Which size SuperTrapp muffler should I use?
For the best sound reduction, use the largest muffler you can fit in your application. In general, larger diameter and longer mufflers are quieter than smaller mufflers. The 4" diameter mufflers are recommended for engines up to 250 HP or 4.0L (250 CID). The 5" mufflers can handle up to 400 HP or 5.7L (350 CID). Larger or more powerful engines should use two or more mufflers in parallel.
Is there a downside to using more than one muffler?
In general, the fewer the cylinders per muffler, the louder the exhaust will be. Using one muffler per bank of cylinders on a V-8, for example, will be louder than a similar system with both banks going through one muffler. The tradeoff here is that running all of the exhaust through one muffler will increase back pressure and reduce high-end power.
What do the SuperTrapp discs do?
SuperTrapp mufflers and diffusers use a closed end cap to force the exhaust gases out sideways, rather than out the end of the muffler. The discs are installed between the end of the muffler and the end cap. Each disc adds a small gap for the exhaust gases (and noise) to escape through.
How many discs should I use?
Adding more discs under the end cap will increase the number of gaps for the exhaust to escape, while fewer discs will decrease them. More gaps means more flow, more high-end power, and more noise. The upper limit would be to remove all discs and the end cap, making the SuperTrapp into a flow-through glasspack muffler. Fewer discs means more restriction, more low-end torque, and less noise. This also means that you can change the number of discs to suit different tracks and weather conditions.
How many decibels will a SuperTrapp muffler cut from my sound readings?
Unfortunately, there are far too many variables to be able to predict how much the exhaust sound will be reduced. Bore, stroke, compression ratio, number of cylinders, RPM, header design, and even the weather can all affect decibel levels.
I have to comply with a sound limit. Where should I start?
Start with the largest SuperTrapp muffler you can fit on your application. This will be a compromise between weight, available room, and pipe diameter. Try running just three discs at first. If you are well below the sound limit, gradually increase the number of discs while monitoring your sound readings. Stop adding discs when your sound readings get close to the limit. We recommend keeping a safety margin of 2-3 dB under the limit. Note that you may reach a point where adding more discs no longer increases power, or bottom-end torque suffers. In that case, just run the number of discs that balances high-end power with low-end torque.
How does weather affect noise?
High barometric pressure (cold, dry days) transmits more noise than low pressure (warm, humid days). Also, low cloud cover can trap and reflect sound, increasing your readings. On days like that, consider taking out one or two discs as a precaution against sound violations. (Note to physics majors: Yes, these are broad generalizations that are mostly true for the frequencies that race cars produce.)
How do I care for my SuperTrapp?
All SuperTrapp mufflers and diffusers require high-temperature anti-seize on the bolts. It's a good idea to take your SuperTrapp muffler apart every year or two (depending on use, storage, weather, etc) and apply fresh anti-seize to all the bolts to guard against corrosion. When you notice your glasspack muffler getting louder, it can easily be repacked to restore effectiveness. Replacement cores are also available to restore mufflers that have suffered internal corrosion damage.
What is the proper torque for the bolts on a SuperTrapp?
Fifteen inch-pounds (1.25 foot-pounds), or about two full turns after the head of the bolt contacts the end cap and disc stack. Be sure to use a liberal amount of anti-seize. Copper-based anti-seize (such as Copaslip) withstands higher temperatures than nickel-based anti-seize.