ChampCar Endurance Series Sound Levels

ChampCar rules require all cars to have mufflers. Even at tracks that traditionally don't require them. ChampCar does. This page was written a few years ago towards passing sound at tracks like Laguna Seca that have limits below 90dBa. Currently ChampCar's are limited to 96dBa max at all tracks. Some tracks like NCM Motorsports Park, Atlanta Motorsports Park, and Thompson may have lower maximum sound levels. This page should help you to meet those sound requirements.

From an article, a few years ago, it seems like the focus is up the hill towards turn 6. photo courtesy of South Bay Riders.

1. You MUST have a QUIET CAR! You will be kicked out of the event after three strikes. That is 3 for the whole weekend.
2. You MUST have a QUIET CAR! You will be kicked out of the event after three strikes. That is 3 for the whole weekend.
3. You MUST have a QUIET CAR! You will be kicked out of the event after three strikes. That is 3 for the whole weekend.

Three strikes and you are out.

I said that three times for a reason!

Remember that your intake system can add to the overall sound of the car! It is not just the tailpipe. Intake roar can add significantly to the sound level. When testing your car, make certain it is under load, like on a dyno, or on the road.

The 3 strikes start from Friday test day and end on Sunday.
There is NO testing. There are no retries. If you fail three times you are done for the weekend.

If you fail and get kicked out by the track, it is your fault., You have been given plenty of warning via our communications, via the CCES forum, social media, email, and our website. Put at least one or two mufflers on the car, and quiet those intakes.

90.3dB would have you going home.
Again… Your race car must be quiet. All cars will be required to have mufflers. There are NO EXCEPTIONS to this rule.
“But I don’t have room for a muffler” is not a valid excuse.
These are county and track rules.

90db at 50 feet or you are asked to leave the event by the county and the track.

Even quiet cars should have the exhaust exits pointed up and to drivers left. Keep the intake air filters UNDER the hood and don’t try and add ram air unless the intake is baffled as the intake roar sound will exit the front and add to your overall noise (dB) number.

EVEN A STOCK EXHAUST MAY BE TOO LOUD!

Good read…
https://www.counterspacegarage.com/blog/publications/these-stock-cars-fail-laguna-seca-sound-limit/
If you have any questions email us at media@champcar.org
Bill Strong
Marketing Director
ChampCar Endurance Series

More Useful Information

It's always good to have some spare bents and exhaust piping in the trailer to fix issues at the track.

Side-pipe hookup kits are fantastic at allowing different ways of making exits or even fixing crash damage.
They come in various flavors, 2.5" and 3" for some cheap money. Unfortunately, it looks like 3" is out of stock. These are slip-fit mandrel bends with exhaust clamps, so no welding is needed.
Speedway Motors Side Pipe Kits

Having a couple of these combo bends is an excellent way of getting that "just right" bend.
Speedway Motors Stainless Steel Mandrel Bent pipes

I am using 2.5" exhaust, and I know that goes against every instinct to use big pipes on race cars. But the smaller pipes can also be quieter when it comes to the sound that the track is measuring. 2.5" is a good compromise when it comes to reducing back pressure and keeping sounds low.
As with any racing car, it's always good to build two systems for your vehicle, one on it and one in the trailer or pickup, to fix damage either during the race or after. I find buying these kits is super cheap and makes fixes easy.
Speedway Motors Mild Steel Mandrel Bent pipes

Exhaust flange gaskets.
After years of testing on the V6 MR2, I found different ways of making a very reliable flange setup for endurance racing.
The most reliable setup was the Chrysler/GM style ball and socket flange. Although heavy and costly, they are the most bulletproof setup I have ever used. In addition, these make great exhaust adapters where you can adapt dis-simular exhaust diameters, like make an 89db Laguna exhaust system. You can quickly put your 96db exhaust on when you race at Willow Springs.
Chrysler / GM style heavy duty ball flex

Header collector or general exhaust gaskets.
I have used the supplied gaskets for headers, and for the most part, they failed almost within the first stint. Especially the Chinese manufactured "eBay/Amazon" stuff. I have successfully welded new American-made 3-bolt flanges onto my Chinese headers, had about a 1/2" overlap on the joints, and made a pretty bulletproof setup combined with the copper gaskets. It's not perfect and doesn't take to moving around well without some flex. I also double-nut the bolts. Drilling the nuts and safety wiring, them also works well.
Speedway Motors Exhaust Header Flanges

V-Band interlocking clamps.
I started using these clamps a few years ago. Good ones are not cheap. But they are pretty damn reliable if you use them in conjunction with flex joints. These slip over the pipes and always have an overlap to act as the gasket.
Summit Racing V-Bands

Exhaust pipe flex tubes.
My car experience has shown that the ball and socket are the best for my racing applications. But sometimes money and maybe the location of the needed joint does not allow the use of one of those. The typical wire-wound flex is good as long as the inside is not braided wire. Those cheaper versions failed after one of two race events. Having an interlocking smooth inner section like this is much better and does last much longer. It was about a season of endurance races(10 or so).

Trailer tools.
Of course, everyone wants to do this racing stuff on the cheap. One of the best tools to load into your toter home and 40' triple stacker trailer is a welder. It's always good to have a tool to fix those pesky exhaust leaks that can keep you from racing. Welding with a MIG welder is not that hard to learn. Can you weld dimes as you see them all over the Internet? Hell no. But you can quickly learn to MIG weld your exhaust to easily pass sound. Of course, your buddies who hang out in welding groups on the Internet will frown upon the tool I will post up. You can easily spend five figures on welders, and the more pricey welders will probably make the job easier, and look better. But for just over $100 you can get a Flux MIG welder that can do an excellent job at field welding parts on your race car. Flux wire does not require a gas bottle, can get better penetration, and works fantastic in windy outdoor conditions. It's not a pretty weld like you see on the Internet. But it works. And remember, even if you don't know how to weld, 20 others in the paddock can do it as long as a welder is used. It operates on 110v power. It won't weld thick stuff in one pass, but it does a beautiful job for the exhaust pipe. Get some suitable gloves, an auto-darkening helmet, a roll or two of flux-core wire, and some good wire brushes. All that can be had for under $200.
Harbor Freight Welders

Exhaust hangers and clamps.
Those clamps you connect the pipe up with can hang down pretty low. Racing can take you places that might be good to those low-hanging bits on your car. However, they can dig into the dirt, which can catch on curbing, and when that happens, that can weaken the joint and cause the exhaust to hang or fall off. Keep the threads and nuts at an angle of at least 90 degrees to the ground.
Your muffler with its flat face can catch stuff too when you get off-road or even on curbing. I weld a 16-gauge steel sheet to the leading edge of the muffler to act as a ramp. This can also make the underside of your car more aerodynamic. Remember that it may be a good idea to add a ramp to the back of the muffler too. Your vehicle may not always be moving with the nose forward.