VVC inlet valve sizes. Is bigger better?

[Kal-El]

Is it worth having the 32.5mm inlets and larger exhaust valves fitted when having a VVC head ported? Will this bring a benefit regardless of other components and state of tune, or could it actually be detrimental if not running DTH throttle bodies bigger cc and lairy cams?
I'm trying to decide if its worth doing whilst the head is being worked on or not. Thoughts?

[DVandrews]

It's always worth doing if the porting is done to match, the difference on a low tuned engine will be minimal so the cost benefit probably doesn't stack up, on a higher tuned engine where you are chasing every horsepower the benefits are much more easily justified. Bear in mind that you can get > 230BHP on the stock VVC valve sizes if the head is correctly ported (and with appropriate cams, TBs etc.).

It is perfectly possible to see > 200BHP on smaller valves (29.5mm/26mm) provided the head is properly worked.

One thing to bear in mind is that none of the stock pistons, or the off the shelf forged pistons have valve pockets big enough for 32.5mm/28.5mm valves.

Dave

Edited by DVandrews on Tuesday 15th July 06:50