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maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 12:22
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hey guys,
Can someone please tell me if it's possible to have an exhaust so big (in diameter) that it becomes inefficient? what would be the optimal diameter for a 1jz exhaust? finance is irrelevant (i am speculating)
ryan
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Location:
Newcastle
Registered:
September 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 12:31
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if it is turbo then u can have it dump out the side(but not legal) i would recomend about 3in as any bigger and it may start to get a bit loud(very illegal) 
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Location:
Newcastle NSW
Registered:
June 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 12:56
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if its the turbo them 3 inch would be good but if its modified 3.5 to 4 inch will give good performance. any bigger and you couldn't lower your car cos if would scrape on every bump on the road. even 4 inch is almost too big
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Location:
Newcastle
Registered:
September 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:01
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anything over 3 inch is goin to be loud and over the legal noise limit of 90-96db unless u fit a restrictor which will reduce performance 
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:02
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I would say that a twin 2.5 inch system would be cheaper and easier to fit!
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:10
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On a turbo engine a bigger system doesn't necessarily mean it will be louder! Most of the time a smaller system can be louder due to the fact that the gases will resonate! But this theory will come down to who designs it! I reccomend getting a fully computer designed system, not one that is just put togeather with bits an peices that the shop has on the shelf!
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Location:
Newcastle NSW
Registered:
June 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:15
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i 3 inch system should be good for a stock engine or even a lightly modified one and would definitely be cheaper than 2 x 2.5 inch as it takes less room and you don't need to buy 2 of everything.
but a twin system always looks the goods
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:22
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Belive it or not the 2.5 inch piping is much cheaper than the 3 inch! With the twin 2.5 inch system you can merge the 2 pipes into 1 large cat and muff box wich will make the job look pretty damm good and cheap!
I have some photos of a twin job I designed for an Escort! I could try and scan them if you wanna see my great design work?
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Location:
Newcastle NSW
Registered:
June 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:44
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thats an interesting concept, i thought u meant 2 separate systems. the only problem i see with your twin setup is turbulence caused by the merging and splitting of the gas.am i right,front of system--> ===>--<====>--- <--muffler (just a shitty interperetation but i think it works)
BUT after doing some maths the 3 inch comes up tops with 2.1 square inches more surface area or effectively 30% more flow potential... you cant argue with that.
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Location:
Newcastle NSW
Registered:
June 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:50
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 stupid me whoops i forgot to double the 2.5 inch figures... its actually tipped the other way in favour of the 2x2.5 inches.... for about the same amount 30%
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:50
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Thats true but doing it the way I said will save a bunch of money, plus it looks great! And yes there can be a problem with the gases merging if it is'nt designed correctly! I did make that mistake 
For some reason when you go above 2.5 inches the price seems to double for every half inch! Has anyone else noticed this?
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Location:
Newcastle
Registered:
September 2002
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 13:55
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i priced a 3inch for my et pulsar and it was $1050 mandral bent and about$550 in 2.5in 
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Location:
Forrestfield, WA
Registered:
August 2002
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 Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 15:18
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I got a 3" Dump, 3" HiFlow Cat, Huge riceboy muffler.
ITs pretty loud... actually when you floor it and hit about 5-6k rpm it sounds like a dumped v8 
Just a note, if its an auto like mine, and you value your hearing, get at least one resonator fitted. I dont mind because i like the noise, but inside the car the drone is deafening when your at around 2000 rpm (ie doing 60-70km/h) and i get heaps of complaints from passengers and rude looks from people in cars next to me whos windows vibrate
Apparently manuals dont suffer from this... but yeah. I like the loud drone, it does take a bit of getting used to, im tone deaf to it now so its ok, but the hummm can give you headaches if you do alot hill driving as its always working in the low rev range.
Mine was Fitted by GENIE in WA. All up it cost me $1500 fitted and that included a restricter they made up but im yet to pick up.
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Re: maximum sensible exhaust size for 1jz
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Wed, 04 September 2002 22:19
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Big is good, twins are best!!
