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Location:
parkdale, Victoria
Registered:
May 2005
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Valve lift?
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Wed, 16 November 2005 07:24
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Someone told me that once the valve opens 1/4 of its diameter, there's no more flow increase. So, purely longer duration gives you more flow per intake stroke once the 1/4 dia lift is reached.
Can someone confirm this.
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: Valve lift?
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Wed, 16 November 2005 10:33
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| shelldrake wrote on Wed, 16 November 2005 18:24 |
Someone told me that once the valve opens 1/4 of its diameter, there's no more flow increase. So, purely longer duration gives you more flow per intake stroke once the 1/4 dia lift is reached.
Can someone confirm this.
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Nope, it's wrong. Really crappy head might do that, but a 4AG will keep on increasing flow up to heaps of lift.
However, it's true that tha vast majority of flow is gained up to about 1/3 of the diameter of the valve.
From my site ->
"Ok, I've got a good example here of some flow figures for a basically standard Toyota 4AGE TVIS 1600cc twin cam head @ 10" of water.
Inlet port -
Lift CFM
0.060" - 31.5
0.120" - 65.0
0.240" - 108.4
0.300" - 111.1
0.360" - 112.5"
There's some figures to work with.
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: Valve lift?
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Wed, 16 November 2005 10:37
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Forgot to add - Different port shapes will vastly improve the flow at higher lifts. The 20v does this to a degree.
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Location:
parkdale, Victoria
Registered:
May 2005
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Re: Valve lift?
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Wed, 16 November 2005 22:53
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Thanks for that Bill - Good to know!
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