SD

There's an Impreza (Pre MY01) just down the road from me. I don't know what exhaust he's got on it but it's definitely not standard! What got me thinking was why is the Impreza's engine noise so distinctive?

I understand perfectly the arrangement of the engine, but apart from the physical layout of the cylinders and knock-on effect on the anciliaries everything is pretty 'normal'. There are still just 4 cylinders so why the different engine note?

Simon.

Neil Smalley

It's also to do with the unequal length of the manifold. Get an equal length one and the scoob sounds like a hairdrier

logiclee

Yep, unequal length manifold.

Each cylinder fires even but the time at which the noise enters the exhaust is staggered due to the length it has to travel down the manifold. Fit an equal length maifold and you get 10% more power loose all the boxer beat.

Lee