, in bigger diameters like 1 7/8 or even 2" you
can get heavier gauges that will last longer.

[drddan]

Find out what diameter pipe the OEM auto B6s were using and then go from there. You don't want this thing too wide open and you'll want to try to adapt readily available pipes, cat and mufflers that are in keeping with space that's available under the car.

Good thinking!

at least get aluminized steel, in bigger diameters like 1 7/8 or even 2" you
can get heavier gauges that will last longer.

I had 1 7/8 in mind.

Where do I find 1 7/8 pipe bent for a Festy without paying out the nose?

Stock Festiva is like 1 3/8 or 1 1/2 or something.

I was also thinking of a straight thru NON-catalytic converter. :p

http://www.siliconeintakes.com/index...967672a0e9ba66

[Safety Guy]

I've gone 2" piping and all diameters of cat and muffler on my three cars: two B6s and one B3. Works okay, but obviously I can't provide any numbers or even a pants-seat comparison.

I think 1 and 7/8 would be fine.

Karl

[Bert]

You're going to want to learn to weld or befriend someone that does. Often there are pipe and muffler product catalogues that have details and measurements from which you can determine (adapt) your needs. Custom shops will make up pipes for you but they'd appreciate being supplied with the downpipe (or header), cat and muffler you plan on using. In Ontario it is illegal to circumvent (ie use a 'delete' pipe) the cat, and a muffler shop can be fined and lose it's license to operate for doing so.
Now what you do in your own backyard is a little more difficult for government to control, but if passing emissions standards is something you'd better hang on to one.

[Festy46]

I used 2" O.D. for all my 1.6 and 1.8 engines. I would get a straight piece of 2" pipe and a steel brake line that was as long as my pipe. I would then hold the brake line up to the edge of the exhaust manifold and bend it to make a template to the correct angle for the exhaust pipe. Then take the bent brake line and your straight pipe to an exhaust shop or garage that has a pipe bending machine and have them bend your pipe to match the angle(s) of your brake line. I use a 3/8 piece of plate for the exhaust flange and make the pipe going from the bottom of the car to the exhaust manifold a little long so I can cut it to the perfect length to go through the 3/8" plate and just have enough clearance under the bottom of the engine. I used a good quality 2" metal cutting hole saw with plenty of oil and a drill press to cut the hole in the 3/8" plate and an exhaust gasket for a template for the mounting holes.

[Movin]

Make sure you tell the exhaust shop this is for your new cornfinder machine..maybe
they will bend your pipe and swedge the ends. More likely you will need to buy
the cheap HF hydraulic pipe bender and the cheap pipe expanders and do your own.
You will need a pipe cutter and a good vice too.

[drddan]

:p

Well...I think I know a little muffler shop... (heh heh) .... just down the street

No emissions here 1995 and later

[BigElCat]

Here's my 2" cat back no muffler. It's not ideal, but it's working.

I'd recommend 1.75" SS304 all the way back to the stock muffler position, then hang a cheap 2.5" core stock oval muffler. The smaller diameter primary will keep the exhaust velocity and torque up...in theory. Smaller diameter can use larger radius bends with out crimping the tube, a larger radius small diameter will out flow a big diameter, tight radius as well.

[BigElCat]

The 2.5" stock oval will serve as a expansion chamber for performance, and keep it quiet with a rumble...as much as a 4 banger will rumble.

The system would bolt together using 2 bolt flanges where ever necessary to get it to fit under the car.

I can burn 10g SS two bolt flanges for the primary pipe at a nominal cost (i'll pm you). You'd have to come up with some thin brass or copper gaskets. At the muffler, you'd have a 2 bolt flange the same size as the one on the primary pipe except with a hole large enough to weld over the muffler inlet.

[BigElCat]

The sections would be removeable for maintenance work without running it up on a lift.

Here's what my 2" pipe from the cat back, no muffler sounds like.

http://youtu.be/QK03LP5OXY8

[Bert]

I guess the appeal of 'sticking it to the man' is universal no matter how benign the 'powers that be'.
But 2 inch pipes might get ya more air than the motor can handle if this is supposed to be a daily-driver.

Way back (mid 70s) I put a Chevy truck muffler and pipes on a sprint-modified Mini Cooper S and never regretted it. Never lost a race but that car never liked to sit still, or idle. But then the cam and other goodies in it likely never noticed the big pipes either. A few other idiots at the time stuffed steel wool in the tailpipes which would catch fire and make them look 'hot'. Didn't make them go any faster but did impress the ladies.

[BigElCat]

I guess the appeal of 'sticking it to the man' is universal no matter how benign the 'powers that be'.

I agree 2" all the way is too much.

I'm not suggesting we lose the cat in order to defy the EPA. We lose the cat because we eliminate one potential problem. We lose the cat to save weight and gain room under the car...to gain better exhaust flow. It's a legal gray area because it's not enforced around here.

Any large displacement new vehicle, even with its emission controls, is going to polute more than a Festiva without a cat.

Maybe I'm reading too much into your statement. You are one of the 'benign powers that be' along with the rest of us, aren't you? It sounds condescending, if read the wrong way.

[blkfordsedan]

IIRC, the stock B6 downpipe is 1.50" ID. It looks bigger because of the double wall tubing. 6or a stock B6, I would stay with 2" or smaller. If you look at my build thread in the garage forum, I have pics of a custom 2.125" mandrel bent downpipe and a comparison to the factory diameter.