Bench Flow
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Joined: Dec 1969
Posts: 3,499
From: PORTLAND, OR, MULTNOMAH
Bench Flow
Probably in the wrong pew again, but curious as to how heads are flowed. Is the figure given at 28" for one cyl or all eight? If for one cyl then how could you possibly clainm that all 8 are the same, even with CNC?
If for all 8, do you assume that all intakes and exhausts flow the same?
Are they flowed with valves installed (i.e. is that how they can tell what the flow is at .200 or .600 lift)?
Mine flow 261/186 @.500. That's with 2"/1.56" Manley Race Flows. Would the larger undercut valves provide more CFM?
Can't recall seeing much on Flowing process. Sure find lots of bragging on numbers though.
Move it if you believe this can be answered factually in the Lt1 tech.
Thanks.
If for all 8, do you assume that all intakes and exhausts flow the same?
Are they flowed with valves installed (i.e. is that how they can tell what the flow is at .200 or .600 lift)?
Mine flow 261/186 @.500. That's with 2"/1.56" Manley Race Flows. Would the larger undercut valves provide more CFM?
Can't recall seeing much on Flowing process. Sure find lots of bragging on numbers though.
Move it if you believe this can be answered factually in the Lt1 tech.
Thanks.
Registered User
Joined: Oct 2002
Posts: 2,931
From: Upstate NY
Re: Bench Flow
Originally posted by BUBBA
Probably in the wrong pew again, but curious as to how heads are flowed. Is the figure given at 28" for one cyl or all eight? If for one cyl then how could you possibly clainm that all 8 are the same, even with CNC?
28 in of water is the depression or amount of vacuum sucking air thru the intakes or blowing it thru the exhaust. That's just about 1.0 psi or approximately the vacuum in an unrestricted intake near torque and power peak. Each port is checked individually.
If for all 8, do you assume that all intakes and exhausts flow the same?
Never assume. Flow all of them.
Are they flowed with valves installed (i.e. is that how they can tell what the flow is at .200 or .600 lift)?
Exactly right. A weak valve spring and a fixture with a screw pushing on top of the valve sets the lift.
Mine flow 261/186 @.500. That's with 2"/1.56" Manley Race Flows. Would the larger undercut valves provide more CFM?
Maybe, maybe not. Try them on the flowbench to see.
Can't recall seeing much on Flowing process. Sure find lots of bragging on numbers though.
Move it if you believe this can be answered factually in the Lt1 tech.
Thanks.
Yeah, guys like to brag about big numbers (except ETs and golf scores). Like a lot of things, it isn't always the size but what you do with it that matters...you know, cam timing, intake manifold, etc.
Probably in the wrong pew again, but curious as to how heads are flowed. Is the figure given at 28" for one cyl or all eight? If for one cyl then how could you possibly clainm that all 8 are the same, even with CNC?
28 in of water is the depression or amount of vacuum sucking air thru the intakes or blowing it thru the exhaust. That's just about 1.0 psi or approximately the vacuum in an unrestricted intake near torque and power peak. Each port is checked individually.
If for all 8, do you assume that all intakes and exhausts flow the same?
Never assume. Flow all of them.
Are they flowed with valves installed (i.e. is that how they can tell what the flow is at .200 or .600 lift)?
Exactly right. A weak valve spring and a fixture with a screw pushing on top of the valve sets the lift.
Mine flow 261/186 @.500. That's with 2"/1.56" Manley Race Flows. Would the larger undercut valves provide more CFM?
Maybe, maybe not. Try them on the flowbench to see.
Can't recall seeing much on Flowing process. Sure find lots of bragging on numbers though.
Move it if you believe this can be answered factually in the Lt1 tech.
Thanks.
Yeah, guys like to brag about big numbers (except ETs and golf scores). Like a lot of things, it isn't always the size but what you do with it that matters...you know, cam timing, intake manifold, etc.
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