Quote:
Originally Posted by roflwaffle
It's not a mistake, just out of context (Use the search Luke!  ). Mazda seems to have designed their exhaust manifold to minimize the amount of hot gases left in the cylinder, and along with other changes this allows them to increase the CR w/o knock, which is where the mileage improvement comes from. |
Green Car Congress: 2012 Mazda3 to offer new SKYACTIV gasoline direct injection engine and SKYACTIV automatic transmission
It seems that they are claiming the 4-2-1 exhaust is one of the factors that allows them to run a 14 to 1 compression ratio.
While it may or may not be a high flow exhaust as the OP thinks improves FE, it may be both or it may not. Certainly looks like a high flow system but I would think it is more designed for low speed efficiency since everything else seems to be pointed in that direction.
regards
Mech