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Porsche 911 SC Lightweight – Roock Motorsports

by | Jan 23, 2008 | Classic Porsche Blog, Modified Porsche Hot Rods

Mention carbon fibre to most Porsche fans, and their thoughts turn to prototype racers like the RS Spyder. But Rainer Armitt’s outwardly standard SC hides an enviable selection of secrets up its significantly lightened sleeves. John Glynn reports.

Once upon a time in Leverkusen, Germany (1997 to be precise), an early 911 SC Coupe was bought by one Michael Roock, of Porsche tuners Roock Sportsystem fame. The car was quite superb, with fewer than 50k careful miles covered in 19 years. The initial intention was a simple valet, to bring the car back to showroom condition. But within a few days, the urge to improve had triumphed, and the spotless SC had been stripped for an almost complete rebuild.

Rainer’s Roock SC 1 Snetterton Rainer’s 911SC Snetterton track day 2 New Interior Porsche 911 SC Gt Classics seats

Though manufactured in 1978 (the year the SC won the Monte Carlo rally), this 911 is a 1979 model year car, an excellent choice of base vehicle. Firstly, it had a fully galvanised shell, so the bodywork was in great shape. Secondly, it had been delivered without a sunroof, not an easy thing to find post-’78, and a perfect starting point for a lightweight special. Finally, buyers’ guides of the time had short-sightedly labelled the early SCs as ones to avoid, so they were relatively cheap, even in immaculate condition. Anything the Roock brothers did was likely to be regarded as an improvement.

The earliest SCs were down on power compared to later models (180bhp as opposed to 204bhp from the 1981 model year), but the rated output of the first SCs was more political than mechanical. The management of the time had decided to phase out the anachronistic 911 in favour of the 928, and the run-out model could not be seen to be faster than the more expensive V8-engined flagship.

The early SC shares most of its motor with the preceding Carrera 3.0, which produced an easy 200 bhp. The SC engine uses a slightly bigger 9-bolt 3.3 Turbo crankshaft, but almost everything else is the same. Revised cam timing meant power was down against the Carrera, but this somewhat devious device gave the new arrivals better torque lower down the rev range, making them irresistible driving machines.

The earliest SCs employed the C3’s gear ratios, housed in aluminium rather than the lighter magnesium cases found in most Carrera 3.0s. Identical ratios with less power meant that the SC had a lower top speed: 141 mph against the C3’s 146, but this can be considered almost irrelevant. There is more to the fun of any 911 than simply holding the winning card in Top Trumps.

Back at Roock, the SC’s engine and gearbox were removed for rebuilding, and the car was treated to a glass-out, bare-metal respray in its original Guards Red. The front and rear bumpers and valances were replaced with fibreglass units, mounted on custom lightweight brackets. The front and rear lids were also left out for the bin men, replaced by high-end carbon fibre panels weighing fractions of the originals.

Paintwork complete, the windows were reinstalled. The door glass was converted to manual operation, and the rear quarter windows and rear windscreen were replaced with polycarbonate. The original pinstripe interior was left virgo intacta. When the engine and transmission were wheeled back in to rejoin the chassis, both had been completely overhauled, and were also significantly different from the original specification, more of which anon. Other modifications included an in-house front strut brace, and sports Bilstein dampers on uprated suspension. The car also received a set of 7 and 8 x 15 Fuchs alloys, refinished in the distinctive Battleship Grey hue seen here.

The Roock family enjoyed their bespoke creation (dubbed the SC ‘Club Sport’ in house) for a few years until in late 2001, it caught the attention of an inquisitive 911 shopper. With another project waiting in the wings, and an open wallet being waved politely in front of them, the family decided to sell. In February 2002, the SC came to a new home – in the UK.

In February 2002, Rainer Armitt was the owner of an underused E-type Jaguar. As an engineer, Armitt was well aware that prolonged lack of activity was not good news for the car, so he began looking for a more practical alternative. Living in Congleton in Cheshire, the nearby Classic Car Shop seemed like a good place to start.

A test drive in a 1991 964 Carrera 4 Cabriolet, a manual car in Grand Prix White, was a real eye-opener, and a deal was struck on the spot. The Cabriolet served its delighted new owner well for 18 months, until a chance stop at the same dealers led to a 1994 993 C2 Coupe, again Grand Prix White and manual shift. The following year, family commitments saw a Cayenne S replacing the 911. Summer 2006 marked the end of Cayenne ownership, and Rainer was again free to buy something ‘to have a bit more fun in’.

Flicking through the classifieds, the confirmed Porsche fan tripped over an ad placed by classic Morgan enthusiast Rupert Richards, of nearby Gawsworth Hall. The advert was for the Roock SC, which Rupert had bought to do the Tour Espagne. “I originally bought the car because it ticked all the boxes for what I wanted out of a classic 911” recalls Richards. “It could be used on road or track, and had been rebuilt with great attention to detail to fit that bill. At the same time it looked beautifully understated, and compared favourably with the driving satisfaction I derived from the previous RS & Club Sport 911s I had owned”. Though the car was past the top of the price range for an SC, a few hours after seeing the ad, Rainer was back at home breaking the news of his fourth Porsche to a less-than-impressed domestic audience.

