STROKE GENIUS HARTGE 2.7-LITRE Z1 Is a Z1 fitted with a Hartge 2.7 a good bet? / #BMW-Z1
Stroke of Genius. We love the #BMW-Z1
and here’s one that answers the lack of power criticism with a #Hartge
2.7 engine. If you thought the Z1 looked gorgeous and handled brilliantly but was lacking in the power stakes you could always have endowed it with some more urge thanks to a Hartge 2.7 conversion. Words: Adam Towler. Photography: Gus Gregory.
‘Look, that car is driving along with no doors’ – that’s what the assorted traffic cruising on the M40 this morning is thinking, it’s written all over their faces and readily decipherable from a spot of lip reading; confirmed by the camera phones that are being raised as we pull alongside. I could drive this Z1 with the doors ‘up’, of course, but for the sake of novelty it just has to be tried, even if it means a decidedly fresh blast of slipstream air up my left-hand trouser leg. Given the ‘motorway’ speed we’re moving along at that’s hardly surprising, but then this is no ordinary Z1 – as if the word could ever be applied to BMW’s late ‘80s sports car in the first place.
I’ve never driven a Z1 before today, but I’ve certainly been curious ever since my school bus passed a black Z1, parked, usually, en-route to and from school. It was an attractive, exotic sort of machine, and that perception was more than just skin deep. For the time, the Z1 was quite unlike any other car in production.
Said to have been inspired, at least in part, by comments from a journalist made to then-BMW chairman Eberhard von Kuenheim, the Z1 (Z for ‘zukunft’ meaning ‘future’) project was expedited by Wolfgang Reitzle, the famous head of BMW R&D in the 1980s and who would later go on to head up the Premier Automotive Group at Ford, before exiting the industry under something of a cloud.
The car was first seen in concept guise during 1986, and was built by BMW Technik GmBH as a way of exploring new methods of production. Technik decided to illustrate its new thinking through the medium of the roadster, with another famous name at the helm: Ulrich Bez, later of Porsche and finally CEO at Aston Martin for many years. Production began in 1988, with cars delivered from 1989 - 1991 .
The core of the Z1 is a galvanised steel monocoque, with notably high sills and an additional tubular frame that runs up the A pillars, increasing the rigidity of the structure. The floor is a sandwich of GRP and foam, bonded and bolted into place. This has three advantages: it’s strong, it won’t rust and it provides a ready-made smooth underfloor to the benefit of aerodynamics. In fact, #BMW
maximised this feature by exiting the air over an aerodynamic rear silencer and gap in the rear valance, thereby negating the need for a fixed rear spoiler.
The actual body you see, the skin if you like, is not in any way structural. It’s made from a mixture of Xenoy thermoplastic (the front, rear and side panels) and an epoxy glassfibre for the bootlid, roof cover and the bonnet. A special painting process was developed to maintain the required quality of finish on the panels. As for those iconic doors, they disappear down into the sills, and are operated by a push button in the rear panel from outside the car, and by pulling the door handle from inside in the normal fashion: it’s an odd feeling to do this for the first time and watch the door automatically drop rather than swing outwards.
It wasn’t just the construction of the Z1 that was ground breaking; it actually contained a very forwardlooking mechanical layout that still has ramifications for today. Although the car is based heavily on the E30 325i of the same period, the inline ‘six’ was moved back within the wheel base and sits behind the front axle line, giving the car the near 50:50 weight distribution once so heavily marketed by BMW. The McPherson struts of a regular #BMW-E30
are used on the front axle, but the Z1’s other major innovation was the introduction of the so-called ‘Z-axle’ rear, a form of more advanced multi-link suspension that would transform the stability and handling of the forthcoming E36 3 Series that the Z1 pre-dated.
What of that sonorous 2.5-litre engine? In standard form it cranks out 170hp, which although sounds faintly quaint by modern standards, it looks altogether more promising when you consider the diminutive proportions of the Z1. That is until you look up the kerbweight, and notice that at 1250kg, it’s 105kg heavier than a 325i. That may only be the weight of a very rotund passenger, but when your power-to-weight ratio is constructed more from a lack of mass than outright horsepower, these numbers matter. Correspondingly, the Z1’s performance stats were impressive, but hardly scorching for a car that promised so much in the handling stakes. Michael Scarlett, writing in Fast Lane magazine during December 1988, commented that: “It’s an exhilarating performer without being quite as quick as such a secure and responsive chassis deserves”.
That’s where the car I’m due to drive today comes in. It’s parked to the rear of Birds Garage when I arrive, accessed by a stroll through a showroom full of nearly new BMWs of various descriptions. Next to them, the Z1 appears tiny, and in its resolutely dour and functional Urgrün Metallic paint it makes a completely different sort of impression. The design is very much of its time, but particularly attractive if you can appreciate the proportions, the restraint in the details and the precise nature of what styling flourishes there are. It’s especially successful at including the BMW kidney grille into a low-slung sports car shape, while the treatment at the rear of the car is redolent of the E36 3 Series. Talking of low slung, its meagre stature and the provision to drop the doors vertically was apparently inspired by Reitzle’s fond memories of his uncle’s Triumph TR6, where a cigarette end could be stubbed out on the road when pulled up at some traffic lights because the car was so low to the ground.
