Porsche’s turbocharged 917/10 was the first 1000bhp racing car. It could reach 1OOmph in less than four seconds — all in first gear — and was good for 230mph! Paul Fearnley climbs into one — and lights the fuse
Okay, so the 200mph warning signs were there: an engine note that registers on the Richter scale; a power-to-weight ratio capable of punching you through the exosphere — and beyond; a hitman’s sense of purpose. But into that mix you have to factor… me. Had they been asking for volunteers I would have skulked at the back rather than be oooo-me-me-ing down at the front.
But they weren’t asking for volunteers. They’d already found their senseless sacrifice… me. I’d not had even the condemned man’s luxury of a decent breakfast. Some people ease themselves healthily into a new day with freshly squeezed juice and a bowl of muesli; others go for the caffeine kick-start. Me? I strap myself into a 1000bhp sportsracing car.
It’s 7.30 in the morning at Bosch’s thankfully out-of-the-way Boxberg test track when they fire up the pool table-sized flat-12. This five-litre twin-turbo runs Texas oil baron rich from cold; when combined with its 6.5:1 compression (just about the only spec figure that doesn’t verge on the unimaginable), this makes it as grumpy as me in the wee hours. In the good old, bad old days, two or three attempts at starting were all you got before it was an all-plugs-out job. Bearing in mind that there are 24 of these, the front four of which require you to slide the engine back before they can be swapped, this is not a quick fix. Thanks to modem plugs, however, and a practiced hand on the throttle linkage, this is a rare occurrence these days. Today included. Curses!
After four or five minutes at a constant 3000rpm, my 1000-horse carriage awaits. Its vast, one-piece rear bodywork section, which from certain angles looks like a particularly tricky crazy golf hole, is clicked into place and the hinged-forward driver’s door is swung open. Willi Kauhsen, the charming man who 30 years ago did thousands of kilometres of testing in this very chassis, and who’s owned it since 1972, beckons me over. He appears completely unconcerned about what’s to come. Such is his confidence in fact, he’s even brought some wets with him: 1000bhp, turbo lag, differential-less rear axle, in the rain? No thank you.
I step over the wide sill that contains one of the massive fuel tanks (77 gallons in total) and plonk myself into the driving seat. I fit. Curses again!
I’m behind an Abarth (!) steering wheel, the plentiful diameter of which hints at the muscular ride that lies ahead. The pedals are offset to the left but fall easily to foot. The throttle is meaty, but the triple-plate clutch and unservoed brake feel remarkably road-car. Seen through the top half of the three-spoke wheel is a VDO rev-counter that’s redlined at 8400rpm; to its right, canted-in at a gentle angle, is a boost gauge that’s red-lined at 1 bar. There are some other smaller, piffling gauges — oil temp, water temp, that sort of thing — but it’s impossible to peel your goggling eyes from the big ones that matter. Except when you accelerate, at which point you involuntarily scan the heavens.
In pull-left-and-push forward first the car had shunted unfussily through the two automatic barriers that lay between it — and me — and the wide-open sweeps of the 1.9-mile banked oval. But that same ratio is also good for 110mph — it’s amazing what you can do with a Giant Redwood-pulling 720lb/ft of torque. Willi had advised that I change up at about 5000rpm in first and second to avoid wheelspin during the quantum leap from 380 to 1000bhp. Eagle-eyed and pussy-footed, therefore, I squeeze on the revs: 4000, 4500, 4750. Sky! My crash helmet thuds into the roll-hoop as the turbos go Full Ahead Both. Thankfully, the same rag-doll momentum sees me pull, semi-auto, through into second. Four-speed, all-synchro, this unit is robust (as you might expect) rather than rapid. This fact, when combined with the more sensible default option in my Fight or Flight Response, means the selected cog drops into mesh just as I drop off the boost. My chin nods onto my chest. But it doesn’t stay there for long. We’re off again. Second gear is good for 150mph — which is exactly where we’re headed. Quickly.
With my neck muscles boosted, I determinedly see 6000rpm before engaging third (good for 190mph!) with an unsteady hand. And, despite my understandable circumspection, we’re off again. This is a runaway train of a car. And she blew. It’s not a shrieking power, though; its builds menacingly, unstoppably, like a Europe-sized storm in the Caribbean. This is the car, remember, that crashed into America and swept all before it. This is the car you can see from space.
When Mark Donohue, clean-cut Captain Nice, the racing driver who probably could have brought Apollo 13 home safely, first drove the turbo version of this car (chassis 001, the project’s development hack) it scared him half to death once they’d got the damn thing started. Porsche wasn’t introducing turbocharging to racing – Offys had done that at Indy five years before – but it was the first to adapt this format to stop-start, on-off road courses rather than rolling-rolling-rolling, full-throttle ovals. And just months before the first race for its 917/10, the car was nowhere near race-ready. Its throttle was a lightswitch – with a delay. Now you see it, now you don’t, now you see it… And we’re talking 600 extra horsepower here, not 40 feeble watts. In a car with a short wheelbase (2100mm) and weighing 810kg (100 more than the McLaren M20), this power delivery was a recipe for disaster.
