RUF YELLOWBIRD CTR-4
Words: Johnny Tipler Photography: Antony Fraser The latest Ruf Yellowbird CTR-4 is the most radical offering yet to fly the Pfaffenhausen nest. We winged it on the Swabian blacktop
It’s a Porsche, but not as we know it. Ruf’s new Yellowbird features a full carbon tub, race suspension and a full carbon body, plus 700bhp
Yellow plumage – and a cocksure attitude: that’s about all that the latest Yellowbird has in common with its trend-setting ancestor. It is a true technical tour-de-force, because although it presents itself as something approaching a 964, ruffle those feathers and you’ll find it’s anything but. This freshly-hatched CTR employs racing car construction technology, miming the same structure as a DTM (Deutsche Touring Meisterschaft) saloon, for which the regs stipulate a common-chassis construction of carbon-fibre monocoque and steel rollcage, with front, rear and lateral crash elements, which also serve to locate the suspension componentry.
Alois Ruf’s vehicular affections proudly embrace the imagery of the classic air-cooled 911s, and to that end the Yellowbird’s body shape emulates a 964 rather than a 991. Our run out into the Swabian countryside with both examples, old and new side by side, emphasises the growth of the modern car’s girth and stature. The new car is only 911-esque, because what you’re looking at is a carbon-panel clad chassis. Whilst the cabin interior corresponds exactly with normal 964 proportions, the exterior has swollen, very subtly, and it takes Alois’s guided tour to appreciate the niceties.
Three decades separate the two Yellowbird CTRS, one introduced in 1987, the latest in 2017. As Alois tells us, ‘the original idea was to make a motor car that was not so large because, remember that in the same year, ’87, we had the 959 which was a very big car, relatively, and we wanted to follow the same principle with the new car, and make it smaller than the current 911. The entire monocoque is carbon, whereas the Ultimate that you saw last year only had a skin of carbon, but here it’s the whole monocoque. Most people think it’s based on a 964 or a 993, and it’s some kind of a backdate. But it’s based on a Ruf, and it’s coming from a clean sheet of paper.’
In fact, there’s a full-blown Le Mans racecar underpinning this traditional looking car. ‘It could have a modern body,’ Alois says, ‘but we wanted it to look as much as possible like our original Yellowbird. This is why the car handles so nicely and feels so great, because it’s a modern, state-of-the-art racecar underneath. The push-rod suspension includes upper and lower wishbones, and at the rear there are the horizontal cross-mounted shock absorbers with coilover springs, while in the front they are longitudinally
mounted, and that’s pure racecar engineering.’
Nothing is left to chance or done on a whim. ‘We needed to accommodate these larger wheels and tyres to have an “adequate stance for the horsepower, because output is 700bhp and it’s a lightweight chassis, so we made it wider, but the eye does not read it as a very wide car. To start with, we put 4cm more in the tail-lights, and when you compare that with the old one you’ll see the difference, that the tail-light and that section of bodywork has broadened out.’ Typically for a Ruf, the Yellowbird roof has no rain gutters. ‘The old one didn’t have gutters, and neither does the new one. But what we’ve done here is to give the doors and the wings more shoulder. When you open the door, you’ll see how much thicker it is than normal. The size of the cabin inside hasn’t changed, the glass area is still the same; we still have the same side-window glass and the door frame that the old one has, as well as the windshield and the rear window.’ However, the glass in the rear-three-quarter windows has changed because it’s acrylic and there’s a discreet air intake either side for the combustion air. The two large ducts in the tops of the rear wings (fenders) provide cooling air for the intercoolers. ‘Take a few steps back and you will notice we have a 70mm longer wheelbase, and the eye doesn’t notice that, because the overall length of the car hasn’t changed. It is still the same length as the other one, but we have less overhang, front and rear. The headlights have been moved up by 20 millimetres, and nobody can tell that. The rear axle has moved by 50mm towards the back of the car and the front one by 20mm towards the front. We’ve lengthened the door by 25mm, and although it’s longer the pivoting points have not changed because that would make it more difficult getting in and out when you’re parking next to another car.’ Was it difficult to accommodate the front edge of the door
We made it wider, but the eye does not read it as a very wide car
within the structure because of its extra length? ‘All the body parts are different,’ says Alois. ‘There is nothing structural that you could exchange with a 911. You can carry over the wipers, the windscreen, the side glass and the door frame, and that’s all; the rest is completely new.’ The LED headlights are specially made for Ruf, and the door mirrors are also to Ruf’s special design, while the rear bumper corners are slatted in the interests of heat dispersal. ‘We’ve just put it on Dunlop tyres as part of the testing programme; we had been trying Michelin tyres, and now we’re trying the Dunlops to see if there are any significant changes.’
