STR13 | Power Unit
One of the most interesting changes for the 2018 season was the engine swap saga that took place between Renault and Honda. This all started with Sauber, back in April 2017, when they announced the termination of their 7 year partnership with Ferrari to switch to Honda for 2018. As part of this, Sauber would require a transmission from McLaren. Three months later, with Frederic Vasseur as the new Sauber Team Principal and rumours of McLaren leaving Honda, Sauber decided to cut their ties with both McLaren and Honda and reignite their partnership with Ferrari.
As the relationship between Honda and McLaren continued to break down, it was no surprise when they announced in September 2017 that they were dropping the Japanese outfit for Renault. This then left the door open for another team to partner Honda, ideally one who could develop their own transmission, such as Scuderia Toro Rosso who took the chance. Although to terminate their deal with Renault, Toro Rosso had to hand over Carlos Sainz to the French works team. In summary, Sauber stayed with Ferrari, Toro Rosso and McLaren switched power units.
Normally, teams start defining the concept of next seasons car as early as winter testing, with serious design work commencing in June. Therefore, with the power unit swaps announced as late as September, this left limited time for Toro Rosso to fully optimise the installation of an entirely new power unit into their STR13. However, Toro Rosso’s previous history of having to quickly adapt to a new engine helped them prepare for this transition.
‘It was very late but we were confident that Honda had planned their way out of a difficult 2017,’ explains James Key, Technical Director of Scuderia Toro Rosso. ‘But there was a certain amount of anticipation of this possibly happening, so on that basis we prepared ourselves for a reschedule of our production deadlines. Everyone collaborated very well to get the design process under way and the essential data transferred as early as possible between ourselves and our colleagues at Honda.’
One of the challenges for Toro Rosso was adapting their STR13 car to the different architecture of the Honda power unit compared to their previous Renault. The Honda approach, which is similar to Mercedes, is to split the turbocharger so that the compressor is mounted at the front of the engine block, with the turbine located at the rear and the MGU-H situated in the centre of the cylinder banks. Renault’s approach which is similar to Ferrari’s is to have the compressor at the back of the engine block, the MGU-H behind it, with the turbine rear of that.
‘Luckily the Honda engine is a very tidy installation indeed so infact, the implications on architecture weren’t particularly significant,’ highlights Key. ‘There was a lot of engineering work to do but it didn’t fundamentally change the architecture of the car. We were able to take what we’ve already done and transfer it to a Honda installation. It also meant we could redesign our gearbox in a way that allowed some of the rear suspension internals to be better installed, so there were several benefits to the installation itself.’
