Having abandoned their faithful super-capacitor, Toyota have this year opted for a turbocharged engine with KERS batteries, which should provide more power and better acceleration; two areas in which Toyota was lacking in compared to their competitors. Pascal Vasselon is a firm believer than two KERS are better than one.
“We will just change the engine concept, but we will stay with two KERS and this is the important bit” asserts Vasselon. What is more efficient? Two KERS or one KERS with gas recovery? Our answer is two KERS because that has the best performance density simulation.
What I mean by performance density is the lap time gain per kilo. The KERS is heavier, but the performance it provides is full charge if you recover if you have a good braking system. In the case of an exhaust system, it’s not full charge; you generate back pressure in your exhaust and you lose efficiency on the compression
engine. Of course the system is light but the energy recovered comes at a cost, so this is the balance.”
Recoverable energy is now an area we now take for granted, but its early days in Formula One, KERS technology has come a long way.
“A good braking system allows you to hand over from electric braking to caliper braking in a seamless way so that the Hybrid doesn’t feel it” Pascal explains. “In Formula One, initially in 2009 there was no brake by wire, so the recovery was happening on top of the rest. This was quite bad as the recovery – around 60kW – was very low, but small enough to be manageable. Now we have to recover several hundreds of kilowatts, so you can’t do that without the system handling it. “
As such, the KERS system is the first defining force , with the traditional concept of braking regulated to being a secondary influence.
“That’s where you can make differences in the way your control system works”, adds Pascal. “So that the brake system is consistent.
The brake pedal is the first sensor. It has no direct mechanical effect. It is a force sensor from the driver saying ‘I want this level of deceleration’ and then the system engineers it to compliment with the mechanicals. The quality of this control system makes the performance of the braking and this is the first requirement of this kind of system.”
Assembling the batteries in-house might seem like a straightforward arrangement, but as Williams Advanced Engineering have found in supplying the Formula E grid, the practicality of doing so is anything but. In competition, there are no off-the-shelf solutions.
“Everything is new and difficult within these systems because the auxiliary systems are prototypes” reiterates
Vasselon. “These kind of high powered batteries are unique to the WEC. The battery technology is different compared to Formula E. Formula E only relies on the electrical energy stored in two races. In our case we don’t need so much energy density, we need power density so we are using high-powered prototype batteries which need a lot of cooling. So it has to be difficult because it’s unique.”
So having weighed up their options, what advantage does Toyota believe batteries have over the super capacitor?
“At the moment our power density is better. For a long time the capacitors offered better power density. They were always lower in energy density, but that wasn’t important in storing energy” explains Pascal.
“Now batteries are better in energy and power density. The battery technology is developing faster than capacitors. It’s good to be able to locate the boost exactly where you want. It’s an additional benefit
of the battery in some places that you cannot do with gas.”
And what about turbo-charges vs normally aspirated engines.
“Better management of efficiency” Vasselon says a pragmatic Pascal. “Basically a naturally aspirated engine can be efficient but on a small range. The turbo can make that range much wider because you have more parameters and control with the air-flow.”
Outside the power-train, Toyota’s new challenger will feature a brand new monocoque and aero configuration, with Pascal clarifying that “it has to be a new monocoque for many reasons. One of them is for the new engine/hybrid system.”
Compared to its German rivals, Toyota has always been thrifty with its WEC budget. In inverse proportions to its Formula One campaign, Toyota Hybrid Racing has always punched above its weight, but is there enough money for another championship and Le Mans assault?
“Since Le Mans. Yes. Just enough” admits Vasselon. “Our motor company (Toyota) has been persuaded by the facts. It’s true that last year approaching the 2015 season we went through a cycle of emotions. During 2014 we were concerned by 2015 because we knew our resources were not allowing us to continue to develop the engine concept. So we knew that we were quite strongly limited. During 2014, we were already raising a flag that we may not be developing at the correct rate, but we were dominating, so it was very difficult to be credible and say that we saw problems while we were dominating.
Then we started to test the 2015 car. The chassis has been extremely good. We gained 2 to 2.5 seconds everywhere. That is something that in my experience I have never seen. In a stable regulation period like now I’ve never seen a chassis gain two seconds a lap at every circuit, so we thought things would still be okay. During winter we were reasonably optimistic until the Prologue were we began to feel some doubt. At Silverstone we were still in the game, but really the game changer was Spa. At Spa we completely understood the situation and then quite quickly our company reacted. We didn’t get a package that was close to Audi or Porsche, but we got what was needed to jump start. We were supposed to do another season with this package but we knew there was no point.”
Amidst the backdrop of Formula One’s financial impasse, Toyota has been the most vocal WEC in calling for an arrest on spiralling development cost, with the team even favouring a “token regulation” similar to F1.While Vasselon admits cost-capping may be higher on his own team’s agenda, he believes doing so is in the interests of the entire category.
“We are favouring this, because it’s our strategy to ask for it” says Pascal. “We need it and the series needs it. We have to be careful, because we are very close to entering an ‘F1 crisis’. We feel our position is fragile and then you are left with two manufacturers from the same group – this is fragile as well. What we have proposed is to cap some spending so that it’s not so easy to buy performance. We can’t buy performance we can just do the strict minimum to be there. We were doing thirty test day and they (the opposition) were doing eighty, which is just ridiculous.
Images: Toyota Hybrid Racing