But not only was Porsche wrestling with turbo lag, it was also getting to grips with big wings and massive slicks for the first time. Low-drag had been its (successful) policy until now, but with more than 750bhp at their disposal, the Chevy boys of Can-Am had fast learned the benefits of downforce. Donohue was aghast when engineer Helmut Flegl explained how Porsche had no plans to fit a rear wing to the car. Initially dumfounded, by the time he was halfway home Donohue had half-convinced himself that Stuttgart must have a secret ground-effect scheme up its sleeve. At which point he unconvinced himself and diverted back to Stuttgart to impress upon Flegl the need for a wing. Thankfully for him – and me – he and Don Cox, Penske’s razor-sharp tech chief, came up with a convincing argument.
I can certainly feel it working now, that snowplough nose digging in ever harder, that crashing-wave rear wing squashing and trimming. It was reckoned that the car generated its own weight in downforce at 180mph; I, of course, am going nowhere near that quickly. It all feels remarkably planted, though, rock-solid courtesy of inch-thick rollbars and 600lb springs front, 800 rear.
Confidence building, I attempt an experimental jab on the middle pedal. The car tramlines as the not-yet-warm, Porsche-built four-pot calipers grab at vented, cross-drilled discs. A nice, steady, one-two downchange follows and I hold the revs at the slump end of the boost. And then boom! The needle flicks to 0.9 bar (about 900bhp) and I’m pinned back from a 100mph rolling start, in third! This is what I’m missing by running on the oval: the neck snap, overrun crackle and turbo pop of braking, cornering and acceleration. (I had hoped to drive on the handling course, too, but it proved a mite twee for a car that is almost as wide as it is long.) The handling was another aspect that had failed to impress Donohue on his early runs. The unsorted 917/10 had an unnerving habit of weaving at high speed, while corners had to be taken in two or three stabs rather than one smooth sweep and that was with a 5.4-litre atmo engine amidships! Donohue and Cox lengthened the front wishbones to reduce camber change and stabilise the contact patch, and the rear roll-centre was raised: the car was now more manageable, if not totally perfect
I had expected it to be truly terrifying, to shoot off at right angles, to swap ends, given even a smidgen of throttle. But that, when I thought about it latterly, was an irrational fear. The M20 of 1972 was the latest in a long line of McLaren Can-Am beauties: it had 800bhp, a monocoque chassis, and its drivers and team were imbued with years of domination. To beat it you would require a finely honed racing car, not an untameable monster. And this Porsche beat it.
“I drove a McLaren M8 on the Porsche test track,” admits Kauhsen after 30 years, “and it was much, much nicer to drive than the 917/10. Much easier. But there was no way, no way, that it could live with the Porsche when Mark Donohue was at its wheel. He was fantastic.” Donohue’s driving style was to carry speed deep into a corner; for him, there couldn’t be enough power or downforce. “I remember the first time I saw him in the car,” Kauhsen continues. “He came into the S-bend sideways, changed up in the middle of it, and was gone. I thought he’d made a mistake, but he did exactly the same thing on the next lap, and on the next. He drove like it was a go-kart. He was only a tenth quicker than me, but it was a very short lap at Weissach and I had done thousands of kilometres there. I knew then that I would have to change my driving style. But I could not. I could get the car a little sideways, too, but only when I saw the exit of a corner. To be quick in this car you had to be aggressive with it, on the brakes and on turn-in, and Donohue was the master of that.”
If Kauhsen is the unsung hero of this immense project — testing, testing, testing — Donohue is The Man, in and out of the car. When the turbo engine, fresh from flash readings of 1500bhp on the dyno, continued to refuse to run at low and mid-range revs it was Donohue who asked if it had ever been tuned to run minus the turbos. The answer was no. His request that the Porsche engineers return to the absolute basics paid dividends. No longer blinded by those flash readings, they, and Bosch, took a more measured approach to factoring in a new, third parameter to what we now know as engine management: boost, as well as throtde opening and rpm. The resultant fuel injection control cam was not much bigger than a 50p piece but it floated this million-pound project. The resultant fuel pump became known as the ‘happy pump’, and Donohue cracked one of his famous smiles — now he had a car he could race with.
This is the ‘user-friendliness’ which I’m benefiting from today, 31 years later. The boost is epic in its scope and scale, but it does not come in as aggressively as that of the Porsche 956 I drove last year. It’s fatter, plumped out by all that torque.
I’m on my second run now and I’m beginning to enjoy myself. I espy a Merc in the middle-distance and prepare to pour past it. I don’t, though; our speed differential appears to be not much more than 20-30mph. (It doesn’t occur to me that the Merc might have been doing 140 or so!) I decide to speed up — well, the mechanics are watching this time. Another 500rpm is spooled out. Approx 7000rpm. Storm’s a-brewing.
