Have you guys have ever wondered why the 2.7 and 3.5 Ecoboost turbos sound so different?
Even the Gen 1 3.5 which has turbos that are barely larger than the Gen 1 2.7 turbos still makes more compressor wheel sounds.
If you guys didn’t notice, the 2.7 turbos are standard rotation turbos meaning each turbo spins the same direction.
If you’re facing the front of the truck, each turbo spins to the right. This is easily figured out by looking at a picture of the turbine housings coming off the cylinder head.
The passenger side turbo sits up a little higher which is why it’s really visible from the engine bay.
The 3.5 is a mirror image setup. Both turbos spin the opposite directions.
Couple reasons why ford did this is probably because the 3.5 has exhaust manifolds, which uses up more space on the side of the engine. Having standard rotation turbos would not allow enough room for the turbos, hence ford did mirror to be able to pack them tighter, underneath the manifolds.
As you can see from the exhaust housings, the turbines spin the opposite direction.
This difference in spinning rotation probably causes the sound difference. Same direction rotation is probably quieter due to the difference of air swirling. But intake piping and tubing contributes as well. But my guess is that opposite rotation is louder in a shared y pipe intake system.
