Porsche sports car tech is about noise, oil and AWD

PORSCHE has shown what it sees as the future of electric sports cars, but what customers are able to buy from the brand might not have all the same ingredients as the German specialist’s GT4 e-Performance prototype model.

That model amalgamates the battery technology used in the Taycan sports sedan and shoehorns it into an existing 718 Cayman body, along with some 6000 other unique parts, to represent what the future of electric racing might look like for Porsche customers.

The car - and the project manager behind it, Björn Förster - were in Australia recently, and we had a chance to speak with the man behind the machine to see what he thought were the ideal ingredients for a superfast electric sports car from Stuttgart.

Mr Förster explained that a crucial component for the success of any electric racing car is going to include oil.

In this instance, as part of a bespoke cooling system for the battery packs. The 80kWh battery system uses an oil-based cooling system developed in conjunction with Mobil 1 that cycles oils through to maintain an ideal temperature for operation.

“So as long as you can keep it at 45 degrees, there won’t be any damage,” said Mr Förster of the battery system.

He explained that the battery system can also use that oil-cycling cooling unit to help it cool back down after a track session. The 900-volt architecture of the car means that, using a 350kW charger, it can recharge from five to 80 per cent in 15 minutes, and the oil cooling system can regulate the battery temperature while that is happening.

Beyond that there is also a manmade bespoke radiator system that plays its part in keeping it cool.

“We can cool the system while charging. We don’t have any air-conditioning in the car. We’re only cooling the system with ambient air, we don’t even have a fan,” he said.

“The trick is that we have a radiator that is made of three kilometres of plastic tube, which is handmade… those 30 litres of cooling fluid are really flowing very slowly through this radiator, but it works, and it’s about 10 times the price of an aluminium system, but 20 per cent more efficient, and half the weight.”

Mr Förster indicated that those systems are “five years” ahead of what a production EV might offer, which may give an indicative timeline on when the production EV racing variant of the new 718 models will be offered to customers.

He also explained that the all-wheel drive system in this car is not only there for better acceleration, but also to improve braking, limit rapid range loss, and remove weight from the car.

“If you add all-wheel drive on a combustion engine car, yes, you raise your traction a bit, but you're also adding weight,” he added

“On electric cars, it’s a completely new playground. We have, on each axle, one electric motor and so we can recuperate energy on both axles. With each minute we are racing, we can recuperate up to one kWh per axle.

“So, it's very sensible to use both axles for recuperation. But we also have the same drivetrain in the front and in the rear, so 500-something horsepower in the rear, and the same in the front.

“If we only had a rear-wheel drive car, we would need about 250kg more batteries to reach the same drive time. And that's massive. So the decision to go for all-wheel drive, it's very clear for a race car.”

For context, the GT4 e-Performance weights “less than 1550kg”, which is less than 200kg more than the petrol 718 Cayman it’s based upon.

“The advantage is to save weight, but also to save batteries - because batteries are expensive, you also save money. If you can reduce both of those by putting in an additional motor in the front which doubles the power of the car….it isn’t even an option,” he continued.

“It's also about the drive cycle – because on a regular drive cycle like WLTP because going up to 50km, holding the speed and braking, stopping, going to the autobahn – but you never have the chance to break out.

“On a race course, you do nothing else but pushing hard, braking hard. So the potential of the drive cycle is way higher to get energy back when you’re racing a car, either as a race car, or as a street car on a race track.”

Aside from the mechanical elements, Mr Förster added that street EVs of the future should have some kind of atmospheric experience to them in terms of the sound in the cabin.

But in relation to the EV racing GT4 e-Performance, it simply wasn’t a viable thing in a race car due to the excessive noise intrusion from the powertrain - twin electric motors and two single-speed transmissions make a bit of racket when there’s no sound insulation, apparently.

“In the beginning I was the only one in the whole team who said, ‘if we’re doing an electric car, we have a lot of new technologies in this car - let’s try to put some speakers in it’,” he claimed.

“Everybody else was saying ‘it’s not real’, ‘we don’t do fake stuff’. But since I'm the project manager, I got to keep the speaker system in the car.

“We had two 400W Burmester speakers from the Taycan windows in the pillar area behind the driver’s seat, and we designed some futuristic, cool sounding noise to add to the battery and the sound of the gearbox, but as soon as the car started to run, the gearbox was way louder than any speaker you could hear.

“So you just won’t hear it, and that was the point when I just had to leave it.”

However, Mr Förster said that production sports EVs in future may have their own soundtrack that invokes one of the major sensations of a Porsche – he even tipped his hat to the team at Hyundai N for their game-changing work with the Ioniq 5 N, and surely the new Abarth 500e is one that brands are paying attention to, too.

“One major topic is the sound. The regular road car, the EV, will always have a speaker. But it’s up to you as a brand if you use this speaker to fulfil pedestrian protection measures or if you use it for a sound you can experience,” he said.

“As soon as it is an emotional and cool feature, you should have it, Hyundai did it in a very good way, I would say. It’s completely fake, but people are loving it. So, I think we need to come with something.”

Mr Förster suggested Porsche will debut the sporty 983-generation 718 Boxster ahead of the Cayman coupe, possibly within the next 12-18 months.

The production models may well make use of a similar 900-volt architecture, allowing them to recharge in as little as 15 minutes at a full-speed 350kW charging station using a Type 2 CCS combination plug.

The GT4 e-Performance model takes an existing version of the 718 Cayman and frankensteins a Porsche Taycan sedan’s battery bank across three positions in the body – under the bonnet, in the passenger footwell, and down behind the seats.