Persistence of Vision

A 911S 2.7 Prototype Clone

Persistence of Vision 1
March 4, 2016

For the sporting enthusiast, the normal progression of the privately owned Porsches is as follows: you purchase a completely street legal sports car with ride height set to pass U.S. Department of Transportation headlight requirements. You immediately lower the ride height, stiffen the suspension and upgrade the engine for increased output. All these measures prove detrimental to the car’s factory-bred comfort, real world drivability and emissions legality.

When this path of “improvement” reaches its apogee, your modified Porsche is no longer fit to be driven on the street or enjoyed in conventional usage. Hence, you relegate it to track contests requiring trailer transportation. The final step in this inevitable downhill trajectory is consignment to disuse and permanent garage status. How many temperamentally tweaked Porsches, having outgrown their intended competition role, serve as shelters for homeless mice?

By 2011, 1972 911T Serial Number 9112100753 had become one such candidate for recycling. When new, this Aubergine (Kunstharzlack 024 9-1) coupe represented a significant breakthrough for the 911 model range. With its new-for 1972 mechanically injected 2,341-cc flat-six engine producing 157 hp at 5,600 rpm and 166 lb-ft of torque at 4,000 rpm, the ’72T offered a significant 11 percent increase in torque over its 2.2-liter predecessor. In fact, it proved to be such a strong performer in Patrick Bedard’s Riverside Raceway test for Car & Driver that he stated, “The new 911T has exactly the same acceleration in the quarter mile (15.1 seconds at 91.7 mph) as the 2.0 liter 911S of 1969, and is a whole lot less fussy about the way it’s driven.”

But back in 1992, even an 11 percent bump in torque was inadequate for racing technician Craig Watkins to get excited about. He had discovered the eggplant colored coupe languishing in the want ads of the San Francisco Chronicle: “’72 911T needs clutch $4K ofr.” Back then, comparable 911s were going for $11,000, so Watkins thought the purple T presented the perfect opportunity for a track car makeover.

Way ahead of his time, Watkins had just completed an RS replica which he and I profiled in “The Poor Man’s RS” (Excellence #22, August 1990). Two decades before Porsche had a clue about the cult status their duck-tailed RS would ultimately achieve, Craig Watkins was already turning out replicas. When a friend of his, Edwin “Win” Seipp, spotted the newly acquired purple 911T, he commissioned Watkins to transform it into a club racing mount for Seipp to campaign.

The Build

Watkins pulled the motor and sent it down to FAT Performance in Orange, California, where the VW/Porsche specialists employed by Ron Fleming and Greg Aronson converted the T’s original 2.4-liter engine to 2.7-liter RS specification by retaining the stroke while increasing the bore to 90 mm. FAT dynoed their build at 220 hp. For comparison purposes, the first U.S. legal 2.7-liter 911S engine, which Porsche introduced for model year 1974, made just 167 hp and 168 lb-ft of torque. Even the vaunted 2.7 RS motor, which was unavailable in the U.S., made 210 hp at 6,300 rpm.

Persistence of Vision 2

To handle the extra thrust of the FAT rebuild, Watkins tore down the chassis of the 911T and rebuilt it like a race car. He replaced the front cross member with an aluminum piece, raised the front spindles, replaced the front torsion bars with hollow 22-mm bars, added turbo tie rod ends and installed a shock tower brace with slotted top mounting holes.

At the rear, the RS-style transformation consisted of cast aluminum trailing arms, upsized 29-mm hollow torsion bars and adjustable spring plates. Delrin bushings at all front and rear suspension pick-up points eliminated unwonted play, and adjustable 22-mm sway bars front and rear allowed fine tuning of the set-up while trackside. Bremtek four-piston calipers, activated by an MBZ master cylinder, clamped Carrera front and 911 SC rear discs, with Cool Scoops providing fresh air to the front brakes.

After deleting sound insulation, Watkins installed a mild steel roll cage with a main hoop constructed of 1.5-inch diameter tubing with a wall thickness of 0.25 inch. Doors were protected by bolt-in sidebars. The Aubergine tub was stripped to bare metal, and equipped with a pinned carbon fiber hood, RS flares, a front spoiler and rear valance, a lightweight IROC tail and RS-style interior door panels. Repainting in Aubergine followed. Plexiglass windows substituted for factory glass. The windshield was replaced with flush-fit Lexan. Under the front hood, a 17-gallon ATL fuel cell replaced the steel 22-gallon factory tank.

