EVO BLUEPRINT
WITH THE EVO ENCYCLOPEDIA SERIES DRAWING TO A CLOSE, WE’RE STARTING A NEW SERIES CALLED THE EVO BLUEPRINT! THIS MONTH, WE DISCUSS THE HEART AND SOUL OF THE AUTOMOBILE – THE ENGINE
A new section from this month that gives you an insider look at tech in the automotive industry!
IN PERFORMANCE CARS, THE TURBOCHARGED INTERNAL COMBUSTION ENGINE (ICE) HAS BECOME THE NORM AND LED TO DOWNSIZING. WILL THIS CONTINUE? Dr Frank Welsch, board member for technical development at Volkswagen: ‘I call it rightsizing: there has been a trend for lightweight engines with a comparatively small displacement, not just for particularly powerful vehicles, but in general – due also to emissions reasons. Power and torque outputs that would have been almost inconceivable just a few years ago are now achieved through forced induction, intelligent injection processes and use of high-tech materials.’
Richard Moore, propulsion director at Lotus: ‘Yes, we think it will – turbocharging complexity continues to develop, with twin-turbo arrangements starting to be replaced with [electric] e-turbochargers.’
Phil Hopwood, head of engine and emissions control products
at Ricardo Automotive & Industrial: ‘The downsizing trend via turbocharging is set to continue but there are applications where naturally aspirated engines make the most sense, including low-cost small vehicles, non plug-in hybrid vehicles and some supercars. There are still development road maps for both naturally aspirated and turbocharged base engines with increasing use of electrification.
‘Whilst diesel engines can continue for larger vehicles, application in sports vehicles is reducing in favour of petrol engines, including hybridised options. A gasoline engine has a clear cost benefit against diesel.’
Giles Muddell, chief engineer of advanced technology at Prodrive:
‘Downsizing has led to improvements in efficiency at the expense of transient response. However, the efficiency improvements are important to fuel economy, hence I think this trend, in performance engines, will continue as emissions targets become tougher.’ The throttle response of turbocharged engines has improved considerably. What’s the key? And what’s the next technology that will improve the response of the turbo engine?
Improvements throughout the turbo system – and beyond – have improved response, says Hopwood. ‘Taking the turbocharger itself, better matching of turbine and compressor wheels with wider operating maps, higher turbo speed limits, improved materials, twin-scroll turbines and ball bearing shaft systems have all reduced inertia and time to boost.
‘In the wider system, advances such as water charge cooling and optimising boosting pipe layouts have reduced volumes between the compressor and cylinder to improve response. Improved control systems such as drive-by-wire, electronic wastegates and turbo speed sensing have also improved response.’
Hopwood also notes the contribution of transmissions with more ratios and says that electrified turbochargers filtering down from motorsport could virtually eliminate turbo lag. Welsch says that lag has practically disappeared through advances in both hardware and software but also thanks to ‘complex simulations performed in advance’.
Moore credits twin-turbocharging – mainly parallel, sequential and two-stage – with reducing lag considerably, and says the next technology is e-turbocharging: ‘The torque gap, historically created by the time the turbo takes to spin up, is “plugged” by an electric machine spinning the compressor for this short time.’
‘The next generation will see both 48V electric compressors to supercharge the intake, as well as directly adding torque at the crankshaft using a large electric motor,’ says Muddell. ‘The latter has other benefits, such as allowing the vehicle to drive in electric-only mode when combined with a lithium-ion battery.’
How much longer will manufacturers be able to offer naturally aspirated petrol engines?
Moore says that Lotus expects the naturally aspirated engine to be with us until the late 2030s. ‘The cost of EV product and infrastructure in the first instance will drive this, then focus will come onto well-to-wheel and so the source of the electric energy. Combustion engines do not yet have infinitely variable timing – this, combined with mild electrification, lightweighting and friction reduction should enable one more complete development cycle of the combustion engine.’
‘Nat-asp engines will continue to be used particularly for entry-level engines and in markets with fluctuating fuel qualities,’ says Welch.
Ricardo sees a long future for naturally aspirated engines within cost-sensitive sectors and markets, says Hopwood. It is also developing dedicated hybrid engines for future HEV (Hybrid Electric Vehicle) and range-extender BEV (Battery Electric Vehicle) applications. He adds that Ricardo’s road map for naturally aspirated petrol engines extends past 2035, enabled by new technology including higher-efficiency aftertreatment/catalyst options to meet expected new emissions legislation.
