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Location:
Arthurs Creek, Victoria
Registered:
May 2002
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Crackling noise out of exhaust
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Mon, 17 June 2002 10:27
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I've got a bit of an exhaust on the peugeot, and when I downgear, it crackles. Which I like. I'm curious as to what the noise is, and how I can get a turbo (Ie mine) to work the same way, I just love the noise.
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Location:
Rocky Mountains, Canada
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Mon, 17 June 2002 10:49
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The crackle is probably caused by unused fuel exploding in the exst manifold. Most of the time its caused by vaccuum leaks on the inlet manifold or carb. Although some poeple have said that the change from leaded to LRP has caused it.
So... to get it to happen on a turbo, youll need to explode some fuel in the exst manifold or in the exst tubing.
Pumping large amounts of fuel into the engine during idle (off-throttle) could make it happen, but itll probably damage your turbo in time.
The way the rally guys do it is quite cool. Turbo anti-lag.
They pump excessive fuel into the engine during idle, and then on opening of the exst valves, they spark that cyls spark plug again causing the unburnt fuel to burn as it leaves the engine. The extra explosion then keeps the turbo spinning during gear shifts.
This is what causes the crackling on thier cars.
To do this though requires quite a cool ECU system.
I think this also shortens the lifespan of the turbo.
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Location:
Arthurs Creek, Victoria
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Mon, 17 June 2002 10:59
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I figured it was just unburnt fuel and doing it the way that the rally guys do, shortens the shit out of the life of the turbo.
I didn't think that it was going to be possible to make a turbo car do it, just given the way the car works and all.
oh well, it was a nice thought.
now to make the bmw do it.
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Mon, 17 June 2002 11:22
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I had this happen to me on my old Scorpion before I sold it... I loved hearing it decelerate in 3rd and 2nd gears. At one stage it was running really rich on the carby setup I had, and it was flaming out the exhaust on 3rd gear compression/deceleration. 
I asked one of the guys here in Ballina about it and he said it was to do with the different lobing on the camshaft (being small or 'torque' cam), and/or the timing setup. He actually re-curved the dizzy on it and tuned the Weber's I had installed, so that it didn't do it as severely, but still did it - I couldn't fix it properly for some reason (not that I really wanted to), but the flaming was fun... not real good for the fuel tank. 
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Location:
Montrose, VIC
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Mon, 17 June 2002 12:43
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I've been a bit of a long time lover of this... My ke30 dirt road bashing/pizza delivering car has been through 3 mufflers cos of this, probly because of me turning off the key to make it happen  I've tried playing with mufflers to try and get the maximum amount of noise happening I can too, and I've suceeded in putting dents in the floor of my boot! Scares the absolute buggery out of other traffic too, they pull over and think their tyres are gone. Do it under a large concrete bridge, absolutely sensational.
My turbo ae86 also does it, cos of the harsh Haltech rev limiter that insists on backfiring. When it backfires through the intake, I'm NOT happy, but through the exhaust is fantastic, lets out quite decent looking flames...
So enjoy and encourage it! Retarded timing should help it, as will thrashing the thing and getting the exhaust really hot. I'm gonna try and study it 
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Location:
windang
Registered:
June 2002
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Re: Crackling noise out of exhaust
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Wed, 19 June 2002 07:29
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Hi my RA65 does it also just ask YOGI 
it's got a K&N filter so she also is also load on the breathin side and all gases are expeled through a 2 1/4 inch system leadin into a 3 inch cannon .had it tunned and even went 2 the trouble off buyin a air/fuel ratio gauge and all is sweet 
GOT 2 LOVE THAT DOWN SHIFT POP
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Banned member
Location:
Brisbane
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Wed, 19 June 2002 10:06
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steve i get that too in my ra65, my system is 4-2-1 extractors into one muffler only no catalytic convertor or resonator bullshit , 2.5 inch exhaust, uni filter fitted, mildly worked motor
i downshift constantly to pull up at lights, sve a bit of brakes probably use more fuel but you get lots of attention, i get more of an exploding cannon fire, like a machine gun
awesome
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Location:
gold coast
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Wed, 19 June 2002 10:50
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If you want that noise on your turbo car, set your programable ECU to give it more fuel on overrun.
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Location:
Western Sydney
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Wed, 19 June 2002 11:07
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That noise can also be caused by an exhaust leak coupled with unburnt fuel in the exhaust.
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Location:
Arthurs Creek, Victoria
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 02:13
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Well, it sounds like something bad occuring in a turbo car, so I won't go to the effort of doing it.
:-_)
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Location:
Newcastle
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 07:35
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hey i have just started getting this crackling on my 18R-GEU celica i just put a straight through muffler on it off a racing 4 stroke dirtbike and it is cool sounds like a rally car.
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Location:
Melbourne
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 08:47
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At least i know my car is operating properly then (ie. no crackles)
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Location:
Newcastle
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 09:05
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G'day all,
My 18rg used to do this too. i was told that it was due to the straight through exhaust! sounded cool...
Now i make cool turbo sounds instead... Don't worry stradlater the 1g makes plenty of cool sounds to amuse yourself with!!!!!
Enjoy
Stew
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Location:
Victoria
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 09:44
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you guys are on the right track... it is due to unburnt fuel entering the exhust manifold, but its not all bad. THe sound is more prodominate in extracted cars, as most sounds are amplified. This un burnt fuel enters the manifold on over run because the carbi (im not so confident with EFi donks yet) is still pumping (allowing to pass)fuel, due to the engine having rev's up (and thus vacuum). The crackling can be altered by changin gthe overlap of your cam (being the reason why race/rally cars crackle REALLY loudly.. or have flames because they run enormous amouts of overlap)
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 10:41
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As someone else said though, a lot of the newer/race cars will be doing it because of the anti-lag
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Location:
Victoria
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 12:28
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sorry.... i cut myself of eariler... adding to my post.... crackling (or blatting as also know) isnt bad for your exust... as long as the carbie / EFi isnt pumping an inordinate amound fuel, producing flames out the back of a road car (i know we would all love to be shooting flames a la fast and furious), but yeah, its not good (espicially forr exhust O2 sensors). I think the whole of fast and furious is a load of crap, flames out of exhusts on full revs or load is bad (unless its a methanol or nitromethane drag car..... in that case more is best) I am sure that there is more in consistancies in that movie, my mate swears everythign that he sees in that movie is real..... so i just accept that he is a six pack short. Back to the topic.............. my car blats well, and i love it.... sounds wicked pulling up to lights, a real impression that you mean business.... and my car as a true sleeper (although not that quick, it beats VL NA's regularly) it has many scratches, and is at least a 4 tone paint job..... 2 tones of green, bog and primer... hehe 
anyhow.. have a good one all
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Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 13:07
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My car does it all the time. Whenever decelerating it goes snap-crackle-pop constantly. Just put a leak in the exhaust system. Mine is at the flange gasket (there is no gasket). Although this makes the carsound like shit when the foot is down (a pfft-pfft noise whenever one of the cylinders fires). Kinda sounds like a VW beetle. an old one.
Tim
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: Crackling noise out of exhaust
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Fri, 21 June 2002 13:47
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Even a shitty old Scorpion that's barely been modified can blow off a N/A VL... but a tall gear range does help somewhat in that race.
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