Does adding a massive exhaust to a car decrease performance?

[Stissy]

I've heard a lot about this... i'm just wondering if its true,

and if so, why?

[JamesR]

Big backbox = No

Bigger centre section than its needed = Yes

I assume the manifold is the same as the centre section.

[de4n0]

A big back box shouldnt reduce power but putting a system on it with a centre section pipe thats too big will make it louder but the back presure will be shit and slow the car down, would feel better at high speeds but lower your 0-60 time. not worth it if you ask me. and if you de-cat it aswell it makes it soo much worse.

[Sparco_Tom]

depends on bore size, bends, length.

[JamesR]

A big back box shouldnt reduce power but putting a system on it with a centre section pipe thats too big will make it louder but the back presure will be shit and slow the car down, would feel better at high speeds but lower your 0-60 time. not worth it if you ask me. and if you de-cat it aswell it makes it soo much worse.

No it doesnt :wacko:

[Sparco_Tom]

yes it can, if the bore is too big after the cat and you then add a decat it will make it worse

[Slugshead]

No it doesnt :wacko:

+1 biatch

[JamesR]

yes it can, if the bore is too big after the cat and you then add a decat it will make it worse

But why would you have part of the exhaust too big? :wacko:

[Sparco_Tom]

what im saying is. IF you were running cat - centre section with a too bigger bore

adding a decat would futher damage pulse tuning and reduce even more pressure causing a bigger drop in performance

[JamesR]

what im saying is. IF you were running cat - centre section with a too bigger bore

adding a decat would futher damage pulse tuning and reduce even more pressure causing a bigger drop in performance

I know that, but i dont see why anyone would be running a centre section where the bore is too big?

[Krys_23]

I'd imagine the likes of powerflow and jap cheap systems would have a bigger diameter centre section than the more sought after models. So i'd agree with if it was decatted and oversized centre pipe it'd be shite.

[Sparco_Tom]

point of this thead my friend.
explaining what can happen and does happen when fitting a big exhaust and decat. Sort of things people get from powerflow etc

[Stissy]

point of this thead my friend.
explaining what can happen and does happen when fitting a big exhaust and decat. Sort of things people get from powerflow etc

:y::y:

[Sparco_Tom]

Now if you have a turbo engine you want a big bore centre and back box to let the gases out without restriction so the turbo can spool up quicker and easier creating more power/less lag

[KrisB]

Agreed, or a supercharger, or if its a diesel.

[Sparco_Tom]

ayye :y: hope that answers your question now mate

[Krys_23]

Not aimed at this thread but i'm nearly suicidal from reading this sort of stuff. And i know there's nothing else to talk about to do with saxo performance/ Engine components, But it's seriously sad how i'm remembering basically everything to do with a saxo.

[Sparco_Tom]

Its down to the new breed of saxp-ers

[gouldy87]

its all to do with pulse tuning, back pressure, nominal bore, turbulence in the pipe work etc

there is a real lot of thought that goes into designing an exhaust system. like subaru imprezas, they hav a flat 4 engine with a specially designed manifold that has differnt lengths for each cylinder that gives it that really nice pur when moving through the rev range.

the question you have asked is rather expansive, you could be slightly more specific.

if you put a 6 inch back box on a naturally aspirated saxo standard exhaust, you will lose a very minute amount of power, but you would not notice although you might get the placebo efffect of hearing a loud roar as you move through the rev range and thinking to your self "wow this is fucking well fast now!"

when actually its not.

[gouldy87]

Now if you have a turbo engine you want a big bore centre and back box to let the gases out without restriction so the turbo can spool up quicker and easier creating more power/less lag

i agree, now i have no cat on my car and my down pipe has been replaced with 2.25 inch from 2 inch my turbo spools up alot faster

[Stissy]

yeah cheers.

i was just wondering thats all. i was talking to a lad the other day who had a corsa b with an absolutly massive exhaust at each side of his rear bumper and he was claiming its adding break... but i didn't really know anything about it

[KrisB]

It'll add to top speed, but won't help with acceleration.

[Krys_23]

Its down to the new breed of saxp-ers

True maybe i was wrong, At least some people take decent advice off here and benefits them in the long run, Considering a few years ago 5" zorst's were a must have.

[Sparco_Tom]

It'll add to top speed, but won't help with acceleration.
top speed is for kids

True maybe i was wrong, At least some people take decent advice off here and benefits them in the long run, Considering a few years ago 5" zorst's were a must have.
they will be coming back round again soon :y:

[gouldy87]

yeah cheers.

i was just wondering thats all. i was talking to a lad the other day who had a corsa b with an absolutly massive exhaust at each side of his rear bumper and he was claiming its adding break... but i didn't really know anything about it

there will be a loss in power if the car is not boosted. if a 300bhp impreza only has one exhaust why does a corsa need two?

it doesnt, the best thing your mate can do is go back too a single pipe, single back box system witha 2 inch nominal bore and preferably the same size back box.

[Stissy]

there will be a loss in power if the car is not boosted. if a 300bhp impreza only has one exhaust why does a corsa need two?

it doesnt, the best thing your mate can do is go back too a single pipe, single back box system witha 2 inch nominal bore and preferably the same size back box.

:y::y:

[de4n0]

I know that, but i dont see why anyone would be running a centre section where the bore is too big?

