Searching a naturally aspirated engine

gasoline direct injection (GDI), also known as petrol direct injection, direct petrol injection, spark-ignited direct injection (SIDI) and fuel-stratified injection (FSI). 
 variable valve timing (VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions.
 can be used with both direct and indirect injection 
 
 best would be to find a indirect injection engine, like on Mazda 6 GH 2.0 pre-facelift (2008-2010) and all Mazda 6 GH 1.8 (2008-2012). 
 VTi (Valve Timing injection) engines created by PSA Peugeot Citroën and BMW Group uses indirect injection
 there are 2 variants, 1.4 with 95 bhp and 1.6 with 115bhp 
 
 MIVEC is the brand name of a variable valve timing (VVT) engine technology developed by Mitsubishi Motors 
 Honda VTEC .. 
 Ford TI-VCT, non GDI 
 PM (particulate matter) is produced only by engines with direct injection 
 EURO 6
 it is achived basically only with direct injection with very few exceptions 
 Toyota has some small 1.33 MPI EURO 6 engines 
 
 EURO 5
 most engines are designed with direct injection, 
 few exceptions for >1.6, like Mazda MZR 1.8i 
 easier to find for small engines, <1.4 
 
 EURO 4
 many engines can be found with indirect injection 
 but many use with direct injection, think about VW/Audi FSI