Multiair's head has too small ports according to FIAT's policy. Manufacturer's strategy for maximum driveability, maximum percentage of torgue in lowest rpm and lowest amounts of pollutants are the main reasons. Small ports provide high speed of incoming mixture in low rpm, but also decrease dramaticaly the maximum flow capactiy. As a result, engine can't be supplied with enough amount of a/f mixture when power demands are icreased too much.
Our efford is to port the head in a way that maximum flow capacity is increased providing gains in high rpm ,while low rpm torgue is least effected.
Why is important to combine camsfaft upgrade with head porting?
According to our analysis multiair's valve opening cachacteristics are insufficient for big power demands and high revving. So, porting the head and increasing flow rate while the new amount of mixture dont have enough time to enter the combustion chamber before valve close again gives minimum gains. Porting could be done with any setup, but porting in way perfectly combined with upgraded camshaft would give maximum gains.