Porsche 910 Special — Zimmerized

The enthusiast who transformed a damaged Porsche into a car of rare excellence

You wouldn’t call a racing Porsche a “sow’s ear” but the transformation of the car you see here into a “silk purse” would qualify for just such a makeover. It began with a Type 910 Porsche, so we’d better get an idea of just what kind of Porsche this was.

The Type 910 was the first big step from the 906 Carrera 6 that was the launch vehicle for Ferdinand Piëch as an engineer who would thrust Porsche forward as a motor-sports competitor. Starting in 1966, Porsche built some 30 of its 910 model for long-distance endurance racing. They were powered either by a fuel-injected 2.0-liter flat six, creating a 910/6, or a 910/8 with an ex-Formula One 2.2-liter eight. In 1967 the factory team of 910s scored class victories in the Daytona 24 hours, Sebring 12 hours, the 1,000-kilometer races at Monza and Spa, the Targa Florio, Le Mans and the Reims 12 hours.

A 910 won outright in the Nürburgring 1,000 kilometers, driven by Joe Buzzetta and Udo Schütz. Placing second with Paul Hawkins and Gerhard Koch was chassis number 910-013. In 1968 it was in the hands of Italian Alberto Luti, who entered 013 several times and raced it once at Mugello. Coming out of storage the Porsche was acquired by Canada’s Burt Kuehne, who with Harry Byzak raced 013 through the 1972 season.

Lurking at the curb, Jack Zimmer’s Porsche 910S was a completely new vision of a sports car in ultra-modern form, forecasting the speed of which it was capable.

By then the 910/6 was due for a major overhaul. Over the border in Brooklyn Center, Minnesota it came to the attention of Jack Zimmer, owner of Porsche special-equipment company Carousel Racing. Seeing the Porsche as the basis of a special for club racing in the USA, Zimmer crossed Kuehne’s palm with silver. When the Canadian traveled south to deliver the 910, however, he flipped the transporter on its roof. The damage was severe enough to cause scrapping of the original coupe body.

This didn’t daunt Jack Zimmer, but the Sports Car Club of America put a stick in his spokes. The SCCA decided to merge sports-racing classes A and B into a single class that would include the heavy-duty Can-Am-type cars. “Because the car would be less than competitive,” wrote Joe Rusz, “Zimmer decided to use its still-respectable performance—175-mph top speed—in a one-of-a-kind street coupe that would rival the best Italian dream cars in looks and performance.”

That was a tall order. America had few of the enterprises that the Twenty-first Century would bring in the way of freelance stylists and coachbuilders. But Zimmer had been reading his Road & Track. He remembered that the Reventlow-built Scarabs, world-beaters in their heyday, had clever designers and fabricators. The former was Chuck Pelly, responsible for the Scarab’s good looks, and the latter Dick Troutman, who with Tom Barnes did extensive fabrication work on the sports-racers.

Both men were still on the job in California. Chuck Pelly had just established DesignworksUSA as an independent industrial-design contractor while Dick Troutman still had his Culver City workshop though partner Barnes had departed. Ready to rumble, Zimmer considered them “the best in the business”. But what would the car look like? The options were infinite.

A first big step by Ferdinand Piëch, at its nose the Porsche 910 showed its 906 origins. It also showed that Porsche was serious about its long-distance racing.

According to Zimmer, “Pelly and I made some initial sketches of what we thought the ultimate Porsche street machine should look like.” Inspiration came from a motor-show stunner that the Porsche’s new owner fancied—and as he was paying the bills, Zimmer was influential. He remembered a Pininfarina design that had turned heads at the 1969 Turin Salon. It was the work of Filippo Sapino, who had the task of clothing a mélange that Ferrari provided. Based on the chassis of a 312P sports-racer, it had the 6.0-liter engine of a Can-Am Ferrari—though with nothing inside it.

This was the Ferrari 512S Berlinetta Speciale that put the Americans on the right track. Ultra-low and striking in yellow, it majored on crisp lines while eschewing the “origami” look that some designers were favoring. Its influence on the Zimmer car is clear but Pelly adopted lines that were unmistakably his to create a superbly clean and chiseled coupe body with hippy flanks and a plunging nose. Chuck showed it once in California, winning for him and his creation the 1975 California Design Excellence Award.

With the design taking shape, Pelly asked colleague Ed Stulik to create a model. Stulik did this is quarter scale, using the designer’s “cheat” of a mirror so that only half the car had to be modeled. After this was perfected, full-scale drawings of the body were made. Stulik worked with Troutman on the fabrication of the wooden buck that guided the final form.

The sheer lines mandated by Pelly’s design made heavy demands on the skill of Dick Troutman. Working to a wooden buck, he succeeded in manipulating its aluminum.

