[inbits]

I want to have a go at building my own exhaust for my h20 v6 vitara from the headers back that flows better. While doing this i was thinking about a high flow cat to suit, I can get a catylitic converter off a brand new v8 commonwhore thats has done about 10k will this work in the same way?

What would be the most suitable diameter for this sized engine?

Ill be tig weldeing it using mandrel bends aswell.

cheers inbits

[steak_knife]

inbits wrote:

I want to have a go at building my own exhaust for my h20 v6 vitara from the headers back that flows better. While doing this i was thinking about a high flow cat to suit, I can get a catylitic converter off a brand new v8 commonwhore thats has done about 10k will this work in the same way?

What would be the most suitable diameter for this sized engine?

Ill be tig weldeing it using mandrel bends aswell.

cheers inbits

yep that'll work, don't think you would want to go much above 2 & 1/2in

[inbits]

yeah cool i wasn't sure wether 2 and 1/2 would be to big I dont want it to be to noisy either

[matty87]

so are ya gonna cross it over underneath to help with scavenging? or run both banks of cylinders down into one tail pipe? tuned length extractors and no bigger in diameter than 2 and a half inch id think too else you run into problems with the old backpressure vs velocity scenario.

and a couple of high flow mufflers at the back for a nice noise.

the biggest flow inhabiter in a standard exhaust system is the factory muffler.

and not exactly legal but grab a cat bash the center out and fit it like that highest flow cat you will ever get.

EDIT: power and quiet dont go together. and by upgrading the whole system and restricting it at the muffler you may as well not bother at all.

[JrZook]

matty87 wrote:

EDIT: power and quiet dont go together. and by upgrading the whole system and restricting it at the muffler you may as well not bother at all.

WTF?

Glass pack striaght through mufflers and heimholtz resonators work on absorbsion not restriction to lower noise levels. Can make a very quiet and effective exhaust system.

[Jccck]

JrZook wrote:

matty87 wrote:

EDIT: power and quiet dont go together. and by upgrading the whole system and restricting it at the muffler you may as well not bother at all.

WTF?

Glass pack striaght through mufflers and heimholtz resonators work on absorbsion not restriction to lower noise levels. Can make a very quiet and effective exhaust system.

My Accord has a glasspack muffler and a tiny 9" Resonator
It'll hit 114 dBs.. Glasspacks are generally one of the louder options as far as compliant mufflers go

Edit: Commodore V8 Cat, wouldn't it be a 2.5" from factory? It could be HUGE overkill and very restrictive to a little Zook motor

[matty87]

JrZook wrote:

matty87 wrote:

EDIT: power and quiet dont go together. and by upgrading the whole system and restricting it at the muffler you may as well not bother at all.

WTF?

Glass pack striaght through mufflers and heimholtz resonators work on absorbsion not restriction to lower noise levels. Can make a very quiet and effective exhaust system.

good im glad the glass pack on my ute is quiet not. Used to not be able to hear the thing before the straight through and headers were put in now its not super loud but it will set off alarms in carparks if reved.

sure you can make a nice system that isnt too loud but if you want better flow its going to be a bit noisier. and if you want everything you can get out of it its going to be loud.

[Jccck]

matty87 wrote:

good im glad the glass pack on my ute is quiet not. Used to not be able to hear the thing before the straight through and headers were put in now its not super loud but it will set off alarms in carparks if reved.

sure you can make a nice system that isnt too loud but if you want better flow its going to be a bit noisier. and if you want everything you can get out of it its going to be loud.

Mine can be sorta quiet, if you really try.. Haha
At WOT on a nice night, 2-3kms through houses, trees, everything.. People call me saying they can still hear me ><

[Fatzook]

I'm just about to do this for my j20a vitara. 2" is big enough if you are using mandrel bends.

[NotNormal]

noise does NOT equal power. well designed mufflers can quieten an exhaust while improving performance.

[303zuke]

NotNormal wrote:

noise does NOT equal power. well designed mufflers can quieten an exhaust while improving performance.