Because if someone goes into a powerflow dealer and says ''nah init i want a maziv exhuast yea with a masive tube like da subaru hav'' then thats why they would have a pipe thats too big, and getting rid of the cat on a an exhuast system that has a centre section too big for the car will decrease back presure and there for power.

[gouldy87]

Because if someone goes into a powerflow dealer and says ''nah init i want a maziv exhuast yea with a masive tube like da subaru hav'' then thats why they would have a pipe thats too big, and getting rid of the cat on a an exhuast system that has a centre section too big for the car will decrease back presure and there for power.

anyone that goes to powerflow should have there car taken off them and be banned from driving for life

[de4n0]

anyone that goes to powerflow should have there car taken off them and be banned from driving for life

Agreed, the work ive seen by them is shocking. I hear they get know training, just shown how to weld and jobs done.

[gouldy87]

Agreed, the work ive seen by them is shocking. I hear they get know training, just shown how to weld and jobs done.

i have seen several "custom" exhausts

they done everything from "throwing" the baffles out the back box to literally falling off a car altogether. i once saw a powerflow system on a r32 golf rust to bits in 8 months from new.

[DaN90]

anyone that goes to powerflow should have there car taken off them and be banned from driving for life


Most powerflow dealers yes are rubbish. There are a select few who are excellent at what they do. Unique exhausts in stafford aka phil is known through out stafford, cannock, burntwood for how good his exhausts and advice is. Just because its powerflow do not tar it with the same brush.

I am a mechanical engineer who works for west midlands fire brigade. No points and have a hgv licence so you think i should be banned of the roads for life because i have a decent powerflow system!

Grow up mate you sound pathetic!

[de4n0]

Most powerflow dealers yes are rubbish. There are a select few who are excellent at what they do. Unique exhausts in stafford aka phil is known through out stafford, cannock, burntwood for how good his exhausts and advice is. Just because its powerflow do not tar it with the same brush.

I am a mechanical engineer who works for west midlands fire brigade. No points and have a hgv licence so you think i should be banned of the roads for life because i have a decent powerflow system!

Grow up mate you sound pathetic!



get real mate, so youve found 1 good powerflow dealer. yaaaaaaay.....no.... most are shit and is this we base our coments on, powerflow them selves offer very little training and this bloke you speak of has probobly had much more training by people other than powerflow, so he is good, powerflow is not. read more carefully and give propper advice other than crap. happy christmas, laters.

[gouldy87]

Most powerflow dealers yes are rubbish. There are a select few who are excellent at what they do. Unique exhausts in stafford aka phil is known through out stafford, cannock, burntwood for how good his exhausts and advice is. Just because its powerflow do not tar it with the same brush.

I am a mechanical engineer who works for west midlands fire brigade. No points and have a hgv licence so you think i should be banned of the roads for life because i have a decent powerflow system!

Grow up mate you sound pathetic!

now now love, no need to throw your teddy out of the pram and start insulting people. its a discussion no a slanging match. people have the right to give there opinions.

granted yes im not denying that there area very select 1 or 2 that could be good, but 99% of them are very very poor.

[DaN90]

get real mate, so youve found 1 good powerflow dealer. yaaaaaaay.....no.... most are shit and is this we base our coments on, powerflow them selves offer very little training and this bloke you speak of has probobly had much more training by people other than powerflow, so he is good, powerflow is not. read more carefully and give propper advice other than crap. happy christmas, laters.

Ohh so i was giving advice in this comment. No i was pointing out the fact that just because you have a powerflow does not mean you 'should be banned off the road' its people like you who back up silly comments that ruin this site so you have a happy chrstmas mate xxx

[de4n0]

to be honest id prefer if you dont put kisses at the end of your messages to me haha, the quality of powerflow is very bad, the quality of there training is very bad, we wernt saying every dealer is shit we was saying powerflow are shit. can you not see a difference?
Theres a powerflow on my focus and its quite good, so im sure the dealer was good at his job, its not the best but does the job untill i can get it replaced.
it was a coment mate, no need to get all upset over it.
and its people like you that make this forum look so babie'ish.

happy christmas

[Scott-jarvis]

My mate had a powerflow exhaust built by Top gear in Bridport on his Ibiza, They did an excellent job, welding was spot on, bends was spot on. had it a year and its still perfectly fine.

[LSOfreak]

my mate has a powerflow, not sure how well its made but it sound immense. performance isnt really a necessary must have to some people

[LeeM]

the build quality on mine from powerflow in bolton was excelent, and it didnt show any signs of rust after 18 months

[maddison_vts]

i've only ever heard good things about powerflow in exeter.

with them being franchises its very hard to 'vet' who works for them. you'll get good ones and bad ones.

its very unfair to say they are all crap though, its like saying all halfords staff are idiots, they aren't all idiots just quite a lot of them are. :fcuk:

anyway, powerflow aim more at the 'show' market instead of people who are interested in track using their car, so they aim to make a good quality exhaust that looks and sounds good which most branches do.

[titchster]

Back pressure isn't a good thing.

One of many sources:
http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm

[adamm]

i have a powerflow exhaust system how wi i know if im loosig back bressure anyone got a pcture of there centre section so i can compare it to mine. thanks