When the FAT motor arrived, Watkins fitted a lightweight Tilton starter, front mounted oil cooler with Aeroquip lines, SSI heater boxes and B&B stainless steel headers which exhausted through a reworked Porsche sport muffler. He coupled the engine to a revised 915 gearbox fitted with a short shift kit and a ZF limited slip 7:31 differential. Shorter 4th and 5th gear sets borrowed from a 911 SC improved straight line performance at a slight expense in top speed.

Inside the semi-gutted cabin, the driver conducted affairs while belted into an SPG race seat, while the passenger observed proceedings from a Recaro touring seat. The 911T’s original issue 6 × 15-inch Fuchs alloys gave way to 7 × 16-inch front wheels and 9 × 16-inch rear wheels, also of Fuchs manufacture.

To the Track

With his newly potent purple Porsche, Win Seipp entered his first PCA Club Racing event in December 1995 at Sears Point International Raceway in Sonoma, California. His vehicle logbook testifies to previous experience in SCCA National competition. In September 1996 Seipp and the 911 competed at Elkhart Lake, Wisconsin, followed by a Club Race at Hallett, Oklahoma in September 2004, and an SCCA outing at Laguna Seca in 2004. At the 1996 Sears Point event, the 911T weighed in at 2,104 lbs dry, and 2,297 lbs with half a tank of fuel. Weights were noted as follows: “front 865 lb (37.7%), rear 1,430 lb (62.3%).”

Persistence of Vision 3

By April 2004, Seipp had transferred his interest in the 911T to another friend of Watkins, Kate Cavell of Chico, California. She submitted her new charge to PCA’s required Technical and Safety Annual Inspection. At that point, the form reveals the Porsche was fitted with a Recaro Pole Position driver’s seat, 3-inch Simpson safety belts, and 8 x16-inch front and 9 × 16-inch rear alloys. Horsepower was listed at 215 hp, and curb weight at 2,105 lbs. For the next six years, Cavell periodically fielded her 911 at a variety of Porsche Club events. But by 2011, she was ready to part with her stiffly sprung, unyieldingly precise track demon.

A Racer Buys a Race Car…

For the Street

The car’s next—and current—owner has made a career out of driving other people’s very expensive race cars in high profile international events. As a long-time friend of builder Craig Watkins, Johannes van Overbeek had been familiar with this 911T since its original build for Win Seipp. Over the intervening years, he had kept in touch with subsequent owner Kate Cavell, occasionally inquiring if she might be interested in selling it to him.

Now what would a guy like van Overbeek want with a tired, disused and outdated club racing Porsche? After all, Extreme Speed Motorsports, his current team, pays him handsomely to jet around the world as driver of their Ligier-Honda JSP2. This Le Mans Prototype endurance racing car competes at the very pinnacle of the sport. The team ran most of the World Endurance Championship (WEC) events in 2015, and van Overbeek is under contract to repeat the effort in 2016, co-driving with endurance ace John Fogarty and team principal Ed Brown.

But long-time Porsche racer Johannes van Overbeek harbored a specific vision for the Watkins/Seipp/Cavell 911T that did not involve racing at all. In fact, his intention was quite the opposite. He wanted to strip the old warrior of its war paint and consign most of its race gear to the trash bin.

In his travels through Porsche lore, van Overbeek had discovered—from the milestone 1992 book “Carrera RS” by Dr. Thomas Gruber and Dr. George Kondrasheim—the little known fact that Porsche had built nine prototype 911S 2.7 test cars from April to October 1972. The first example was brought to fruition by engineer Wolfgang Berger, who, according to the “Carrera RS” book: “wrote the parts lists out by hand and personally ordered the materials.” That first finished example “was originally intended to be a 911S 2.7 and was based on a body shell from the 1972 model year.”

Persistence of Vision 4

Subsequently, eight more examples were constructed, all of them based on 1972 911s which had been divested of their 2.4-liter engines in favor of 2.7-liter S-tuned powerplants. For seven months, according to “Carrera RS,” Porsche engineers evaluated these prototypes: “They were used for tests, practice, internal presentations, and licensing procedures. Later Porsche made these vehicles available as company cars to its factory drivers.”

