4GTS/7.5R/182
Hello everyone!
I know this is a long shot but I am looking for someone with good knowledge on camshafts and valve springs.
I have purchased a set of "sport" cams which ran for about 25000Km, until the engine died due to a valve hitting a piston. This is a K4M engine (1.6 16v) if it matters any. The RPM limiter was lifted from 6500 to 7000rpm.
A couple of local mechanics at the time stated that the OEM valve springs might not be stiff enough to cope with the extra lift at high RPM.
The camshaft manufacturer also sells stiffer valve springs which they recommend, although stating the camshafts should work on a stock engine.
A quick google search got me warnings as to running stiff springs may damage other components.
Just how much is too much, regarding spring stiffness? I got all the manufacturer's data on both OEM and "sport" cams and springs, but to be honest all those numbers are Chinese to me.
I post them below just in case someone can help me figure out if they "sound" right.
My main question would be if these springs could cause me trouble elsewhere in the engine in the long run.
Thanks for your time and also for any help
I know this is a long shot but I am looking for someone with good knowledge on camshafts and valve springs.
I have purchased a set of "sport" cams which ran for about 25000Km, until the engine died due to a valve hitting a piston. This is a K4M engine (1.6 16v) if it matters any. The RPM limiter was lifted from 6500 to 7000rpm.
A couple of local mechanics at the time stated that the OEM valve springs might not be stiff enough to cope with the extra lift at high RPM.
The camshaft manufacturer also sells stiffer valve springs which they recommend, although stating the camshafts should work on a stock engine.
A quick google search got me warnings as to running stiff springs may damage other components.
Just how much is too much, regarding spring stiffness? I got all the manufacturer's data on both OEM and "sport" cams and springs, but to be honest all those numbers are Chinese to me.
I post them below just in case someone can help me figure out if they "sound" right.
My main question would be if these springs could cause me trouble elsewhere in the engine in the long run.
Thanks for your time and also for any help
Code:
CAMS
OEM (Intake|Exhaust) Sport (Intake|Exhaust)
Clearance [cl] 0.00mm | 0.00mm 0.00mm | 0.00mm
Duration [0.1mm+cl] 238º | 229º 249º | 245º
Duration [1.0mm+cl] 189º | 182º 211º | 204º
Valve lift [cl=0] 9.15mm | 7.95mm 9.70mm | 9.50mm
Cam lift 4.65mm | 4.05mm 4.90mm | 4.80mm
Peak angle 105º | 98º 105º | 98º
Timing [1.0mm+cl] -11/20º | 9/-7º 0/31º | 20/4º
Lift at TDC [cl=0] 0.30mm | 0.50mm 1.05mm | 1.35mm
VALVE SPRINGS
OEM Sport
Fitted length / load 36.0mm / 20Kg 36.0mm / 32Kg
Max. allowed lift / load 11.0mm / 66Kg 12.5mm / 82Kg
Lift at spring coil collision 12.3mm 14.5mm
Lift at retainer: valve seat collision 13.5mm 13.5mm
