i was doing a search a while back about JDM ITR header dyno plots. i came across a thread, i dont have it, that the kid had "ported out inside of the header and re-welded the outside". why did he do this and what benefits if any does it have rather than just leaving it alone. thanks

 

The weld beads (the connects the primaries to the header flange) are located on the inside of the primaries (holy crap!, I'm glad I took all those english classes or else that sentence would make even less sense).

If you were to remove those weld beads, you would infact remove a bottle neck and the venturi effect that these weld beads create. In my opinion, there is NO advantage to have a venturi effect at the exhaust ports.

Because your removing welds that hold the primaries to the flange, you need to replace them with welds on the outer perimeter of the primaries.

 

As ic108 said basically you just weld outside all of the primaries so that your port doesn't go through, and then you port the inside of the flange out until it is flush with the primaries. A few of my friends around here have done it and it works great.

 

Pics to help.
http://www.sandmracing.com/m_e02_jdmheader.html

Will
-who stole the link from S&M

 

I think I asked this question to D... I don't think he noticed any difference though.

D, any comments?

 

i can't comment... my header was never installed before i ground the sheit out of it.

D

 

i knew a guy here in fl, that modified his to fit a 3''thermal exhaust..w/jr supercharger..i dont think he ported it though

 

I never rewelded mine and still gained a very nice amount of power. D: wanna switch them out during the dyno day? I'll do some pulls early in the day, then swap it and do more pulls later? I'll just have to pay John for more pulls I guess..

 

heh, if you want.... but i guarantee you i'm leaving tampa wif my header...

D

 

...just curious, how long did it take you to get it like that?