After the evaluation was completed, Porsche abandoned the idea of a building a 911S 2.7 all together in favor of selling the Carrera RS. But without the proven lab success of those nine prototypes, there would have been no Carrera RS. When the Carrera RS supplanted it, the 911S 2.7 instantly became the best car Porsche never built.

Fully aware that the 911T he purchased from Cavell met all the basic parameters of the Berger prototype, van Overbeek resolved to rebuild the Aubergine 911 as a tribute 911S 2.7.

“I wanted the engine and the flares, but nothing else,” says van Overbeek. “This car was going to be a tribute to the precursor of the RS. That’s exactly what I wanted. I think there are four in existence of the pre-production cars they made. They all had 2.7s and were all ’72s, so it worked out perfectly with this car.” He would follow the original factory prescription for this rare model to the T.

Making it Real

Johannes van Overbeek found the challenge of building such a tribute car irresistible. The amalgamation of the early body style, pronounced RS fender flares, and RS specification 2.7-liter motor all add up to the perfect formula for building the ultimate pre-crash bumper 911. Best of all, this project boasted legitimate, historical precedent. He insisted that the finished product not resemble the flashy, overwrought Carrera RS: “I don’t care for the whole RS look,” van Overbeek said. “But I really like the ’73 911S. I wanted a nice street car. I didn’t want a racy car.”

Johannes’s father, Tom van Overbeek, is a racer like his son. For the past several years he has campaigned the Max Moritz 1974 911 RSR in historic events. Johannes borrowed his dad’s tow vehicle and trailer to bring the 911T back to the family home in San Jose. He also borrowed his father’s Porsche mechanic, Nico Castellaccio, former crew chief on the Peterson White Lightning Porsche team. Working side by side for the better part of six months, the two stripped the 911 of most race paraphernalia.

Persistence of Vision 5

“Nico and I took the engine and the transmission out, the fuel cell out, and removed the suspension,” explained Johannes. “Nico, who now has his own shop in Lathrop, California, spent six months driving back and forth from the Central Valley to help me out.”

The carbon fiber hood, racing seats, ATL fuel cell, strut tower brace, Plexiglass and Lexan windows, roll cage, Delrin bushings, and amped-up torsion and anti-roll bars were all summarily binned. The only items that made the transition were the aluminum front cross member, adjustable rear spring plate and aluminum rear banana arms.

The 22-mm hollow front torsion bars were replaced with 19-mm units. The 29-mm rear torsion bars were tossed in favor of more compliant 26-mm pieces. Still, this 911 is considerably stiffer than stock, because Porsche originally equipped the 1972 911T with 18.8-mm front and 23-mm rear torsion bars. “We refurbished everything and put back rubber bushings everywhere,” says van Overbeek.

The engine passed its compression test, although it was not dynoed again. The gearbox, which had a leak, was rebuilt by Jerry Woods Enterprises in Campbell, California: “They fixed that and took a look inside,” explained van Overbeek. “They said the LSD (limited-slip differential) was fine and the clutch plates were good, but we put in a new clutch anyway since it was all apart.” The gearbox retained its stock 1st, 2nd, and 3rd gear ratios, as well as the SC 4th and 5th gears.

The front valence would carry the abbreviated steel chin spoiler of the 1973 911S 2.4. There would be no ducktail spoiler. No tail spoiler at all, in fact—just an unadorned engine lid bearing the rather deceptive nomenclature, “911T.” Beneath that badge the 2.7-liter RS-spec motor still made 220 hp with its 9.8:1 compression ratio 90-mm pistons. After being dismantled and mechanically refurbished, the car went to Jerry Woods’s body shop where it spent the better part of the next year being refinished in Aubergine, a deceptive shade that looks black rather than purple in dim light.

Ron Gruener, who formerly oversaw Dave Morse’s collection of historic Porsche race cars, took charge of the 911T at Woods’s shop. “I first got it back in the fall of 2013,” recalls van Overbeek, “but after a couple of months the doors started to look wavy.” Gruener agreed, and replaced them with new door skins.

