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Location:
Sydney
Registered:
September 2004
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 no muffler?
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Sun, 03 October 2004 13:02
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hiya ppl
my friend has an ae82 corolla (not sure if it's really relevant) but it has no muffler
to be more precise the muffler has been cut off
what are the effects of this, apart from obviously making the car sound louder
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Location:
Montrose, VIC
Registered:
May 2002
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Re: no muffler?
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Sun, 03 October 2004 13:07
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People will think you are a tool, because you can't afford a milo tin, but wanted the gawdawful racket anyway  Is that an effect?
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Location:
Sydney
Registered:
September 2004
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Location:
Potts Point, Sydney
Registered:
October 2003
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Location:
Montrose, VIC
Registered:
May 2002
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Re: no muffler?
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Sun, 03 October 2004 13:21
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So he paid $100 to have the muffler chopped off? Interesting..
Sad thing is, I've actually done the same thing to a couple of cars for people - chop the muffler off, weld on a piece of old tailshaft - just never had the gall to charge $100 for it! Sounds horrid, but keeps them happy.. for a little while..
Often the car ends up running worse for it though
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Location:
Sydney
Registered:
September 2004
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Re: no muffler?
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Sun, 03 October 2004 14:28
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LOL
NOOOO
what kind of idiot would pay $100 for that?
he bought the car for $100 and it already came with a chopped off muffler
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Location:
Sydney
Registered:
September 2004
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Re: no muffler?
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Sun, 03 October 2004 14:30
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i know next to nothing about cars so would you be able to tell me why it would result in power loss or run worse after a while?
all in the name of learning 
cheers guys
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Location:
Dandenong Ranges, VIC
Registered:
July 2004
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Re: no muffler?
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Mon, 04 October 2004 13:19
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without getting too detailed, for your motor to work efficiently it needs to have some ammount of back pressure (resistance to the exhaust gas flow) present in the exhaust system. usually with a drop in back pressure you get a drop in bottom-end power, and, if done correctly, a gain in top end power. but in this case, a shitty stock AE82 with bugger all back pressure due to being de-mufflered would most likely have less power down low and probably no more up top. and would sound criminally shithouse.
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Location:
Sydney
Registered:
February 2003
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Re: no muffler?
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Mon, 04 October 2004 13:21
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but the system has two mufflers doesnt it? so there would still be a muffler on there and a few feet of peashooter piping. id say thats fair backpressure
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: no muffler?
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Mon, 04 October 2004 14:09
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| greenta22 wrote on Mon, 04 October 2004 23:19 |
without getting too detailed, for your motor to work efficiently it needs to have some ammount of back pressure (resistance to the exhaust gas flow) present in the exhaust system. usually with a drop in back pressure you get a drop in bottom-end power, and, if done correctly, a gain in top end power. but in this case, a shitty stock AE82 with bugger all back pressure due to being de-mufflered would most likely have less power down low and probably no more up top. and would sound criminally shithouse.
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that all depends on how mismatched the cam is to the rpm range 
the backpressure myth stems (imho) from V8 kiddies who put 300+ deg cams into a motor that revs to 5grand and (miraculously) they find that they need backpressure to keep the mixture in the cylinders....
backpressure is a myth. a well designed exhaust system helps the exhaust get sucked out....
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Location:
Sydney
Registered:
September 2004
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Re: no muffler?
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Mon, 04 October 2004 14:54
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from memory there's just ONE exhaust pipe with a muffler but now there is no muffler
so its just a tiny pipe
so this whole thing about back pressure is a myth?
it won't harm the car's performance? 
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: no muffler?
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Mon, 04 October 2004 15:00
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it will harm the performance of your car when the police defect you.
it will harm the performance of your car when your neighbours complain about the noise to the EPA.
it will harm the performance of your car when your neighbours get even more pissed off, roll it out into the street, douse it in petrol, and set fire to your unmuffled car. 
the backpressure thing works for motors that are designed improperly. show me an F1 car, an indy car, a V8 supercar.. or any performance car, that uses backpressure to enhance it's performance...
if backpressure (ie exhaust restriction) is good for low revs.. what happens when you double the revs and you still have the same restriction?
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Location:
Sydney
Registered:
September 2004
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Re: no muffler?
