Time Well Spent: The Cummins Railton

Mike Humble:

Being the chatty natured person I am, I’m rarely left speechless these days. But after spending a day with one of the most extraordinary machines encountered, included feelings were being numb, cold, exhausted and exhilarated… I could have played all day with one mans tribute to a Brooklands racer…

The completely mad Cummins Railton

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Its taken one man the best part of six years to build, but worth the wait. The crazy Cummins Railton.

Having driven many vehicles over three decades of driving that’s included countless cars, tons of trucks and a cacophony of buses and coaches, it’s nice to try something really special once in a while. My own personal and family ties with Cummins in the UK stems right back to the opening of the Darlington production facility (the home of the cars beating heart) in the mid-60s. Needless to say, I needed little persuasion to become involved with the Cummins – Railton project back when the car was little more than just a rolling chassis.

The original car, The Napier Railton, was a 1933 Brooklands built race car driven by John Cobb, designed and engineered by engineering supremo Reid Railton and driven by the World Record driver John Cobb. Propulsion came from a 24 litre 12 cylinder engine of aeronautical origin known as the Napier Lion. Ever since seeing this car in book some years ago, Terry Clarke, this current vehicles creator, decided that he was going to build his own version of the car and be road legal too. Through a contact of his who was an ex Cummins employee, the engine company donated a power unit and associated engineering support from its Darlington plant. The rest, as they say, is history and brings us nicely up to the present day.

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The only software and computer input in this car came from the Cummins engineers who have burned a few pints of midnight oil re-mapping the 6.7 litre iSB power units management system. Those twin fishtail exhausts produce a sound that cannot be described in worlds alone. At full cry the car emits a howl and buzz akin to a Spitfire or Hurricane in a vertical dive.

One of the first things noticeable upon initial contact with the Cummins – Railton is just how good the quality is. In fact, the less informed actually think this is a vehicle that’s been designed and engineered with the usual modern day 21st century input of simulation software and computer aided design. In reality, nothing could be further from the truth. The man who built it, Terry Clarke, used little more than pencils and paper to sketch out his ambition to create a homage of the renowned 1930s Napier Railton – a car that smashed many speed trails thanks to skills of its driver and creator.

But of course, there has been some serious cutting edge technology involvement with the car right from the start. Cummins engines were keen to assist and their Darlington based team of diesel boffins and engineers have spent a great deal of time honing, finessing and fine tuning the UK built 6.7 litre (409Cui) iSB unit to the point of power perfection. Being also blessed with turbo and supercharging, the engine now develops over 480bhp and an amazing 900LbFt of torque. But it doesn’t stop there. Plans are afoot to re-map the engine management software to marine specification to 500+ bhp and over 1000LbFt of torque.

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The Darlington UK assembled Cummins engine is normally found in applications all around the world that includes trucks and buses – minus the hybrid turbo and supercharger installation of course. Plans are afoot to retune to marine spec which will give over 500bhp and 1100LbFt of torque – all from just 6.7 litres.

“Obviously with this obscene amount of power you become very wary of each and every input from your hands and feet… you are now on a very short, steep learning curve”

So, what’s it like to drive? Well it would be fair to say that it’s an experience unlike anything else I have experienced. When sitting there idling the car sounds remarkably similar to a typical truck ticking over. The only clue when at rest to the disturbing performance potential comes in the form of a distant whistle from the turbocharger emitting from the elegant twin fishtail shaped exhaust tailpipes. The engine installation and its fixtures and plumbing puts some major car manufacturers to shame. Nothing has been skimped or cost analysed – everything has been properly fitted for both form and function.

Getting into the aluminium cockpit isn’t exactly a glamourous affair, but once settled into the home made nappa leather clad alloy bucket seat you know from the outset your soul will be stirred. Ahead of you is a bake-o-lite rimmed monster of a steering wheel, a far cry from the shirt button affair I fitted to a tuned up Mini 1275 I once owned. In your left hand you shift the gear selector for the truck sourced ZF S series five speed gearbox into first and your mouth very quickly becomes dry. Obviously with this obscene amount of power you become very wary of each and every input from your hands and feet… you are now on a very short, steep learning curve.

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The cockpit is rather snug and exposed to the elements. Driver and passenger feet are literally a few inches away from the truck sourced five speed ZF gearbox and the beautiful handbrake lever. Amazingly though the car has a rather decent ride comfort when cruising. The level of quality and attention to detail under the skin is even greater than what’s on view outside – NOTHING has been skimped or penny pinched. The digital display left of image is a GPS speedometer

“Being very exposed to the elements, any feeling of cold or wind is simply forgotten about as you are purely driving on your primeval instinct of human survival”

Strangely enough, with minute power applications, the car is very torquey, forgiving and flexible. Forgiving maybe but equally so this car requires the ultimate and highest of respect when behind the wheel. One over-eager moment or lapse of concentration and your thrash into the countryside becomes a one way trip to the Promised Land. As you become acclimatised you press on that little bit more, your heart races, your pupils dilate and your sense of touch seem to multiply – you’re now at one with the car and start to enjoy it all that little bit more. There is no real word, or one that can be printed anyway to describe the experience.

The staggering way the Cummins – Railton reaches out and pulls the horizons vanishing point towards you is utterly beyond belief. Being very exposed to the elements, any feeling of cold or wind is simply forgotten about as you are purely driving on your primeval instinct of human survival… but egged on to nudging the envelope that little bit more due to the adrenaline and endorphins surging through your bloodstream. The power delivery is instant, constant and linear from its idle speed almost up to cut off point of 3600rpm. It’s unlike the diesel power delivery normally encountered of nothing then power then fade away.

