We custom designed these valve springs for the 4e/5e engine platform to combat valve float often encountered in engines running a higher than standard RPM or higher boost levels which force the valves open when in a closed position resulting in a loss in power, valve flutter, miss-fire and massively increasing the risk of detonation/knocking/pinking.
The valve spring in OEM form is very soft for its applications, even in comparison to other turbocharged engines of the same period, Because of this we recommending fitting these to all our inhouse engine builds and performance applications.
STD Valve Spring
35lbs Seat Pressure (based on a 31.39mm spring height)
72lbs Nose Pressure (based on a 7.5mm cam lift*)
21.75mm Coil Bind
8.64mm Maximum Cam Lift (based on a 1.0mm from bind)
TB Developments Valve Spring
82lbs Seat Pressure (based on a 31.39mm spring height)
141lbs Nose Pressure (based on a 7.5mm cam lift*)
22.11mm Coil Bind
8.28mm Maximum Cam Lift (based on a 1.0mm from bind)
*Camshaft lift measurements based at the lobe, not the valve, so to obtain maximum cam lift based on our measurements you need to add the valve clearance.
for example our stated maximum lift of 8.28mm with a shim clearance of 0.381mm(0.015") gives a maximum cam size of 8.66mm advertised cam.