Quote:
Originally Posted by Cupcar
I posted looking for someone who could tell me the lobe separation angle of a 2004 GT3 and nobody responded, but I did a little measurement and found it is 122.5 degrees as cam is installed and at idle.
Factory literature says the intake cam (Variocam only on intake in this engine) can be advanced 22.5 degrees at the cam, this is a whopping 45 degrees of crank angle.
So, the lobe separation varies between 122.5 degrees at idle, decreasing, depending on load, to a full load angle of 100 degrees between 1000 and 5000 RPM and then increasing again to around 116 degrees between 5000 and 7800 RPM. See graph below showing curve in degrees of crankshaft angle.
The Cup race cars do not have Variocam and are set at a static 105 or 110 degree lobe separation angle.
Anyone else find this interesting?
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I'm fascinated, the difference is probably due to the needs of a street vs race car. Gearing I'm sure makes a huge difference in the torque curves that you are looking for.