The flat-six engine

A few months back we stretched your patience by making parallels between the shriek of a V12 and the spine-tingling results of a soprano hitting her vocal redline. But don’t worry, we’ll not pursue the exercise by comparing the sound of a flat-six motor to the vocal utterances of John Michael Osbourne. RIP Ozzy. That would be pushing things too far.

So, why has the flat-six become arguably the second most iconic engine layout for road cars? Calm down, you V8 fans – I said ‘arguably’, and maybe we’ll get around to your favourite (sorry, favorite) layout someday. Well, you might remember from the V12 article that a lot of its virtues came from the fact that an inline-six is an inherently balanced engine – V12s pretty much seek to double that goodness by sticking two of them together.

But an inline-six – and I do love a straight-six: I’ve previously named the RB26 Skyline engine as one of my all-time favourites – has two weaknesses. First, it’s a ‘long’ engine. Lining six pots up side-by-side makes it a long, skinny lump to shoehorn into an engine bay. Said RB26DETT engine in the R32-R34 Skyline series is about 870mm long for its 2568cc displacement: that’s 2.95cc per mm of engine bay length consumed, if you will.