If you've ever heard a Highway Patrol Commo do a u-turn and floor it, you'll know this is true. All you'll hear is "Pffftt...."

[MacDaddy]

inbits wrote:

I want to have a go at building my own exhaust for my h20 v6 vitara from the headers back that flows better. While doing this i was thinking about a high flow cat to suit, I can get a catylitic converter off a brand new v8 commonwhore thats has done about 10k will this work in the same way?

What would be the most suitable diameter for this sized engine?

Ill be tig weldeing it using mandrel bends aswell.

cheers inbits

I would say 2 1/4in max... YES get a high flow cat, it makes a big difference, you cannot see daylight thru a standard cat, a high flow cat you can...
I had a 2in sports system put on my GV, with a High flow cat, and a straight thru glass filled muffler, so the only slight restriction is the cat, and you can feel the difference... my muffler is noisy, much noisier than i was expecting, i just said i want a bit of noise, but i really love the growl my GV has now, when you put it in 3rd, and put your foot down, it sounds really good as it winds out and when i am in Low range 2nd or 3rd, at 4000rpm, it sounds like a rally car, he he.. But when i am H'way cruising, i can only just hear it...

I would get a mid range noisy muffler, you got to have some noise, and i think you will like/love the exhaust growl, makes your zook sound tough, he he...
Dont forget to show us some pics of your work !

[Jccck]

303zuke wrote:

NotNormal wrote:

noise does NOT equal power. well designed mufflers can quieten an exhaust while improving performance.

If you've ever heard a Highway Patrol Commo do a u-turn and floor it, you'll know this is true. All you'll hear is "Pffftt...."

I'd hardly call a VE SS Highway Patrol a fast/modified car.. Lmao

I kinda like to hear my car, a good note is half the enjoyment of an exhaust.

[matty87]

303zuke wrote:

NotNormal wrote:

noise does NOT equal power. well designed mufflers can quieten an exhaust while improving performance.

If you've ever heard a Highway Patrol Commo do a u-turn and floor it, you'll know this is true. All you'll hear is "Pffftt...."

because the restriction type muffler on the hwy patrol cars are high tech. have you ever seen an Australian police car catch someone going really quick? No there are two reasons for this they arnt allowed to go really quick 140 is the limit and those hwy patrol cars are buckets of bolts.

There are three types of muffler in reality. the restrictive type which is used on most cars from factory, its cheap and nasty and works to keep the thing quiet but is rubbish for flow.

then there is the absorbing type like a glass pack straight through. much better for flow but louder than restrictive and louder than the third type

the third type is reflective and works on the principal of reflected sound waves cancelling like sound waves out problem is this is a complicated piece of physics and doesnt work for the whole range of sounds bouncing down an exhaust pipe as it has to be tuned to a certain range of frequencies, this makes them good for getting rid of drone and probably the best at killing the most noise they are still not as good performance wise as a straight through absorber.

[Jccck]

matty87 wrote:

303zuke wrote:

NotNormal wrote:

noise does NOT equal power. well designed mufflers can quieten an exhaust while improving performance.

If you've ever heard a Highway Patrol Commo do a u-turn and floor it, you'll know this is true. All you'll hear is "Pffftt...."

because the restriction type muffler on the hwy patrol cars are high tech. have you ever seen an Australian police car catch someone going really quick? No there are two reasons for this they arnt allowed to go really quick 140 is the limit and those hwy patrol cars are buckets of bolts.

There are three types of muffler in reality. the restrictive type which is used on most cars from factory, its cheap and nasty and works to keep the thing quiet but is rubbish for flow.

then there is the absorbing type like a glass pack straight through. much better for flow but louder than restrictive and louder than the third type

the third type is reflective and works on the principal of reflected sound waves cancelling like sound waves out problem is this is a complicated piece of physics and doesnt work for the whole range of sounds bouncing down an exhaust pipe as it has to be tuned to a certain range of frequencies, this makes them good for getting rid of drone and probably the best at killing the most noise they are still not as good performance wise as a straight through absorber.

