valverguy
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Registered: 9th May 06
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This is for a 1.6 sport. The ideal diameter for this kind of engine im assuming is 2 1/4 or 2 1/2 pipe work. Would there be any sort of problems going higher to say 3 inch?
i ask this because i believe that you would have naf all back pressure with anything bigger which would have a negative result ?
[Edited on 01-02-2007 by valverguy]
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valverguy
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anybody?
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Dave A
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Registered: 10th Dec 03
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no such thing as back pressure.
bore of the pipe depends on the engine thats joined to it.
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valverguy
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exscuse me theres no such thing as back pressure. I may not be the cleverist person in the world but i reckon ur wrong there.
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Dave A
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well I build exhausts and engines every day for a living. I am not wrong.
exhaust design is a lot more complicated than people realise. most off the shelf exhausts are more for the look and sound rather than perfomance really.
what some people term as 'backpressure' does exist but its not strictly backpressure as such. Making an exhaust that is well designed isnt easy, to do it properly everything from inlet design, cylinder pressure, valve overlap values need to be taken into account (sometimes refered to as 'pulse tuning' )
the Idea behind 'backpressure' is this: as exhaust gasses exit the combustion cylinder into the exhaust posrt and into the manifold they are at a high speed. once the exhaust valve closes the gasses create a virtual vaccum behind them, this helps to suck the next load of waste gasses out and so on... if the exhaust bore is too big or too free flowing or the primaries of the manifold are too short or long then the amount of pressure pulling the next lot of waste gasses out of that cylinder is reduced therefore the gasses escape slower and the speed of the engine is reduced and the inlet gasses enter slower and so on....
there is a lot more to exhaust design than you might think......
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DAZ1985
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Registered: 3rd Sep 06
Location: Scholar Green, Cheshire
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You learn something new every day.
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valverguy
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Thanks dave a for that. So in reference to the first post.. Say i put a 3" system on a 1.6 sport. i assume it would have a negative impact on the car?
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DAZ1985
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Registered: 3rd Sep 06
Location: Scholar Green, Cheshire
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I'd say so and im no expert. I thought 3" was best for LET's.
Thread Hi-jack !!!!
What is the best diameter for an XE corsa ???
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Dave A
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standard 1.6? if so then a 2" is fine for now and up to 150bhp. over that or a 2 litre corsa will be ok with a 2.25" system. 2.5" will be fine for a LET and 3" is reserved for turbo engines with silly power.
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valverguy
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Thabnks for the info. i knew 2.5 inches or above was to much for a 1.6 sport!
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Dave A
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also, the bigger the bore, the louder the exhaust. 2" will be fine.
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jimmy 2.1
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Registered: 17th Oct 05
Location: Shipley, West Yorkshire
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Dave, i've got an Xe in mine and the the exhaust diameter is 2", am i 'strangling' it considering its been lightly tuned aswell?
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SportBoy
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Registered: 5th Oct 01
Location: Retford, Nottinghamshire
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i used to have a standard 1.4 corsa centre section on my old xe and it got 128bhp at the wheels on the rollers so i wouldnt of thought 2" would be bad at all
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