[phantomgreen]

I was recently talking to a mechanic about cam timing and he said changes in cam timing changes engine pressure which requires running premium fuel. Is this true?

[Joseph Upson]

Originally Posted by phantomgreen

I was recently talking to a mechanic about cam timing and he said changes in cam timing changes engine pressure which requires running premium fuel. Is this true?

Cam timing can change cylinder pressure however whether or not you need premium fuel depends on how the pressure is affected. That is why high performance cams cause a rough idle, they reduce low rpm cylinder pressure and increase cylinder pressure at higher rpm due to the valve openning and closing point. Once I get my desktop setup I'll try to track down the link to a calculator that demonstrates how the dynamic compression ratio
differs from the static ratio due to cam changes. The premium fuel requirement depends on a lot more variables than the camshaft itself.

[SappySE107]

I can see this in dynomation:P You cannot possibly time the stock cams on a stock compression motor to the point of requiring premium.

[phantomgreen]

Cool thanks for the clarification.