Oversize head cylinder valves

[dfx16]

Good day sifu

I tried do a search with regard oversize valves
Nothing much was discussed

What's the pro and con for increasing the diameter of the valves 1~3mm over stock
How much bhp one can expect to gain from 1.6 na or 2.0 na

Thanks

 

[mona-vie]

Bigger valves allows more air to enter the combustion chamber. This improves power at high RPM.

However, bigger valves will also reduce air velocity at low RPM. Hence worse low RPM power.

Bigger valves alone is not useful, it needs to be used in conjunction with your cam + other mods.

 

[dfx16]

Thanks mona-vie.. i understand those principles
My concern for con for eg. will this mod cause errand idle?
And for pro what can i benefit from this mod?

 

[upontheriversky]

i would think get bigger valve along with oversized piston for power balance across rpm. need to think about fitment of the valves too

 

[kambing69]

the cons i think will occur overheat..or maybe dmg some of the internal parts in the engine, if it not been strengthens..