1NZ port & polish

[Galavoxx]

Originally Posted by Dragonacc

Larger valves won't help unless you increase the redline or go FI. Bigger valves kill air velocity which hurts bottom end power.

I don't entirely agree with that. OF course a higher redline is going to showcase the potential of larger valves. However, with a flow bench designed head and larger valves, the hp should be avilable everywhere, not just up high. I'm not saying that the 1NZ has the potential to make more power with just valves and a head job but the potential of a stock internal 1NZ engine with just head work has yet to be realized. Many head jobs (good ones) will bear the ideal combination of performance, reliability, and drivability. This is done by balancing all of the head elements such as matching valve size and shape to seat geometry to port configuration. Bottom line: a head alone on many cars can conservatively net horsepower gains of 5 – 10% (and occasionally even more) and this is stage 1 on stock internals. But you probably already know this. Of course we will also have to get into the electronics...