Why did the Porsche 919 use a V4 engine?
The 919 Hybrid is one of those Porsches that we’re going to look back on and really celebrate in years to come. Much like the brutal Can Am 917/30 and 956 Group C monster, the 919 came, saw and obliterated the competition, much in thanks to technical mastery across the board.
One of the weirdest aspects of the LMP1 hero however is its powertrain. With its rivals mostly opting for V6s and V8s, the engineers at Porsche went for something very different, ending up in the research, develop and manufacture of the rarest of rare car engines – a V4.
Almost exclusively found in motorbikes, V4s can only be found in a very select group of cars. So why did Porsche opt for this layout?
The first reason was the new regulations. For the LMP1 class, manufacturers had fairly loose regs when it came to internal combustion engines, with the only main ruling governing fuel consumption. Porsche naturally wanted something efficient as well as powerful, so a four-cylinder engine – if done right – could be the perfect solution.
Then came the next part of the regulations – hybridisation. You could pick what electrical energy output you wanted from your car, with that choice depending on how efficient your internal combustion engine was. Porsche knew that it was going to sink money into a seriously thoroughbred motorsport power unit, so they opted for small fuel consumption to allow them to grab the biggest hybrid system of 8MJ after initially messing around with a 6MJ system. The more powerful the recuperation system, the less fuel could be burnt.
Unlike Audi who only went initially for a 2MJ system (eventually upgrading to a 6MJ system) that used regenerative braking at the front axle, and Toyota who went for a 6MJ system that regenerated from both axles, Porsche utilised a KERS system at the front which worked in-tandem with a exhaust-driven system, similar but also slightly different to today’s F1 cars.
A quick insight into how the 919's hybrid system works.
So now not only did the engine in the 919 need to be efficient and powerful, it also had to be a neat package to have a hybrid system coursing in and around it.
An in-line four-cylinder (like we saw on the ill-fated Mazda DPis at Daytona last month) is immediately a problem because it’s tall, relatively flexible and needs extra bracing to keep it in place within the chassis. So some bright spark at Porsche decided that a V-layout was the perfect solution.
Set at 90-degrees, the open banks of a V4 allowed the certain parts of the hybrid system as well as the turbocharger to sit directly above the engine, I guess resembling something similar to a ‘hot-V’ setup.
The compact, stout nature of a V4 also means that it can be used as a stressed member within the car, becoming integral to the 919’s chassis in the same way that Colin Chapman pioneered back in the ‘60s with the Lotus 43 (everyone thinks it was the Lotus 49, they’re wrong).
Let’s recap – you have an engine layout that now nicely incorporates an electric propulsion system for your hybrid LMP1 car, that keeps the car stiff by being in a V-format, and is efficient enough to keep to the regulations by being a four-cylinder. So now what?
Well, you make the damn thing as powerful as possible. Using essentially F1 engine fundamentals, the small crankshaft and cylinders could be revved to 9,000rpm, making for a power output of around 500bhp in racing trim and coupling with the 400bhp hybrid system to create a 900bhp, downforce-happy racer.
Without any silly FIA restrictors on it, the little V4 has produced 710bhp (720PS) in the 919 Evo, helping the car to an outright Nürburgring record and a lap around Spa Franchorchamps faster than Lewis Hamilton’s F1 Mercedes. And let’s not forget the ‘stock’ racing car’s three Le Mans wins and three WEC titles. Not bad for a little four-banger…
Here's THAT lap from Spa. Phenomenal.