Quote:
Originally Posted by rmay635703
Lean burn virtually eliminates soot, by oh the terrible Nox
On a related topic water mist systems can improve fuel economy, seems like that would also cure the valve coking issues.
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This might be true of PFI ( port fuel injected ) engines, but not for GDI. Many Asian market GDI engines have lean burn and suffer the same black carbon production. It is inherent to the injection and combustion profile.
Water injection at the ports will clean up the valve's back faces but will cause displacement of air and reduce the specific power of the engine which is the advantage of GDI in the first place. The injector will have to be in-cylinder to provide the power/emissions benefit but then there will be no valve cleaning effect.