Once the car was home, Rainer began to make a few changes. The perfectly preserved pinstripe interior might have added to the Q-car appeal for the previous owners, but to Rainer, it contradicted the lightweight exterior theme, so it had to go.

The first purchase was a pair of BF Torino Rallye ST seats, supplied by World-Wide Classics. Southbound Trimmers supplied a rear seat delete carpet kit and a custom centre section to tidy up holes left by the console delete, adding an integrated handbrake gaiter at the same time. Southbound also supplied the RS door panels. Schroth road-legal harnesses were then fitted, attached to a Weltmeister harness bar. Pelican Parts supplied a new exhaust system, consisting of SSI heat exchangers and an M&K silencer, as well as the replacement oil lines required. Toyo Proxes T1R tyres were fitted on the 15″ wheels; 205/55 front, 225/50 rear, with short tyre valves used, to counteract valve flex at speed.

Fast forward to today, and we’re with some other members at a Goldtrack track day in Snetterton, Norfolk. By the time snapper Woodall finds us, we’ve done a couple of sessions each. Rainer is clearly enjoying the day. “My first track day in the car was at Oulton Park in May, a birthday present from the kids” he explains. “It were terrifying. Great fun, but terrifying’.

We move the car to a quiet corner of the paddock for some detail shots. Despite a quick post-dinner look with another SC owner at our regular pub stopover last night, this is the first chance I’ve had to really appreciate the detail at work here. Early SC clues remain; no side repeaters and no rear fog lamp for example, while the later additions work well also. One possible exception is the offside Durant mirror, which Rainer rightly reckons is fixed too far forward.

The most common misconception regarding early 911s regularly used on track, is that such cars are worth little in the marketplace, and are basically being thrashed on a budget. This is a fallacy. Running an early 911 on track is an expensive exercise in time and money. Maintenance costs and consumables quadruple, and the only way to enjoy reliable track action is to keep the car in better condition than a strictly road car. An effective track day 911 is not cheap, and this SC proves the point perfectly.

Every square centimetre of paint on the car is first class, and the carbon fibre bonnet and engine cover are flawless. Once the lids are opened, the reason for the quality finish is obvious. These parts have been made using compression moulding, where resin-impregnated carbon sheets are pressed between moulds at high temperature. The underside of the bonnet has been finished to leave the vast centre section raw, which looks superb. The use of a bonnet prop in place of the gas-filled dampers is an essential one – bonnet shocks would be far too strong for a panel this light.

The finish on the bumpers is equally impressive. These replicas have been painstaking painted to exactly match the original aluminium blades and rubber accoutrements, and they are virtually indistinguishable from the factory parts at anything more than a metre away. The original rubber bumper ‘accordions’ are retained in this application, helping to make up the very slight difference in size, due to shrinkage of the fibreglass resin during curing.

Rear lid open, we finally get to inspect the engine. This motor is claimed to generate 230bhp, which if true is quite a hike from the original. Rainer has not yet verified this, but having owned two more powerful 911s, he doesn’t feel any lack of power when driving the SC. This is not so surprising, as exponential improvements to the power-to-weight ratio are the whole point of shedding excess pounds from any 911. Every little helps.

Take Rainer’s first 911: a 1991 964 C4 Cab. Assuming the engine was in good health, it was putting out 250 bhp. In a car weighing 1500 kilos, this means a power-to-weight ratio of 166 bhp per tonne. Rainer’s second 911 was a 1994 993 C2 Coupe. That was 272 bhp in 1370 kilos, so 198 bhp per tonne. The little SC Coupe recently weighed in at 960 kilos: 200 lighter than stock. If this car really does have 230 bhp, it would mean a power-to-weight of almost 240 bhp per tonne, 20 percent more than the 993 and 44 percent more than the 964.

Notes in the history tell how the engine was reworked. Once stripped, the crankshaft was inspected, balanced and polished. The heads were ported and polished, despite running bigger ports as standard. Almost everything else was replaced: valve guides, bearings and so on. There is no mention of cams, so we will assume they are retimed stock items. The engine was blueprinted during reassembly. Hydraulic chain tensioners were fitted and the car retains its original plastic-lined injection system, featuring the bigger intake runners and adjustable fuel distributor. The superfluous air pump and heater blower are both long gone, and the cabin heat is in a semi-backdated ‘work in progress’ state.

Returning to the question of whether this is a 230bhp engine, the answer is we don’t honestly know. The car has only covered 37,000 kms since the rebuild, so the motor is nicely run in. The modifications we know about should be good for another 30 bhp in my experience, and if the machine shop added a few other straightforward modifications, such as a gentle hike in compression, then perhaps a bit more. Better-breathing SSIs and a freer-flowing muffler, such as the M&K fitted to this car, normally add north of 10 bhp to a healthy SC powerplant, so we could be looking at 40 bhp up on stock.