To access the cabin, I first press the button on the door lever and the lever swings out a little way in the fashion of a similar Jaguar item, revealing a discrete Ruf logo. You only have to get into any Ruf and you’re sitting in something rather special. In this case, the seat upholstery is black-andcream hound’s-tooth cloth, and the seat belt passes through an aperture in the side of the sports seat beside your thigh. The steering wheel is characteristically black padded leather without any of the gizmos that infest modern wheels, so you’re looking through the apertures in the wheel arms rather than having switches to operate. Of the gauges, the rev counter is Ruf logo’d, the digits are in green against a black background, and the whole car has been re-trimmed so that the panel gaps in the elements of the interior are all pretty well perfectly aligned. There’s Kevlar cladding to the inside sills and the outer skins of the footwells, and the cabin rear has been retrimmed with flat surfaces and storage bin where the rear seats would otherwise be in a conventional 911. There’s a carpeted roof and Alcantara around the ‘A’ posts and ‘B’ posts, cladding the integral roll cage. The inside door handle levers are very neatly concealed by the armrest and door-pull, and we have trademark Ruf aluminium pedals and a serious footrest for the left foot. Overall, the interior is deliberately minimalistic because it’s a CTR. There’s no glove compartment and instead there are what resemble sponge bags in the lower door liners, which provide storage nooks.
I pull the engine lid release knob and the lid lifts of its own accord, revealing a very different engine as far as the visible ancillaries are concerned. The oil filler in particular is handily placed, projecting backwards for easy filling. Alois disabuses my colleague from taking any photos of it as the motor is still a work in progress and could eventually look somewhat different, certainly more refined and less
racecar than it does currently. ‘It’s functional the way it is now, but not photogenic,’ he says. ‘To give it the feeling of the air-cooled engine we’ve put the alternator into the centre, and we have relocated the air conditioning compressor to the front with an electric motor, and the power steering pump is also in the front with an electric motor, so we can afford to have a very clean engine here.’
Back in the day, we thought the 964’s suspension was radical when it shifted from torsion bars to wishbones: the Yellowbird is in a different league, taking a leaf out of its mid-engined CTR-3 sibling’s set-up – and then some. Its coil-over spring-damper units, assistor shocks and adjusters are mounted horizontally, front-to-back on either side under the front lid, rather than vertically, and the similar rear units are also mounted horizontally, but laterally, from side-to-side. According to Ruf PR MarcAndré Pfeifer, the benefit of having them horizontal rather than vertical is that, ‘the car doesn’t bounce on bumps like it would with conventional vertical springs and dampers, so it doesn’t lose contact with the road surface, and therefore it doesn’t lose traction.’ It also provides greater space for “accommodating wider tyres and bigger brakes. The fuel tank occupies a large proportion of the front boot area, but you fill it up via a race-style funnel accessed through the cap in the front lid. This shorter filler pipe also enables a larger capacity tank, currently 8-litres more, and which will eventually be 105 litres.
Marc points out that this is, really, ‘the prototype, the first driving car, where we can collect experiences and make notes as to how it’s working, what we need to alter and adjust.’ In which case, we’re privileged to be able to see how they’re getting on, and even at this stage this is a truly incredible car. I buckle up, fire up the deepthroated flat-six, and ease out of Pfaffenhausen on the flat farmland blacktop to one of our photo locations, a wonderful sweeping B-road, which we have pretty much to ourselves. The quicker I go, the more the steering lightens up. It’s unfailingly
The Yellowbird is in a different league, taking a leaf from the CTR-3
very precise, and there’s no drama moving the steering wheel, partly because the new suspension allows the road wheels to turn more freely. Frankly, it’s kind of uncanny how smooth and direct it is, and how silky the ride. It’s all very acute, from the turbofused acceleration to the braking punch and tight turn-in. Everything about the driving experience is extraordinarily exact, there’s an uncanny smoothness to the steering lock, and when I press the accelerator pedal there’s a dramatic surge forward, accompanied by the whistling of the wastegate with each shift. This is a distinctly macho car, requiring some 3000rpm to actually get it going, and then every gearshift is a minor workout; it’s certainly not a soft touch. I’m using mostly 4000rpm before each shift, and it has seven speeds, and though I’ve engaged 7th it’s not for long on this fast, serpentine B-road. Actually, there doesn’t seem to be much difference between 6th and 7th, and I’m still accelerating hard in 7th. The rev counter is zinging round to 5-, 6000rpm, and the boost gauge is equally agitated, going right round to 1.2-bar with each throttle thrust. Turn in is hyper-sensitive and the steering is extremely sharp, and the surge of energy it delivers when I apply the accelerator literally pins me against the backrest. Conversely, the stoppers are so strong that, under braking, my torso lunges forwards into my belt.
