A closer look inside the Lexus LFA’s V10

LFA engine 02

Making the LFA was one of the greatest engineering challenges ever undertaken by Lexus. As well as developing new technologies, materials and processes – irrespective of the difficulties encountered in their adoption – the model recalibrated the world’s perception of Lexus as a performance car manufacturer.

LFA naked

At the heart of this supercar was the breathtaking 1LR-GUE engine, a bespoke 4.8-litre V10 that is widely regarded as an engineering masterpiece. Rich in motorsport technology, it is endowed with an exceptional peak output of 553bhp at a soaring 8700rpm. With a specific output of 115bhp per litre, it is one of the most powerful engines ever unleashed in a production road car.

Surprisingly compact and constructed from exotic aluminium, magnesium and titanium alloys, the dimensions of the engine are equivalent to that of a traditional V8 yet it remains as light as a conventional V6.

LFA engine 01

Inside you find moving parts manufactured to incredibly high tolerance levels, beginning with a fully integrated lightened crankshaft acting on titanium alloy conrods that are 40% lighter than equivalent iron components. These, in turn, connect to lightweight forged pistons designed to cope with the pressure of a high 12:1 compression ratio and the capacity to shuttle backwards and forwards at approximately 25 metres per second at the rev limit.

The 72° angle between each bank of cylinders is wider than most other V-formations but was determined as the optimum point for balancing the primary and secondary movements of the internals for smooth operation. It also created a neat valley that was used to position both the oil cooler and positive crankcase ventilation chamber.

Similarly non-conformist was the fitment of dry sump lubrication, a feature usually only found on dedicated race cars. By deleting the traditional wet sump from the bottom of the engine and directing oil to specific parts through an external ventricular arrangement, the V10 was able to be located deeper within the chassis. This lowered the LFA’s centre of gravity, which improved its resistance to G-force loadings. And because lubrication was supplied at a constant pressure the oil could not cavitate from where it was needed, the LFA could handle sustained high-speed cornering in excess of 2G.

An unwavering focus on low inertia and low friction enables the V10 to rev from idle to its 9,000rpm red line in just six-tenths of a second, yet remain as refined and reliable as any other Lexus powerplant. Interestingly, this incredible ability to gain and lose revolutions meant that Lexus had to design a new digital rev counter for the cockpit, since an analogue meter simply could not keep pace with the engine.

LFA steering wheel

In view of this accelerative performance, the valvetrain hidden behind the magnesium alloy cylinder head covers also came under intense scrutiny. Light but strong titanium alloy was employed once again in the construction of the valves, while the valve springs are cylinder-shaped and of a low-inertia design to remove the chance of valve float at high revs. These were partnered with ultra-lightweight solid rocker arms featuring a special diamond-like wear-resistance coating and integrated oil jets.

Meanwhile, the application of intelligent variable valve timing on both the intake and exhaust cycles allowed the engineers to tune the ECU to produce at least 90% of the V10’s formidable 354 lb/ft torque peak from 3,700rpm upwards.

LFA engine 03

The engine was also designed to deliver linear and predictable power through natural aspiration, each of the ten cylinders breathing through its own independently-controlled throttle body rather than being force-fed by a multiplication of turbos.

This short, direct airflow into the engine is a key element in the hyper-responsive feeling coming through the throttle. But another factor is an innovative calculation programme that uses throttle position to estimate the total air intake volume, using this driver input information to prime each 12-hole injector to deliver the appropriate volume of fuel for any given engine speed and load. So precise is the air and fuel management that the engine exceeded stringent Euro V emission regulations.

LFA engine 04

Incoming air arrives through a dual intake system that switches from a primary inlet port at low to medium speeds to dual ports at higher revs to boost breathing efficiency. Within the intake system is a surge tank responsible for generating the engine’s F1-style induction roar. Inspired by the design of musical instruments, the tank is horizontally split and tuned using rigid walls with horizontal ribs to generate optimal acoustics.

After combustion, spent exhaust gases exit through separate, equal-length exhaust manifold runners, a layout that enhances torque through optimised back pressure and creates a crisp sound quality. Harmonic management is also used at the titanium dual stage rear silencer, which incorporates a valve-actuated structure to either minimise or maximise exhaust sound. Above 3,000rpm all sound-deadening chambers are by-passed; the exit route straightens and the engine announces its delight at being unleashed with a spine-tingling scream.

LFA exhaust

It’s not just for the benefit of onlookers, however. Induction and exhaust sounds are directed into the LFA’s cabin through three channels, giving the driver centre stage in a surround sound concert of engine performance.

But for the full-on supercar experience, there’s nothing better than a standing start. In that respect the 4.8-litre V10 propels the Lexus LFA to the 62mph benchmark in just 3.7 seconds and will keep pushing to a top speed of 202mph.

“What we needed – and what we have created – is a car that moves the driver in more ways than one,” explained Haruhiko Tanahashi, the LFA’s chief engineer. “The LFA is a car that stirs all the senses.”

Production of the LFA and its V10 may have ended but it appears that Lexus cannot give up on a good thing. Visit this link to see how the race-prepared LFA Code X might hint at future sports car technologies.

Lexus LFA Nurburgring Presentation Photoshooting Details 23.Sept. 2009

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