OK, if this is a "who can guess the magic number" exercise, I'm guessing a mildly ported head with stock valves is going to do:
Intake: 200-225 cfm (if you have to have a single number, then 222 cfm)
Exhaust: 125-150 cfm (or a single figure of 133 cfm)
Flowbench conditions of: 0.350" valve lift & 28" wc pressure drop.
These are close to what a stock Supra head flows with no porting. I'm guessing with a "little" work, the narrow valve angle 1UZ head can be made to flow as well as the 45 degree stock 2JZ-GTE head.
Obviously if you went crazy with your die grinder you can make them flow whatever you want, but I don't think you'd do that, nor would your head porter.
For oversize valves, I'm guessing to bump both the previous flowbench figures by about 10%, so it would be:
Intake: 244 cfm
Exhaust: 146 cfm
The owner of one of the fastest Supras in the US told me about a year ago that they saw no improvement in 1/4 mile times when they went to bigger valves. Of course that was probably 300-400 HP ago, and nearly a second slower than they're running now, but back then, the valves just weren't the restriction in the system....yet.
Will bigger valves increase your flowrates on the flowbench? No doubt, yes.
Will you see a difference on the dyno or at the track? Dunno, how much HP are you planning to lay down?
When will you have the "real" figures on your head porting?
