I posed this question a little while back on a thread about quiet exhausts, and it went nowhere. I'm wondering how the disc-based silencers do when the number of discs is reduced to attain more moderate sound levels, like 95-98dB. Has anyone tried tuning their CT/Sparks/White Brothers E Series down from the max number of suggested discs (and re-jetting) to see what kind of power differences are possible at lower sound pressure levels?

 

I have a white bros. on my warrior with 13 disks and its loud. I took them out one by one to get the sound down and I ended up with only 3 disk in where it was quieter and it had no power.
I would like to try a quiet core insert and see how well those perform.

 

I started out with 12 discs in my E-series slip on (Raptor). WAY too loud. I worked my way down to 8 discs. This change makes it much quieter, and is now has more low end torque. I can't tell that it lost much if any high end when going to 8 discs.

P.S.- I just bought a 400ex for my son that had the E-series also. It had 12 discs, was too loud, so I went down to 8 discs on it also. I could tell the difference in low end on it also. Since most of my trail riding is in the 3000-6000 RPM range, I think that low end to mid range power is more important anyway.

Good luck,
Lorrin

 

Those are encouraging results, Lorrin.

KJMAXXX, did you rejet after you cut down on the number of discs?

I'd like to see Dirt Wheels do a quiet pipe test with the pipes they used in the the last test. Just put on less discs for the disc-based silencers and throw in the quiet core inserts for the non disc-based ones. Ask the manufacturers for recommended jetting and airbox mods, just like in the "loud" pipe test.

 

Lorrin, how much louder do you find the 8 disk exhaust setup than the stocker?

 

I was running the quiet core and 14 discs on my E-Series with 94 dB being the target at 3500 RPM. Now I'm down to the quiet core and seven discs and it's quieter but hard to quanitify. Tachometer should be here April 1 so I'll know then how loud it is. I borrowed an industrial grade sound meter but have no idea where 3500 RPM's is to check it. 94 dB @ 3500 RPM is the limit at our local dune area this year (Silver Lake). 5 days until opening day!

 

2fiftyX, I have a w-bros E on my 01 Raptor. With 7 disc in the volume is more than double (sorry no sound meter) I first tried 12 disc, it was so loud I wanted to return it (fat chance of that happening) So at 7 it is tolerable, I have had lots of comments on how mean it sounds wide open. I told them that I wasn't to crazy about it but after a hand full of comments I've gotten use to it. And there is a differnce in power, MORE [img]i/expressions/face-icon-small-happy.gif[/img]

With 12 disc in you can't stand next to the machine at idle and talk, yell is more like it.

 

Just to elaborate:
When I first put my E-Brothers slip-on on in the garage, and started the Raptor, I jumped a few feet in the air- Holy Crap! I'm talking straight pipe Harley-crackling/popping-obnoxiously loud. I took it down the street just to make sure that the enclosed space in the garage wasn't making me think that it was louder than it really was. Nope, it's really loud. I made my son wait to go riding while I changed the number of discs to 8. That sounded WAY better, and it really must give the Raptor at least 6-8 horsepower more, cause it's WAY noticeable. Ton's more torque, even at low chugging speeds. I still have to turn it off to talk to other riders when you stop on the trail, but the sound is much more subdued and much easier on the ears. It sounds really nice now, when friends get get on it and ride it for the first time, they always comment on how unbelievably fast it is. Some people have trouble riding it because the amount of low end torque and instant throttle response is hard for them to get use to. Any touch of the throttle, and it instantly launches forward, no hesitation and you better be hanging on. The Raptor is just one of those engines that was really restricted from the factory. I don't know that it's worth putting a pipe on a 400ex for 1 horsepower...

Good luck,
Lorrin

 

??? when I dropped down in disks on my warrior it ran like crap. Everybody is say'n they gained torque but I lost it. I have 12 disks on mine and its loud but runs strong, then I drop down to about 8 and its a little quieter but the power loss is unbelievable so I rather have it loud then ball-less. Am I doin something wrong ???

 

I've experimented a little with E-series discs and the quiet core insert. After I first tried the quiet core insert I thought it was a waste of money. I just set it aside and ran the silencer with 12 discs. Due to a problem with a weld on the silencer, I had to call WhiteBros- while talking to the service rep I mentioned that the quiet core wasn't one their best products. He chuckled a little and agreed somewhat. Then he told me that one of their guys had better results by spacing the quiet core with a few regular discs between it and the end of the silencer. I tried that and it did seem to work better. However, it still seemed a little too restricted for my machine so I punched out the three washers that are inside the quiet core and reinstalled it. I was quite surprised at how well that worked. I had a total of 12 discs (3 between quiet core and the silencer and 9 between quiet core and endcap disc). It was noticabley quieter than it was before with 12 discs and no quiet core AND I didn't seem to lose any power. It is louder than the quiet core with the washers in place but it flows much better.

If you have the quiet core, its worth a try. I'd be interested to hear what your results are. It was a little tricky punching the three washers out- I'd recommend leaving them in place and trying just the spacers first.