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The cars creator – West country based automotive engineer Terry Clarke

“This is possibly the nearest thing to having a machine or a man-made object wired in and connected to a human central nervous system”

The usual long stroke diesel power tail off at high revs is virtually eradicated thanks to the Rotrex supercharger installation. Changing gear isn’t quite Mk1 Escort slick and instant, a definite shove and tug action is what’s called for here. The action and feel is akin to loading an Army field gun but it snaps through the gears with no vagueness or uncertainty. This is possibly the nearest thing to having a machine or a man-made object wired in and connected to a human central nervous system. Every action and dare I say it every sensation from the road upwards is feed directly to your buttocks, feet and hands… it’s simply wonderful.

It will never be a true track race car, the centre of gravity is wrong and the steering reaction time isn’t fast enough for that. Just like the original Reid Railton built Napier powered car, it’s designed for circuit events and straight line speed and the latter it most certainly has. On a private road my bravery faded away at an indicated 135mph and yet there was much more in reserve. On his larger 19 inch rims Terry reckons the car is good for 150mph and if you can get the power down to the tarmac the tried and tested industry sprint from zero to sixty is comfortably under six seconds when fitted with smaller 18 inch wheels and tyres.

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A vehicle with supercar performance requires good anchors. The car uses huge all round grooved and ventilated discs with braided hoses and an internal bias control system. Front suspension uses Jaguar double wishbones and a transverse leaf spring while at the rear, the Jaguar / Land Rover hybrid rear axle is located by link rods and coil springs

“There’s nothing, and I do mean absolutely nothing whatsoever to give the driver or passenger a clue that this one off vehicle was conceived and constructed by just one man in a small industrial unit in the West Country”

By now you may be thinking this car is a beast to drive… far from it. Owing to sheer powers that’s always there, so long as progress isn’t baulked you rarely need to change gear. The fly-by-wire throttle pedal has a car like feel to it, the brakes are atlas strong and require only moderate pressure to operate and the clutch is no heavier than you’d find in an average light commercial vehicle. Thanks to its long gearing and monumental torque, driving around town is effortless and weirdly rather relaxing to do. Other motorists stare in admiration, pedestrians look on in amazement and inquisitive small boys drop their bottom jaws in awe.

But it’s not about showing off in urban areas, the Cummins – Railton is all about action. From the ability to pick off slower traffic with zero effort through to high speed touring, the car just simply excels. Even at high speed the car remains fluid and stable to control, only at the upper limits does the car become skittish and more challenging to keep arrow straight. There’s nothing, and I do mean absolutely nothing whatsoever to give the driver or passenger a clue that this one off vehicle was conceived and constructed by just one man in a small industrial unit in the West Country. Terry is rightly pleased with the outcome generally speaking, though his only minor concern was the slow self-centring action of the steering.

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Early days of a rolling chassis showing the ladder frame cruciform chassis, Cummins iSB engine, its gearbox and rear axle.

“…even now some weeks after the drive and experience, the hair on my neck stands proud just recalling the event”

Terry recently changed the steering assistance from an electric (E-Pas) system to a more traditional hydraulic powered type. There is a slight lack of instant positive self – centring but I was told this is much better than the E-Pas ever was and that a modification is in progress to quicken up the steering when exiting a bend. Even the ride comfort is the right side of agreeable too. The Jaguar sourced live rear axle is located via coils while up front the Cummins – Railton uses a Jaguar XJS double wishbone set up but without the coils. A transverse leaf spring provides the suspension up front – think of a Triumph Spitfire idea but the other way round.

But I walked away with a warm glow at the end of the day, I was cold, I was numb and I was thoroughly exhausted. But even now some weeks after the drive and experience, the hair on my neck stands proud just recalling the event. Laugh out loud is a sentiment which is used too freely these days, but the Cummins Railton is more than that, it’s a scream out loud affair and one I shall forever remember – what a hell of a weapon to use!

If you want to see the car in the metal and meet its creator, you can see it this year on the Cummins Engines display stand at the 2017 Goodwood Festival of Speed. If not, you can keep up to date of events and progress by joining the Cummins Railton FACEBOOK GROUP

Also, there is a more in depth look at the car and its creator on this site by CLICKING HERE

PLUS POINTS:

  • Utterly superb build and engineering quality
  • Beautiful looks
  • Mind blowing performance and speed
  • Turns heads and halts traffic everywhere you go
  • Surprisingly easy to drive on and off the limit
  • A showcase of British engineering and ingenuity at their very best

MINUS POINTS:

  • Respect and care of the machine is always in the back of your mind
  • Steering feel and self centring action still requires improvement
  • Eye wateringly cramped cockpit
  • One silly or overeager moment easily results in half a day with the undertaker
  • Every other car feels disappointing afterwards
  • I will never actually own this car

SOME CUMMINS RAILTONS SPECS:

Engine: Cummins iSB 6.7 litre (409Cui) in-line six featuring 4 valves per cylinder

Power: 485BHP & 900FtLb torque (at time of publishing)

Aspiration: CTT (Holset) hybrid turbocharger & belt driven Rotrex supercharger with charge cooling and custom fabricated cold air box

Performance: 0 – 60 in the region of 5.5 seconds with 150+ max speed

Driveline: Rear wheel drive via ZF 5 speed manual gearbox

Brakes: All round vented discs with adjustable bias control

Suspension: Front: double wishbones with single transverse leaf spring. Rear: live axle with coil springs. All round variable rate adjustable dampers.

Estimated Cost: circa £250,000 if ever replicated


One thought on “Time Well Spent: The Cummins Railton

  1. Oh my lord that looks rather loopy!

    Worked with Cummins all of my life so that’s bound to be one hell of a decent engine if the Darlo lads have been spannering. Look forward to seeing this at the festival. John

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