Exhaust Products - Case Study
High radiant heat emitted from the muffler shell can cause grass browning*, engine vapor lock**, fires and excessive bumper and shroud temperatures. Muffler temperatures started increasing an engine OEM's created leaner burning engines to meet the EPA Tier 1 Regs issued back in 2001. The engines continue to become increasingly leaner burning to meet Tier 2, Tier 3 and now Tier 4 Regs.
To date, Lawn Mower OEM's have added heat shields above and below the muffler to reduce grass browning and vapor lock. But the additional parts have increased the complexity, cost, labor, and increased the likely hood of a fire. The shields create areas for dry debris to build up, increasing the chance of a fire. The current consumer muffler has a top shell temp of 980ºF and bottom shell temp of 800ºF.
We recently developed a new consumer muffler (Patent Pending) with a top shell temp of 350ºF and a bottom shell temp of 200ºF in response to the heat issue. We have eliminated all internal baffles and flat outer reflective surfaces to significantly reduce the radiant heat emitted from the outer shell. The lower radiant heat allows our customers to remove the top and bottom heat shields reducing parts, complexity, cost, labor and the likely hood of a fire.
Our overall sound level is at or lower than the current consumer muffler but with the advantage of a lower frequency level (improved sound quality). As mentioned about we removed the internal baffles substantially increasing the size of the expansion chamber which lowers the sound frequency.
*Grass browning will occur if the grass temperature exceeds 140ºF. When grass temperature exceeds 140ºF, the outer protective layer of paraffin melts causing the grass to dry up and brown within 24 hours. The condition is most likely to occur if the lawn mower operator stops the mower, idles the engine and does not move the mower for more than 10 seconds.
**Engine Vapor Lock will occur if the temperature of the carburetor float bowl exceeds the vapor temp of the fuel. This will most likely occur within minutes of engine shut down. You will not be able to restart the engine until the engine has cooled down.