Prodrive’s Muddell is less optimistic, saying that the naturally aspirated engine probably doesn’t have much longer in the automotive environment, except ‘as a range-extender engine, where its simplicity and easier heat management is a benefit’.
Will the internal combustion engine persist with small-volume specialists or in very small volumes only?
Volkswagen decides on which engines to use according to the needs in various global market regions, says Welsch. ‘Naturally aspirated engines are available both as smaller three- and four-cylinder engines for emerging markets and as six-cylinder engines for North America.’
Hopwood says that low-volume specialists are moving to downsized ICE slowly because there are other beneficial attributes with naturally aspirated engines that sit well with their brand DNA and customer
expectations. ‘Moving to a moderately boosted engine or including mild hybridisation is a better bridge than shifting to a heavily downsized ICE,’ he says. ‘Ricardo forecasts that the market share for hybridised vehicles with nat-asp ICEs will increase in volume and complexity in response to many market factors.’
Lotus reckons ICE will persist in small volumes till major cities ban it, says Moore. ‘One solution we will move towards will be a long-range PHEV [Plug-in Hybrid Electric Vehicle] that can “handshake” with the city as it enters and leaves, ensuring that it has enough battery life to operate electrically while in the urban area.’
Could the ICE still be rescued by using hydrogen or carbon-neutral fuels?
‘Unfortunately, legislators have so far not taken into account the progress made in the production of environmentally friendly fuels in terms of CO2 emissions when calculating the fleet consumption values,’ says Welsch.
‘As an example, in Germany, 50 per cent of CNG-powered [Compressed Natural Gas] vehicles are today already fuelled with almost carbon-neutral biogas.’ However, he adds, because this is not recognised as part of VW’s fleet average, and also because of slow sales, CNG vehicle development is halting for now.
‘ICEs are very versatile and robust and can operate with a wide range of fuel types including more renewable bio or synthetic lower-carbon fuels,’ says Hopwood. ‘Engine developers such as Ricardo researched hydrogen as a combustion engine fuel decades ago. There is now renewed focus on hydrogen as a zero-carbon renewable fuel for both ICE and fuel cell vehicles.’
He adds that the industry is looking into ‘bridging’ fuels and technologies to move towards a sustainable low-carbon future. ‘Ethanol and hydrogen can improve both performance and emissions. In the case of hydrogen there are practically zero emissions.’
Muddell says that while carbon-neutral fuels are useful for CO2, they don’t help with other harmful emissions such as NOx and particulates. ‘Using hydrogen in ICE is possible but not as efficient as using a fuel cell.’ Moore is more blunt: ‘Not long term, in my opinion.’
Ultimately, how much longer has the Internal Combustion Engine got?
‘Our current expectation,’ says Welsch, ‘is that Volkswagen will still offer ICE-powered and electric vehicles in parallel for a long time, until a complete changeover to electric vehicles becomes possible, not least due to progress made in the area of infrastructure measures.’
‘Due to the strong legislative driver, it is unlikely new engine programmes will be started in the future,’ says Muddell. He thinks existing engines will be developed while they can costeffectively meet emissions legislation. ‘How long will depend on the cost competitiveness of electric vehicles, and in particular battery prices. If EV prices reach parity with ICE vehicle prices in 2025-2027, ICE will quickly become an ever decreasing niche market.’
Moore says: ‘In my view, mass production circa 15 to 18 years in automotive, but around 25 years in heavy duty. After this, niche will continue for some time.’
‘Ricardo has a road map for ICE applications across a wide range of automotive and nonautomotive sectors spanning global markets past 2035,’ says Hopwood. ‘Within automotive, hybridisation and full electrification is being led by the passenger car market as the average power and electric range requirement are lower. BEV and FCEV [Fuel Cell Electric Vehicle] will increase market share, especially in Europe where the fast-reducing fleet average CO2 target is enforced with significant fines.
‘In the next ten years especially, these CO2 targets can be met with a mix of powertrains where the vast majority have ICE. If greenhouse gas targets are later set on a well-to-wheel basis, including the CO2 for fuel or electricity production, or a life cycle basis, including embedded CO2 within manufacture and recycling, this levelling of the playing field will benefit ICE vehicles.’