Resonators and your aftermarket XPipe

[camaro1]

the large baffle/resonator that the L99 cars have is actually straight through,, the pipes go in and come right out ,,, but even though when we cut mine off to do the x-pipe you could see right through to the other side,,, BUT there is some funky flow inside this big box,, the whole top of mine near the center was turned blue from heat, also when we added the x-pipe the exhaust got louder and the car ran WAY better, so i can say even though you can see straight through it something inside messes with the air flow and made a hot spot inside the resonator

i would suggest anyone with a L99 that wants a cheap performance gain, to take off the center resonator/baffle and get an x-pipe in its place and if you cant deal with the afm/dod sound then have it turned off, you really wont loose much fuel mileage, my 415LS3 is still getting 23mpg at 70mph

[JoshJ81]

So was that box creating the extra heat? Is it safe to remove it without worry of high heat? If it's safe then that might be why you are feeling better performance, because there is not much heat build up, yes/no?

[JoshJ81]

Ok, i did some research. It seems that it's not a big deal as it turns out. Borla has already done the research and they have a full cat back with xpipe that gets rid of the "box" in the middle.

[BLACK10]

current video added to the end of post #12

[bobby35ny]

Originally Posted by Doc

A crossover improves the efficiency of an exhaust system by allowing exhaust air pulses to find the path of least resistance on their way through the pipes. As each cylinder "fires" it sends an exhaust pulse out through the exhaust pipe. With 8 cylinders doing this there's a timed series of pulses being sent out into the exhaust system. As an engine accelerates the rate of those pulses increases and can do so very quickly. This means the pulses that went out a few seconds ago are being crowded from behind by a string of more and more pulses pushing faster and faster.

After a point the pulses begin "backing up" and you have what in fact is known as back pressure. Some back pressure is desirable but too much begins to cause a "traffic jam" of air pulses and can actually start pushing on the valves and interfering with the new exhaust pulses trying to be pushed out. This will rob your engine of it's potential power which is typically why stock exhaust systems are referred to as being "restrictive" because they are actually restricting the amount of power the engine can produce.

Anyone who wants to increase power can do so by unrestricting the intake/exhaust system so the engine can "breathe" more freely. This is usually a combination of a less-restrictive intake often known as a CAI or Cold Air Intake, sometimes a new intake manifold, headers which are less restrictive exhaust tubes, larger exhaust pipes, and less restrictive mufflers and/or catalytic convertors (cats).

The purpose of a true crossover is to allow the string of exhaust pulses that increase as the engine revs increase, to find the path of least resistance by being able to "crossover" to the other side of the exhaust pipes if that side has lower pressure at that moment. An exhaust pulse is a pocket of high pressure air, in between those pulses are pockets of low pressure. So the crossover basically functions like a traffic cop at an intersection by improving the flow of traffic.

The key here is "low pressure" so a crossover is more effective than an H pipe because air can move through it easier with less resistance. Air doesn't like to turn corners and can quickly lose it's velocity. Crossovers are more costly to make which is why you usually see something like an H pipe if a manufacturer does anything at all.

Simply sticking pipes of various sizes, anything that can restrict/unrestrict the airflow, etc. in an exhaust system doesn't automatically produce the best results. Companies that make good custom exhaust systems do in fact put in a lot of time testing the results based on size of pipe, lengths of each section, bends in the pipes, location of the crossover, etc. so they can get the best results at enabling exhaust gases to quickly and efficiently move through the system. So as you can see there's much more to it than just coming up with a "mean sound".

Long post I know, but it helps to give you some background on why some of these systems are priced the way they are, and why some might be better than others when they're all "just exhaust pipes".

Being "old school" I really feel the X pipe gives a raspy sound and the H gives a deeper tone which I like.

