The V8 is in decline. It’s rare already in some countries but here in the U.S you can still find one relatively easily on a showroom floor. However the reality is the twin pronged attack of government meddling by way of fuel economy regulations along with demand for economy and ecologically friendly cars from consumers means the end is coming for the V8.
The reality is a turbocharged V6 uses less fuel than an equally powerful naturally aspirated V8.
Except of course a turbocharged V8 will be able to make even more power, so the rise of forced induction hasn’t made “there’s no replacement for displacement” a dated truism, and don’t anyone tell you otherwise because math.
However, a six cylinder car will always be more economical and take the place of V8’s when they are legislated out of existence and forced induction will be how we make real power.
“So why not a V6 instead of a straight 6?” I hear you ask.
It’s a good question. After all, a V6 can be made from an existing V8 relatively simply by removing two cylinders from the existing design which cuts out a lot of R&D time and money.
Well, sort of yes. There are issues and it mostly boils down to the angle between the cylinder banks. The angle between cylinder banks on a V8 is inevitably 90 degrees. A V6 generally ideally needs to be at a 120 degree angle to allow it to run somewhat smoothly. The problem there is that you have now made the V6 wider with that more splayed out V. Not such a problem with a four banger boxter engine where the cylinders are laid flat and horizontally opposed, because there are two less cylinders to take up room.
If you see a 90-degree V6 it will have had a lot of work done to balance everything out so it doesn’t just shake and vibrate itself apart (looking at you Mercedes). That’s added complication in an attempt to solve an issue that can be avoided by spending the money developing an inherently smooth inline six in the first place. BMW for the longest time built their cars on that predication, and as far as I can tell are still the only car company on the world stage doing so.
More will start to develop them now though. Three cylinder engines are becoming more common place so car companies developing a series of three, four and six cylinder engines off of the same basic blueprint makes a lot of sense. A four cylinder engine can be developed, then a cylinder removed or two added without the issues that grow from trying to make a V8 into a V6. A modular engine system for a car company will certainly make the accountants happy for the cost savings, and the marketing departments happy because it makes very easy model distinctions to cover multiple demographics – all the way from the eco warrior to the people that want to be able to put their foot to the floor and something exciting happen.
Personally, I’m not that bothered about the V8 going away as we have reached a stage in engine development where six cylinders are capable of making plenty of power. BMW were knocking out the naturally aspirated M3 fifteen years ago with 340bhp.
Now, bear that in mind while I mix a metaphor so hard that if an English teacher read it they would surely try and hunt me down to inflict physical pain…
Once the arms race for BHP starts with inline sixes then all the car companies will be racing to build a better mousetrap.
That means we will have an all new horsepower war with the net result being a broad choice of smooth and fast as hell inline sixes.
Just as god intended.
(A very good comprehensive explanation given here on angles and balancing V engines here)