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exhausts!
Posted: Thu Sep 11, 2008 4:02 pm
by iainbig
im putting a new cat converotr on my car so while im at it im going to put a new exhaust on it any recomended products re anything what you think of this one?>
http://cgi.ebay.co.uk/CHERRY-BOMB-UNIVE ... otohosting
Posted: Thu Sep 11, 2008 5:42 pm
by vw-po-low
Lol a mate of mine had a cherry bomb on his mark 1 clio. Use to pop like hell on de celeration. I wouldn't put one on a mark 4 though. Not a fan of exhaust systems on polos, unless their the stripped out caged look.
Posted: Thu Sep 11, 2008 5:55 pm
by dub_jack
yes mate i reccomend that backbox! My brother has it on his mkv polo and it sounds the absolute b****x! His work mates refer to his car as a mini subaru!! When he first put it on he noticed a difference in his accelleration aswell.
Posted: Thu Sep 11, 2008 7:11 pm
by vw-po-low
Lol it will make no differece in acceleration. If anything a large, (i know this is not large) backbox can cause low back pressure and reduce power.
Posted: Thu Sep 11, 2008 7:19 pm
by dub_jack
vw-po-low wrote:Lol it will make no differece in acceleration. If anything a large, (i know this is not large) backbox can cause low back pressure and reduce power.
But there is no actual 'back box', it is just a straight through pipe!anyone knows that a straight through pipe releases more power. Im not saying this is gonna give an extra 50bhp, im just saying it definately made a difference.
Posted: Thu Sep 11, 2008 7:21 pm
by Torq-Al
vw-po-low wrote:Lol it will make no differece in acceleration. If anything a large, (i know this is not large) backbox can cause low back pressure and reduce power.
Got to agree, a more free flowing exhaust will reduce back pressure, which in turn reduces torque. On a small engine it will actually make it pick up slower. May give you 1 or 2mph at the top end, but thats it!
Posted: Thu Sep 11, 2008 7:23 pm
by vw-po-low
dub_jack wrote:vw-po-low wrote:Lol it will make no differece in acceleration. If anything a large, (i know this is not large) backbox can cause low back pressure and reduce power.
But there is no actual 'back box', it is just a straight through pipe!anyone knows that a straight through pipe releases more power. Im not saying this is gonna give an extra 50bhp, im just saying it definately made a difference.
Well yeah, your remving the back box to put another back box on. If you have a 4 branch manifold, with no cat and a straight full through system there would be a difference, this will just make noise. May sound faster but i very much doubt you'll get noticable power increase.
Posted: Thu Sep 11, 2008 7:28 pm
by Torq-Al
Most standard exhausts are designed to be cheap quiet and inoffensive. Performance is a long way down the priority list. The performance of an engine is proportional to the amount of energy you can release (and harness) by burning fuel and therefore the more fuel you burn (assuming good combustion) the better the performance. To do this, not only do you have to get the fuel and air into the engine quickly but you have to get it out quickly.
It follows that you can improve an engine's performance by fitting a free flowing exhaust and performance claims for aftermarket exhausts vary from about 2 to 10 BHP. I would take these claims with a pinch of salt, changing the exhaust alone (and I mean the entire system, not just the back box) may yield 3 or 4 BHP but nothing particularly noticeable on most VWs. You will tend to get perkier performance higher in the rev range where it becomes important that the engine is breathing well. That is not to say don't bother but do be realistic, it is no good getting gases out of the engine if the intake side is not breathing properly. Performance exhausts work well with aftermarket air filters to improve the overall breathing of the engine and you will notice it rev far more freely after these two mods. They should be regarded as a good starting point for further mods and there is no point spending money on cams and heads etc if the basic breathing is not spot on.
Performance exhausts tend to flow better by having larger diameter pipes and less restrictive silencers. When forcing exhaust gases through a restrictive standard exhaust the engine uses BHP on the exhaust stroke to expel burnt gases. By reducing resistance to this expulsion of gas less power is wasted and therefore more becomes available at the flywheel. The amount of gas an exhaust can flow is proportional to the velocity of air multiplied by the average path area so simply fitting greater diameter pipes ought to yield gains. This is true up to a point but as the pipes get wider the velocity of air decreases and there comes a point where the pipe diameter is simply too big. This particularly affects low down torque which benefits from higher velocity air flow.
Posted: Thu Sep 11, 2008 8:17 pm
by dub_jack
[quote="vw-po-low]Well yeah, your remving the back box to put another back box on. If you have a 4 branch manifold, with no cat and a straight full through system there would be a difference, this will just make noise. May sound faster but i very much doubt you'll get noticable power increase.[/quote]
I didnt say he has a power increase, i said it had an effect on accelleration, say what you want, quote me with facts, im just saying it definately did have an effect on his accelleration. He has an air filter aswel, and thats the only 'performance' mods he's done, and he can easily show up all the gary boys at the lights in their escorts.
Posted: Thu Sep 11, 2008 8:33 pm
by Torq-Al
Only giving you advice, you'll only land up with a car that sounds like a chavvy 'kev-mobile'. Or as you put it, a 'gary boy'!
Put a standard exhaust on, it'll be cheaper & get you less attention from 'plod' too.
Only my opinion!
Posted: Thu Sep 11, 2008 9:52 pm
by kyle1b1
big bake bean can exhausts looks foooking stupid on polos.
Posted: Thu Sep 11, 2008 10:07 pm
by Polo96CL
Subtle look exhausts can make a polo sound much better but as others have mentioned, don't go for a large exit! I'll eventually get a down pipe on the exhaust for mine so it'll sound good but wont have a pipe sticking out of the back
Posted: Thu Sep 11, 2008 10:30 pm
by kyle1b1
^^^ way foward
Posted: Fri Sep 12, 2008 12:33 am
by NOZ
by the way, just noticed the add doesn't specify what size the tailpipe is. if its 2.5" biggest then it'd still look ok depending on how you have it fitted.
I think what Dub_Jack is trying to say is the response is much better. I used to have a 4" backbox on my previous *cough* 'gary polo'. The response was crap as it'd take a fraction of a sec to pass air through the system. It was far too big and not force air out of the system.
How big a systems pipework is needs to be weighed equally with intake etc to make a difference. Go too far without the later and you loss out basically.
Posted: Fri Sep 12, 2008 1:57 am
by kipper
funny u should say that. i got a 3 or 4 inch back box on my car but not keeping it on there as, when i complete my new rear bumper the exhaust will be changing to either a small twin exhaust slightly cut into the bumper or i might not even have one showing i havnt decided yet. my car does make quite a noise, not cherry popper noise but quite loud.
no offense but i really dont see the point in them....... wat exactly do they do........ they make a big popping noise which is more like a bang n e way, but dont get why n e one would wanna draw attention to theyre gary car or watever u called it (which normally looks $H!t n e way) but they think looks amazing......... halfords here we come....... chavving it up!
not being critical to u but thats my opionion so obviously its up to u wat u do but im just saying i dont want one or see the excitment in them.