By 1982 the Porsche 935 was at the end of its competitive life in Europe, but the Americans kept finding ways to make it ever faster. JLP-4 became its apotheosis
Writer Mauro Borella
When Porsche decided to stop production of the legendary 935 at the end of the 1970s, it was private teams who took on the job of racing and modifying them, or even building new ones. In later years, non-factory cars won some of the most prestigious races – the Porsche 935 Kremer K3 triumphing in the 1979 Le Mans 24 Hours, for instance. In America the Porsche 935 was the car to have and some US teams built and raced such specials with great results, especially JLP Racing. This is the story of the last and wildest of its 935s, the JLP-4 – the machine that brought ground-effect to GT racing.
During the 1981 season IMSA wanted to cap the 935’s supremacy by allowing purpose-built GTP Prototypes – such as Lola’s T600 – to race against them. Although the 935’s top-level race career was already almost dead in Europe, it was still in full swing in the US.
One of the most familiar racing dynasties in the States was JLP Racing, founded by John Paul Sr with his son John Jr, rapid racers both. JLP always had the latest and quickest cars and, after some experience with big Corvettes and other cars, the team started a programme based on the Porsche 935, but effectively turned it into a prototype to beat the GTPs at their own ground-effect game.
This eventually ran to four increasingly radical cars. JLP-1 was destroyed in an accident, while JLP-2 was basically a modified 935 K3. For JLP-3, however, they abandoned the Porsche chassis and mated the latest twin-turbo, 3.2-litre Porsche engine, with about 800bhp, to a complete tube frame built by GAACO in Georgia. The whole was cloaked beneath 935 K3 bodywork.
The tube-frame choice was not new. Back in 1978 Porsche used one for its 935/78, the famous Moby Dick, followed soon by replicas from privateers such as Joest and Kremer. The production 911 steel platform simply could not cope with such huge power. A tubular chassis brought much improved rigidity and stiffness.
Highly successful though JLP-3 was – in 1981-82 it would take nine wins from 27 races – Paul Sr was sure they could build something even more advanced to win the ’82 IMSA Championship outright. During 1981 he asked Dave Klym, owner of FABCAR in Georgia, a respected racing car company that was repairing and even manufacturing Porsche 956/962 monocoques under licence and today produces Daytona Prototypes, to start building the definitive 935: JLP-4.
In charge was Lee Dykstra, the engineer later responsible, among other things, for the design of the Jaguar GTP Prototypes. Dykstra used all the latest technologies available at the time, including a centre monocoque chassis stiffened by tube frame structure front and rear, double wishbone front suspension, rocker arm rear suspension and, most radical of all, full ground effect with lateral skirts like period Formula 1 cars.
“I did some aero work on the JLP-3,” Dykstra says, “designing some venturi shapes in the rocker panel area that exited in front of the rear wheels. That was successful, so John Sr commissioned a complete car to incorporate more ground effect. It was a challenge trying to get tunnels around the engine, but we gained some space by using rocker-arm rear suspension with the uprights completely in the wheels.”
The only Porsche parts used were the roof and side window frames (to comply with IMSA regulations), the brakes, wheels and the latest upside-down four-speed 935 gearbox, fitted with big titanium axles. Like the factory-built Moby Dick, JLP-4 was right-hand drive. “It’s the only car I raced with left-hand shift,” John Jr says. “It was hard to get acclimatised.”
Full-width Moby Dick-style bodywork incorporated a massive rear spoiler, optimised in the wind tunnel.
“The underbody configuration was pretty well fixed, but we spent a lot of time in the Lockheed tunnel sorting car attitude, wing location and front downforce,” Dykstra says. There were some snags to sort, too.
“When we first built the car we had the air for the engine going into the doors,” John Jr says. “But when it went to the tunnel we found that the air in the NACA duct was turning around and coming back out, so we had to modify the design. This was one of the many problems encountered in building such an advanced car in the days when ground effect was a fairly new science.”
Pushing it along was the final version of Porsche’s Type 930/80 flat-six, air-cooled, twin-plug 3.2-litre engine, with flat fan and Kugelfischer mechanical injection, producing about 840hp at 1.2 bar boost pressure. Built with the specific intention of winning the sprint races, leaving to JLP-3 the long-distance events, JLP-4 was not even fitted with lights, while air jacks and centre-lock wheels made for quick tyre changes during races. The car apparently cost more than $750,000 when a ‘normal’ Kremer 935 K3 could be bought for one third of that. Dave Klym from FABCAR says he recently found some old JLP-4 invoices and it took more than 3600 man hours to build.
