Quote:
Originally Posted by chiefshayan
Subaru's have a characteristic sound because they have a horizontally opposed four cylinder engine, also known as the "boxer" engine. Hence the term boxer rumble. UEL only promotes the sound, EL is a bit more raspy and hides the rumble but it's still evident. Both cylinders on one half of the engine fire, then the other 2. This causes the exhaust pulses to not be evenly spaced, which creates the Boxer Rumble.
Think about it, it's not called the "UEL rumble".. it's the BOXER rumble  |
No. How much boxer rumble do you hear in any of these?
H6 swapped impreza (still a boxer)
[ame="https://www.youtube.com/watch?v=wqnuj58lFQI"]EFI Logics Track Car - YouTube[/ame]
Older 911 (yes, those are boxer engines too)
[ame="https://www.youtube.com/watch?v=WMXH6I9ray0"]'89 Porsche 911 Carrera dyno run - twin exit exhaust - YouTube[/ame]
New 911 (yep, still boxers)
[ame="https://www.youtube.com/watch?v=20xhYn1QnCA"]Porsche 991 Carrera S Dyno Test and Tune Exhaust Bypass Pipes - YouTube[/ame]
Yet another 911 (again, still a boxer)
[ame="https://www.youtube.com/watch?v=-UQ-Psx0ZgU"]Porsche 993 RSR 2 61 litre twin turbo dyno - YouTube[/ame]
There are two main reasons the (non FRS/BRZ) Subaru 4 cylinder boxers sound so different.
1) The stock manifolds are VERY UEL and merge the ports right at the head instead of having individual runners for each cylinder.
2) They have different firing orders than most engines, and fire both left cylinders then both right cylinders.
The firing order combined with the manifold design is why they rumble so much stock. If you swap out to an EL manifold you'll definitely get rid of the rumble.