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From the September print issue of AE

Bentley Motors engineering chief Dr Ulrich Eichhorn breaks into a smile each time he fires up the engine of his beloved 1960 S2 model. One of the earliest Bentleys to feature V8 power, it has an aroma reminiscent of motoring in an era long before the arrival of the catalytic converter.

“I love it when I start it up from cold because I get to remember how cars used to smell,” says the man who has just given a fresh lease of life to the world’s second longest-running automotive power unit.
Eichhorn’s affection for his car leaves him ideally placed to contrast the differences between the original and latest versions of the remarkable engine known simply as the Crewe Eight - the driving force for most of the exclusive vehicles that have left the gates of the famous English factory over the last half century.

Enthusiast: Bentley chief engineer Ulrich Eichorn owns a 1960 model with the then-youthful V8 engine

Back in 1959, the hierarchy at Crewe had no truck with going public on details of power or torque output of its products. “Adequate” was the only response that would ever come from the company, and “adequate plus 50 per cent” was the way it described the torrent of power developed by the venerable Eight when a turbocharger was added for the Mulsanne Turbo more than 20 years ago.

“In reality, the original engine developed around 200bhp and 400Nm torque. The latest version adds 300bhp and takes the torque figure up to 1,000Nm. But while we have 250 per cent of the power and torque of the original engine, we also have a reduction in fuel consumption of more than 40 per cent.

“In addition to all this, we are also able to talk about a reduction in emissions of 99.5 per cent…I suppose that means theoretically, our new engine could run at idle on the unburnt hydrocarbons of my old engine,” smiles Eichhorn.

The former VW Group executive director of research took charge of 500 engineering staff and 50 designers at Crewe in 2003 as the five-litre, W12-powered Continental GT was driving Bentley to fresh prominence across global markets as the new face of traditional English sporting transport.

The 2007 Arnage (above) goes back to the Crewe Eight engine after its BMW dalliance

But the company’s flagship Arnage model was not forgotten, and the following year saw significant improvements to the chassis, steering and braking systems to allow the car to cope with additional power.
“Two years ago we brought the Eight to the Euro IV level and LEV1. This year, for the stage two on-board diagnostics requirement, we had to rework the electronic system and upgrade the gearbox to talk with the diagnostics. This was a good opportunity for us to add to our revisions and introduce a more modern gearbox with six speeds instead of four.

“We also did work on the engine to update the turbo units for lower
inertia and better flow dynamics. These give us roughly 50 per cent improvement in the build-up of torque. In addition, we replaced our flat tappets with roller tappets to reduce friction, but more importantly to achieve better control of the valvetrain and allow us to run valve timing that is more suitable for what we want to do.

“We have put in a completely new engine management system, and, together with the new gearbox, we have a torque converter that provides lock-up in all gears from 30mph to allow a mechanical connection between the driver’s foot and the speed of the car to eliminate the rubber-band effect of the previous unit. It’s given us a car that is much more suited to keen motorists because it drives like it has a mechanical gearbox,” he says.

Amazingly, some of the design features of the Eight made it easier to achieve Euro IV and will also help achieve foreseeable standards.
According to Eichhorn, the 1959 Eight had to fit into the space that had been allowed for the in-line six-cylinder engine it replaced. “One of the reasons for having in-line valves and wedge-shaped chambers was to keep the engine very narrow. That helps us now, because in wedge-shaped chambers of this size, we get less ‘dead’ area and better raw emissions, especially for unburned hydrocarbons.

“Because the V8 also had to make use of the same radiator as the six, very short exhaust valves were specified to keep the heat out of the water, and these now help us light up the catalytic converter quicker to benefit emissions – it’s incredible that we are being helped meet exhaust emission targets by features that were designed in for completely different reasons,” he says.

Though most engine production at Crewe concerns the W12, the Eight remains at the heart of Bentley, believes Eichhorn. “This unit was designed with such care and robustness that modern technology for bearings and oil allowed it to take much more stress and I find it interesting that the current unit is so much like the original because the dimensions of the main crank are the same and the bearing sizes are almost identical.

“I can’t see any limit on the Eight in the immediate future. In all of its architecture and in the driving experience, it is so unique and is so appreciated by our customers that I don’t see any fixed date in the future when it will not be able to run any more.

“It has the characteristic that we want in particular – torque at very low engine speed and a very flat torque curve to give a refined and relaxed feeling, but always with power in the background. That’s the feel that goes right back through the decades to the first engines made by W.O. Bentley and is best epitomised in the eight-litre motor that could be driven at three miles per hour in top gear and was able to motor away in the same gear with complete smoothness.

“It also speaks volumes for the Eight that sales of the Arnarge with the BMW engine collapsed as soon as the return of the Crewe-powered car was announced and the fact that those models are now changing hands at much lower prices.”

*The engine with the world’s longest production run is the Chevrolet small-block V8, which was introduced in 1955. It was described by the company as the Turbo-Fire V8 but became widely known as the ‘mouse motor’ because it was smaller than contemporary V8 units.

Initially, the 265 in (4.3-litre) engine was used for the Corvette sports car but the displacement changed over the years, eventually reaching 400 in (6.6-litres). However, the most popular configuration was the 350 in (5.7-litre) version, and though Buick, Cadillac, Oldsmobile and Pontiac also designed V8s, the Chevvy 350 became the GM corporate standard and was used by every US division of the corporation.

As a result, production totalled more than 90,000,000 by the time US output ceased in 2002 – but it continues in production at the GM Toluca plant in Mexico for the Goodwrench replacement engines division.