I'm referring to the welds at the top where the header bolts into the head. Has anyone taken a dremel to these? Notice any difference in power, was it hard to do?

What about header wrap? Does it really ruin the header in the long run?

 

http://www.sandmracing.com


One of those guys cleaned up a JDM header

 

Nice... hrm... well worth it... I wonder how long it took.

 

when these were dynoed in the "great header test" they were shown to be lacking some HP. I think if they were to test one of these with cleaned up welds the results would be quite suprising.

 

I noticed that sandmracing's cleaned up jdm 4-1 had extra welding done around each pipe at the manifold... makes sense because the welds that i wanna clean up seem like they are the only ones that hold the piping and manifold together.

 

yup, I would want to get the welding done first (on the outside) so i dont get to excited with the dremel and end up with a two piece header instead of one

 

But then you could said that you had headers and kinda be correct!!!

 

There is a Carbide bit made for the dremel that costs about $10. It would make grinding out the JDM flange welds an easy task.

 

Most people agree that you want to torque the flange to a jig before welding, to ensure that it doesn't warp.

 

Hrm... I'm going to have my dad add extra metal around the pipes... doesn't seem too harsh... is there a real big possibility that it might warp?

 

Around the pipes? No, it's to prevent the flange from warping not the pipes...

 

I did this on mine. It was pretty easy, just like on S&M racing. I didnt weld any extra on the outside, and it seems to be holding up fine. Im not sure how much it helped since i did it before i put it on.

 

My guess is that the performance will reach the DC JDM if you remove the welds. So, that's about 2 HP or so. It can't be more than the DC JDM 4-1.

http://www.automotiveperformanceengi...om/header.html

 

Why?

 

Well, the collector has the same size, the primaries of the OEM JDM are 1 mm smaller, design is similar and the DC JDM has smooth head flanges. How can the OEM JDM perform better than the DC JDM if you remove the welds only?

 

Ah ok... so the flange doesn't warp, makes sense...

 

Huh? I mean the pipes!!!

 

So the JDM header used in the Great Header Test was un-modified? That's good to know.

 

Yep, they should put that on the website. I was confused too. The OEM JDM performed quite well with the welds not removed..

 

I agree, I'm contemplating picking one up for the kaa....

 

i was talking to doc cortez(not sure he'll see this) last night and he had it done on his and said it was easy.. he didn't have the welds redone and hasn't had any problems.. my JDM is supposedly coming soon, so I'll probably be doing the same.. hopefully I'll be able to contain myself with the dremel and not screw it up..

anyone got any tips, that's done this?

 

I had mine done. It's nice.

 

I cleaned mine. What I did was took it to my local welder- had him weld around the outside of the header. Then with a carbide nibbler and an angle grinder smoothed out the inner weld. All in all it took about 2hrs of work. I didn't dyno before and after so I really can't say if it helped or not- I cannot see how it wouldn't though. Good luck.

matt