Built using the best Porsche 924 parts available, this Turbo takes what rallying versions in period started and improves upon it – greatly

2018 Robb Pritchard and Drive-My EN/UK

Sliders… Built using the best Porsche 924 parts available, this Turbo takes what rallying versions in period started and improves upon it – greatly… Story & Photography: Robb Pritchard.

On a snowy French mountain pass in 1980 a young Thomas Schöfer stood watching the cars of the Monte Carlo rally slither by in the slush. The works Fiat 131s and the lone Lancia Stratos of Bernard Darniche were the top cars of the day, but they weren’t the ones that left a lasting impression on our young German. It was a few years before Audi would burst onto the rallying scene with its 4×4 turbocharged Quattro, Jurgen Barth and Roland Kussmaul only finished in 20th place in their Porsche 924 Turbo (not exactly a ground-breaking result) yet the turbo’d car was at the cutting edge of the day’s technology.

Robb Pritchard Porsche 924 parts available, this Turbo

Porsche 924 Turbo

Turbos turned out to be a career path for Thomas, he went on to complete successful stints at KKK, Borg Warner and, more recently, Pankl Turbosystems – a company that supplies both F1 teams and the LMP1 class cars of the World Endurance Championship. A couple of years ago he decided to build himself a classic rally car that was a bit faster than his Mk2 Ford Escort or Mercedes-Benz 280CE C123. As a lover of Porsche vehicles and a turbo expert, one car combined his two passions – the 924 Turbo.

The German-based Slowly Sideways club is the brainchild of two guys who owned a couple of original Group B cars but had nowhere they could properly enjoy them. Far too powerful to enter in a normal rally, they were also far too valuable to bash around on forest stages… So the genius solution they came up with was organising a festival for original rally cars, one where their cars could be driven on tracks that look indistinguishable from normal rally stages, but were actually designed to be non-damaging to the cars. The idea proved to be very successful and, once expanded to include accurate replicas of famous cars, it became a real extravaganza. The hugely popular Eifel Rally is the main event.

This is what Thomas built the car for, however, you can’t simply turn up with something you’ve cobbled together and put some stickers on, all the cars entered have to be near perfect replicas. Before he started Thomas needed to find the homologation papers that Porsche used for its rallying efforts back in period. All initial lines of enquiry to Stuttgart proved fruitless and the original Monte Carlo cars are hidden away somewhere deep in the secret vaults of the Porsche Museum. There was absolutely no chance of Thomas getting near them with a camera and tape measure.

There was another car though. In 1982 a privateer 924 GT was made by the team headed by Jurgen Barth and Roland Kussmaul for Schmidt Motorsport. In February they ran Jackie Ickx on the Boucles de Spa rally in Belgium in a blue Gitanes livery. But it was when reigning world rally champion Walter Röhrl joined the team for the German Rally Championship, and some selected ERC events, that this car grabbed the headlines. In the gold and black Monnet cognac colours the reigning (and future) WRC champion won four rounds, and the Rallye Hessen – also an ERC round.

More than thirty years after the Porsche was built Thomas contacted Schmidt Motorsport to see if it had any information on the old car. At first it didn’t seem very promising, however a guy who had been a mechanic on the original car agreed to have a rummage in the dusty draws and boxes at the back of the office… He came across a stash of dust covered binders full of blueprints and homologation documents on the car in question. Thomas drove halfway across Germany to spend a frantic afternoon leafing through the treasure trove on the office photo copying machine. Amazingly it wasn’t just the FIA papers he had, Schmidt had kept all of the car’s testing and development notes and so he copied those too. Looking through the files gave a fascinating insight into how much effort went into the car’s creation. A random document Thomas pulls out to show us is from a three day test at the Nürburgring, with notes on what suspension components were specifically tested and how much fuel was used to gather that information.

With these absolutely invaluable files Thomas had all he needed to make a very accurate replica of the original car, then began the search for a suitable donor vehicle. A few were far too nice or expensive to cut up, but he also found a tired high mileage 1981 Turbo in Italy with engine problems, after €5,000 (£4,440) was handed over, a trip across Austria with a trailer was undertaken and the car put in the garage for stripping to the bare shell.

Group 4, the rules that governed what modifications could be used for rallying’s top teams in the ‘70s and early ‘80s, stipulated that a car’s bodyshell must remain unaltered, but many performance upgrades were allowed to engine, gearbox and suspension. Thomas began the long job of sourcing parts from 924 GT and GTS models with many evenings spent on internet forums making enquiries and chasing leads. The crank shaft came out of a GT engine, the intercooler from a GTS, the rear differential is a GT LSD, while the manifold intake and ignition system are of GTS origin. In 1982 the original engine was worked on by Mahle, when Thomas contacted them someone kindly agreed to have a look around in the cellar where they stored old parts, some high performance pistons from a 924 GTS were found and Thomas was happy to buy.

