Merlins Ralliart and EvoX TUNING GUIDE Version K.pdf - EvoScan

MERLINS RALLIART & EVOLUTION-X TUNING GUIDEBy 2000 rpm and 100-120 load, most tuners agree the intake advance should setto 30 degrees, or thereabouts. Fortunately we have eight rpm bands in which to geta nice progressive tune, something lacking with the Evo9.Due to higher exhaust gas back pressure, from 4500 rpm on, the intake camadvance should be progressively reduced, as per the GST tuned map, or similar, sothat at 6500 rpm and 100 load and above the advance is minimal. Numerous protunershave reported no benefit to adding cam advance in this area on engines withstock exhaust, and doing so will likely show reduced power. On engines with lessrestrictive exhausts, the exhaust manifold gas back pressure (EGBP) is reduced, sothis top load and rpm area can benefit from some cam advance, though usually notas much as would be used on normally aspirated or supercharged engines.Examine closely the tuned maps supplied by GST to the Evo community. Note howthe amount of advance is reduced as the engine starts to make reasonable boost,and considerably reduced at the top-end. This is to get rid of the valve openoverlap as the back-pressure in the exhaust will fight the inlet manifold boostpressure, thus reducing the amount of inlet charge in the cylinder and its effectiveoctane rating. Measurements by tuners have shown in excess of 40psi in theexhaust manifold when under boost.REV: 0.K merlin@three.com.au Page 64 of 134