Gernby

iTrader: (1)

That X-pipe resonator really is interesting, but I've already committed myself to the HKS axle-back. Maybe combfilter should try something like that if my HKS doesn't dyno well!

Irishman06

That's a straight-through "pre-muffler" type resonator like you'll see on racecars in series that have a sound restriction...interesting that they crossed the two inlets, but too bad that they did it in a way that significantly reduces the cross-sectional area. I think maybe that's one of those "no x-pipe better than a crappy one" scenarios.

Gernby

iTrader: (1)

Where did they reduce the cross-sectional area in the X-pipe? There is only one "pulse" of exhaust flowing through either direction at a time, so the cross-sectional area shoud be as constant in either straight line as possible. That's why I think the Burn's X-pipes are so much better than the other stamped X-pipes (Magnaflow, Megan, etc.).

Irishman06

My concern (and the reduction in x-section I talked about) is that its one tube fishmouthed onto the other. In theory, a good idea, but in practice, you may have pulses running into each other at an angle, which usually causes disturbances in the flow. If you were to cut into one of the Burns x-pipes, you'd see its construction is more like two tubes crimped together and an ovalized hole cut in the shared wall, which brings the pulses together parallel to each other, reducing this disturbance.

lobuxracer

iTrader: (2)

Sounds like picking fly shyte out of pepper. The pulses will never arrive at the same time, so collisions are unlikely at best. I won't argue the Burns pieces being the ideal solution (no doubt they are), but only for getting the last few percentage points out of the system. This isn't a competition platform in a series where 2 - 3 hp will make the difference between a win or a loss. It's just modding a street vehicle for a little more than what the factory gave us.

GNN60GT500

Just so you guys know, Magnaflow makes that same muffler with the better center X design-

All Magnaflow dual in/ dual out mufflers use that design in fact- except with out the reduction-

Gernby

iTrader: (1)

Are there any pages on Magnaflow's site showing the insides of one of these? I didn't notice the "Tru-X Perforated Core" until you mentioned it.

GNN60GT500

There is nothing online- Ill see if I can get something to show you guys-

Gernby

iTrader: (1)

I would like to see whatever you find. Thanks!

BTW, I just looked into my stock muffler with a flashlight, and it seems to be very similar to the mufflers on my S2000. It is a triple-pass perforated pipe design (not baffled), which tends to be very good. People always complained about how tiny the gains were on their S2000s when they went with "straight through" exhausts. I hope I'm wrong, but I imagine there won't be much gain from replacing them...

lobuxracer

iTrader: (2)

Here's how they work. Not straight through, and definitely chambered:

Gernby

iTrader: (1)

Wow, that's good to know! The S2000 was just a big S pipe that actually went all the way through the muffler into an external pipe that rerouted it back into the muffler again. Thanks!

Irishman06

A point that I couldn't quite figure out a way to get across in my previous post (hence why its not included), is that the pulses are not infinitesimally "thin," so even if two peaks don't run into each other, there's still a strong possibility of the tail end of one sine wave and the head of another running into each other at an angle.

But again, none of this is based on fact I've run into somewhere, its purely my speculation based on the knowledge I do have. Absent real world testing, that's what most engineers rely on .

lobuxracer

iTrader: (2)

True enough, but the point of the exercise is exactly what you describe - setting the pulses up in a way that promotes the high energy leading edge moving down the pipe, and having a low energy region in front of the high energy region is just what the doctor ordered. Because they're approaching at an angle means we'll have some vector arithmetic instead of a pure pulling effect (and it is an effect because it is impossible to pull air anywhere), but we're also pretty certain that even at an angle, it beats letting the pipes dump straight to atmosphere. Anybody's X is better than that.

Gernby

iTrader: (1)

My HKS exhaust is "Out for delivery" right now according to UPS, so I expect it any time today. I just removed my stock exhaust, and weighed it. It weighed 39.5 lbs on my scale, which is a little disappointing. I was hoping it would weigh more, since the HKS is expected to be near 40 lbs too.

I also took a couple pictures of the inside of the stock resonator. It is a totally straight through unit with a smooth perforated inner pipe. You can even see the y-pipe on the other end. I wish I could have gotten a better picture, but my camera's flash didn't seem to light it up well.

Gernby

iTrader: (1)

Here's another shot of the resonator.