'93 wrx
I'm removing my exhaust manifold (to port) very soon and am thinking of porting the standard uppipe also,

but have heard you need to weld the uppipe before porting (I'm guessing so that I can take plent off)

but have also heard if I weld it then it is likely to crack?

what is best to do?

don't want to go with uprated as I don't want it too laggy!

also can the uppipe be removed while still attached to manifold? (thought it might be easier)

cheers
Mark.

 

Hi Mark,

In regards to removing the up-pipe, I would:
remove the exhaust headers 1st then undo the 2 x 14mm nuts from the engine mounts & raise/lift the engine up slightly. This will help you to remove the up-pipe, otherwise it get stuck on the subframe/crossmember.

There are some good pictures of standard ported up-pipes on Nasioc forum.
You don't need to remove that much material/metal from the up-pipe.
I would lightly port the up-pipe instead of going heavy on it then having it welded.

Ticky

 

The headers have to come off to remove the up-pipe as Ticky says.
Do NOT weld the up-pipe.
Gains from porting the up-pipe are not very good because of its actual design. No idea why it is made like that.
I found there were very good gains to be had after I designed my own up-pipe to compliment my ported headers and the up-pipe was designed specifically for the porting employed. To arrive at that conclusion involved flow bench testing over a period of time and subsequent real world results.

 

Excellent advice!

cheers guys

Harvey...tell me more about the uppipe you made and the kinda gains over standard and uprated pipes. (is it a solid pipe, flexi or slip jointed?)

Is there more that can be done to the standard uppipe?

How much work is involved making my own uppipe? I'm quite handy with a tig, but wouldn't know whats the best materials to use

 

Magnex do some nice replacement uppipes that are the same bore as the OEM uppipe and match the headers outlet and turbo inlet quite nicely.

 

what is the internal diameter of the standard up pipe?


anyody tried the one off flat4online? (£50 fleabay jobbie) what diameter is that?

 

standard is 44mm IIRC.

 

The standard up-pipe is 41.8mm.
I doubt that making your own up-pipe is a viable possibility.
My up-pipes are slip jointed, heat wrapped and purpose designed for the headers that I port.