Do I Need The Split In The Downpipe?

[sussex_gti 0]

After fitting my mi16, im not really hapy with the downpipe. Ive cut and re-welded it but its by no means perfect, and is blowing slightly. ive a friend who is a fantastic tubesmith, and has offered to make me a frontpipe. I wondered if the split in my downpipe is really beneficial? Ive seen people talk about it quite alot, but slightly unsure what purpose it serves, and whether i should really worry about i.

 

Chris.

[welshpug 1,661]

its there to create a 4-2-1 effect, without it it'd be a VERY short 4-1, losing you torque.

 

If your friend is a tubesmith I'm sure he'll know exactly what to do.

[nick 3]

I wouldn't bother with the split, I've had both on my Mi and 8v and couldn't notice a difference on either.

 

Nick

[welshpug 1,661]

now this is the bit I dont understand, why did peugeot go to the effort of designing a good system, and for peugeot sport to replicate it in a larger bore, if its not worthwhile?

[sutol 0]

How far down should the split continue to be effective.

 

reason is that I have an aftermarket system which has no split and was thinking of modifying it.

[whizzer71 0]

Wouldnt worry about it Chris,just Do what ya gotta do,wont have that much of an effect with your Mi in a 205 !

 

[Miles 331 1 Cars]

The split effect's top end power, I noticed this on a old 309 GTi (Say old it was fairly new at the time) and wondered why performace had dropped off at the top end, Took the downpipe off and noticed it had burnt thru, Changed it over and all was back to normal, So I would keep it there or do what the Moongoose did and use to seperate pipes

[d-9 0]

I found the split had a massive effect on the torque of my cammed MI, when i went from a downpipe with no split to one with it improved it a lot.

[pacey205 2]

I agree. I replaced my exhaust on the Mi a while back and coulnt find one with a split for love nor money so had to use one without. And its definietly not as torquey mid range as it used to be . Used to it now but would much rather have had one with the split present.

 

Michael

[Alastairh 47]

I don't bother unless its new.

 

They just crumble and become restrictive leading to you needing to buy a new one...

[felix2566 2]

What happens in the case of the later Mi's and Gti6's that had cats, do they still have a split down to the cat? Or were they designed to run with out the split pipe?

[welshpug 1,661]

the 2.0 Mi16 and the S16 still had the split in the downpipe till the cat.

 

the GTi6 is a different animal and has a properly matched 4-1 arrangement.

[felix2566 2]

So its fine to not have the split on a GTi6 conversion?

[sutol 0]

How far down should the split continue to be effective.

 

reason is that I have an aftermarket system which has no split and was thinking of modifying it.

Judging by the info on here I think I will construct a twin pipe system as far as the first box.

[welshpug 1,661]

So its fine to not have the split on a GTi6 conversion?

 

 

Yes, its quite a different engine to the Mi even though it has many similarities.

 

the split on an 8v usually runs the full length of the downpipe, to about 12" from the centre silencer.

[sutol 0]

Any ideas on size for twin downpipes ?

i have some inch and a half pipe - is that a bit big do ya think ?