I have twin 2.75 inch from the turbo's (twin pipes) into twin 2.5 inch cats and twin 2.5 inch straight through mufflers, joining (behind dif)into a single 3.5 inch truck resonator!
system owes me very little, and its as quiet as a mouse!!
I'll try for some pics.
but it flows good and has no ground clearance issues.
Matt
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 02:27
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Yeah I prefer twin systems myself! If I design a system in the future for my Celica i'll be most likely doing a twin 2.75 or a twin 3 inch system! I'm can get those 2 sizes in stainless piping for about the same price as the cheap crap! Then i'll just need somebody to do the bending for me!
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 02:56
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is it right that bigger isn't always better as you need a certain level of back preassure?
(this message turned me into a forums junkie  )
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 03:40
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Back pressure is only an issue on non turbocharged engines, with a turbo there is more than enough back pressure produced by the exhaust turbine so as big as possible is the best possible option ofr turbo exhausts. that said there is some benefit to be had from certain designs.
I would not run a split system on a NA 4 cyl, 4 into 1 extractors have long been proven to make best torque and power, you need the pulse from all 4 cylinders to scavenge exhaust gasses from the other cylinders.
Matt
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 07:41
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just remember that beyond about 3.5", you're not going to get any gains at all (unless you're going for a 700bhp car).. all you're going to do is make lowering your car harder, cops pay more attention to the god-awful noise, and add extra weight.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 07:46
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what i find funny is when you look at full rally spec cars like evo's wrx's ect on many of them they could only have 2inch exhaust where you see someone in there fat standard CIVIC with 3" exhausts 
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Location:
Cabramatta, NSW
Registered:
May 2002
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 Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 08:01
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I've seen many CRXs with 4 2.5" exhausts... One for each 400cc cylinder I suppose...............
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 08:08
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and if they were really 4 separate exhaust systems they would go CRAP !!
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Location:
Canberra
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 08:47
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Hey guys,
Im getting a 3inch mandrel system for my 1G-GTE next week, and ive been looking arounda bit. The best price i came up with was $1000 for whatever i wanted in 3 inch.
So i get a good hiflow muff and Cat, nice tip, new 3inch turbo dump pipe, and either under or over diff depending on what fits better.
Cant wait for next week when it all happends!
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Location:
_Sydney _
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 09:02
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That sounds like and alright qoute, I enquierd at Hi tech mufflers for twin down pipes off the turbos and 3" stainless steel all the way and they quoted me $2800. Bit pricey for my taste.
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 09:09
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hey guys!
thanks alot for your suggestions, they will be taken into careful consideration.
money isn't an issue as i can get mandrel bends up to 4.5 inches at work. (truck exhausts!)
i'm buying an mx73 cressida, so a dual exhaust will probably not be do-able.
i guess a 3inch looks like the best answer.
once again thanks alot!
ryan
btw: is 2000-2500 a good deal for an mx73??
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Location:
Sydney
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 10:09
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i'm going twin dumppipes 3" all the way through
costing me just under a grand
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Location:
_Sydney _
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 10:37
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where u geting that done?
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Location:
Sydney
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 11:52
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i'd tell ya but i'd have to kill ya!!!!!
i'm getting it done mates rates plus im providing the cannon type muffler
its actually less than a grand
look if job turns out good i'll tell you guyz else yeah....
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Location:
Sydney
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 12:13
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Originally I had a 3" dump off the cast Y-piece into 3" Flex, 3" hi-flow cat to 2 X 2.5" resonators and 2 X 2.5" mufflers with standard tips - relatively quiet. Ground clearance was pretty bad, especially in large shopping centre speed humps and driveways.
Went to Brendan's twin dump pipes straight off the turbos and went 2.5"all the way incl. 2 X 2.5" flex, 2 X 2.5"hi flow cats and previous twin 2.5" resonators and mufflers/tips - it became loud as hell at idle even though the original resonators and mufflers were retained. Sweet music to my ears at full song though. Ground clearance is great now.
