In the mid-1970s, Porsche developed the 911 for racing, and in the process, it created the all-conquering 935. In 1978, Norbert Singer was responsible for building the ultimate factory 935, the Moby Dick 935/78, and although this race car had a very short active racing life, it has gone down in history as one of the most iconic 935s of all time. Despite winning only one race, the Silverstone 6 Hours on 14 May 1978, Porsche’s Moby Dick became one of the most copied 911s of its era.
After the Moby Dick 935/78 had raced at Silverstone and in the Le Mans 24 Hours that year, the car was retired, as the factory’s attention turned to the next generation of race cars. However, Porsche allowed some private teams with close ties to the factory, to continue purchasing components and drivetrains for the 935, but they were left to design and produce their own upgraded chassis and bodywork. One of those privateer teams, Kremer Racing, did a particularly good job during the late ‘70s, creating the 935 K1 (1976), K2 (1977) and K3 (1979). Kremer Racing, based in Cologne, Germany, didn’t restrict their work to just mechanical preparation and assembly, but they also developed their own bodywork which really set them apart from the rest of the field.
While these newly constructed vehicles were still generally referred to as Porsche 935s, in reality, they were entirely new designs that advanced the 935 concept to a new level of speed and sophistication. The history books will show that #41 Kremer 935 K3 went on to win the 1979 Le Mans 24 Hours, the most sought after endurance racing crown any team could hope to win, and the last production based car ever to win overall at Le Mans. That victory resulted in a flood of orders for the K3 bodywork which Kremer sold to numerous other privateer teams, earning the Cologne racing team a tidy sum.
As a result of the 935’s continued national and international successes in the hands of its privateer teams, Porsche resumed research and development of the 935 at the end of 1980, so that its loyal customers could continue to rely on a supply of factory parts. The question on everyone’s lips though was, what was Kremer going to follow the K3 with for the next season? Perhaps it was no surprise that the next iteration of this iconic racer was the 935 K4, but this was quite a different beast altogether from the K3.
It is fair to say that the K4 was Kremer’s ultimate 911 racer, the product of Kremer’s constant development of the model from the team’s first foray into international racing with Erwin Kremer’s 911 T in 1968.
Enter the Kremer 935 K4
Only two K4s were made by Kremer, K4-01 and K4-02. Work began on K4-01 back in October 1980 with the aim of providing greater torsional stiffness, improved rear suspension, reduced weight to allow optimal weight distribution, an improved CD and a lower overall height. Brake ventilation was improved through larger air ducts, and airflow through the intercooler was increased. The K4 three-piece body was fabricated by Ekkehard Zimmermann’s company, DP Motorsport, near Cologne. It was Zimmermann’s company that had designed and fabricated the bodywork for all of Kremer’s K-cars, from the K1 right up to the K4.
In an effort to reduce the weight to below the minimum allowed, the K4 was also specifically modified to fit the driver in question thereby eliminating the need for pedal, seat and steering adjustment mechanisms. The factory provided a 935 engine with reworked conrods, pistons and combustion chambers, lubrication system, cooling fan, fuel injectors and turbocharger. This guaranteed an engine output of between 750-800 bhp at 1.5 bar. Although Kremer kept the first K4 to race themselves in ’81, the car was marketed at $174,000 for a complete race-ready package.
Very little resemblance to the original 935 of 1976 remained, as the K4 was a full tube frame race car. The K4 retained the standard roof panel of the 911 and the front windscreen, otherwise it was a purpose-built racer from the ground up. The first car, 935 K4-01, was track ready in June 1981, and Bob Wollek was contracted to drive it in the Deutsche Rennsport Meisterschaft (DRM) that season. Wollek competed in the DRM in K4-01 sporting Jägermeister livery and failed to finish only once in nine races, scoring two firsts and four second place finishes in ’81.
John Fitzpatrick Racing team formed in 1981
John Fitzpatrick, who had been driving for Dick Barbour in the IMSA series during ’80, decided to start his own team when Barbour pulled out of racing at the end of that season.
