exhaust bore question.

[kevin.s]

ive done a search on here and it seems that the best sized bore for a 1*2 is 2.5" but ive been told by a few friends that anything more that a 2.25" on a N/A car will lose back pressure and power as well as creating flat spots. is this true or is it because the clio`s have quite a high compression ratio or somthing like that? looking at getting a new exhaust from a local place but want to know what the best bore would be and dont want to end up losing power because i made the wrong decision.
cheers

 

[172Ben]

Cant of searched that hard

http://www.cliosport.net/forum/showthread.php?t=366096&highlight=best+exhaust+bore+size

from what i understand 2.25" is fine for a car with a few mods, but 2.5" will benefit when having ITB's etc? Sure someone will confirm

 

[kevin.s]

Cant of searched that hard

http://www.cliosport.net/forum/showthread.php?t=366096&highlight=best+exhaust+bore+size

from what i understand 2.25" is fine for a car with a few mods, but 2.5" will benefit when having ITB's etc? Sure someone will confirm

looks like i am better off getting the 2.25" one then as i only have an induction kit on it and only plan on getting an rs tuner on it eventually. other than that dont really have any engine plans as they cost a fair bit (as you should know lol)

 

[Nick172Cup]

I run 2.5" with no centrebox on mine and I havent got any flat spots, though it is quite loud! Feels certainly better than standard!

 

[Chrisjk]

2.5" all the way.

 

[kevin.s]

just had a word with fred and he said 2.5 is ideal so thats what i think ill go for as he knows what he is talking about and i trust him when it comes to things like this.

 

[kevin.s]

I run 2.5" with no centrebox on mine and I havent got any flat spots, though it is quite loud! Feels certainly better than standard!

thats the only thing. i dont want it too loud. its not the droneing noise that will do my head in but the sound of my missis going "this cars too loud now, you ruined it, it sound crap now, dont know what you did that for, sounds like a boy racer car now" etc etc.
do you recon if i was just to have a rear silencer that would be ok or do you think i need to keep the centre box.

 

[Nick172Cup]

If you want it quieter, definately get 2.5" bore but have a large centre silencer... That will quieten it down a bit...

 

[kevin.s]

sound. think thats what ill go for, even though all my mates are saying get a strait through system and de cat lol.

 

[Nick172Cup]

Well it really depends on who wears the trousers in your relationship. I have a cat with 2.5" straight through system, thats loud enough for me and mrs!

 

[kevin.s]

its not so much as she wears the trousers. its more a case of, can i put up with her winging at me everytime we get in the car and me not end up killing her lol.
does yours get through the emissions ok ?

 

[Nick172Cup]

Yeah completely fine as I still run a cat. Would never run a decat unless it was purely a trackcar as its not worth the risk getting caught with a decat these days...

Vosa pulling people at the side of the road around my area testing modified cars for emissions. Plus there not stupid anymore, they know the difference between a cat and decat/silenced decat!

 

[DannyR]

What happens if you get caught?

 

[Cookie]

2.5" on mine, it's not quiet

 

[Greeny.]

What happens if you get caught?

Points + fine I would have thought.

Would of thought there would be more effort put into f*****s not paying for any insurance or tax tbh. MOT's are a joke at the best of times!

 

[DannyR]

I doubt points, the c***s would probably crush it! Although, how do Rally cars get away with it as they need to be road legal too don't they?!

 

[Nick172Cup]

I doubt points, the c**ts would probably crush it! Although, how do Rally cars get away with it as they need to be road legal too don't they?!

It is a good point on Rally cars, maybe its just not as strict... But it can't be as simple as that.

 

[DannyR]

MOT is an MOT at the end of the day!

 

[Martin_172]

I doubt points, the c**ts would probably crush it! Although, how do Rally cars get away with it as they need to be road legal too don't they?!

WRC cars have cat's

as said before a decat isnt illegal, a car which cant pass emissions is..

 

[m4rkie23]

If you want it quieter, definately get 2.5" bore but have a large centre silencer... That will quieten it down a bit...

this is what im getting on saturday (prospeed - charlie recommended 2.5 i i dont want it too loud)

will a 2.5" look......right, in a 182 surround? anyone with pics of a 2.5" bore with 182 surround?

 

[Plummer]

Yeah completely fine as I still run a cat. Would never run a decat unless it was purely a trackcar as its not worth the risk getting caught with a decat these days...

Vosa pulling people at the side of the road around my area testing modified cars for emissions. Plus there not stupid anymore, they know the difference between a cat and decat/silenced decat!

What about a cat, that has the insides smashed out?

Would you get away with a faulty cat?

 

[Nick172Cup]

What about a cat, that has the insides smashed out?

Would you get away with a faulty cat?

Well I dont condone that, but i'd imagine you could blag it!

 

[Andyman]

Never knew this till recently but apparently its illegal to run a exhaust louder than the factory exhaust noise level.

Bit of a grey area tho as not sure how or where the feds would get the data to compare..


BTW, dont worry about this straight through exhaust bizz. Just about all after market exhausts are straight through, ie, you can roll a golf ball from one end to the other with no restriction.