What's h point of this port shape??

[SammoHung]

on the exhaust outlet and manifold port number 2? is egg shaped!!

1) Any one shed any light as to why this port was designed with this shape on the interface??

2) I can see it being a pain for the custom manifolders....how did you guys get around this problem?

 

[AMY]

Amongst my vast collection of MA heads I have some JDM heads, the bottom of this port has a blanked off area on the Uk cars, but on the JDM heads there is a port that runs straight through to a port on the inlet side. It would appear to be some sort of EGR.

 

[james betley]

i have it on my car as well

 

[SammoHung]

Wow AMY,

That's amaizing info!! Thanks

I knew there must be some explaination but couldn't think what

I guess there must be some type of valve fitted in the JDM heads too somwhere in the port?

Out of interest, does anyone know what advantages/disadvantages such an EGR system would offer...

 

[Alienfish360]

increased economy decreased performance lower emissions

 

[AMY]

I havn't really looked in to it in too much detail, but I think there is probably a valve on the inlet manifold. The emission k10's have a similar set up but the gas is recirculated from the exhaust manifold. As far as I see it, hot exhaust gasses in your intake is never going to be a good thing, apart from an emissions. The exhast manifold should be treated as an extension of the exhaust port, so it's not a good thing. Most four branch manifolds I have seen just cover the extended part with the flange, ideally it should have an extension to delete it.

 

[Ed]

Some K10s used this UK too. Many are blanked off and some (K10 with ECC) had this and additional recirc. It reduces the Nox content on the exhaust.

Ed