“The car was very different to drive, because of the ground-effect. That was a real challenge,” Paul Jr says. “It was bottoming at speed on the straights, and we had to respring the suspension because of the downforce it was creating. But after we sorted that problem the car was very nice to drive. And very quick. It was four seconds a lap faster around Road Atlanta than JLP-3. I set many lap records ahead not only of the other 935s, but also against full GTP cars like the Lola T600.”
Once the 1982 IMSA season began, the Pauls won the two first races – the Daytona 24 Hours and Sebring 12 Hours – in the ‘old’ JLP-3, the first car to win both in the same year. In the meantime, to add another weapon to his armoury, Paul Sr also bought one of the latest Lola T600 GTPs, with which John Jr scored other championship points. But the racing world was waiting for JLP-4 and on July 11, 1982, at the IMSA Championship round held at Brainerd Raceway, Minnesota, the car finally appeared, resplendent in its new Miller Beer livery.
Opposition was fierce, including Danny Ongais and Ted Field in their sinister black Interscope-sponsored Lola T600 GTP and John Fitzpatrick with his Porsche 935 Kremer K4. Paul Jr and JLP-4 started from the front row alongside Ongais and won overall, setting fastest lap en route. With this win and points obtained with JLP-3 and the Lola T600, Paul Jr was looking good to win the 1982 IMSA Championship and was also well placed in the Porsche Cup.
In the next race, at Sears Point on July 25, Paul Jr had to retire JLP-4 with an engine problem, but he won again at Portland ahead of Fitzpatrick, Field and Hurley Haywood (in another 935). Paul Sr and Haywood were only ninth when they shared the car at Road America, after assorted problems, and it was then badly damaged in a testing shunt at Road Atlanta. While JLP-4 was rebuilt, Paul Jr reverted to JLP-3.
The final race of 1982 took place at Daytona, by which stage Paul Jr had already clinched the IMSA title. The car sported number 1 for the weekend, rather than the usual 18, and was back in the team’s customary blue and yellow livery, sponsor Miller having departed. There were other changes, too, the rear bodywork having been extended following tests in the Lockheed wind tunnel.
There was still another title up for grabs, the coveted Porsche Cup. Unfortunately for Paul Jr, JLP-4 suffered a tyre blowout at high speed on the banking, damaging the rear suspension and putting him out. The trophy went instead to Bob Wollek, who finished second in John Fitzpatrick’s 935 K4, behind the Lola of Field and Ongais. Even so, Paul Jr was happy with his season. “I won the title as a 22-year-old,” he says, “and that made me the youngest winner ever. The competition was very tough. I had to race against big names like Ongais, Haywood, Fitzpatrick and Wollek. They were great times and I remember them fondly.”
JLP-4 was used only once in 1983, at the Road Atlanta 500Kms in April. This time Paul Jr was co-driving with René Rodriguez and they finished sixth overall. The competitive days of even the most sophisticated 935s were over, even in the USA, because the GTP Prototypes had become simply too fast.
Shortly after JLP-4’s last race, THE team was beset by business and legal problems: Paul Jr became mired in a world of lawyers, court cases and even prison, while Paul Sr found infamy through drug trafficking and attempted murder offences. The team folded and Paul Jr gave the car to Phil Conte, a racing friend. Later JLP-4 went to the famous Petersen Museum in Los Angeles, where it remained on display for almost 15 years.
It was subsequently restored by Robert Tornello, an enthusiast from Florida. JLP-4 has since been used in some historic events and at a couple of Porsche’s Rennsport Reunions, where Paul Jr had the chance to drive it again. He calls JLP-4 as the best 935 he drove, adding that he almost cried when he and the car were reunited.
Now this unique piece of engineering is in Europe, ready to be seen at major events including the Goodwood Festival of Speed.
Not only are many original parts still with it, including the full set of moulds to replicate the unique bodywork, chassis and suspension, but also more than 100 original drawings and build sheets, some about 4.75 metres long. There are also photos, race programmes and posters, and even a rare model of JLP-4 issued to celebrate the 1982 IMSA Championship win.
But there is a poignant end to this tale.
Paul Jr is fighting Huntington’s Disease, which affects the neurological system, and is patron of the Huntington’s Disease Fund (for more information go to www.johnpauljrhd.com).
The intention of JLP-4’s new owner is not only to display and race the car, but also to use it on fund-raising occasions to help Paul Jr and others affected by this terrible disease.
A blast from the past is being used to create fresh hope for the future.