We stuck a 2" cross pipe after the cats and this reduced the noise somewhat - plan is to drop in another cross pipe before the cat to quieten it down even more.
I believe that inadequate backpressure on the 1J may be detrimental to performance. When I fitted Brendans twin 2.5" dump pipes in the backyard, I had to drive about 8 kms to my exhaust place when I had to remake/refit the exhaust - I was dumping straight to the atmosphere just below the gearbox. During the whole 8 km drive, the engine refused to make any boost - like driving with blown turbos - would not rev past 4500 rpm !!
Was loud as hell too - should of seen the look on everyones face as I approached and passed by in 7.45am peak hour traffic
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 13:33
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dylo... castle hill exhausts can almost certainly do it for you cheaper than $1000, you might wnat to give them a call (unless it's too late to pull out, or there's somehting special about your system)
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Location:
Perth
Registered:
August 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 15:27
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whatever you decide just don't do what this guy did!!!!
http://www.coolcars.yo.lv/cars.htm
13th picture down on the right..
most of you have probable seen these pics before
for those who haven't.... SOOOOOOOOO funny
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I supported Toymods
Location:
Perth WA
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Thu, 05 September 2002 16:11
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I have a 3 inch system from turbo Y piece and it is loud!
It is 3 inch downpipe to 3 inch flex then high flow cat, 2(!) resonators AND a muffler. I think exhaust design is a bit of a black art (or you need a supercomputer). I took the car back twice to add resonators each time because it was too loud for me. The system does get quieter after a few thousand Km's as carbon builds up in the pipes. It still resonates at about 2000rpm (a consistent problem with 1JZ's I think), enough yo set off car alarms in undercover car parks.
Also, With the 3 inch system, I had them put in some bash plates because I keep scraping on speed bumps. There's no worry about denting the stainless pipe though - that stuff is STRONG!
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Location:
Canberra
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Fri, 06 September 2002 03:37
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Draven,
Yeah i probably could get it cheaper in Sydney, but im in ACT and driving to sydney in my unrego'd Celica with no exhaust is a bit of a worry!
So yeah the cheapest one i found round here was a grand (and also closest to my house! )
Does anyone in ACT know where i could get it cheaper tho maybe?!
My quote was from Braddon Exhaust.
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Location:
_Sydney _
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Fri, 06 September 2002 09:20
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I want to get an exhaust system oneday but i want the performance without all the noise, seems like u cant have it to much like that can ya? coz i got sick of having a heaps loud exhaust in the corolla
a cat and one muffler it gets to ya
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Location:
Canberra
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Fri, 06 September 2002 09:51
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if you want a quiet system, look for a decent muffler, this will make far more difference than pipe diameter or system design. A well designed system will still resonate with a shit muffler.
Just because a muffler is quiet does not mean it will be restrictive. The best value to go for is an imported second hand 3" (or larger if your pipe diameter requires) straight through muffler from Japan, one particularly good brand that sells for between $80 & &100 at jap import wreckers is Fujitsubo. be aware though that the jap mufflers have quite a large body, and may be difficult to fit under a TA/RA celica, but fine on a larger car.
I made my own 3" mandrel system, its a hell of an intensive job without a car hoist, but much cheaper than paying for labour at a workshop! straight pipe, mandrel bends & donuts cost me $195. I also bought a cheap locally sourced new muffler (3" straight through Supercat Brand) for $100 cash, and it sounds shite compared to the jap muffler for $80 second hand.
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Location:
Hobart, Tas
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Fri, 06 September 2002 13:39
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| TOYO3T wrote on Thu, 05 September 2002 13:40 |
I would not run a split system on a NA 4 cyl, 4 into 1 extractors have long been proven to make best torque and power, you need the pulse from all 4 cylinders to scavenge exhaust gasses from the other cylinders.
Matt
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I always thought 4-1 extractors were only for high rpm use, and 4-2-1 were best for torque and driveability.
