By 2013 we’ll miss the piercing shriek of today’s V8s… But how do they achieve such startling revs?
We’ll have to look in the history books for 2020 to assess whether the year 2000 was some sort of peak for F1 engine sophistication. Since then the economic rev-limiter has been wound back and back until now we are looking ahead to an engine spec which sounds like a family hatchback. But the F1 world is confident the forthcoming 1.6-litre turbo four will match today’s 750bhp (perhaps 600 from combustion, the rest from KERS), and still cut fuel consumption by 35 per cent. If it does, it will be thanks to techniques learned in the unfettered development era, when soared to almost 20,000.
Since the DFV, outputs have doubled without any major change in design. How has this been possible? To a great extent it has been through sky-high revs — twice almost any road car — plus a host of refinements which are virtually invisible. That’s not just because they’re inside the block; today’s piston or valve might look similar to a few years ago, yet is able to reliably last two race weekends. And this powerhouse is even more compact, particularly thanks to small clutches which allow the crank to sit lower. Much of this progress is now stalled by regulation, with minimum bore spacing, crank height, and engine weight specified in order to stop teams spending excessively. Even the angle of the 2.4-litre V8 is fixed at 180 degrees. But the techniques will carry over to the future four, and to road cars.
Despite its immense power, an F1 engine may well have less torque than your road car. What’s different is the bhp per litre, which at 300 is more than double any road engine. And those car-piercing revs. Even the 17,000 they’re now pegged to is staggering, while the 19,000 of two years back was unimaginable just a few years before. One of the crucial leaps has been in reducing piston weight. New materials such as metal matrix composites (for example beryllium alloy, which lops a third off the poundage) were significant, but the drive to slash costs has outlawed such exotics. But although we’re back to forged aluminium pistons and iron crankshafts, CAD allows dead weight to be safely nibbled away without affecting strength. The skimpier the piston, the less the load as it changes direction over 300 times a second, hitting 90mph mid-bore before stopping dead and reversing, experiencing an astonishing 8000g as it does. And in one Grand Prix it does this over a million times.
It’s not enough, however, simply to make parts ‘stronger’. In a racing engine it may not be excess load but going into resonance which causes a fracture. Every part has a natural resonant frequency, and if it’s allowed to vibrate at that frequency for long enough a fatigue failure is likely — think of the opera singer and the wine glass. Identifying that frequency and refining the design to shift it above or below the engine’s likely operating regime can boost reliability without technically making the part any ‘stronger’. Elaborate computer programs help predict this type of behaviour under simulated high-rev conditions. Although it requires huge processing power, this sort of dynamic analysis saves time and money over making and physically testing parts.
Better metallurgy and lubrication have also boosted performance. Sophisticated ultrasonic and X-ray techniques mean fewer unsuspected flaws in engine parts, which feeds back into yet lighter components with more predictable stress performance. At the same time eversmarter surface coatings and treatments have both reduced friction and increased wear resistance. The grind of piston against liner can be eased with super-hard coatings — and what’s the hardest substance of all? Diamond. No, even F1 engine innards aren’t carved from De Beers’ finest, but there is a carbon substance which boasts much of the gem’s hardness plus low friction. It’s called Diamond-Like Carbon, and it can be deposited on many materials. You probably own some already — it’s commonly applied to safety razor blades. In an engine, DLC eases the life of, for example, cam against follower, giving more revs on the track — and better mpg on the road.
Sustained high revs demands sophisticated lubrication, and synthetics have permitted thinner oils — which again reduce friction — to endure the intense temperatures and abrasion within block and gearbox. One result of both these areas is slimmer main bearings — again, less friction, more revs. Computer studies of internal oil movement has also reduced ‘windage’ — the drag that oil spray causes.
The single biggest leap in the rev race, though, was pneumatic valves. At high speeds conventional valve springs can go into resonance (valve float), or break. The short stroke and big bore of an F1 unit demands large valves with greater inertia, and making the springs stronger just compounds the problem by increasing the loads. It was only Renault’s introduction of pneumatic valves in 1986 that released the brakes.
Such valves avoid all these problems by using gas as the spring medium, the valve top sliding within a chamber like a tiny piston and compressing a charge of nitrogen. All the chambers are connected to a common top-up bottle in the sidepod, keeping pressure at some 1000psi. It’s lighter, more compact, self-damping and it’s adjustable: you can soften the ‘springs’ for lower speeds, releasing a fraction more power. The downside is that spare engines must be permanently connected to a nitrogen bottle to prevent the valves falling onto the pistons. This is one innovation which has yet to reach the road.
One other crucial but invisible element is electronics. All teams use a standard engine management system which tailors the fuel burn under all conceivable conditions, while the whole system manages fuel flow, ignition, clutch and gearchange to extract every last fraction of energy from each gramme of pump fuel injected down the intakes. And as always, lessons of race efficiency can be down-tuned to boost economy on the road.
Having learned to make an engine spin at 19,000rpm, winding back the revs brought a reliability surge, helping toward the goal of allowing only eight engines per driver each season, and two GPs between rebuilds. If we keep that up, maybe the 12,000rpm fours will make it to 12,000 miles between services…
With thanks to the Lola Design Office for their consultation. For more information on Lola click on to www.lola-group.com