“At the time, we lived in San Diego, California. The phone went in the middle of the night and it was Peter Gregg, this was in the winter, and he asked me if I would drive with him the following year. This would have been the end of 1980, because I had already made my mind up to run my own team the next season. He asked if I would come and drive for him the following year as he had got Porsche sponsorship. And I said to him ‘no’ that I was going to run my own team, but thanks anyway. And he went out and shot himself the next day,” John Fitzpatrick admitted sadly. Needless to say, Peter Gregg’s death profoundly affected many people, not least of all John Fitzpatrick, following this telephone call the previous day.
Nevertheless, Fitzpatrick went ahead and formed John Fitzpatrick Racing (JFR) starting at the beginning of the 1981 season. He bought a 935 from Kremer with which to do the ’81 season, actually it was a 935 K3/80 that Fitz had driven previously, the latter parting with US$200,000 for the car. Fitz raced this car in the USA wearing the Sachs sponsorship in 1981 which he had taken over from Dick Barbour after Barbour ceased racing at the end of ’80. But at the end of 1981, as Fitz was looking for a car and a sponsor for the ’82 season, he was approached by Jerry Dominelli, a Californian investment banker, who proposed a sponsorship deal with Fitzpatrick for the next season.
Building and prepping the K4 for IMSA
With his plans in place, John Fitzpatrick took on Jerry Dominelli as an equal half owner of the JFR team. Dominelli was adamant that Fitzpatrick was only to drive a Porsche, but if he wanted to be competitive, he needed to get hold of one of Porsche’s new Group C racers. However, Porsche would not sell the new 956 to privateer teams in 1982, the first year of the Group C series, as these were to be raced by the factory only that year. And so, it was agreed that Fitzpatrick would purchase the 935 K4 from Kremer that Wollek had driven.
Fitzpatrick agreed a price with Kremer Racing of $250,000 for the K4 at the end of 1981 and had it delivered to his workshop in San Diego. At that stage the K4 was still wearing its Jägermeister livery which was how Bob Wollek had raced it in ’81 for Kremer.
John Fitzpatrick explained, “We set about sort of IMSA-ising the car in a way because there were just certain things that you could do in IMSA that you couldn’t do in Europe. We stripped the whole car down and rebuilt it from start to finish. We fitted two intercoolers, one for each bank of cylinders instead of one big intercooler, and we took the air for that from the top of the front fenders where there is a lot of air pressure, which is something that Kremer hadn’t done. The air went through the top of the doors inside the car and into the engine, it was really efficient. The rear wing was different, and we gradually did more and more modifications to it.
“I mean, we always put everything we could into the cars, we never skimped on anything. There was some fairing underneath the car, but the problem with the 935 was behind the driver’s seat there was nothing really, the engine just formed part of the chassis so we had to put a bit of fairing underneath. And the other thing was the cooling, you couldn’t shut the Porsche engine off completely because it’s still relied on air for the cooling. So, it had minimum aerodynamics underneath, it was all about brute force and downforce on the car itself,” Fitzpatrick explained.
The JFR team did not make any modifications to the engine, it was the regular 3.2-litre engine as supplied by the factory which was rebuilt after every race. The main improvement power wise, though, was the replacement of the single large intercooler with the two intercoolers, one for each bank of cylinders, with the intakes located on top of the front fenders. “That gave us a massive cooling advantage, in the order of 10° difference per bank, and we could see this because we had an air temperature gauge for each side, and it made a massive difference. With the turbo, the cooler the air the more you can turn the boost up, so we were able to run a lot more boost,” Fitzpatrick added.
The rear trailing arms were made out of 10-gauge Duralumin which were very heavy, and this was changed to a tubular frame set up. The shocks were changed too because Fitzpatrick had a contract with Sachs, whereas Kremer had always run the car on Bilsteins. The tyres too were switched to Goodyear where Kremer had always run Dunlop tyres. “These changes all made a bit of a difference but the thing is you had a lot of downforce, so we had to run really hard springs to stop the car sitting down,” he pointed out.
