Rep Power: 294

Hey all,
Last weekend I bought a gasket at Honda to install my Kamikaze header, but I noticed that the gasket hole diameters were smaller than the ones of the header. I was just wondering?

1) Wouldn't this decrease outflow of air and therefore constrict available HP?

2) Should I therefore resize the diameter of the gasket to make it the same size as the header ports?
or
3)Do the engine ports have different diameter than the header and thus not making a diference wether I bore it or not?

I noticed that gearbox bored his gasket but I don't know if I need to do the same.
Thanks in advance.
Mike.

 
Rep Power: 323

if the Exhaust ports on you head are stock, than no. Opening up the gasket will do nothing. The gasket should be the size of the smallest hole.

 
Rep Power: 294

You mean the smallest hole on the header or the engine ports? This is were I'm confused, since I haven't yet remove the OEM exhaust manifold, I don't know if the diameters are different between the header I bought and the engine ports.
When I placed the gasket on top of the Kami. headers, the gasket holes are smaller than those of the header. Hence my question about resizing the gasket.

 
Rep Power: 0

Is your head ported?

 
Rep Power: 294

No, it's not.

 
Rep Power: 323

then leave the gasket alone. making it bigger will not help anything.

 
Rep Power: 294

It may or may not.
Let me see if I explain my self better this time.
Lets say that the ports on my header have diameters of...I don't know, maybe 50mm(I haven't measure it yet).
The diameter of the gasket holes are maybe 40mm and therefore smaller, so if you place the gasket on top of the header there's a diference of what? 10mm right? This is what I'm talking about, once I'll install the gasket and then the header there will be some outflow restriction, unless the engine exhaust ports are 40 mm in diameter just like the gasket. Do you guys see what I'm trying to ask now? Please, let me know.

 
Rep Power: 291

dont bore it out, the holes in the gasket should be the same size diameter as the port on the head, not the header. As long as the holes in the gasket ARE NOT smaller then the ports on the head then you will be fine.

 
Rep Power: 323

since the exhaust is coming out of a (your example) 40mm hole and passing thru a 40mm gasket, into a 50mm header. the gasket has no effect at the stock or enlarged width. Unless you port you head.... until then leave it alone.

 
Rep Power: 294

Got ya, that's what I wanted to know, thanks guys.

 
Rep Power: 812

Okay everyone answered already. Here's my diy if you're curious about why I did it.

http://www.7thgencivic.com/forums/sh...haust+manifold