Cost to benefit: oversize valves?
 

Mild build up of a f22a. 86mm bore by 95mm stroke, bisi stage 2 cams, and 12.1 pistons and more, those are just the basics.

Now anyways, bisi just added new valves you can buy on their site. +2mm intake and +1mm exhaust. That seems TOO big for a street motor but other than that the only other option seems to be +.5mm valves. Does a motor like this really NEED bigger valves? Or would i just be throwin money away for nothing? I havent really seen a lot of people mention going bigger on here, and some even swear by the stock valves with just a valve job.

Any opinions welcomed, thanks!

Re: Cost to benefit: oversize valves?
 

how high are you planning on revving? you might benifit from a larger valve if your going to rev to 9k and only need power up top.

for a street engine...well unless you work it into the design the gains will be almost nil.

Now say if you had plans on maybe adding a bit of juice down the road or something then its a different story

Re: Cost to benefit: oversize valves?
 

My builder said i could safely go to 9k... but i will mostly keep it to a 7.5k - 8k max. With its long stock stroke im really hoping that it will be more of a very streetable torque monster making good power in a usable RPM for cruising but also with the pistons and cam make some good top end.

Guess they arent really worth it for my application. I figure if i end up re-sleeving and boring out to 89mm and go for broke with that 100mm stroker crank i'd benefit more.

Re: Cost to benefit: oversize valves?
 

When Honda designed the K24, (86x99), they went with 36mm INT valves. Just sayin.

Re: Cost to benefit: oversize valves?
 

why dont you ask bisi ;)
he is definetly the master of the f series.