A team’s success depends to a large extent on the members who make it up, and here Fitzpatrick made some key choices. A pair of New Zealanders were his first appointments, Max Crawford (team manager) and Bruce Jenner, along with Fitzpatrick’s nephew, Karl Jennings, who also worked for the JFR team as from ’83. “When Max was working for me, his wife Jan, who was also a New Zealander, used to come in and help out. And when we got the K4, we wanted to make a lot of body changes and we needed to make the mouldings, and so Jan did all the mouldings and the layups for the carbon fibre. She was incredible, she would just get stuck in there! Then we had a guy who was really good on the engines, Mark Popov-Dadiani, he had worked for Gurney for a long time, and he came down to San Diego and built our engines, he was terrific. And Glenn Blakely, he was a fabricator. You could give him anything and he would make anything from it, he was fantastic. So, I had Max Crawford and his wife Jan, Mark and Glenn, they were all really fantastic,” Fitzpatrick acknowledged.
Driving the 935 K4
With the 935 K4 packing such a potent punch, I asked John if the car was unpredictable and scary, or just plain great to drive. “Well, scary is not really the word that comes into it,” he laughed, “but it was a big improvement [over the K3] because there was a lot more downforce. You could see that it was a lot wider, the front spoiler and the rear wing were bigger, and of course the intercooling was very good.”
The twin intercoolers made a huge difference to the engine’s performance, as he went on to explain, “It had a 3.2-litre engine, and by putting the twin intercoolers on it, meant that we could run it up to 1.7 bar in qualifying, but then we used to race it at between about 1.2 or 1.3 bar.”
John Fitzpatrick is known for his masterful use of the car’s adjustable turbo boost, changing it at different points on different circuits. So how did he balance the requirements of keeping the car on track, where and when to turn the boost up or down, changing gear and braking? “Yes, you are focusing on a lot of different things at the same time, but on the other hand ninety percent of those things you are just doing automatically, you’re not really thinking about them. So, for instance, you’re not thinking about changing gears because you have done enough laps to know where you have got to change gear.
“I used to fiddle with it coming off the corners, but not every corner, just the medium speed corners where you had some speed. On the slower corners, the revs were lower and the turbos didn’t really kick in, but in a medium speed corner where you have got quite a lot of power on and the revs are up, as I came off the apex I would give it bit of a tweak for 200 or 300 yards, and that would give me another 30 or 40 hp. And then I would turn it back.
“Basically, race boost was about 1.2 or 1.3, but qualifying boost could be as much as 1.7. I used to turn it up to about 1.5 coming off the corners, but you would use more fuel doing that, so you couldn’t use it too much. Certainly, in qualifying, you would probably use the higher boost for most of the lap. But I never used to talk about it,” he added with a smile.
Racing the K4 in 1982, 1983, 1984 and beyond
In the first three races at the start of the 1982 IMSA season (Daytona, Sebring and Road Atlanta), Fitzpatrick drove the 935 K3/80 that he had driven the previous year. The following race at Riverside was the first of eleven consecutive races for the JFR Kremer Porsche 935 K4 in the ’82 season. Of those eleven races in the 935 K4, Fitzpatrick scored four first places (two with David Hobbs) and a second place that year.
In 1983, Fitzpatrick ran the K4 for a second year and scored a fourth place at Miami and then another victory with David Hobbs and Derek Bell at Riverside in April that year. “We won a lot of races with it in America, beating the GTP cars. In ‘83 I had also been driving a 956 internationally and I won a Can-Am race with it at Elkhart Lake, but at the end of ‘83, I stopped driving,” he admitted with a hint of sadness.
Within the first few weeks of 1984, the wheels came off the JDavid investment machine, as his underhand actions had finally caught up with him. This meant of course that any thoughts of sponsorship for John Fitzpatrick Racing for the ’84 season went immediately out of the window. At this point, John Fitzpatrick swapped his helmet and fireproof racing suit for a set of headphones and a clipboard, as he took on the management roll of JFR.