Aluminum and steel sheets as specified were placed on the mockup, cut to size, and shipped to the California Metal Shaping Company in Los Angeles for rough forming. Their stampings returned to Troutman’s shop, where the coachbuilder shaped, fitted, and welded the pieces into a homogeneous form. Aluminum was used for all body panels except the tub and the roof, where steel sections were needed for rigidity. Side windows were Plexiglas while a Cadillac windscreen was trimmed to fit. The glow of the finished car’s Porsche metallic-silver lacquer is to the credit of Hawthorne, California’s Creative Car Craft.

Conversion of 910-013’s rolling chassis to the semi-final version of Zimmer’s 910S coupe occupied Dick Troutman for almost 14 months. While he was forming its body the chassis was stripped, sand blasted, X-rayed, magnafluxed and straightened. Meanwhile Zimmer supervised the fabrication of many custom-made components including door handles, hinges, molded-in steel bumpers and dashboard using 911 instruments, all hand-crafted by Californian artisans.

In profile the Zimmerized 910S most resembled its Pininfarina inspiration, although with the convenience of side-opening doors.

New substituted for old throughout the car. Suspension components and running gear were all restored or, in most cases, replaced with new parts purchased from the Porsche factory’s racing arm. Every nut and bolt (titanium) was replaced. The ventilation system and electric pop-up headlamps were Porsche 914/6 while tail lamps were Audi Fox. Porsche black leather covered the Lotus Europa seats, with tartan cloth inserts, and the rest of the interior. The original aluminum lateral fuel tanks were converted into 45-liter fuel cells on both sides of the car. Wider wheels—9.5 x 13 front and 13 x 13 rear—carried Firestone racing tires.

The most significant modification was to use a 2.8-liter engine. The reborn Zimmer-Porsche was first driven early in 1975, close to three years after the project started. “After we had run it with the original rebuilt two-liter,” said Zimmer, “we found that the increased weight of converting from a race car to a street machine was just too much for two liters. By my standards the car was slow. I sent the original engine (910-014) to Arnold and Dieter at Andial. They made it into a 2.8-liter using the original internal titanium valve gear and of course bigger valves. The resulting output was 280 bhp, a welcome uptick from the original 220 bhp.

Porsche values were maintained with the use of the 914’s mechanisms to lift and lower disappearing headlamps.

“I had good friends at Mahle,” Zimmer added. “They helped me with special cylinders and pistons. I never did get around to running new ‘performance’ tests with the Andial 2.8-liter but it was flat-out faster. Running it at Donnybrooke through turns 1 and 2, braking at turn 3 was hilarious. Get hard on the binders and the car would leap from the inside braking area to the outside of the track. When the corner workers at turn 3 saw me coming they would desert their post en-masse. That was the limiting factor of my 910S: no brakes. My last but unfinished project was to change over to 908 front and rear suspension including bigger, ventilated 908 brakes. The car was bloody fast, but you couldn’t stop it in a straight line. Funny but scary.”

Although Jack Zimmer said he eschewed performance timing, some figures do exist for his coupe’s acceleration. They are 1.7 seconds to 30 mph, 4.4 for 60, 6.9 to 80 and 11.2 seconds to 100 mph. The standing quarter mile was covered in 12.5 seconds with a final speed of 134.9 mph. Top speed was given as 187 mph, a nice round 300 km/h.

Chuck Pelly is at the center and Jack Zimmer on the right as they survey their joint achievement. The new special 13-inch wheels take a high polish.

This was outstanding performance for the 1970s, probably matching the potential of the Pininfarina Ferrari that inspired the car’s design. Zimmer said that his 910S—as he dubbed it—rode better than his Porsche Turbo Carrera, was much quicker and, indeed, nicely noisier. The whine of the cams at 8,500 rpm screaming just behind your head somehow sounded better than the less-busy swoosh/whoosh of the Porsche Turbo.

In subsequent years Jack Zimmer’s Carousel company became an Audi dealer. In this format the business was bought by local SCCA racer Tom Countryman, complete with the Zimmerized Porsche. The tender loving care that such a car required was not in the offing. An unknown party decided it would best be returned to a Porsche and discarded the work of Pelly and Troutman. In the garb of an original 910 Porsche 910-013 with engine 910-014 is thought to have been sold to Japan.

In its day the 910S was a stunningly handsome sports car that outpaced all other contemporary efforts to create advanced two-seater designs in America. Nonetheless it received little recognition in its heyday. Jack Zimmer admitted that he was partly to blame. The 910S should have been a star at all the venues from Pebble Beach to New York City. But its owner was worried about possible transport damage—shades of the accident that made its chassis available—and about the petty vandalism that was prevalent at most auto shows.

A picture taken soon after the car’s completion shows temporary glazing for its rear window and predates the final livery of its tail. It’s a striking view.

We haven’t even the suite of professional images that would have captured such aa icon for eternity. However we do have the pictures that accompany this article. They make the case that the 910S was a gorgeous car in its day and an American achievement worth celebrating.