Landracing Forum
Tech Information => Aerodynamics => Topic started by: panic on February 27, 2018, 03:32:31 PM
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Never mind
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That sounds like a neat idea. Test it on a flow bench first with some clay or something around the stem to see what it does. Making the ellipse out of something ( guide extension effectively) becomes an engineering challenge from vibration, heat and other conditions where a thin section of something is likely to break off and whoops, though the cylinder (or out the exhaust as the case may be) it goes. Can't make the stem elliptical as the valves rotate.
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Actually most valve guides on contemporary V8 engines are .502 (with a .003 or so press fit in alloy heads) O.D.
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I went to Darin Morgan's cylinder head seminar last year and one of the tools he uses on the flow bench is a small wing that he moves around in the port on the flow bench. This helps him decide where he needs a wing, or whatever they call it. I have looked at many of his heads and they seem to have some form of this.
There is the other extreme though, years ago my cousin told me to knock the valve guides out on my CB750 and to just smooth the entire port out and to pop the guides back in and do my valve job. My valve job guy said I had ruined the heads, but we went out in a 200 mile race and won the 750 class and took 3rd overall against the 1000's. Sometimes overall flow improvement means more than just smooth flow.
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I went to Darin Morgan's cylinder head seminar last year and one of the tools he uses on the flow bench is a small wing that he moves around in the port on the flow bench. This helps him decide where he needs a wing, or whatever they call it. I have looked at many of his heads and they seem to have some form of this.
There is the other extreme though, years ago my cousin told me to knock the valve guides out on my CB750 and to just smooth the entire port out and to pop the guides back in and do my valve job. My valve job guy said I had ruined the heads, but we went out in a 200 mile race and won the 750 class and took 3rd overall against the 1000's. Sometimes overall flow improvement means more than just smooth flow.
In the end a Flow Bench is like a Micrometer. It doesn't care how much time or thought you put into your port or design it just gives you a measurement. I wish I had a dollar for every time I "thought" I had improved a port but the Flow bench told me otherwise. Take nothing for granted.