Quote:
Originally Posted by TurboIQ
Well you're a boxer fanatic, so you will obsiously be biased from the start.  But chances are you might be right... I fell inline 4's run more smoothly than their flat counterpart. |
But you have to be a little bit careful, there.
Comparing to the Subaru flat 4... it has an offset firing order, and unequal length exhaust on the turbocharged engines. It is set up to make big exhaust pulses, and put them through to a turbo that is mounted high and on the side of the engine, closer to one set of exhaust ports than the other.
The Subaru H4 could run smoother, theoretically, with an opposing firing order, L-R-L-R -> rather than L-L-R-R-> (EJ firing order is 1-3-2-4), which no EJ engine has; as well as the equal length exhaust that the 2010 Legacy GT seems to offer, with a turbo, possibly a twin-scroll, mounted just below the crank pulley, rather than high-right-side... But it would sound a lot different. no lumpy burble from the exhaust. It would probably sound a lot like a light-inertia inline 4, with perhaps a bit of bass from the fact that it is a big of a big-displacement 4-cylinder, compared to something 2 liters or less.
With a flat 4, pistons 1 and 3 are on the opposite side of 2 and 4. On an inline 4, that particular firing order would skip over adjacent pistons, except from 3 to 2, in the center of the block, where it would minimize rocking motion. On a Subaru, 1 and 3 ARE adjacent pistons, as are 2 and 4. Like a V-engine, where odd numbers and even numbers are on opposite banks from each other.
A flat 4 could run smoother than Subaru happens to set them up, if I am understanding it correctly. It would be interesting to see an EJ25 with a 1-4-3-2, or 1-2-3-4 firing order.
A flat 6 has a 60 degree firing order, rather than 90, and the newer EZ motors use the following firing order: 1-6-3-2-5-4, which I believe is in common with the EG33. That further smooths out power delivery, and the staggered even-odd numbered firing order means that it fires across the block, and in a diagonal pattern, not all on one side at a time, then the other, like the H4 does.