Oversized valve

[pernati]

If i want to install oversized valve what i need to do? And what brand is better?

[robokill]

Be aware you need to make some serious power to have use of oversize valves. The size of the valve is standard

27.5mm exhaust
30 mm intake (if I am correct)

oversize are

32mm intake

exhaust is 29mm i believe.

Its actually no use if you are below 170hp caus everything needs to be grinded in again. Its alot of work

[4agze]

pernati Wrote:If i want to install oversized valve what i need to do? And what brand is better?

3 years ago i just took my head to a machine shop that do ported polishing, 3 angle valve job and have them do the oversize boring on my valves. i matched it with my toda cams long duration and high lift. here are the old pic when i got it back from the shop

valve size
33.4mm, Intake
28.0mm, Exhaust

[Morten]

robokill Wrote:Its actually no use if you are below 170hp

Just curious if this is based on experience or rumors?

[S.K.]

I have 200Hp in my racecar, and i still have standard valves. The machinery shop only grind a 3-angles to original valves...

[robokill]

Morten Wrote:

robokill Wrote:Its actually no use if you are below 170hp

Just curious if this is based on experience or rumors?

experience from a friend of mine he is running 181 hp on the crank using original valves. He did a calculation that you could easily go to 200 hp with standard size valves. It depends on how the air gets sucked into the engine. If that flow is optimum the standard valves would easily make more. (200+)