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Mon, 04 October 2004 15:07
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| oldcorollas wrote on Tue, 05 October 2004 01:00 |
it will harm the performance of your car when the police defect you.
it will harm the performance of your car when your neighbours complain about the noise to the EPA.
it will harm the performance of your car when your neighbours get even more pissed off, roll it out into the street, douse it in petrol, and set fire to your unmuffled car.
the backpressure thing works for motors that are designed improperly. show me an F1 car, an indy car, a V8 supercar.. or any performance car, that uses backpressure to enhance it's performance...
if backpressure (ie exhaust restriction) is good for low revs.. what happens when you double the revs and you still have the same restriction?
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as you may have guessed i don't know much 
why is exhaust restriction good for low revs?
isn't it better if the air is allowed to keep flowing through?
i have no idea, i hope somebody can answer that
and oh, it's not really that noisy at all
it just sounds like any other car that has a quietter aftermarket exhaust
it's just a tiny bit riced =P
[Updated on: Mon, 04 October 2004 15:09]
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: no muffler?
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Mon, 04 October 2004 15:19
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| thu187 wrote on Tue, 05 October 2004 01:07 |
as you may have guessed i don't know much
why is exhaust restriction good for low revs?
isn't it better if the air is allowed to keep flowing through?
i have no idea, i hope somebody can answer that
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if cam timing is such that there is a lot of valve overlap, then at low rpm the fresh intake charge will tend to flow out thru the exhaust valve while both are open.
if you have a restrictive exhaust, the backpressure will stop the air/fuel mixture going out the exhaust before the exhaust valve closes.
at higher revs, this pressure builds up and makes it harder for exhaust to get out, reducing 'power'.
basically, if your engine needs backpressure, then you have selected a cam with too much valve overlap..
but thats just my unfounded opinion
read a book called "the scientific design of intake and exhaust" or similar. by P.Smith.
Cya, Stewart
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Location:
Sydney
Registered:
September 2004
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Re: no muffler?
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Mon, 04 October 2004 15:22
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that actually made sense to me 
okie dokie, i'll try and get it some time
thx stewart!
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Location:
Sydney
Registered:
September 2004
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Re: no muffler?
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Mon, 04 October 2004 15:28
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| greenta22 wrote on Mon, 04 October 2004 23:19 |
without getting too detailed, for your motor to work efficiently it needs to have some ammount of back pressure (resistance to the exhaust gas flow) present in the exhaust system. usually with a drop in back pressure you get a drop in bottom-end power, and, if done correctly, a gain in top end power. but in this case, a shitty stock AE82 with bugger all back pressure due to being de-mufflered would most likely have less power down low and probably no more up top. and would sound criminally shithouse.
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hmm.. are you saying back pressure is good for higher rpm because at lower revs it creates the back pressure then at higher revs the valves stay open for longer so you're releasing all power + the air that's stuck to get some kind of huge power hit?
or am i totally lost?
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: no muffler?
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Mon, 04 October 2004 16:33
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like it said, back pressure is a myth. some say its good some say its not.
personally i have tried quite a few exhaust set ups on my old car and realized that its much more fun with less backpressure. I myself removed my muffler and cat. converter when i go to tracks. (didnt bother making a side pipe)
My opinion is, get as little backpressure as possible with as little noise. Cant explain Y but it feels better.
Just my opinion
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Location:
Brisbane
Registered:
May 2002
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Re: no muffler?
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Tue, 05 October 2004 02:31
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As already discussed at length, an engine does not need any backpressure to "run properly".
I think part of the reason for this myth is people replace their highly-restrictive factory exhaust with a free-flowing one, and don't re-tune the engine to match the new VE characteristics. This can result in flat-spots due to incorrect fuel mixtures.
What this means in a nutshell is an engine will perform best with ZERO backpressure, if it has been tuned properly, and if it doesn't have weird cam timing as discussed by Jason.
Remember backpressure = exhaust gas left in the combustion chamber = not good for performance.
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I Supported Toymods
Location:
south Melbourne/KL
Registered:
June 2004
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Re: no muffler?
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Tue, 05 October 2004 02:41
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exactly what i was gonna say except i timed out and couldnt be bothered typing again earlier.
As for piping size, u'll need to find just the right size. too big piping, u will lose power but ur car will still run PROPERLY. Piping diameter is like blowing air out through a straw, big diameter, more air out but slower and vice versa. Its all about finding the right combination for different engines.
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