If we estimate the original motor at about 185 bhp, as so many 180 bhp engines are, then we could be talking about approximately 225 bhp in current trim, and a dyno run will give a more accurate assessment. Rainer is about to fit PMO carbs to the car, so the dyno is definitely coming, but the best way to test the power here today is to drive it, so we head for the track to give it a whirl. I do my first laps as a passenger, to get a feel for how this 911 differs from those I am used to, and to watch how Rainer prefers to drive his magnificent SC. I don’t want to give the car any more of a hard time than Rainer would give it himself.

First impressions from the passenger seat are positive. The seatback on the BF Torino is slightly more reclined than I would prefer, but it is at once snug and relaxing. The 4-point Schroth harness is a welcome feature, adding comforting security. The interior is beautifully finished; the new panels and carpets are up to Southbound’s usual high standards, and the radio blanking plate is also a welcome sight.

The noise limit for this event is 105dB, and while Snetterton don’t always insist on a noise test, today they do. The SC tests at 108dB at 4,000 revs, which should mean problems, but thankfully Rainer manages to escape with a caution. Knowing that the SC Cabriolet I am running today tested at 98dB, I am anticipating quite a rise in engine volume as we roll out onto the track, but the ambient noise is substantially lower than expected.

Full carpeting and sound deadening undoubtedly help, but interestingly, the polycarbonate rear windows seem to be as effective as glass. My previous experience of plastic windows is that flex across a panel as big as a rear screen can sometimes sound like Rolf Harris and his Wobble Board, but thankfully, the fake thunder from down under is nowhere to be heard, and a symphony of air-cooled excellence is all our ears are treated to. A few laps later, we return to the pits, check the tyres and then it’s my turn to drive.

Sitting in the driver’s seat of a 911 waiting to go on track is always exciting. Serious steering wheel envy sets in when I first put my hands on the rare all-leather Momo 07, a wheel Porsche used in many racers. The deep dish of the Momo is welcome; Rainer’s 6′ 2” frame has a 5inch advantage on yours truly, yet the optimal position for him is pretty good for me also.

The gear lever catches first with a characteristic 915 snick and a slightly shorter throw – that’ll be a short shift kit then – before the familiar floor-mounted clutch pedal gets us rolling. Wow, this car is light! My own rebuilt Carrera 3.0 Coupe is also light, weighing the same 960 kilos, so they should feel similar. The SC feels somewhat ‘tighter’ though, which I ascribe to the low miles on the tub and the fully sound-deadened interior, something mine does without.

The blueprinted 3.0 in this car demonstrates a sublime superiority, even at low speed. Shunting down the pit lane at tickover revs in second gear is not the helmet-nodding, clutch-slipping challenge it would be in the C3. Past the green pit lane light we go, shifting up into the full-fat Porsche zone that is third gear in an SC, and a smile arrives on my face that stays there for the rest of the day. We warm car and driver for a couple of laps before starting to push a bit harder.

Turn one at Snetterton is great. Crest the summit of the start/finish straight, pick a braking point and lean on the middle pedal, then pitch it in to Riches on a steady throttle, squeezing the gas harder as the right-hander unfolds. A 911-racing buddy tells me there are two apexes in this first turn and we find both first time around. The short straight joining Riches and Sears is all about the braking at the end of it, and with the lighter weight, the stock brakes perform perfectly.

We take a wide exit and say a big hello to the tarmac runoff on the outside of turn two, before firing the car down the Revett Straight. Descending towards The Esses, the acceleration goes on and on until we burst under the bridge and stand on the brakes, threading our Guards Red needle through the left-right complex before leaning on the throttle and diving flat-out through the Bomb Hole, balancing the car through the never-ending right hander that is Coram. We eventually brake hard for the final chicane at Russell, floor the loud pedal on the exit, and fly back up the hill to do it all over again.

I’m no Lewis Hamilton (Christine Hamilton would be more like it), but driving this crisp little car is so easy that we are soon pushing the envelope. ERC has the same lower final drive and limited slip diff as my C3, and it weighs the same, but there is no doubt that it has a bit more grunt than my car. Taking the weight it is carrying into account, I would estimate the power at about 220/225 bhp, so it will be interesting to see what the dyno says.

I can’t imagine what this must look like from outside, but inside it’s fantastic. I am whooping excitedly as, lap after lap, we turn in to corners at what seems like breakneck speed, the car drifting towards the outside kerbs, Rainer encouraging me to go for it, and the SC doing the same. As we scorch around this thrilling circuit, grinning wider than a gravel trap, the car allows me to squeeze the throttle open a little wider every time, leading to increasingly incredulous slides, all ultimately controllable.

Ten laps later, the chequered flag falls on our session. The car has earned a breather and we laugh our way back to the pits. Once in the garage, I can’t thank the man enough for letting me drive his pride and joy, and my congratulations on his purchase are entirely genuine. From the quality of the finish inside and out, the incredible engine, delightfully precise transmission and the communicative low-mile chassis, the Roock SC ‘Club Sport’ is a recipe for success that no true lover of the classic 911 can live without. Luckily for Rainer Armitt, he doesn’t have to.

Thanks to: Rainer Armitt, Snetterton Circuit, Goldtrack


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