rev up your engines, today I'm going to talk about why you shouldn't change the
muffler on your car, and to explain why, we'll have a little history lesson, in 1897 the
Reeves Brothers of Columbus Indiana patented the first modern muffler system
for engines, now mufflers do exactly what their name says, they muffle sound, making
it quieter so engines aren't loud and obnoxious, here's my wife's Lexus when
you rev it up a little, rev it up, okay
it's about 42 decibels, not that loud, and here's my Triumph motorcycle that doesn't
have any mufflers, it's a racing setup they look like mufflers, but there's
nothing inside,
okay that's 110 decibels, and as you can see on a decibel chart, the
Lexus is quieter than a speaking voice, while the motorcycle, hey it's up there
almost as loud as a pile driver, which is 112, so if everyone with all their
vehicles took the mufflers off, and either put straight pipes with no
muffler, or a fake muffler that had no baffle plates inside, it would be really
loud outside, now yes mufflers do restrict the power of an engine some
because it restricts how fast the exhaust gas can leave, but if you've ever
gone to a racetrack, last year I went to the Indianapolis 500
and man, that is loud, those babies don't have any mufflers on them at all, I couldn't hear
for a couple of days, I didn't wear any earplugs or anything I wanted to
experience the whole thing, you could feel it in your chest, everywhere I mean
those babies are loud, and I know a lot of young guys, especially with Japanese
cars, they're taking their mufflers off, throwing them away and they're putting on those
little free flow mufflers that sounds kind of like bees when they're driving down
the road, and if you listen closely to a lot of them, you'll hear that they don't
sound like they're running right, and that's because they aren't running right
their cars were made to run correctly with the muffler system on them, the gas
is made to flow at a certain speed, the oxygen sensor measures how much residual
oxygen is in the system, they store some of that oxygen in the catalytic
converter, and if you take the muffler off and you make the system flow a lot
faster, that messes with the anti-pollution system, it can also mess
with the air fuel ratio that the computer gives the fuel injectors and
they actually can end up running worse, if you take the original muffler off, now
I have to say that this Mustang that I just tested out, it's got a great sound
just listen to it
but guess what, that baby was designed by engineers, they spent a lot of time
having to make the sound that they want, having it work with the anti-pollution
system to make it legal, and even to have it pass the decibel ratings, there are
certain ratings that cars can have to be sold in the United States, now I know people
are going to say, Scotty you're a hypocrite, your motorcycle back there, hey you
took the mufflers off of that, but hey I got fancy software in a computer, it's an
English motorcycle and the English are nuts about modifying motorcycles, so there was
a great website where I could just download different patches for what
exhaust you put on, and reprogram the computer, so it would run perfectly and
that's why I see so many guys driving around in Harley's that backfire and
even sometimes Ferraris that backfire, they change the exhaust system but they
don't reprogram it to run correctly, so then they run really badly, even though
they make a lot of noise, hey they're not running right and that's not what
you want, a loud car that doesn't run right, now when I was young mechanic in
the sixties, hey it wasn't that hard to change your muffler out and put a
freer flowing system, because they had carburetors, they have jets in them that
allow more or less fuel and air to come in, and you could re-jet the
carburetors to compensate for putting a free-flowing exhaust in, anybody with a
little time and a little imagination could do it, but modern cars they're all
fuel-injected, they have air fuel ratio sensors, that are very sensitive you
can't just change the exhaust system of the car, even just putting a free-flow or
a muffler in is going to mess with all that computer software and usually the
check engine light comes on, they don't run right, you get worse gas mileage, so it's
not a smart thing to do if you're just planning on making a little bit noise
with your car, and really even if you have all the equipment in order to
reprogram it and know what you're doing, you only get a very minimal power gain
by taking the muffler and changing it it, doesn't make all that much difference
for actual power, so now you know why you shouldn't take your stock muffler off
and put on one of those performance mufflers, and I'm sure there's going to be
plenty of people that are going to put those loud mufflers on
and think it sounds cool, but at least I can say I warned you about it, so if you
never want to miss another one of my new car repair videos, remember to ring
that Bell!