This is a much more macho car than its Pfaffenhausen siblings, including even the mid-engined CTR-3. It’s quite different in character to other Ruf models, which could be described as relatively placid by comparison. This Yellowbird you can’t be soft with, you’ve got to grasp the controls and really go with it. The paradox is, its very lightness and delicacy of handling and steering is at odds with the massive power available. ‘Sure,’ says Marc, ‘the more you get the feel of it the better you know how it’s going to behave. It has a huge personality, and it asks what you’d like to do with it, very directly, and you are the driver, you decide what to do, and that means in a very tough way. A major factor with most modern sportscars is that you’re not afraid because you have so many electronic aids inside that you know that, no matter what I do, it will save me. But here we are in the realm where you can go over these limits, but it’s you that has to take care of it. Of course, we have standards and safety regulations, but the limit of this car is so much higher in performance and cornering that first you have to get used to it. Its light weight means you have much higher braking efficiency; you can brake later, you can accelerate earlier, you can go at higher speeds around the corners, so everything is one or two steps above the limits that you’ve been used to before.’
The person responsible for achieving these standards is Alois himself. Whist Stefan Roser was the test pilot for the original Yellowbird, Alois has the most experience in the behaviour of rear-engined
cars, so it is he who has raised the bar and set the parameters for the new Yellowbird. ‘We’ve tried to achieve a weight balance that matches the behaviour of the midengined CTR-3,’ says Marc, ‘and this new push-rod suspension, front and rear, provides many more possibilities for us to achieve that goal. Then, of course, you just need a lot of test driving, and you either hunt for performance limits like top speed or acceleration, or, what is more important from our point of view, is that the car should give you as much fun as possible when driving it, because that’s what it’s all about, the pleasure of driving. You can make a lot of calculations and theoretical concepts, but in the end it always comes back to experience, and this is our strength. Next year we celebrate 80 years of Ruf, and that’s what we’ve tried to put into this car.’
Back at the Pfaffenhausen showroom there’s a group of Brits enjoying a guided tour – hi there, readers – and after refreshments I head out again in the new Yellowbird, reflecting that life just doesn’t get any better than this: it’s such a thrill. Its colossal power is instantly delivered, and the whole tactile experience of the new CTR-4 is above and beyond what you would normally expect, even in a Ruf. This is a very sophisticated sportscar with racing connotations as well, the way the power is delivered, a slight shudder accompanying each shift, almost like a hint of torque steer with each gear change as the power comes in. And I don’t have to be trying very hard to make that happen: squeeze the throttle pedal and we’re off! Let’s not talk about horsepower: this CTR deploys elephant power – and of course that’s partly down to its lightweight construction, too. So, it’s a muscle car in the sense that it requires you to use your muscles to actually control it when you’re accelerating hard. But as well as deploying brute power it will pootle with the meekest of them in an urban context. Its ride is amazing, too, and that’s mainly to do with the orientation of the springs and dampers. As Alois puts it, ‘you feel the unsprung weight is really minimalistic, and you notice when you drive how nicely the wheels stick to the road; the suspension still delivers very good ride comfort, too. At the front we’ve gone longitudinal, so we have more space for the fuel cell and for luggage capacity and the other ancillaries we have
The CTR-4 is above and beyond what you would normally expect
in there. We made a different fuel cell that’s filled up from the aperture in the front lid, and by doing that we’ve gained 8-litres more fuel capacity, because you don’t have the filling pipes of a normal 911. Also, we wanted to have steering that is very direct and very precise, and it’s hydraulically assisted but with an electric pump, which means we can keep the engine compartment cleaner and bring weight to the front for better weight distribution, and we gave up on the rear seats for that reason, too, so instead you’ve got a luggage box behind you.’
Alois takes us the few kilometres to the Ruf skunkwerks where the chassis for Yellowbird CTR-4 number two is in the process of being created. The skeleton of the chassis sits on a dais in the workshop, looking for all the world like a racing module. Two technicians hold up a complete carbon side of the car for Antony to shoot, demonstrating the lightness of it by using just two fingers. Alois obliges by picking up the entire roof panel by himself. The front and rear subframes are crash structures, made of lightweight steel, and bolted to the carbon monocoque. ‘The bonding happens only between the parts that are made in carbon-fibre. The tub is made by a German firm, the same company that makes all the DTM tubs for the race series.’ Some areas are solid and extremely rigid, while other box-sections are voids. ‘You probably felt when you drove the car how rigid it is; there is no squeaking, there is no flex, you don’t have the feeling that something is moving around, like in a steel body; it’s very solid. So, we are very proud that we have done something with the traditional 911 shape that didn’t hurt it. Usually whatever people do to modify a 911 only makes it worse, not better, and here we have put something together that could have been an evolution of that iconic body.’
There is no doubt that the new Yellowbird CTR-4 is a masterpiece, hints of which were manifest in the air-cooled, carbon-bodied “Ultimate” that we featured last year; but the Yellowbird is nothing less than a quantum leap in Ruf’s ever-evolving take on the 911. Come home to roost? Far from it: these flights of fancy are still very much on the wing. PW