Exhaust sizing problem

[Ada7]

I\'m getting really close to finishing off my single turbo conversion now but have an issue with the new downpipe not matching up with cars existing system.
the new downpipe is 3.5" diameter, while the mid pipe is only 3". So i\'m wondering what is the best thing to do...
A: Get the flange of the downpipe cut off, the pipe reduced and then a smaller flange welded on so it matches the midpipe. Or...
B: Cut a section off the mid pipe and have welded on an increased sized piece and a larger flange put on this.
I realise that both sound the same really but wasnt sure if it matters how far away the reduced section should be from the turbo. Both bits have been cut and welded in the past and arent anything special so not bothered which one to cut, just want it to be the best thing for gas flow and power
Thanks for any advice

Adam

[lee mills]

I would of thought the further away from the turbo the reducer is the better flow youd get although not reducing at all would be better

[hairyhoover]

What turbo are you running mate? I presume the exhaust housing on the turbo has a 3 inch outlet?

[Ada7]

I would of thought the further away from the turbo the reducer is the better flow youd get although not reducing at all would be better

I did think the further away the better too but wasnt sure. I guess no reduction would be ideal but just at the moment i cant afford to change the whole set up for something new, plus i have a duel tip Racing beat back box which i quite like and want to keep

What turbo are you running mate? I presume the exhaust housing on the turbo has a 3 inch outlet?

I\'ve now got a To4r. The downpipe is fitted on with a V-band so the outlet on the housing is the same size as the exhaust.

Adam

[Nik da Greek]

I woulda thought that the restriction will cause a localised buildup of heat too, so another good reason for wanting it as far away from the turbo as possible?

....commendable use of the word "flange" in your OP, btw :Thumbs-up

[Ada7]

Did think of you when i typed it :p
Good point again Nik da. Well made :Thumbs-up

Adam

[Nik da Greek]

Well, I\'m glad of a nice flange coming in from work this time of night :Giggle

[hairyhoover]

To4r should have a 3" outlet :s

[Ada7]

Downpipe..


Got the size wrong on the midpipe. Is only 2.5" :confused:


Adam

[antnicuk]

i would say leave out the silencer and get a bit of 3/5 inch pipe and weld the same size flange on the down pipe end and then a smaller on on the other end that meets the back box.