Hey guys I picked up a set of chambered pipes off eBay to put on my Trans Am when I redo the exhaust this winter. Well they were delivered and looked great until I looked down the middle. What I saw was a tiny 2" ID pipe now the pipe is perforated in half of the area it covers. Now my concern is that this is to small. I know that it would be if it was a solid section of 2" pipe. Now when I start thinking technical about it here's what the gas would do when after it enters the muffler. It comes in a 2.5" inlet into the first 3" chamber then it goes to the second 3" perforated chamber through a 2" opening. Now it goes to a third 3" chamber through a 2" opening. Then it goes into through another 2" passageway and enters an open 3" section about 9-10" long. After that it goes back into 3" perforated chamber through a 2" opening. Now it goes to a third 3" perforated chamber through a 2" opening. Then it goes into through another 2" opening out the other end of the muffler to a 3" chamber then down to the 2.5" tailpipes. Now upon thinking about this I'm wondering if the exhaust gases will be cool enough and that the transitions from the 3" chambers to the 2" tube will create a venturi effect helping suck the gasses through the mufflers.


So do you think these will be able to support 360 rwhp? What do gmmg's chambered pipes look like? If somebody could break out there dial caliper and measure the muffler body diameter and the pinch diameter I could compare them.

 

There will be no venturi effect through the muffler.

The atmospheric pressure at the outlet will be too high to create any sort
of gas speed through the chamber.

The perforations are to dampen acoustic energy.

As for the path through the chambers, it seems like a million miles from your
description. There must be quite a bit of restriction through that muffler judging
by your post.

Measuring inlet ID/OD and outlet ID/OD is not a good comparison. Flow numbers
under equal test conditions would be a better guide.

 

The 3" 2" etc... are just inside diameters of the chambers/openings. The muffler is 24" long overall.

 

I realize that. It was a play on words...

The end result is too much restriction to make decent power; the 360 RWHP
you are seeking (my best guess). Afterall, you are referring to a single pipe
exhaust system correct?

 

Oh sorry I didn't specify my whole exhaust. It would be pacesetter long tubes to 3" duals to the x-pipe after the x-pipe it would be 2.5" duals to these mufflers. After the mufflers it would either be 2.5" again or 2.25" tailpipes I'm stepping the pipe sizes to increase exhuast gas velocity.

 

IMO, those chambered pipes as you described them would be a big plug in your exhaust system and negate most of the good stuff in front of them. The multiple 2" retrictors are probably worse than just having one.

If it were my car, I'd put them back on ebay.

If they will fit, continue the 3" pipes all the way to the mufflers. The gasses are still pretty hot so the flow is still high. If you are using 2.5 inch mufflers, use something like Dynomax Ultraflow or Magnaflow equivalent with a smooth transition (8 inches+ long) in front of the mufflers. Many other mufflers (some with "Flow" in the name) aren't anywhere near as free flowing as those I mentioned, and can cost you power.

As far as stepping up the velocity after the mufflers wilth smaller pipes, that will probably add back pressre and cost you power. OEM's often used smaller outlets than inlets because the flow was less due to 300-400 *F lost in the muffler, it was cheaper and quieter, and it was cheaper. Did I mention cheaper?

My $.02

 

Well I guess these mufflers are going to go up for sale at the car show next week. I would like to put some ultra flow mufflers or some hooker aerochambers on but I would like it to fit where the stock muffler was for ground clearance. I know dynomax makes a round muffler but they are really expensive. The sweet thunder chambered pipes have a 2.5" core and would be about 40 dollars cheaper than the ultra flows. Does anybody make a dual in dual out muffler? where there is one inlet and one outlet per side?

 

im assuming that you mean these type of mufflers

the mufflers CAN be ordered with a 3" inner diameter, so the inside baffles in the pipe are never less than 3".

however, as you can see by the design inside the pipe, all those triangled openings into the chamber form pockets that trap the air on its way out. now im no expert, but im assuming someone that knows about airflow can confirm that these pockets/chambers create very turbulent and restrictive flow.

 

Those are the ones except my perforations don't extrude into the pipe it goes out of the pipe into the chambers. I guess i could try to find somebody with a mild 305 or 283 to put these on it should be sufficient for those engines. Or maybe i should see how the sound on my sisters sunfire j/k.