Shown above are two-disk inserts for 3" collectors. CCInserts are available in 2" to 4.5" diameters, with either two or three disks. Priced from $45ea*. and weighing under one pound, they are a fraction of the cost and weight of a full exhaust system.

We initially reported the price as $45 per pair, we apologize for any confusion.

The inserts come with a set of plugs and restrictions which can be welded on to further tune for sound and back-pressure.

No need for clumsy clamps or expensive welding. Simply slip the insert into the collector as shown (long end first) and secure with a couple of pop rivets or tack welds. If you don't want to drill or weld to your header, you can have a muffler shop weld the insert into a short (12-18") section of pipe, and weld on a flange to the pipe to match your collector. Now you can bolt on the collector and insert.

How they work: The inserts work best when the engine is at normal operating temperature. The hot exhaust gasses coming through the central tube are redirected to the outer disks by the many perforations. The gasses cool in the outer chamber and are flow through the holes in the disks to mix with the hotter gasses. The mixing of cool and hot gasses changes the exhaust sound to a crisp, snappy note.

Just for kicks we slipped the inserts into the back of our 3" Terminator mufflers. Not surprisingly, they did not reduce the sound by more than two decibels, proving that the inserts are more than simple restrictions, but that they indeed work based the mixing of hot and cold exhaust flow. Installing the inserts down stream from the collector is useless, since the gas temperature has dropped dramatically by that point.

We used a handheld decibel meter from Radio Shack to measure the sounds at idle and 3500 rpm, directly behind the car.

"Look ma, no mufflers!" Car Chemistry also sells a complete mandrel bent cat-back system for '86-'93 Mustangs, which utilizes their insert technology in the intermediate pipes. The advantage, besides the unique sound, is increased ground clearance and less weight, while maintaining a stock look.

One of the dilemmas when building a street-legal strip car is what to do for an exhaust system. Most strip cars run best "uncapped" -meaning open headers with no mufflers or pipes. Mufflers, as their name implies, are meant to muffle exhaust sounds. However since exhaust sound is a result of pressure waves from the combustion process, stiffling the sound also means creating pressure buildup within the exhaust system. Built up pressure, or "back pressure", can be beneficial at low rpms, helping to build low-end torque, but at mid and high-rpms back pressure is usually detrimental to power. The ideal exhaust system would be one which creates slight back pressure at low engine speed, but offers no restriction at wide open throttle. Of course the dream system would be quiet enough to meet local government and track sound requirements. The proverbial icing on the cake would be an exhaust system that didn't weigh a lot, or take up a bunch of space under the car.

We've found that most of our race cars (namely Project 11.99 and Project FE) run as much as two tenths and two mph faster though open headers. Unfortunately the local tracks don't always allow open headers, not to mention it is a pain in the ass pulling the exhaust system when we get to the track. Since the cars are typically driven up to 100 miles to and from the tracks we need some sort of muffling to keep the authorities off our tails, and to maintain our sanity.

We recently came across a product that just may fulfill our wishes. Car Chemistry has engineered exhaust inserts, a perforated tube and disk assembly which slips into the header collector or intermediate pipe, and reduces sound through an innovative mixing of hot and cold exhaust gasses. A center tube with perforations directs hot exhaust gasses to a cooler, outer, area between the disks. The gas cools and is drawn back into the exhaust flow creating a unique sound and scavenging affect. Furthermore the CCInserts are tunable, using supplied plugs and restrictors, allowing you to fine tune just how much sound dampening (and thus back pressure) you want.

Best of all they weigh just under one pound and measure about a foot in length, compare that to 40-50 pounds for a complete exhaust and muffler system which spans the length of the car. The inserts install in the collector in a matter of minutes.

We installed the two-disk inserts in our '67 Mustang, and found that they were only a few decibels louder than our 3" Terminator exhaust system at idle and at 3500 rpm. Most tracks have a decibel requirement of no more than 95 dbA (measured at 3500 rpm from 50ft behind the exhaust exit.) Most county ordinances have an exhaust sound regulation of no louder than 90 dB for automobiles. Our results with the two-disk inserts placed us well below the track limits, and just barely below the legal requirements.

We clearly noticed a change in the exhaust note once the engine warmed up. At cold idle the sound was very similar to open header, deep and rumbly, but once the hot and cold gasses were mixing as the insert is designed, the sound became very crisp and throttle response picked up.

In terms of power, we have not had a chance to get Project 11.99 back to the track with the inserts. (When we do, we'll report an update.) Seat of the pants wise, there is a noticeable improvement in throttle response. You can typically expect to jet up one or two sizes from a full exhaust system, or jet down one or two sizes if you previously ran open headers. Extensive testing by Car Chemistry shows a gain of up to two tenths over a fully muffled car, which is on par with what you'd see with open headers. Keep in mind there is also a slight gain from dropping the weight of a full exhaust system.

By the way Car Chemistry has spoken to NHRA about the use of CCInserts, and whether they are considered as legal mufflers for events which require mufflers. So far most tracks are accepting the inserts, so long as the dBA requirements are not exceeded. Car Chemistry tested the inserts on a 557 CID Ford with 13:1 compression, and it met the sound requirements at 94dB. So it is safe to say the majority of cars will have no trouble meeting the NHRA limit.

All in all we feel the inserts are a great product for cars which spend most of their life at the strip. Consider that most strip cars usually have a 3" or larger short exhaust system, using straight-through design mufflers - the CCInserts would not only save on the cost of fabricating such a system, but reduce weight and increase clearance under the car for suspension pieces, and access to the drivetrain. An added benefit, we found, was that there is no dreaded drone as common with many flow-through type race mufflers.

If you're planning on extended street driving, we'd recommend the three-disk inserts for a reduction of an additional four to six dB. The nice thing about the three-disk inserts is that if you find you can tolerate a little more sound you can always cut a disk off. Don't get us wrong however, the inserts are not "quiet" by any means and we wouldn't slap them on a daily driver or heavy commuter, mainly because the exhaust exiting under the front of the car creates a snare drum effect inside the cabin. We measured the decibels inside the '67, at idle it is near 90dB, and once you get moving the sound level inside the car approaches 100 dB. That is enough to cause hearing damage if sustained for long periods of time. Car Chemistry does offer the inserts in a cat-back system with intermediate and tail-pipes routing the sounds and gasses to the rear of the car, which would be ideal for street cars.

Car Chemistry Inc.
http://www.carchemistry.com/
1060 B Enterprise Dr.
Midlothian Dr, TX 76065
Phone (972) 775-8124
Fax (972) 775-8125