^ x2
Especially the bucket of bolts comment.. Lmao

You can get mufflers that are a less restrictive version of the first.. But in reality, unless it's glasspack or similar.. With the correct cat, header(s) and diameter piping.. And a resonator if you wish.. Then the power you've gained isn't the power you could have gained if you put the correct exhaust on in the first place
Noise is a setback for some, but it sorta goes hand and hand with functionality

[NotNormal]

Exactly, but people often think more noise = more power, and then go on to assume that therefore the noisier the better. That is not true. An excessively noisy vehicle usually points to an attention seeking plonker

[Jccck]

NotNormal wrote:

Exactly, but people often think more noise = more power, and then go on to assume that therefore the noisier the better. That is not true. An excessively noisy vehicle usually points to an attention seeking plonker

Haha yes.
Noise doesn't = Power
Noise is just a sideeffect, but you can still make lots of noise and have little power.. Funny how the world works

[inbits]

matty87 wrote:

so are ya gonna cross it over underneath to help with scavenging? or run both banks of cylinders down into one tail pipe? tuned length extractors and no bigger in diameter than 2 and a half inch id think too else you run into problems with the old backpressure vs velocity scenario.

and a couple of high flow mufflers at the back for a nice noise.

the biggest flow inhabiter in a standard exhaust system is the factory muffler.

and not exactly legal but grab a cat bash the center out and fit it like that highest flow cat you will ever get.

EDIT: power and quiet dont go together. and by upgrading the whole system and restricting it at the muffler you may as well not bother at all.

Anyone who knocks the center out of a catylitic converter is a complete f*&k wit theres a reason they are on the car.

By noisy I meant I dont want a droning piece of shit that drives me crazy. I dont mind it having a nice note but when cruising on the highway etc I dont want to have to turn the radio up just to stop the exhaust pissing me off.

I think ill go down the path of a glass pack and a resonator and if its still to loud ill sort that out later. Whats a decent but cheapish brand of muffler

[bazook]

dont go 2 1/2 system you will regret it, you end up not having any low end but alot of top end and you get the wonderful sound of a crumydore

[steak_knife]

bazook wrote:

dont go 2 1/2 system you will regret it, you end up not having any low end but alot of top end and you get the wonderful sound of a crumydore

I thought it sounded fully sic bro!!!

[inbits]

bazook wrote:

dont go 2 1/2 system you will regret it, you end up not having any low end but alot of top end and you get the wonderful sound of a crumydore

which I dont want! i think a nice flowing 2inch system will work good i really dont need to lose anymore low down power the 2 litre seems to make its power at 3000 rpm +

[royce]

yet another thread full of ohi im jcccccccccccck the super expert, I dont know shit but fuck ill post heaps

ffs everyone that doesnt have knowledge in a subject, shut up, given a choice between participating in dumbing down society through internet bullshit and turning this place off, ill choose turning it off

[inbits]

well said royce i have noticed jccccck posts alot and seems to have no idea

Thanks for the helpfull replys guys there sure are some knowledgeable people on here

[chris_mac]

when i did my exhaust i asked for an opinion in 5 exhaust workshops. 2 said that 2" with high flow cat and hot dog is the way to go (the moment when i've heard "hot dog", they lost me )
I wanted 1.75" with high flow cat and muffler but as i don't know much about exhausts so i thought i ask professionals if 2" will give me anything.
in other shops i was told that 2" won't give me much more than an extra noise. I don't like loud cars. i practically use revs between 1500-3500 RPM so i don't need to gain power over 3500RPM and didn't want to loose power down low, so following advise of the shop i end up having high flow cat with same size pipe as the end of extractors (i think it's 2-2.25") and 1.75" pipe with muffler. it feels like engine is reeving nicer and easier up to 3000-3500RPM, and has only touch louder but nicer note. that's what i wanted.
try to ask few shops around for advise and prices. i did mine 55km away from where i live and saved $150-250 comparing to local shops.

