DeTomaso Mailing List: May 99, Message #192

Oops, I forgot to reply to this part.

>As for the extrude honing, if done properly, shouldn't that generally 
>be a good thing?   My limited understanding of extrude honing is that it
>generally cleans up and improves flow without radically changing the port
>shape.  

That would be okay if all you want to do is smooth the port out.
Porting, however, is more involved than than.  A professional porter
with access to a flow bench will determine the areas in the port tract 
that are restrictions and then open and/or reshape them.  Home porters,
without the aid of a flow bench, have rely on information found to work
from experience.  Vizard's book on modifying Chevrolet cylinder heads
is a good place to start. Extrude hone just hogs the port out in a brain 
manner.  Might work, might not.

>I'm assuming they really don't intend to simply open the ports up to
>4V size since that would defeat the purpose of the 2V heads (like you said).

Bad assumption.  I don't think they'll port it all the way down but I bet they
will port match it.  Big area changes and known restrictions don't make for 
good flow characteristics.

Dan Jones