As consumers in a today’s world we are faced with a wider range of products than ever before. One could argue that many companies have been driven by the need to meet the demands of the consumer. While others could introduce new products based on testing and the foresight to tackle a challenge in a different way than before. In the automotive aftermarket world, the latter of the two arguments is usually the more popular of the two. In other words, some speednut found a way to make his car go faster, looked better or handle more efficiently and all his friends wanted to do the same; leading to mass manufacturing allowing the masses of custom car enthusiasts to experience the same improvements themselves.
When it comes to increased performance and power. Tons of parts, modifications and packages are available. We were curious about one of the more highly debated subjects in the performance world; that of exhaust mufflers. While mufflers were invented to do just that, muffle the sounds caused by exhaust gases; those speednuts have worked on various configurations to allow for performance to be maintatined or increased while still muffling the sound.
In theory, testing these performance mufflers seemed to be a simple task. However, through our research we found that “exhaust tuning” really is a true science and many factors can come into play. Serious horsepower seekers also bring into play the size of the tubing, the length of the tubing, which tends to depend on other variables such as camshaft specs and whether it is naturally aspirated, turbo or super-charged, or with nitrous injection. All these variables have different affects on scavenging where the exhaust gases actually help with engine performance. All have different needs that should be taken into account when selecting exhaust.
To keep things as fair and straight forward as possible, comparing apples to apples on the same tree so to speak was the best way to see the differences between performance mufflers. We opted for mufflers that were the most common for street performance drivers from popular brands. The mufflers included Flowmaster, MagnaFlow, Borla Exhaust and newcomer Black Widow Exhaust. We headed over to Westech Performance in Mira Loma, California, to see if they had a suitable street driven engine package that we could perform numerous tests on with similar circumstances on each test to maintain consistency. Their test mule is a 370 CID small block Chevrolet engine that is naturally aspirated and makes consistent pulls between 510-515 HP on Westech’s Superflow engine dyno.
During each test we made sure that the conditions of the facility were as uniform as they could possibly be, as ambient dyno room temperature, as well as the humidity levels were checked over and over again. As far as the engine variables, temps were checked over and over during operation. Further, the engine was allowed to cool down to the same temperature between runs to ensure that the engine would provide consistent results. The mufflers were fitted to the dyno’s collector tubing at the same distance each time as well. Steve Brule at Westech Performance managed the test and also made sure that the air/fuel ratio was the same for each run so that the only variable in power differences would be the mufflers themselves.
Each test began much like that of an actual driver in a performance car. A few pulls warmed things up before steadily providing power up the RPM range to 6500. Each muffler went through 3 runs that were averaged together to show the consistent horsepower and torque numbers from each batch allowing for comparison.
The following graphs show the results from our testing. While the mufflers had similar top end horsepower and torque numbers; what differed and surprised us the most was that some mufflers offered up more low end torque between the 3500-4500 RPM range. For street driving, this is near the top end and for drag racing, this is the range for building power off the line. This means that the Borla muffler and the Black Widow Venom muffler offered more performance where it counts and showed us that there truly can be a difference in muffler design on the same application. Muffler sound is the other important factor when purchasing an exhaust setup, but that can be subjective and depend on the application whereas the performance of the four mufflers was clearly testable and showed promising results.