TWE header pipe sizes ?

[discopotato03]

Hi all , I need to know what size engine pipes and up pipe people use when making EA82T headers .

 

My rebuilt engine has ported heads NA MPFI cams (16-60 instead of std 14-56) and just over 8:1 CR .

The inlet is Spider modded to use the original early (86) throttle body etc .

 

We are considering using 1 3/4 inch 16 gauge stainless tube for the primary or engine pipes and possibly same or 1 7/8 for the up pipe section .

Turbo flange will be T28 to suit a hybrid GT2854R I had made , by hybrid I mean the nicer GT28 NS111 76T turbine and the high temp material S15 0.64 AR turbine housing with the extra deflector vane cast into the back of it . Turbo started out as a GT2554R .

 

The heads siamesed exhaust ports measure ~ 50mm which is probably too big tube size wise so needs to gradually reduce to maybe 1 3/4 or 1 7/8 inch (44 or 47.5mm) . As a rough rule of thumb I consider the wall thickness (x2) to be 1/8 " (3.2mm) so ID's would be ~ 1 5/8 and 1 3/4" (41 or 44m) .

 

I think from memory the std Subaru header measured ~ 33mm round the bend on the far side and a fair bit larger at 41 odd mm at the turbo side . Also that crossover pipe round the front of the sump pan is double thickness with the inner ID being I think ~ 35mm or 1 3/8" .

 

By the look of things it would be easier to have the collector down lower and just a single up pipe tube to the turbos mount flange .

 

Just don't want to lose gas speed with over sized tubes .

 

Thoughts ? Cheers A .

Edited August 30, 2009 by discopotato03