Turbo leaking oil into exhaust manifold
Aquapure code 125 and 194
So I simply took a new gasket and cut out the web of material between the main and EGR port, shown in red below. The basic idea is to make the #2 and #3 ports have a marger opening. In the stock cast iron exhaust manifold, there is a dedicated gas passage cast into the manifold that takes gas from the exhaust runner back to the EGR port hole.
EJ257 Exhaust Manifold Pressure. As the exhaust side pressure nears a 1:1 ratio with boost pressure then overlap will have a more beneficial effect. Otherwise, on a stock VF turbo its best to avoid overlap at WOT beyond 3000 RPM as this will cause reversion and dilute the incoming mix, reducing power. Increased Fuel Economy & EGR Effects