On the topic of exhuast size, on a NA car after a certain size you just loose backpressure. For instance, the guys in the US with HEAVILLY modified 22REs or 20r/22r hybrids don't go bigger than 2.5". Many recommend 2.25" as the optimum.
I don't know the story with a 6cyl car, but I'd be careful about going huge just for the sake of it.
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Location:
sydney
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Fri, 06 September 2002 13:45
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try variflow exhausts. i think there in liverpool.
this place custom makes everything to your needs, down to cats and mufflers are all hand made and desighned for straight thru flow and noise level that you are after.
from what i can tell they are also the only exhaust shop that has done dyno testing on diffrent size exhaust and engines so will be able to give you the best size possible.
they have not yet done any major promotions so are still quite cheap. ( friend just got custom 3 inch system done for $1100 on his fj20 corona)
most of there work up to date has been on race cars etc.
thats my 2cents
and thats where the my 1j cressidas goin as soon as i find the $$$$$$$$$
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Location:
Hobart, Tas
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Fri, 06 September 2002 13:47
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| Bounty wrote on Fri, 06 September 2002 19:20 |
I want to get an exhaust system oneday but i want the performance without all the noise, seems like u cant have it to much like that can ya? coz i got sick of having a heaps loud exhaust in the corolla
a cat and one muffler it gets to ya
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I don't think it *has* to be really loud. I remember reading an autospeed article that reviewed lots of different mufflers. I think the loudest ones actually had the most restriction and it was one of the more quiet ones that won their power gains test.
Don't think I'm against exaust noise - gotta have some character, and I love the sound mine (2" all the way, previous owner did the muffler so don't know what brand) makes at WOT and on overrun. Just don't make it into fart sounding ricerocket, or something that is obnoxious for the sake of it that you can't talk over at idle.
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: maximum sensible exhaust size for 1jz
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Fri, 06 September 2002 15:07
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my friend's 300zx has "a beautiful exhaust system" (in the words of the manager of UAS, castle hill)
twin 3" pipes off the turbos, into twin bullet cats, into twin (small) resonators, then into the 2 biggest mufflers I've ever seen on a car. 8" barrel, and they run from his rear axle to within 3" of the back of the car, onto 4" tips.
Quieter than my car, and apparently awesome for performance
not helpful on a toymods forum, but thought I'd make a mention of it
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Location:
Gold Coast
Registered:
September 2002
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Re: maximum sensible???????? exhaust size for 1jz
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Sat, 07 September 2002 00:18
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I Measured up under my soarer(mz12) there was at least 10 inches so i reckkun u get two 10 inch pipes each reducing down to about 3 inch and that should get u enufffff flow
IF ur worried about bottoming out, dont because u just fit tiny castor wheels to the underside(just weld em on) of the exhaust simple my other option is to hight mount the ct12s high(about 20 inches out of the bonnet and have the same twin 3-10 inch pies goin up to the rola roof racks and then flare the ends 45deg and make them exit about the rear qaurter glass one each side i have drawings available for a small technical fee of $25.00 THATS JUST ONE CASE OF BEER............
THAT should be SUFFICIENT...........
Sorry But i could not help myself
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Location:
Sydney
Registered:
June 2002
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Re: maximum sensible???????? exhaust size for 1jz
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Sat, 07 September 2002 01:20
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Hi
Give VARIFLOW TECHNOLOGY in Wollongong a buzz.
on 0409 288 347 or 0414 416 748.
These guys are extremely good and build bullet proof, custom made, high flow low DB exhaust systems. And there prices are realistic and reasonable unlike many Sydney exhaust shops.
I had my 3.5" system made up on my FJ20ET RT40 Corona and I was stoked with the result. All TIG welded and mandrel bends.
-Regards Mike
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: maximum sensible???????? exhaust size for 1jz
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Sat, 07 September 2002 01:33
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how much did you end up paying for that system?
and congrats on getting your paws on an FJ20DET
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Location:
Sydney
Registered:
June 2002
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