air flow ?

rod · 06-28-2020, 04:52 PM

OK, I didnt think this would be so complicated.
these are actual figures for my SBC 292 [misnamed] turbo heads.
28" H2O @ 70 degrees and at about 575' elevation and almost no humidity.
Intake exhaust

.200 151 136
.300 210 181
.400 246 210
.500 265 223
.510 267 223
no increase, on either side, after.510 lift.

so I understand, that some additional lift could be used, above .510, to make up whatever type of loss. even some extra amount of duration, for the same reason.
however, on my desk top dyno, there is no increase in power output, past about 525" lift.
it appease, on paper at least, that you are just wearing out springs and guides, with additional lift. maybe in the real world, there might be some benefit.

so, new thoughts.
thanks all
Rod in AZ

Stan Weiss · 06-28-2020, 05:27 PM

Quote:

Originally Posted by rod

OK, I didnt think this would be so complicated.
these are actual figures for my SBC 292 [misnamed] turbo heads.
28" H2O @ 70 degrees and at about 575' elevation and almost no humidity.
Intake exhaust

.200 151 136
.300 210 181
.400 246 210
.500 265 223
.510 267 223
no increase, on either side, after.510 lift.

so I understand, that some additional lift could be used, above .510, to make up whatever type of loss. even some extra amount of duration, for the same reason.
however, on my desk top dyno, there is no increase in power output, past about 525" lift.
it appease, on paper at least, that you are just wearing out springs and guides, with additional lift. maybe in the real world, there might be some benefit.

so, new thoughts.
thanks all
Rod in AZ

Rod,
While there is no increase, on either side, after.510 lift. The question still stands what is the flow @ .550" and .600" If it basically leveled off is one thing If it drops and or goes turbulent is another thing. In your desk top dyno program have you entered any flow numbers for .550" or .600"?

Stan

PS Let ask what is your combination? Is it possible that your desk top dyno program is not showing and increase in HP with more lift because you already have the needed flow?

Adger Smith · 06-30-2020, 05:21 PM

Rod,
You simplified it by saying "some additional flow"
look at the real issue. cylinder filling
If the lift maxes at .500 and that is Max flow how many degrees of crank rotation takes place while it is at full .500 lift/max flow?
Lift it past the max flow at .500 lift and tell me how many degrees of crank rotation is at or near max flow. It aids cylinder filling.

06-28-2020, 04:52 PM	#1
rod Member Join Date: Dec 2009 Location: Kingman, NW AZ. in the middle of the longest stretch of Route 66 Posts: 314 Likes: 0 Liked 20 Times in 15 Posts	Re: air flow ? OK, I didnt think this would be so complicated. these are actual figures for my SBC 292 [misnamed] turbo heads. 28" H2O @ 70 degrees and at about 575' elevation and almost no humidity. Intake exhaust .200 151 136 .300 210 181 .400 246 210 .500 265 223 .510 267 223 no increase, on either side, after.510 lift. so I understand, that some additional lift could be used, above .510, to make up whatever type of loss. even some extra amount of duration, for the same reason. however, on my desk top dyno, there is no increase in power output, past about 525" lift. it appease, on paper at least, that you are just wearing out springs and guides, with additional lift. maybe in the real world, there might be some benefit. so, new thoughts. thanks all Rod in AZ

06-30-2020, 05:21 PM	#3
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: air flow ? Rod, You simplified it by saying "some additional flow" look at the real issue. cylinder filling If the lift maxes at .500 and that is Max flow how many degrees of crank rotation takes place while it is at full .500 lift/max flow? Lift it past the max flow at .500 lift and tell me how many degrees of crank rotation is at or near max flow. It aids cylinder filling. __________________ Adger Smith (Former SS)