“I left the K4 in California for a while and Al Holbert paid to run it in Löwenbräu colours in IMSA. Holbert had Löwenbräu sponsorship but he was waiting for his 962, and so for several races early in ’84 he had this sponsorship deal with them to do IMSA but he didn’t have a car, so he used the K4. He put it in Löwenbräu colours and when Canepa got it, it was still in the Löwenbräu colours. But it didn’t win any races in that livery, and so Canepa put it back into the JDavid livery,” Fitzpatrick remarked.
When asked to highlight a race that stood out in his mind, John Fitzpatrick didn’t hesitate to point to the 1982 Lime Rock event on 31 May that year.
“Lime Rock is quite a twisty track requiring some deft handling. John Paul Jr. was driving a Lola while his father, John Paul Sr., was in the 935. Danny [Ongais] was in a Lola and Ted Field also had a Lola. I was on pole, but it was really, really close. I led the race and the others were chasing me but I was pulling away a bit, I was definitely quicker than the Lolas and John Paul Sr. was probably in fourth or fifth place and John Paul Jr. in the Lola, was the best Lola and he was chasing me.
“About halfway through the race I had probably got 10 seconds on John Paul Jr. in the Lola. I came around to lap John Paul Sr. in the 935 and he knew what was going on, and so he drove all over the track to slow me down.
“It was the only race apart from Riverside that my sponsor, Jerry Dominelli, attended. He always wore a three-piece suit and was always immaculately dressed. He was in the pits with my mechanics and he saw that John Paul Sr. wouldn’t let me pass, weaving down the straight and that sort of thing, and as a result, John Paul Jr. was catching up. As we came around on one lap, Dominelli in his pinstripe suit, picked up a wrench and ran across to the pit wall and as John Paul Sr. came past, he screamed, ‘You…(unprintable),’ and he threw this wrench at John Paul Sr. in the 935.
“My guys had to grab him and pull him away! They were thinking of disqualifying us because he went absolutely berserk. By that time, I had got past him and I went on to win, but the organisers got hold of him. That was a good win at Lime Rock,” he recalled with some humour.
“The K4 was probably my favourite car, because although we had bought it from Kremer, we really developed it so much ourselves and made so many changes to it, that it was quite a personal thing. It was very satisfying to win races and beat the prototypes with it, it was a very satisfying project to do and I was sad to see it go really. Obviously the K4 wasn’t as quick as the 956 because it didn’t have the ground effects, but it was as quick on the straights. But the K4 was a real handful, it was like a brick really going through the air,” Fitzpatrick reminisced.
The 935 K4 might well have gone on to even greater success had Kremer produced more of them, but with the Group C Porsche 956 being introduced in ’82 and made available to customer teams in ’83, there was no need to do so.
“But certainly, the K4 was much more of a fun car to drive than the 956. The K4 that we bought off Kremer basically just provided a foundation for building our car. We stripped it down, rebuilt and strengthened it and did all sorts of things to it, but to have done that from scratch would have been almost impossible,” Fitzpatrick admitted.
With drivers such as Bob Wollek, John Fitzpatrick, David Hobbs, Derek Bell, Al Holbert and Preston Henn, this Kremer 935 K4 represents the end of certainly one of the greatest eras of GT racing.
Note: Thanks to John Fitzpatrick for an enjoyable afternoon spent discussing the Kremer 935 K4, and to Zach Todd at Canepa for his help with this feature.
|Fitz – My Life at the Wheel||John Fitzpatrick||Autosports Marketing Associates Ltd, 2016|
|The Porsche Book||Jürgen Barth & Gustav Büsing||David Bull Publishing, 2009|
|Excellence was Expected||Karl Ludvigsen||Bentley Publishers, 2019|
Written by: Glen Smale
Images by: Zach Todd/Canepa, John Fitzpatrick & Virtual Motorpix/Glen Smale