Originally Posted by openwheel44:
Finding an easy way to check cam lift would be nice without having to yank the valve cover off. Being the motor man that I am not.........wouldn't a higher lift cam necessitate more valve relief even on stock pistons? Obviously I don't know how much clearance is built into the valve relief on a piston. Plus unless we degree the cam, we don't know the duration/profile in relation to stock but again........would that create a valve relief issue? So.......if we can determine the piston is stock configuration, any small changes in the cam would not be big HP advantages? At least not enough to worry about unless I am out to lunch. ?????
Phil
The problem is there are not too many motor people out there. There fore when some one tell the non motor person that they think so and so is illegal, even if the other person is no more knowledgeable than the other. The statement is taken as truth and the ugly term cheater raises it head.
You were probably told by a person no more knowledgeable than myself that the Horsepower was in the head or better known as Volumetric Efficiency. The higher the VE is the more power your engine will make. We can even move the rpm that the VE is highest at by moving the opening and closing events of the valves. Creating either a "TORQUER" or a "WINDER" motor. I believe this to still be a very true statement.
I took one of my many blown up engines, I cut off half of number 1 cylinder head leaving the remaining 2 valves visible. When we do this one can see just how close the valves get to the piston at TDC. We have less than >.050" t0 .070" between the piston and valves as the piston comes up on the TDC overlap portion of the stroke. This does not leave a lot of room to change cam duration on the cam as we did on the old automotive push rod engine. So the only way to get more air and fuel in the motor is to increase the valve lift.
Because of the difference in measuring valve opening and closing events between the OEM and aftermarket cam grinders it is hard to compare the difference in camshaft duration between stock and modified cams. It only varies about 20 degrees or so, that piston keeps getting in the way.
However they can weld on the nose of the cam and then grind it down keeping almost stock duration but increasing the lift thus making the engine more powerful. The pistons would not have to be changed to do this, but it might require heavier valve springs to take the RPM's up to where the cam starts making any real horsepower.
Using Web cams specs.
The intake gross lift on a stock zx10r's is .......... .354 inches or 9.1MM
The intake gross lift on Web cam's performance cams vary between .384"-.400" or 9.85mm to 10.25mm. Maximum lift.
That 46 one thousandth of an inch will make a difference at racing speeds. And it does not show up a whole lot on the degree wheel. Another interesting fact is the more fuel and air you cram into a cylinder the louder the "Bang" when it ignites.
That extra lift would show up like a Baby Ruth Bar in the Punch Bowl with the cam lift checker.
Honest Dad himself
