well, according to some app I installed on my cell phone, I knocked around 10dB off the output of my m&k 911r rev1 (w/ 3" pipes), from around 122 down to 110 or 112 dB, most importantly, the drone is gone, the car sounds better at idle and all thru the power band.

I used these:

http://www.carchemistry.com/shop/index.php?l=product_detail&p=19

Lewis

I for one would like to see these installed. Picture please!

Lewis, how are they held in, and how many disks did you use? It's kind of weird that they are based on the od and not the id of the pipe.

Are the inserts indeed sized on exhaust pipe OD? I'm on my phone and didn't look at all the details on the site.

Never mind, went back and actually read this time!

3 discs with the stainless steel wool packing

http://forums.pelicanparts.com/uploa...1283553083.jpg

posted some videos here:

YouTube - VID_20100903_151517.3gp

and

YouTube - VID_20100903_151533.3gp

I installed the baffles with screws, I will swap for rivets soon.

Lewis

Qu'elle Apps...
 

Lewis

Which Apps is that?

J.J.

What's it look like from the back, I kind of like the the old machine gun look of them.

I have an android phone, the app is called SPL meter, there are many available for a variety of phones....

Lewis

pic

screws to be replaced with rivets


http://forums.pelicanparts.com/uploa...1283604149.jpg

Has anyone tried using 2 separate mufflers back to back, with in and out on the same side?

Something like this...

MagnaFlow 14210 - MagnaFlow Performance Mufflers - Overview - SummitRacing.com

Or any opinions on whether it would be drone free or not.

Cheers!

Hey there Lewis,

I'm curious if you're still running the Car Chemistry inserts and if so how are they working out for you? Also is the overall hp/tq loss with the CC inserts substantial?

I've got a dual in dual out GT3 style muffler with 3" outlets and I need to quiet it down and reduce drone for street driving. I made a temporary cap for one outlet and that works well for reducing volume and eliminating drone but long term I'd like to go with something that allows using both outlet pipes.

I think one (or two depending on mood - I'll make them removable) 3-disc CC insert(s) will work well for my application.

Thanks for the help!

yup, still got 'em.

no hard numbers about power loss, there certainly is 'some' but I would call it very minor.

depending how bad your situation, the inserts can be tuned for more/less quietness by wrapping stainless steel wool between the discs of the inserts.

All exhaust other than something you can't hear at all will have harmonic resonance. You can quiet it, but you can't make it totally go away w/o changing something upstream.

If the resonance wasn't somewhere if the powerband, I would think the muffler might be one that takes away performance.

Hi there,

I have SSIs and a Monty twin outlet muffer on my 85 Carrera. The Monty has been retrofitted with 3" tips and the low RPM boominess was driving me mad.

I search for ages for a solution and eventually found the Car Chemistry inserts. I went for the 3" triple disk insert and put the stainless wool between each disk.

The inserts also come with a restrictor and blanking cap that covers the central pipe. The restrictor is like a cap with a hole it in which reduces the internal diameter even further.

For maximum noise reduction, I placed the restrictor cap on the inlet side of the insert (the side nearest the muffler barrel) and the blanking cap on the outside. This means the airflow has to go through the central tube and permate through the holes and then pass through the wool and performated discs.

Here is a pic of the inserts installed. I assembled the unit and then tapped it home with a hammer so that the inserts did not stick out the back of the muffler tips. I secure them with rivets.

http://forums.pelicanparts.com/uploa...1300192697.jpg

On starting the car up, it was amazing how much quieter the car was. For general driving, the car was almost stock like on the inside, but stilll a bit noisy on the outside. Performance low and and throught the mid range was as good as before, however my setup definately choked the top end a bit. This is to be expected with my use of the restrictor and blanking cap. It is interesting, as on the RHS of the car I riveted on the blanking cap, and on the LHS I glued it on with JB WELD. Recently this came off after a sprited drive in the country. This has restored a bit of the top end performance, but a bit of noise and boominess has come back. I actually prefer the car to be quieter so I am getting another cap from car chemistry and will rivet it on again.

Hope this helps

RG5

Here is another view of the car, the inserts are visible from the 3/4 angle but not that noticeable.

http://forums.pelicanparts.com/uploa...1300193582.jpg

True as far as it goes, but in some mufflers the shell (sheet metal) itself will resonate (a lot - i.e. high Q and high amplitude)

a quality built and well designed muffler will... ah... muffle that effect

Will the car chemistry inserts with the restricters and steel wool packing create too much back pressure? I put these in my Timmins exhaust on my 3.6 conversion and I love the sound. I noticed a hit from the butt dyno and I'm concerned the back pressure could cause issues with the motor long term? Should I be worried?
Mike

Mike,

Are you using the restrictors in both CC inserts along with packing in both inserts?

I'm using a single restrictor (the one with a hole in it), along with SS baffle packing, in one of my CC inserts. The other CC insert is just the insert (mostly there for cosmetics) with no restrictor or packing.

For street driving I'm happy with the balance of volume/drone/backpressure that my CC inserts setup is providing.

http://forums.pelicanparts.com/uploa...1301662674.jpg

To answer your question - I don't think you need to be concerned with long term effects of the CC inserts. If anything I'd remove the restrictor off one of your inserts and leave everything else alone.

another option

Dynatech Vortex Insert Cones - Speedway Motors, America's Oldest Speed Shop