There is a bubble wrap that is covered w/ alumn for insulating heating ducts etc, I was going to wrap my HPD pipe in it to help muffle the sound. The aftermarket uses thinner material & is much louder than stock. I was making a secondary muffler, out of thin alumn & pink fiberglass, to attach to the end of the Aaen muffler, also to help quiet it down. Any suggestions on what else I could wrap the pipe in to silence it or any other suggestions on ways to quiet it down some would be appriciated. I only will keep this on during winter months since I ride around the house allot since everything else is closed. In summer, I rarely ride around my neighborhood since theres so many other quad trips to go on. If it matters, I have the HPD 12:1 cool head, reeds, pipe/clutch kit, 39mm carb & Aaen muffler to name a few. This sucker is LOUD!!! Going back to stock pipe & muffler is not an option. No way!!! Thanks
Jim Maloney 98 400 Scrambler

 

Hey Jim~
My uncle bought the HPD pipe and silencer for his trailblazer and it was also quite loud. He bought a muffler for a briggs and stratton motor and screwed it onto the end of the HPD silencer. He painted it the aluminum color and it looked like it came with the HPD silencer! He also welded a couple mounts onto the silencer so he could attach it with springs. It really helped to quiet it down and I don't think it hurt performance much either. By the way, the HPD and AAEN silencer are for the most part identical. Also I have gone to the local 4x4 offroad store and asked about a header wrap(about 50 bucks). It is supposed to retain some heat(and increase performance) and also reduce the noise. I've never seen it in use, so I don't know if/how well it works. Well, those are the 2 things I know of so hopefully they will be of some use. How does your machine compare to stock? Or should I say IS your machine comparable to stock?

 

You brought up a good point, if I insulate it, it will trap more heat so is this a bad thing & will I melt the exhaust port or piston or something? You mentioned it might add performance, how? Yes my quad rides very different from stock & the porting added allot but not as much as I was expecting from all the hype I heard. Not to say it's not worth it, cause I think it's worth every penny, but just not as a dramatic a change as I expected partly since I added thing one at a time so if I had added everything at once, I would probably be saying it will knock you socks off. It's tied w/ a slightly modified Banshee & beats a DS in a drag which I guess is ok for a 4wd but I guess the 14:1 or 15:1 is where it gets wickedly fast. Thanks
http://photos.yahoo.com/jim400scram

 

Jim~
Sorry, but I do not have definite answers to either of your questions. I am guessing you won't melt anything because on the package for the wrap, it sad it's ok for cars, personal watercraft, and snowmobiles. Polaris engines are the same design as snowmobile engines, so I don't think this would be a problem. I'm not positive how it adds performance, but here's my guess from what I've learned in College Chemistry...In a combustion engine, some of the energy is lost as heat. If you can retain that heat, it will translate in to something else...power. That the extent of knowledge I have on the topic...you would be better off asking an engine builder if you are considering this wrap.

 

The header wrap will proabably not work well. They are made to retain heat, but that is not what increases your performance. The wrap keeps the heat from the header from making the air under the hood of a truck from getting hot. As you know the cooler an engine runs, the better. If the air under the hood of a truck gets too hot, it will decrease the performance, as the air intake will be sucking in that hot air, rather then relativly cool air.

One thing I have see people do is put thier stock muffler back on with the new pipe. It will decrease you power by about 3% over using the aftermarket silencer, but it is much more quiet.

 

Thanks for clearing that up Lurch77. I too have heard that the stock silencer reduces sound quite a bit with minimal loses in performance. If it just wasn't so big and ugly compared to the HPD silencer...

 

I'd be very careful about using any of the heat wrap materials. They might help get rid of the ping noise, but really don't do anything at all for the true cluprit, which is an open exhaust. If you plug the end with something, the noise is less, but the power is noticeably less also. Particularly on an engine that has been modified. It's like running thru a funnel.
That's the sound of horsepower.

 

I just put the HPD pipe and airbox mod on my Scrambler, and noticed that even with the original muffler there is a lot more noise coming through the air cleaner. If you drilled holes in the air box much more intake noise now comes out through the air box. I am thinking of putting the stock snorkel back on to help with the noise,
Just an idea...
Lorrin

 

WOW!!! I've made a stealth quad, well not quite but it is half as loud as before or less quiet than a stock one now I think. It looks absolutly like crap though but it's really quiet. I haven't run it yet so as Jack mentioned I probably will be giving up a couple HP but thats ok for winter I guess. I'll be testing it out Saturday.
Jim Maloney 98 400 Scrambler