Valve spring pressure?? April 22, 2019 06:33AM
How much valve spring pressure is required on the seat to run 90 lbs boost? Open rpm roller cam. Thanks
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Re: Valve spring pressure?? April 22, 2019 08:34AM
At least 2 1/2 boost
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Re: Valve spring pressure?? April 22, 2019 10:46PM
pretty vauge question...what is the valve material,and rocker material,retainer and keeper material ?
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Re: Valve spring pressure?? April 23, 2019 02:50AM
I presume you are referring to the theory that boost pressure hold the valve open and thus you need to compensate with the spring pressure. If you have a blower motor with open exhaust that is correct, but at 90 psi I suspect you are talking about a turbo motor and there you have to realize that along with the 90 psi on the back of the valve you also have approximately the same pressure as your turbo drive pressure on the head of the valve. If you do want to calculate the force on the valve from pressure you will need to provide the valve size.

To truly calculate spring requirements your cam grinder will need the info Patches mentioned along with rocker ratio and the weights of everything between the cam lobe and the valve seat.
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Re: Valve spring pressure?? April 23, 2019 04:45AM
225 # seat pressure will work.
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Re: Valve spring pressure?? April 23, 2019 05:17AM
Thanks everyone for the input
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