We’re really shifting now and I lift for the tighter of the bankings — the circuit is cam-shaped; my neck feels the braking effect of of that rear wing. The longer ‘base circle’ banking I can take without a lift — not that I’m flat-out, mind. Even so, I’m definitely having to steer and I feel my biceps bulge (a relative term). The buffeting has just begun, too, that thin strip of a deflector along the cockpit coaming having worked wonders.
Another 500rpm. Faster, faster, faster…
Time to stop.
I’m all alone briefly back in the paddock. I allow the turbos to cool, then switch off. Their impellers, which run up to 100,000rpm at full load, whir on for 10sec or so. My back acts as a heat sink and a shimmering haze passes overhead. Blimey, I’ve got it warm — a fact confirmed by one of those pifffing dials. I hop out and feel the tyres. Hot-ish. Wonder how fast I went?
Willi returns. I ask him what the car is geared to: 345km/h at 8400rpm, he replies. The tell-tale is wedged at 7600rpm. I ask to borrow a calculator.
That’s 41.07 km/h per 1000 revs. Times 7.6. Equals 312.14km/h. Multiply by 0.6214 to get mph. That’s… No way!
I show the calculator read-out to Willi. He shrugs, unconcerned: “For sure, yes.”
“But it didn’t feel that fast,” I venture, almost by way of an apology.
“That’s the problem with this car — it does not feel fast, it does not sound.”
Exactly how fast?
An unofficial 193.96mph.
Running 10 per cent shy of a racing car’s maximum is no reason to boast. Sure, I’ve almost joined The 200mph Club, but there is no disappointment, just an overwhelming sense of humility: I am in the presence of greatness.
Porsche’s 917/10 is unquestionably a car that redefined the sport’s boundaries. It can take you to places you’ve only dreamed of. I know, I’ve been.
Track record: 917/10.001
From the start of 1972, Willi Kauhsen raced 002, sister car to 001, in the Interserie championship. This was the chassis that had been campaigned, in non-turbo form, by Jo Siffert during the Can-Am series of ’71. With sponsorship from Bosch, Kauhsen won at Imola and scored seconds at the Nürburgring, Osterreichring, Hockenheim, Norising and Keimola in Finland. Back at the Nürburging in September, and desperate to make the most of pole position in a bid to close the gap to series leader Leo Kinnunen (in 004), a puncture on the first lap sent Kauhsen into the barriers. On full tanks, the car was burnt to a crisp.
Porsche then offered Willi 001. This car had done more than 10,000km of testing, and so a new space-frame was built for it and a fresh engine dropped in. He ran it at Hockenheim (another second), but with the Interserie title beyond his reach he decided to contest the Laguna Seca and Riverside rounds of the Can-Am series. He retired from the former with a blown turbo, and finished a distant eighth in the latter.
Willi had a new chassis for 1973 (015), so 001 was loaned for one Interserie race each to Charlie Kemp, Günther Steckkönig and Wilson Fittipaldi.
The car now had one more race in its locker. In July 1974, the more famous Fittipaldi drove it at the ‘Ring: he put it on pole, but finished sixth.
Type:T912 air-cooled, DOHC, flat-12 Capacity: 4998cc
Bore x stroke: 86.8 x 70.4mm Compression: 6.5:1 Ignition: Bosch; twin-spark heads Fuel injection: Bosch Max power 1000bhp @ 8400rpm Max torque: 720lb/ft @ 6500rpm Construction: magnesium crankcase, steel crank running in eight plain main bearings, central power take-off and cam drive (gears); aluminium cylinder barrels and two-valve heads (65-deg valve angle: valves sodium-cooled); 5in titanium conrods, Mahle pistons in Nikasil bores; magnesium camboxes Weight: 284kg Turbos: KKK, one per bank Max boost: 1.4 bar Oil system: dry sump Cooling fan: 13in, running at 1.4 engine speed, 3100 litres/sec Firing order: 1-5-12-3-8-6-10-2-7-4-11
Gearbox: T920 – 4-speed, synchro Clutch: Borg & Beck, triple-plate, 7.25in Final drive: solid spool, locked titanium halfshafts, rubber donuts
Type: aluminium spaceframe stiffened by aluminium sheet (65kg) Bodywork: GRP Wheelbase: 2316mm Track (f/r): 1620/1638mm Weight: 810kg Length/width/height: 4350mm/2100mm/1120mm
Suspension (f): double-wishbone, forward-facing radius arms, spring/damper unit, anti-roll bar Suspension (r): reversed lower wishbone, top link, twin radius arms, spring/damper unit, anti-roll bar Hubs: titanium Dampers: Bilstein Springs (f/r): 600/800kg Brakes: Porsche, four-piston trailing calipers; aluminium discs, vented and cross-drilled Steering: rack-and-pinion Fuel capacity: 77 gallons Wheels: Porsche, 15in Tyres (f/r): Goodyear, 12/19in
0-60mph: 2.1sec 0-100mph: 3.9sec 0-200mph: 13.4sec