Exhaust in-pipes baffles (noise reducing)

[pat_thonon]

Pelican people,

After referring to pelican posts, now it is my turn to post something useful for others.

I just got a great way to reduce exhaust loudness and drone for my custom 964 exhaust. After rebuild, and of course mod my engine (3.8l, cams, 993 H/E, chip), one of my friend made a custom exhaust without cat. This is similar to instant-g crab exhaust but home made. However, even finding the exhaust music amazing with open exhaust end pipes, I ( as well as cops and the wife) found it a bit to loud for normal driving, plus a significant drone was present from 2-3k rpm ( highway speed). Searching the net I found this product sold thru Summit racing, made by Car Chemistry, which slip right into pipes :




This is available in many diameters and ,more importantly, are tunable using SS packing ( not provided), or included end caps. I personally used only SS packing to keep sone good flow. Now the noise level significantly diminish, no more drone and more importantly the cops and the wife are happy. The only down side of this product is it only available in steel, no SS

My exhaust ( exit pipes barely apperent)


One of the two pipes coming out with the baffle beside:



Hope this can help someone,

Pat

[Guardsred911]

This may just be the answer to my drone I am getting on my M and K 2in 2out...

[saxen]

^I have the same setup about to go into my m&k 2/2- just need to go home and install it-

[blucille]

I used these with great success, too.

[dw1]

pat_thonon - Thanks for the post & pics.

I've been trying various options to quiet my Dansk 2-out, including making my own baffles, without making a measurable difference.

Can you tell me how long these inserts are?
Because of the curved exhaust pipes, I'm restricted on what I can use with my the Dansk muffler pipes.

[pat_thonon]

Dw1,

They are approximatly 7 inches long, but can fit partialy in a muffler. Also ther is a three disks variant that is even more quiet.

Pat

[paulmose]

Pat,

Being a follower of the street rod scene, I spotted this in Rodder's Journal, they seem to eliminate the mufflers completely.

Thought they would be ultra cool for a 911 hotrod with headers and no mufflers at all.

Spiral Turbo Specialties:

Not sure if it offers a solution to your situation, but worth a look just in case.

Cheers,

[pat_thonon]

Paulmose,

Thanks for the link, this look good also, however I am satisfied with Car Chemistry baffles. However i will keep this in mind if I want to try something else.

Pat

[PetrolBlueSC]

I installed a pair of Car Chemistry baffles this weekend. The PO had installed a B&B muffler (2-in, 2-out), that had considerable drone at 2000-3000 rpms. Wife hated riding with me, and the kids complained. After installing the baffles, the tone and volume of the sound did not change considerably. But, the drone was significantly reduced. If you listen carefully, you can still hear the deep drone at 2500 to 3000 rpms, but it is not iritating any more. Now I don't feel like I have to shift around the drone anymore.

[LPMM]

I just purchased a 964 and the PO installed B&B headers and 2-in-2-out exhaust and the sound is great for the most part, except for the huge drone @ about 2.5K rpms that is downright awful and will quickly give anyone a headache. How do you guys still like the baffles? Are the 2 collar ones good enough or do you wish you had gone with the 3 collars? How do you install this and where? Thanks for any information you may provide.

[sundevil64]

Has anyone run these with straight thru pipes?

[rattlsnak]

I posted about those inserts on here several years ago. ( actually, I just searched and it was in 2003!!! )

But anyway, yes they work great and yes you can use them in straight pipes as they come in varying diameters.

[sundevil64]

Lol. Yes I am digging...

I used 993 HE's on my 84 turbo'd (79 930 motor) twin wg motor and liked them.

I am looking at running these on a test pony targa with a 3.2 that will later be a donor car for my 71. I am thinking I would run 993 HE's with straight pipe and the baffles for a fun car. I may change cams to either 993 SS or 964 cams to wakes it up. I would also like to run carbs like pmo's. I am still researching before I call any vendors.

I want a light weight balls out dependable car.

[Schmierung]

Long ago, I installed these on a modified 928 just after the header collectors. Mean sounding.

[NY65912]

I've got the CC inserts on my M&K sport muffler /w/headers.

I am very happy with the amount of "tone down". Kinda mellowed it out.

[LPMM]

MikeČ --> 2 disc or 3 disc CC insert?

[NY65912]

LPMM,

I used a 3 disc insert with no wool stuffing.

http://img.photobucket.com/albums/v101/Mikes72sb/Widebody%20Projekt/2012-09-22_12-28-00_958_zps9436fee3.mp4

[wayner]

If it is drone specifically that you are trying to eliminate forma 2 in 2 out, try adding a baffle to just one pipe to break the resonance frequency between the two, otherwise adding both might just change the pitch of the drone.

[Bill Jennings]

Sorry to hijack this thread but....
This baffle looks identical to the ones that came with the Vance &Hines Longshot pipes I have on my Harley Softail. They were about ten inches long.
When fitted it greatly increased back pressure and low down torque, when not fitted the pipes had high end horsepower with little low end torque.
Fitted the pipes were very quiet.
Are 911 pipes tuneable this way?
I have SSI's not sure what the muffler is but it is a single out.

[scarceller]

What would be interesting is before and after dyno runs. I suspect installing these baffles will have an effect on the torque curve. Would be very useful to know what if anything changes.