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Cost to benefit: oversize valves?

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Old 03-22-2011, 05:38 PM   #1
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Default 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!
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Old 03-22-2011, 06:21 PM   #2
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Default 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
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Old 03-22-2011, 07:23 PM   #3
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Default Re: Cost to benefit: oversize valves?

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Originally Posted by unusual71 View Post
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
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.
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Old 03-22-2011, 08:11 PM   #4
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Default Re: Cost to benefit: oversize valves?

When Honda designed the K24, (86x99), they went with 36mm INT valves. Just sayin.
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Old 03-22-2011, 08:27 PM   #5
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Default Re: Cost to benefit: oversize valves?

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Originally Posted by bigsnorlax View Post
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!
why dont you ask bisi
he is definetly the master of the f series.
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