‘H5 KWR’ is for sale at Birds when I drive it, but has subsequently sold by the time this story will reach print. What makes it even more special than the other 25 Urgrün Z1s imported into the UK, out of a total UK allocation of 85 cars, is that it features a Hartge 2.7- litre conversion. The increase in displacement has been achieved by lengthening the stroke of the ‘six’ from 75mm to 81mm, with a bore size unchanged at 84mm. So configured, the total capacity is 2693cc, and by then shaving some material from the cylinder head the compression ratio has been taken from 8.8:1 to 9.7:1. Together with a remapping of the ECU, the peak power output jumps to 205hp (at 6100rpm instead of the 5800rpm peak in the standard car), with torque rising from 164lb ft at 4300rpm to 189lb ft at a slightly lower 4000rpm. Both figures make for exciting reading on paper, so I’m very keen to see how that will translate on the road.
Before I thumb that incongruous door-opening button, there’s just one more thing to consider: price. The Z1 was always a very expensive car, retailing in Germany for around £26,000 once production started flowing. Opting for the Hartge engine meant forking out another £5201.39, including fitting, to Birds Garage, then based in Amersham, Buckinghamshire. As a comparison, this would take the list price well beyond that of a new entry-level Porsche 911 of the period. Modifications didn’t end there either, with a full Hartge conversion – including wheels, body modifications and all the other usual tuner items – costing £11,500.
The driver’s door falls down with a chuntering sound that doesn’t match the visual sophistication of the operation. It takes a bit more effort to climb in over the high sill, but once inside it strikes a nice balance between being a cosy sports car and not cramped. I take a look around the cabin and smile, because everything has that late-‘80s west German look and feel to it that as enthusiasts always raises a smile. For a sports car – a concept sports car brought to life at that – it is unerringly pragmatic, with a simple dial pack straight ahead and the familiar BMW switchgear of the time grouped closely together on a small central panel. The leather bucket-style seats have a curious ‘camo’ effect on their darker sections, which looks more like the sort of material you might find on a ladies winter jacket of the period, complete with chunky shoulder pads. The pre-airbag steering wheel is another Bauhaus-like example of simplicity, with a very small central boss: it’s a bit too much of a reach away for me, but fairly comfortable nonetheless.
The hood has already been lowered; it was simple enough, requiring manual unlatching from the header rail and then folding underneath the panel behind the occupants’ heads. The M20 engine fires up with a fabulously organic rasp and rumble, and I’ve already decided I’m going to enjoy this car a great deal. You don’t get that sort of noise from a modern, lowpressure turbocharged four-cylinder engine, after all.
The Hartge Z1 is very easy to drive around in slowly. The assisted steering requires no real effort, although at 3.9-turns lock-to-lock there’s a reasonable amount of arm-twirling to be done. The star so far is the gearbox, which again easily trumps anything modern in the way you can feel one cog giving way to the next. Maybe it’s the 24 years that have passed since it left the factory, grinding it down to smoothed perfection, but it’s just so nice to swap gears, often purely for the sake of it. Why can’t modern cars get these details so right?
It’s the combination of the engine and ‘box that preoccupy the initial attention, the car snapping forward under hard acceleration but hardly forcing my torso back into the seat. But as soon as I’ve dropped the doors then it’s these that take over. It reminds me of those post office Sherpa vans you’d once see: hurtling around with the bare legs of a shorts-wearing postie pumping the pedals with the sliding door always swept back in the open position. If that sounds as though the feeling is one of being exposed in the Z1 then that’s only half true, for me, because the high sills mean you don’t feel as on show as you might, but the sudden blast of cold air confirms this is much more than simply dropping the side windows.
There’s no structural downside to driving along like this, and not only does it garner plenty of kerbside attention, it also brings you closer to the sensations of driving – like you might get from a two-wheeled device. The Z1 turns out to be a smooth character. Predictably it’s much softer in setup and character than a more recent BMW roadster, which gives it a relaxed way of approaching a decent road. The steering response is a little slow, but that works with rather than against the initial roll rate, and once you have the car pointed into a corner it does feel very composed. The ‘six’ has a lusty response to the pedal, and a really invigorating soundtrack when wound out, although would I feel it was fast enough if I’d just dropped over five grand on it (bearing in mind five grand was a considerable sum 24 years ago)?
That I’m not completely convinced by, but then I think that same sentiment applies to the whole Z1 package. It’s a car from the left-field, so there’s not a great deal of point in comparing it with any rival, either at the time or now with our ‘classic’ spectacles on. It does what it does; looks like nothing else, and dishes up a drive that gets more enjoyable the more you experience it.
While we don’t have the weather today to truly maximise those sensations, it seems obvious to me that the Z1 is an esoteric sort of experience – a car that appeals to someone who thinks deeply about the package of talents it offers, and what it represents, and simply wants one. If the only real Achilles’ heel of the Z1 was its lack of outright performance, then this Hartge conversion neatly slays that criticism in one lunge of acceleration – doors open or closed.
Thanks to: The car’s owner and Gordon Ince at Birds Garage – www.birdsgarage.co.uk or 01753 657442 – this car has now sold, but contact Birds for any enquiries on other stock.
EVERYTHING HAS THAT LATE-’80S WEST GERMAN LOOK AND FEEL TO IT THAT AS ENTHUSIASTS ALWAYS RAISES A SMILE
THE M20 ENGINE FIRES UP WITH A FABULOUSLY ORGANIC RASP AND RUMBLE. I’M GOING TO ENJOY THIS CAR A GREAT DEAL
IT’S AN ODD FEELING TO WATCH THE DOOR AUTOMATICALLY DROP RATHER THAN SWING OUTWARDS