Ultra-High RPM Dual Valve Spring / Titanium Retainer Set
Dec 16, 2009, 09:08 PM
#49
A valve spring cannot be tagged with a specific rpm limit, except with a particular cam set, valvetrain, etc. A spring that will effectively track an HKS cam (lazy ramps) up to an 8000rpm limit will not handle a cam with a more aggressive lobe profile (e.g. GSC S2) at that same rpm using the same valvetrain.
The backside of a valve is important to the overall flow potential of the port. This is one area where OEM valves typically fall short of better quality aftermarket parts.
We measured a typical factory EVO spring at around 50 lbs seat pressure and 150 lbs open pressure. That isn't enough to accurately track better cam sets where they are intended to make power.
Valve float causes erratic valve action that compromises power. On the intake side, the valve floats to a point whereby the piston is moving far enough upward bast BDC whereby it begins pushing the intake charge right back through the intake valve. On the exhaust side, the excess overlap begins to contaminate te intake charge. In many cases, the reduction in power may not be readily apparent, but it is there. When the effect is enough to be easily recognized on the dyno or is audibly evident, the problem is especially serious.
It is always better to have a little more valve spring pressure than one really needs than a little less. There are quite a few persons in this forum who are experiencing reduced power due to inadequate spring pressures. They just don't realize it.
The backside of a valve is important to the overall flow potential of the port. This is one area where OEM valves typically fall short of better quality aftermarket parts.
We measured a typical factory EVO spring at around 50 lbs seat pressure and 150 lbs open pressure. That isn't enough to accurately track better cam sets where they are intended to make power.
Valve float causes erratic valve action that compromises power. On the intake side, the valve floats to a point whereby the piston is moving far enough upward bast BDC whereby it begins pushing the intake charge right back through the intake valve. On the exhaust side, the excess overlap begins to contaminate te intake charge. In many cases, the reduction in power may not be readily apparent, but it is there. When the effect is enough to be easily recognized on the dyno or is audibly evident, the problem is especially serious.
It is always better to have a little more valve spring pressure than one really needs than a little less. There are quite a few persons in this forum who are experiencing reduced power due to inadequate spring pressures. They just don't realize it.
Mar 9, 2010, 06:01 PM
#50
A valve spring cannot be tagged with a specific rpm limit, except with a particular cam set, valvetrain, etc. A spring that will effectively track an HKS cam (lazy ramps) up to an 8000rpm limit will not handle a cam with a more aggressive lobe profile (e.g. GSC S2) at that same rpm using the same valvetrain.
The backside of a valve is important to the overall flow potential of the port. This is one area where OEM valves typically fall short of better quality aftermarket parts.
We measured a typical factory EVO spring at around 50 lbs seat pressure and 150 lbs open pressure. That isn't enough to accurately track better cam sets where they are intended to make power.
Valve float causes erratic valve action that compromises power. On the intake side, the valve floats to a point whereby the piston is moving far enough upward bast BDC whereby it begins pushing the intake charge right back through the intake valve. On the exhaust side, the excess overlap begins to contaminate te intake charge. In many cases, the reduction in power may not be readily apparent, but it is there. When the effect is enough to be easily recognized on the dyno or is audibly evident, the problem is especially serious.
It is always better to have a little more valve spring pressure than one really needs than a little less. There are quite a few persons in this forum who are experiencing reduced power due to inadequate spring pressures. They just don't realize it.
The backside of a valve is important to the overall flow potential of the port. This is one area where OEM valves typically fall short of better quality aftermarket parts.
We measured a typical factory EVO spring at around 50 lbs seat pressure and 150 lbs open pressure. That isn't enough to accurately track better cam sets where they are intended to make power.
Valve float causes erratic valve action that compromises power. On the intake side, the valve floats to a point whereby the piston is moving far enough upward bast BDC whereby it begins pushing the intake charge right back through the intake valve. On the exhaust side, the excess overlap begins to contaminate te intake charge. In many cases, the reduction in power may not be readily apparent, but it is there. When the effect is enough to be easily recognized on the dyno or is audibly evident, the problem is especially serious.
It is always better to have a little more valve spring pressure than one really needs than a little less. There are quite a few persons in this forum who are experiencing reduced power due to inadequate spring pressures. They just don't realize it.
Sep 6, 2016, 12:43 AM
#51
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