So i just disassembled my y8 head and noticed that cylinder's exhaust port 4 being closest to the vtec side of the engine, has a very small port inside that leads to the rear of the head / intake side. Why is this, what is it's purpose?




the port exist right of the intake port, above the water outlet.

 

I have no idea...
IF that port leads from the exhaust thru the head to the intake manifold (which is how your wording seems to put it) the ONLY thing I can think of is that's not a Y8 head.
Instead, it might somehow be a Y5 head, because those have exhaust gas re-circulation (EGR) in order to lower emissions, but that means it'd have to run thru an EGR valve or something....
I've got a Y7 head sitting in my closet and I looked at the intake side...there seems to be a circular etching there like something MIGHT go there if it were used for something else, but definitely no hole tapped there
And I don't have a Y8 to compare it to
XP

Can someone else please help because I have NO idea
XD;

EDIT: found pix of Y8 cylinder heads with that weird little port...wtf is that?

 

Y8 and Y5 cylinder heads share the same casting. That port is for the EGR on HX (Y5) but isn't used on Y8's.

 

The one on my Y8 head was blocked off by the Y8 intake manifold. The IM gasket has a hole up like the pic posted above it's blocked off

 

you are right with a little more research last night, i found that port to be the EGR exhaust hole. my y8 head has it, but the manifold doesn't have it so... no EGR. But the prevision exist, i just wonder how much it effects exhaust flow on port #4?




here is a y8 manifold that has the EGR prevision. This thing is horrible looking.

 

LOL can't believe I guessed right on that XD;
As for how it flows....probably the same as other Y8's since they're all apparently cast that way ^^;

Thanks for the weird ****, Honda
XD;