For the non-standard parts things were a little tougher. A rally-prepped 924 Turbo is not like a Ford Escort or 911 where absolutely everything can be bought off the shelf, Thomas had to find specialist fabrication companies for a few parts. He found out that the company that made roll cages for the works cars in the ‘80s still existed, not only that, but it still had the original blueprints. To make a cage exactly as they did for the original they charged only €1,500, (£1,330) which made Thomas pretty happy. The widened arches and spoiler came from a German company that specialises in making Porsche bodykits, that also cost €1,500. The plexiglass windows were made by a local company that normally makes shower doors… With the FIA homologation designs to hand they made a perfect copy, complete with sliding openings. The dashboard Thomas made himself from scratch with aluminium panels based on the designs and photos he had, the original rally cars used the same gauges and dials as the 924 road cars so that was easy enough to recreate.

The suspension is all Bilstein, as on the original cars. The dimensions of the shocks and springs are the same but technology has improved somewhat since the early 1980s, so the modern ones are a lot easier to adjust for specific conditions than they were when Walter Röhrl was busy setting up the car. The brakes are also a lot more powerful than the standard 924 stoppers. Both discs and callipers came from a 930 Turbo.

The turbo itself is what Thomas is most proud of though. He took the standard one from the donor car, stripped it and rebuilt it using what he decided were the best parts from a combination of GT and GTS versions. According to him it’s a proper motorsport version, and he should know – he doesn’t just work at Pankl… he’s the Managing Director! Getting the exact shade of gold paint sorted was also a bit of a challenge. This wasn’t a colour Porsche used and Schmidt didn’t have any records of its code number, the only way Thomas could get it right was to paint a wing, push the car outside to take a photo and then compare that image on his computer with one of the original car. The first attempt proved too bright, the second too dark. It was third time lucky. The black parts and decals were made by a local graphics company.

The car was fired up for the first time just before the spectacular Slowly Sideways Eifel Rally, but it wasn’t quite ready. The normal procedure for a brand new build is to slowly test that everything works and to start pushing the car harder and harder until you’re sure that everything is wired, plumbed and bolted in properly. With a full-time job that keeps Thomas in the office for 12 hours a day, leaving only weekends for working on the car, there just wasn’t enough time for that. Rolling it off the trailer and into the scrutineering park he felt the clutch wasn’t quite right, and that there was also something up with the engine, although he wasn’t too sure because it could have just been the characteristics of the new camshaft and pistons…

With these invaluable files Thomas had all he needed to make a very accurate replica…

The field of 150 cars had a photoshoot at an airfield about 5kms away from the rally base in the pretty town of Daun in the rolling hills not too far fro the Nürburgring, on the way back the timing belt snapped. Thomas assumed it was a seized piston but chose not to try and fix it there, instead he pushed the car back onto the trailer, took it home and came back to do the rally with his Escort.

Once back home he opened the engine up and the true scale of the damage became sadly evident. All of the special Mahle valves were bent, after so many months of building the car for it to last just 5kms was a big disappointment. He pushed it to the back of the garage, draped a dust cover over it and left it for a few months until he got back the enthusiasm for the rebuild.

Of course the car needed a full strip down and rebuild with new rods, valves and pistons, the cost increased to be a lot more than the original budget but then, nearly a full year after the blow up, and with a very nervous hand turning the key, it started again… And it worked. A few more attempts to get the Bosch K-Jetronic fuel injection right to cure a persistent misfire at a certain rev band, and the car was ready.

“I am glad that I kept going with it as it’s such a nice car,” Thomas smiled. “It’s very interesting to drive as it has very big turbo lag, which takes some getting used to when you start pushing the car. It’s not like the Escort which is directly related to the gas pedal where you really have to make sure that you are pointing the right way when the turbo comes in. If you are in the middle of a drift that you will be the wrong way round very quickly! It’s also nothing like a 911 either, but it handles really well and I did fitted just about every single nut and bolt and put every minute of my free time into it, so I love it!”

The stages aren’t timed in any Slowly Sideways event, everything is purely a ‘demonstration run’ so there is a lot more emphasis on drivers having fun behind the wheel instead of just trying to go as fast as possible. The name is actually a little bit of a misnomer though, there are plenty of cars that go sideways at quiet an appreciative rate of knots. With Walter Röhrl being one of the patrons of the event, and Porsche forever one of the most popular marques for entries, as you can imagine, many spectators simply love the Monnet 924 Turbo.

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Additional Info
  • Year: 1979
  • Engine: Petrol L4
  • Power: 180bhp at 5500rpm
  • Torque: 220lb ft at 2500rpm
  • Speed: 139mph
  • 0-60mph: 7.0sec
  • Club:

    {module Porsche 924}