-bobby

[domano 68]

Originally Posted by BLACK10

i did a muffler delete on my LS3, with a magnaflow x-pipe( part # 10791). All the x-pipe did was reduce the interior sound (which is not loud, no drone) and some of the popping when you decelerate hard- for example, high revs, then take your foot completely off the gas. this only happens at certain rpms, not all the time. this happens even with the stock exhaust in tack, if you have an LS3, you probably have heard this, but it is not as loud. The x-pipe also made it rev a little faster, due to the free er flowing exhaust.

the first pic is of the factory h-pipe that is after the cats and before the resonators.The second pic is the magnaflow x-pipe that replaced it.

there are actually two sets of cats on the LS3. the first video shows a look at the stock exhaust on the LS3.




the second video is the LS3 with the muffler delete





headers will make it alot louder. many aggressive sounding mustangs and camaros usually just have an x-pipe and factory resonators. this mod sounds pretty much like an Axel back exhaust, maybe a little louder. no dash lights or any problems. i don't think headers will void the warranty, as long as you keep all the cats in pace.

this mod cost me about $180, not including the new black chrome tips that were $140.

hope this helps.

this is a video of the delete and x-pipe

Great stuff, thanks!

[SPAWN]

True a H will give a deeper tone but the X will create a little more HP.

This is my experience with the new stangs. believe it or not the exhaust is very very similar between our cars. You also have the drone issues we have from the variable timing and the fact that the mufflers are at the rear of the exhaust.

That big Baffle tank (Resonator) is killing power. as the exhaust builds up in it it is also trapping allot of heat generated by the cats in the hump of the car. then as pressure builds it has to find its way out the small holes in the back to the mufflers.

Just like everything else the exhaust needs to flow smoothly with as little obstructions as possible. then you will generate more HP but keep in mind a little back pressure creates Torque and Torque is what the real power is. Torque is what propels you down the road. This is why all those little rice burners with a turbo are so fast. the torque is incredible from a turbo and thus they are so quick. The more of it you have the quicker you will be.

[bobby35ny]

Ya, I'd give up a few ponies for the H tone... I just hate the raspy!

=bobby

[BLACK10]

Originally Posted by bobby35ny

Being "old school" I really feel the X pipe gives a raspy sound and the H gives a deeper tone which I like.

-bobby

on this car, it was actually the opposite

[bobby35ny]

Originally Posted by BLACK10

on this car, it was actually the opposite

All the clips I'm hearing with full catbacks with xpipes sound raspy as hell to me.

=bobby

[D1BADZ]

my uncle has a raspy voice from smoking too many cigs

[Doc]

Originally Posted by bobby35ny

All the clips I'm hearing with full catbacks with xpipes sound raspy as hell to me.

=bobby

Listen to this one; it's the Borla and my favorite so far:

http://www.camaro5.com/forums/showthread.php?t=33283

Based on this and the other Borla clips I've heard I think this is the one I'll be getting.

The reason why a crossover sounds "raspy" compared to the H pipe is due to the odd pulses crossing over to the side they did not come from originally and squeezing inbetween the pulse pattern that is coming from that side. They change the sound because the stream of pulses have a harmonic pattern that gets changed when a "note" is pushed into the stream that is out of time with the firing pattern for that side. This is what gives the exhaust sound that raspy or ratty tone.

An H pipe actually serves more as a pressure equalizer between the 2 sides rather than directing pulses from one side to the other like a crossover does. With an H pipe you're hearing the natural patterned tone coming from each side with far fewer odd pulses which is why it has less raspiness.

The H pipe equalizes the pressure between the 2 sides but has more back pressure. A crossover actively works to move the pulses through the exhaust system easier so it produces less back pressure and slightly more power than an H pipe. Borla has figured out how to make a crossover sound fantastic.

[LS3SSRS]

when i got my bullets welded in place of the big mufflers in the back, i started the car without any mufflers...(straight pipe mod). it sounded good and not really loud. so my plan is to cut out the resonators, and 2 of the catalytic converters... the ones behind the o2 sensors. im thinking about an xpipe but i like a deep tone might just leave the hpipe and see how this sounds.

[JoshJ81]

Hey Doc, that Borla S Type (sport?) system is one of two choices that I have narrowed down to. The other being the MBRP CatBack system. Both are stainless steel/mandrel bent pipes with Xpipe that replaces the resonator/baffles (AKA heat builder/power robber). However, I'm leaning more toward the MBRP. The MBRP is $400+ cheaper (as of now, looks to be a sale) but it's a 3 inch exhaust system where the Borla is 2.5 inch. The tone in the MBRP, to me seems a little deeper than the Borla, Borla has a very good sound to (hard to pick one, really).