Just got my Solo Axle Backs on and I'm loving them. Still tweaking the J Pipes and figured I would see what others have done. I extended them out to 2 inches and it sounds pretty good. Anyone else care to weigh in?
Years ago when I first got mine I experimented with moving them up and down. In the end the default setting that is shipped to you really is the sweet spot in most cases. Solo tested pretty extensively on this. But every G8 is different.
Wait a couple hundred miles until it is broken in, then adjust.
I found the stock position to be the best as well. You will not eliminate all drone at every rpm youll most likely still have it around (1200-1400rpm) but it will eliminate the hwy driving drone (50-70) over 70 I have very little but under it theres nothing.
Not really... it's a Helmholtz chamber. Basically, soundwaves (measured in hertz) are a certain frequency. "Drone" soundwaves have a sharp waveform pattern, which represents the pain in your inner-ear that often causes headaches. Notice the sharp peaks (orange in color) in this 3d soundwave map, this is the ACTUAL sampling that I used to design SOLO's exhaust cancelling technology.
So back to what I was saying.
Normal "throaty exhaust" like when you depress the accelerator while shifted into Park, is a smooth waveform, and thus is not drone. The sharper peaks are drone, and that's the "soundwaves" that the J-pipes target to eliminate.
There's a vintage huge thread on this very forum named "Almost Drone Free" by lspowered65 to read through if you care to dig deeper into the formula and behind "Why" it works and all that. That was my inspiration to bring the Helmholtz technology to SOLO to create an affordable drone-free exhaust system for g8 owners. My way of "giving back to the community" in a way, way back in 2010.
anyways... once you sound sample and find the Hertz rating of the drone, there's a formula that can be applied to give you the exact length of the capped pipe (J-pipe) to target, and elliminate, that frequency. Ahhh, the "sound of silence".
What you need to know:
The adjustable SOLO J-pipes are factory preset to eliminate drone for most g8's "out of the box". Some G8's have different trouble-zones than others, so sometimes a little tweaking is necessary.
The J-pipes work by allowing soundwaves to harmlessly enter the pipe, bouncing off the sides as they go in. The "magic happens" when the soundwaves hit and reflect off of the air-tight cap at the end of the J-pipe. If you have the formula correct as described above, the reflected soundwave will come back in the exact opposite pattern, think of it like a wormy-line going horizontally between negative one and positive one, with "zero" or "quiet" in the middle. The +1 portion of the soundwave gets reflected into a -1, with the net result of zero, and similarly the -1 portion of the soundwave gets reflected as +1, and the zero portion of the soundwave isn't changed. So basically, it elliminates the targetted frequency by "erasing" that frequency, and thus, the drone is elliminated. If you've ever seen an oscilliscope, that is the visualization of waveforms, and J-pipes target a certain amplitude and pitch waveform and elliminate it by reflecting it in exactly "its inverse".
G8's drone spots that the SOLO J's target is v8 mode, 6th gear, 65-72mph, ~1800rpm-2200rpm or there abouts, and slightly uphill. Try that with a "straight pipe" solution and your ears will bleed. Try that with a SOLO J-pipe solution, and it's really stock quiet. Goose the gas to outside of that RPM range and you get the awesome musclecar sound that makes you smile. The best of both worlds.
Some cars have a slightly annoying "thrumming sound" when in v4 mode at those speeds, that's an anomoly of running a performance exhuast with only 4 cylinders... the J-pipes are tuned to the v8 wavelengths, when the 4-cyl mode is active, the overall length of the J-pipes would have to be 4x as long, which simply isn't feasable in the underbelly of a g8... not enough room. Anyways, most find solice by tuning out v4 mode, and from all my testing, it does not effect all that many g8's, but I have proven that the exact same exhaust system on one car doesn't behave the same on another car, just nature of the beast.
SOLO's official "How to adjust your J-pipes" is found here: http://www.g8board.com/forums/showthread.php?t=28831 -- basically, mark your "baseline" with a marker, and find a "test loop" of driving that can easily reproduce your trouble area. Then loosen the clamps and adjust "the tuba part" inwards or outwards an inch. Do this for both sides equally. Then go for your test loop again.
Did it improve? Then you went in the proper direction, if more tuning is necessary, move in the same direction another half inch and run your test loop a third time. Repeat until solved.
Did it make it worse or not effect it at all? Then go back to your marked baseline and move the tuba part in the OTHER direction, your 50/50 guess turned out to be wrong. Repeat process.
When complete, tighten down the J-pipe clamps and enjoy.
I was proud to bring this J-pipe technology to SOLO performance, and I enjoyed working with the owner of SOLO Performance and the team at Mufflerman in Buffalo NY (SOLO US Headquarters) when they used my car as the test mule for trying different solutions and tweaking the design to become what it has become today. I'm proud to have contributed to the G8 community in this way. No, I don't take any credit for inventing this technology (According to wikipedia, Mr. Helmholtz lived in the 18th century and used it for a variety of projects) but I am considered the person who convinced SOLO to try my idea, and it worked out in an awesome way. I've had my SOLO system on my car (in various iterations, between 10 and 15 different designs, all told!) for nearly 50k miles, and it still performs just as good as when it was initially used to solve the drone problem.
Hope this answers your questions, and hopefully the links and the picture provided shed some light on how this awesome technology works.
I read through the almost drone free thread awhile back and that's what made me decide to make my own. After it was finished there was Zero drone from 65-72. Perfect the first time, but I usually cruise a bit higher than that and that's where drone reappears. I didn't know if adjusting the length would have any effect on the frequency at a higher rpm.
Yes, because the sound frequency changes pitch when your engine RPM's raise, so if you adjust them some, you will "retarget" the new frequency that you want to kill. So YES, adjusting the length certainly does make a difference. It shifts the drone cancellation effect, adjust as necessary to suit.
solo performance is full of BS. I bought the axle back exhaust for my Pontiac G8. The interior drone was horrendous. I was told that the J pipes were quieter so I purchased them. WRONG. The drone is just as bad although Solo performance advertise them as having NO DRONE. When I called Solo performance I was advised to " give them a couple hundred miles to break them in".