I just came back from a drive and I’m wondering why my 3.0L I6 engine which has roughly 385HP is relatively quiet besides a low growl compared to my extremely loud lawnmower which as a tiny 6HP single cylinder? Would the muffler of my car make that much of a difference?
In: Engineering
It’s pretty simple, really: your car engine is stuck inside the car itself and there’s a lot of insulation etc going around it
A lawnmower is an engine sitting out in the open with nothing to block the sound.
Yes, the muffler would make that much of a difference.
The sound in the cabin is insulated so you barely hear it but you don’t hear the engine noise outside the vehicle to the degree you hear a lawn mower either. Heck even when the engine bay is open it’s not that loud the exhaust really does make that much of a difference.
Heavy equipment engines, like those found on tractors and bulldozers, do not have said insulation as they are exposed to the air and aren’t as loud as a lawnmower engine because of their exhaust systems.
I once split the exhaust pipe on a car while driving holy hell it got loud. The muffler brings down the sound level from both inside and outside the cabin dramatically.
Your lawnmower’s engine cost a couple hundred bucks. The car’s engine cost a few thousand
A significantly different level of engineering went into both
Your lawnmower has so few power that a muffler would choke it. With a car it lowers the power also a bit, but that’s calculated. That’s also the reason, why tuner cars are so loud: They want their power back.
Would you buy a car that was as loud as that lawnmower?
Would you spend 2-3 times as much money for a lawnmower if it were quieter?
That’s the reason. People will pay a lot more money for a car to be quieter. People will not pay a lot more money for a lawnmower to be quieter.
In addition to the muffler and insulation reasons that have been brought up, the engines also work differently.
A lawnmower engine is a 2-stroke while a car is a 4-stroke. A 2-stroke means there’s an explosion in the cylinder every time the piston moves down while it’s every other time in 4-stroke.
So there’s inherently twice as much noise for every revolution in a 2-stroke on a per cylinder basis.
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You could put a large muffler on a mower engine, but space and weight considerations are more important.
Years ago there was a study on lawnmower purchases. Many consumers preferred the louder mowers, relating a louder mower with more power.
There are a few reasons for this that have already been addressed already. But I’d like to also point out that your car is water cooled and your lawn mower is likely air cooled.
Air cooled engines do not have coolant surrounding the cylinders, which helps aid in reducing sound transmission from the explosions.
Ever driven or been around an older air-cooled VW or similar? They’re quite a bit noisier than water cooled engines. Sure, part of that is the lack of extensive exhaust system. But the air/water cooled also plays a large role.
Crawl under your car and disconnect the headers from the block. Then fire it up and see how it sounds!
(Note- This is a joke. I do not recommend this. )
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