The car’s original builder, Craig Watkins, whose friendship with van Overbeek predates its initial construction, figured into the car’s latest rebuild as well. After Watkins left the Flying Lizard team, where he served as crew chief on the 911 RSR van Overbeek drove, he started making and marketing intelligent suspension products for Porsches (Smart Strings, Smart Camber Gauges, Smart Sway Bars). On the rebuilt 911T you can find his 23-mm front and rear Smart Sway Bars, as well as a set of Bilstein dampers he custom valved for the repurposed car.

Persistence of Vision 6

Fuchs alloys, measuring 7 × 16-inch front and 9 x16-inch rear, received a cosmetic makeover from Harvey Weidman, a wheel restoration specialist in Oroville, California. The frosted look of the rim lends the car a perfect period race appearance. Securing a set of tires proved problematic, however, as van Overbeek found only one manufacturer—Nexen (N3000)—made the size he needed (205/55VR16 front, 245/45VR16 rear). Those tires will soon be replaced by Bridgestone S02 Pole Position rollers that are now being made in the size van Overbeek needs.

Back in 2003, van Overbeek sold a Porsche he dearly loved, the one he had driven all through high school: “It was a theft recovery 911E finished in Sepia Brown that I bought for $3,000. It was the most fun Porsche I ever owned.” All these years later, he hopes to recreate the magic of that first 911 with his 911T project: “I got to thinking, oh gosh, the prices are just starting to get high. If I’m going to do it, I better do it now, not later.”

So far, the peripatetic van Overbeek has only put 200 miles on his handsome tribute car. In fact, it’s only traveled 16,000 miles since Watkins first built it back in 1992. But if our experience with the car is any example, its owner will have more fun than he ever bargained for with this wolf in sheep’s clothing.

The Test Drive

At 6’1”, Johannes van Overbeek is five inches taller than me. Consequently, when I dropped into his custom fitted, hounds tooth upholstered, Recaro Pole Position SPG driver’s seat, I could barely see over the instrument cluster. Hoping to rectify this literal shortcoming, I tried to get his attention, but he and the chase car had already disappeared up California Route 1. So I was going to be stuck with this situation for my short test drive up the coast route. This is probably not exactly the way Extreme Speed Motorsports does driver changes in the World Endurance Championship. While my run only clocked 10 miles, it consisted of 200 of the nastiest curves you’ll ever meet.

The Porsche 911 Johannes envisioned and saw through to completion is brilliant. This stretch of Route 1 dishes out punishment with reckless abandon. Gaping cracks and fissures mar the pavement here at continent’s end. The resultant rollercoaster ride makes a mockery of typical Porsche competition suspension calibration. But van Overbeek’s car handles all the jukes and jives with consummate aplomb.

The Nexen rubber feels dependable and grippy as the 911 hunkers down without a trace of bump steer or tail wag. Watkins’s Bilstein shock valving is perfectly calibrated for coping with this kind of real world pavement punishment. The short shift kit is a huge improvement over the sloppy stock linkage of the 915 gearbox. I instantly felt confident about slotting into the right gear without fear of missing a shift.

As my confidence grew, I started blowing past a few of the usual stragglers incessantly strangling Route 1. It was then I discovered that the 911 was equipped with the kind of brash dual tone horn that makes tourists run for cover. Perfect! The engine itself is a work of art, representing the apogee of early 911 explosiveness. Even without short gears, I found 1st, 2nd and 3rd were perfectly tailored to running the coast route.

With its excellent power-to-weight ratio, this lithe RS prototype blasts off apexes without hesitation. Its limited-slip ZF differential metes out rear traction more judiciously than Judge Judy. By the time my test hop concluded, I had acclimated so well to the many attributes of the purple pothole eater that I had completely forgotten I could barely see over the dash. To overcome that kind of disadvantage says it all. This is indeed a Porsche with special benefits.

Also from Issue 236

  • First Drive 2017 911 Carrera & Carrera S
  • 1955 356 Speedster-based Devin
  • Market Update: 1974-1989 911
  • Blue Chip 996 Turbo
  • Porsche Plane Engines
  • Jägermeister RSR
  • Turbocharging the 917
  • Porsche Water Cooling Systems
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