Related Photo Galleries
Fig 7 The line rising from left to right shows muffler flow versus the percent of maximum power retained compared with open-pipe power. Once the flow reaches 2.2 cfm per hp, the output seen is as per open pipe output. The line descending left to right shows the typical backpressure seen. At 2.2 cfm per hp, the backpressure should be down to as little as 0.2 psi (a little less than 0.5 of an inch of mercury).