luna_s said:
i'm guessing with modern casting methods and design the head is pretty good to begin with anyway, just getting rid of the casting marks cant really do any harm, as for gains no idea - i doubt very much but every little bit helps 😃
why would they say impossible ? unless they didn't want the work, saying that i contacted two companies with no response either dunno..
I've just found this thread but a few comments
The z22se head is lost foam cast which is used because it's quick and cheap, the SAAB turbo head is sand cast because the lost foam one wasn't strong enough. Another problem with lost foam as you can see from before and after of the intake valves is that the foam is cut in section then assembled so you can get seam lines where the sections are put together.
On the power gains front you should see an improvement in the high engine speed perormance as the ports are a design to be curved to give the gas flow alot of 'tumble' at low engine speeds this give a good air fuel mixture and high torque, you can see this in vocky's before and after as there's no clear line of sight through the port. The down side to this is that at high engine speeds the ports are restricting the airfolw. If you look at motorbike ports they are almost straight which give very little tumble at low speed but are very free flowing at high speed.
