Title should be clear but I cannot get a straight answer so hoping you guys&gals can help, I am talking about the "standard" type of small 40-100cc handheld internal combustion 2-stroke engines that power everything from handheld blowers to chainsaws to weed-eaters, I customize/modify my units and there's been discussion in a forum on this topic IE whether or not we want ANY back-pressure from a muffler for a "most powerful build" (keeping a muffler allows scavenged exhaust gas to get back into the casing so it's more efficient, but here I'm only concerned with maximal power output!)

Thanks a ton, my money is on "any & all restrictions/mufflers on the exhaust-port of the engine will decrease power, period", but here to finally resolve this one ;D

  • No, some are specifically tuned to cause a depression at a soecific flow rate or velocity to help extract combustion gases. Even the exhaust ports can be designed with different diameters to stop re-circulation.
    – Solar Mike
    Commented Sep 1, 2021 at 9:03
  • I think this answer may help with your understanding. That is if it doesn't answer it outright. Commented Sep 1, 2021 at 13:17
  • Chain saws are safety rated with a spark arresting muffler, more to prevent combustion fires from igniting dry tinder in forests, less emphasis on muffling noise when ear plugs or hearing protectors are worn. Weed Wackers and blowers, while not used in forests probably follow chain saw design to be as compact as possible. Most two-stroke engines operate at peak rpm and torque so stock mufflers do little to prevent max power. Scavenging, tuned exhaust systems, draws as much combustion byproducts out the exhaust while minimizing pulling out the fresh air/fuel mixture at a specific rpm.
    – F Dryer
    Commented Sep 2, 2021 at 2:09


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