[royce]

Do you know the brand of muffler and approx dimensions of it?

[chris_mac]

royce wrote:

Do you know the brand of muffler and approx dimensions of it?

no, i check dimension tomorrow and try to find out the brand for you

[inbits]

Thanks for that info a brand would be good. I measured standard vit one earlier tonight the inside diameter measures a touch under 50 mm about 48 so it already has 2 inch. I think I'll go 2.25 inch from the cat back and 2" from the headers to the cat.
I was thinking about using 2 cats one for the left bank and one for the right then join into one after the transmission. Kind of hard to explain but illtake a pic and show how I plan to route it andget your opinions.

[steak_knife]

inbits wrote:

I was thinking about using 2 cats one for the left bank and one for the right then join into one after the transmission. Kind of hard to explain but illtake a pic and show how I plan to route it andget your opinions.

I think you will regret that after the first time you rip them off on a a rock or a log..
I looked at the same thing because the Y is a bit of a prick to get off & I had to do 5 clutch's in the gv..

[Jccck]

inbits wrote:

Thanks for that info a brand would be good. I measured standard vit one earlier tonight the inside diameter measures a touch under 50 mm about 48 so it already has 2 inch. I think I'll go 2.25 inch from the cat back and 2" from the headers to the cat.
I was thinking about using 2 cats one for the left bank and one for the right then join into one after the transmission. Kind of hard to explain but illtake a pic and show how I plan to route it andget your opinions.

You have a cat to keep your engine's emissions within the required amount
A V8 generally has two cats, larger diameter.. A 4cyl generally has one little cat
Why would you run two cats, add unnecessary restriction to your exhaust and wasting a few hundred $ on something that will ultimately be bad for your engine

But if it's what you want, make sure you get a really nice pair of metallic cored highflow cats.. They're significant more expensive than the ceramic ones.. But they won't break down after a 10 or so years like the ceramic ones will

[matty87]

inbits wrote:

matty87 wrote:

so are ya gonna cross it over underneath to help with scavenging? or run both banks of cylinders down into one tail pipe? tuned length extractors and no bigger in diameter than 2 and a half inch id think too else you run into problems with the old backpressure vs velocity scenario.

and a couple of high flow mufflers at the back for a nice noise.

the biggest flow inhabiter in a standard exhaust system is the factory muffler.

and not exactly legal but grab a cat bash the center out and fit it like that highest flow cat you will ever get.

EDIT: power and quiet dont go together. and by upgrading the whole system and restricting it at the muffler you may as well not bother at all.

Anyone who knocks the center out of a catylitic converter is a complete f*&k wit theres a reason they are on the car.

By noisy I meant I dont want a droning piece of shit that drives me crazy. I dont mind it having a nice note but when cruising on the highway etc I dont want to have to turn the radio up just to stop the exhaust pissing me off.

I think ill go down the path of a glass pack and a resonator and if its still to loud ill sort that out later. Whats a decent but cheapish brand of muffler

Haha i knew there would be either two ways that that comment might be taken i thought it might have been the way it was. Was a bit of a joke a mate made once to me before i did all the research on the system i put in my junk

Anyway what sort of cash are you willing to spend on the muffler? the no name ones can be pretty reasonable but if your willing to spend some money then i would recommend a magnaflow they are pretty bling but give arguably one of the best notes around. However some of the aussie brands are just as good. and i rate the lukey gear from what iv seen on mates vehicles mind you they were all big v8's

Also what material are you looking at using on the pipe 309 or 304 stainless?

I would also not recommended the use of 2 cats unless you are planning on running a twin system all the way to the back.

The fact is that the flow in the system will only be as good as the most restrictive part also more velocity you can keep in the fluid and hotter you can keep the fluid the better as the less dense the better. if your really keen a heat wrap on the headers is a great idea.
(iv just finished an engineering thesis on fluid flow and as a result learnt a heap of stuff on the side that helped when i did my system. Also my project supervisor is a variable genius in the area of fluid and gas movement and a rev head also so i asked him alot of what iv just put here)