Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Disabling intake and exhaust valves (going to 8 valves in a 16-v head)

Lotusrk · 06-10-2012, 07:18 AM

I learned from my econo-minded father to lower the rpm of maximum torque by increasing the valve clearence. This reduces duration (number of degrees the valves are open), reducing valve overlap to a minimum. Disabling half the valves on a 16 valve head drastically reduces the flow potential which would be counter-productive to torque and horsepower. We have altered lash from the stock .010" intake and .012" exhaust up to 1/4 turn intake and 1/3 turn exhaust. I have not checked this, but this might translate to approximately .030" and .036" or slightly more. The increase in valve lash might be considered drastic by some, but works well with a minimum of noise and no observed increase in cam wear over very long mileage (150,000 miles). Maximum torque is moved to a much lower RPM, in the case of 2 Toyotas, about 2,000 rpm.

06-10-2012, 07:18 AM	#37 (permalink)
Lotusrk EcoModding Lurker Join Date: Jul 2010 Location: Canon City, CO Posts: 1 Thanks: 0 Thanked 2 Times in 1 Post	Easy way to alter cam grind I learned from my econo-minded father to lower the rpm of maximum torque by increasing the valve clearence. This reduces duration (number of degrees the valves are open), reducing valve overlap to a minimum. Disabling half the valves on a 16 valve head drastically reduces the flow potential which would be counter-productive to torque and horsepower. We have altered lash from the stock .010" intake and .012" exhaust up to 1/4 turn intake and 1/3 turn exhaust. I have not checked this, but this might translate to approximately .030" and .036" or slightly more. The increase in valve lash might be considered drastic by some, but works well with a minimum of noise and no observed increase in cam wear over very long mileage (150,000 miles). Maximum torque is moved to a much lower RPM, in the case of 2 Toyotas, about 2,000 rpm.