Sifu, upon reading further about the function of an adjustable cam pulley, i've just discovered that by advancing the cam timing, the inlet valve would open & close earlier while the exhaust valve would open & close later...
hence, izzit correct to say that by advancing the cam, the valves overlap period will increase as depicted below?
if so, an article below stated this would have detrimental effect to our fuel efficiency which i would like to quote below...
"More overlap decreases low-rpm vacuum and response and improves the signal provided by the fast-moving exhaust to the incoming intake charge in the midrange, often providing noticeable engine acceleration improvements. Less overlap can increase efficiency by reducing raw fuel seepage into the exhaust and improve low-end response due to less reversion of the exhaust gases into the intake port."
Variable Valve Timing - VVT For Performance Applications Explained - Hot Rod Magazine
thus, may i enquire has anyone experienced any deterioration to their FC when they advanced their adjustable cam pulley?...