https://www.summitracing.com/parts/jex-a4540s

Any hint or suggestion of rasp or fartiness is completely gone. Warm idle is near stock quiet. Cruising above 2K is completely tame. Acceleration has a bity of deepness, but most of the noise is in the mid and high frequencies, from the intake and engine.

Yes, it's a louvered glasspack, but when using a larger size than stock, you're not likely to lose any significant power. I'm using 2.5" mandrel bent piping from the header with a large Dynomax Super Turbo muffler at the end, and the car pulls to redline the same as with 2x perforated core resonators I used to have. They did little to get rid of rasp and farts, and were almost useless at removing drone. At this point, I can make a quarter wave resonator, get rid of the narrow band of frequencies causing the last of the drone between 1.5K to 2K, and enjoy a quiet yet free flowing exhaust at any RPM.

Here are the other sizes available:
https://www.summitracing.com/search/...eversible%3ano

Remember that the longer the glasspack is, the quieter things will be. I picked the longest one (45") and it 100% KO'd the frequencies I needed it to (rasp between 2.5K and 35.K and freeway drone) and more! And yes, at 4" round, it has no problem fitting under the car.

 

I'd be curious to hear the sound both inside and outside if you have the time?

Good info.

 

I did a set up like this with no muffler on a 1996 Saturn SC2.

30moons.Com - Reviews of the Saturn Aftermarket

 

I'll see what I can do. I have to pick up a wireless lav mic setup for work soon, so this should be something interesting to test it on.


This is a glasspack. Think a resonator loaded with fiberglass behind the louvers/perforations. And twice as long. Different type of sound reduction going on, and it's VERY quiet compared to resonators. Been thinking about seeing how much drone comes back if I remove my muffler, especially after I add a quarter wave resonator to get rid of that last bit of drone at low RPM.

 

In case anyone wants to read about quarter wave resonators and muffling:

https://core.ac.uk/download/pdf/328816729.pdf

 

Is there a formula for how long the glasspack must be for a car to produce the sound you want? In other words, is it based on airflow? Or horsepower? Length of exhaust?

 

From what I've read, temperature also has a large effect on quarter wave resonators. The hotter the exhaust gasses and piping, the more effective they are. The S2K has one stock, and it's right by the cat, vs everyone else that puts them at the end of the exhaust system. Theirs is only 6-7" long, vs the others that need 2-3' to get the job done. I have a spot right after my cat that I'm planning on using to do a similar install as the S2K (they use oval pipe for clearance). I can also say that my exhaust is a bit quieter after driving for around 15 minutes or so, after everything heats up. Even my old setup got a bit less raspy as the exhaust heated up, but the rasp never went away.

Something else, about drone in general, is that there's a TON of tuning done for stock exhausts to eliminate it, beyond just piping size, type of bends, and what kind of silencers are used. Materials, weight, thickness, overall length, positioning of bends and silencers, etc. all contribute to reducing drone. Done poorly, all you're going to be doing is fighting against your own creation. I think adding the mass of the glasspack, plus adding a second spherical/ball joint after the glasspack (to aim it properly; I don't have a welder :/ ), have doubled down on reducing drone by reducing exhaust system vibration. Both by adding mass, and by splitting the exhaust into 2 separate parts, instead of it being a one piece tuning fork.


Not sure, as people tend to shy away from louvered core anything. Yes, they have the potential to restrict flow, but that also depends on how close you are to maxing out your piping. 2.5" on an economy NA 2.2L, without any other mods except exhaust, is a bit oversized for most of the RPM range, so there's room to work with. Adding internals, head porting, upgrading the intake manifold, tuning, or especially, going turbo (3" land), and louvered cores will probably choke the otherwise properly sized exhaust. I'd think finding a flow calculator for exhaust piping, and going 0.25" larger for adding a louvered part, would help a bit. Really hard to say, since it's constant turbulence through the entire core, vs just one turbulent event like necking down the piping at one point.

As far as glasspack sizing, I've read many reports about how an 18" resonator or two will cure rasp, but mine (from a Yonaka exhaust) didn't silence it. A big improvement from a straight pipe, but still ricey. I might try something half the size sooner or later, just to restore the stock ground clearance (I'm using universal clamp on hangers around the glasspack; again, no welder :\ ).