In 1988 GM, then the world’s largest car manufacturer, launched a new single-seater racing category in Europe as a more affordable alternative to Formula Three. Known as Formel Opel Lotus in Germany and as Formula Vauxhall Lotus in the UK (henceforth referred to here as FOV), it echoed contemporary Formula Three in using a production-based naturally aspirated 2.0 litre I4 in a slick-shod monocoque chassis that generated downforce from front and rear wings and (to a much lesser extent) a primarily flat underbody.

Formula Opel/Vauxhall uses this C20XE I4 engine

To gain approval from the FIA, the new category had to be tailored to a performance level below that of (intake air-restricted) Formula Three. But it was this formula’s use of identical cars from which the cost saving came. Typically, existing sub-Formula Three formulae – Formula Ford/Formula Ford 2000 and Formula Vee/Formula Supervee for example – used a specified production engine while allowing engine builders to prepare it within tight constraints. They also allowed access for any chassis manufacturer, again working within the strict limitations of the formula.

By contrast, this new FOV category had all its single-specification engines prepared by a central source to ensure parity of performance, while the chassis was to a designated design and was produced by an approved manufacturer. Initially that was Reynard, which in 1988 was one of the top Formula Three chassis constructors.

Formula Opel/Vauxhall lives on as part of the AVD Historic Race Cup

Component options

This model of all competitors using identical engines in identical cars is of course applied these days in Formula Two. Mind you, whereas contemporary Formula Two specifies each individual component, in this case the competitor had a few item options. For example, while the chassis were all identical, there was free choice of brake pad supplier. Different pads offer different characteristics so that choice was not insignificant.

On the powertrain side the spec engine had to feed through a specified GM production flywheel and clutch pressure plate, whereas there was a choice from a shortlist of approved racing-spec sintered-bronze driven plates. There was then a choice of either a specific Staffs Silent Gears or a specific Hewland (Mk9) five-speed plus reverse longitudinal racing gearbox. Gear ratios were free.

The transmission had to incorporate an open differential. The make of differential and final drive were free, as was the final drive ratio. Both approved gearboxes had dog engagement using a traditional H-pattern selector system and the driver used a conventional gear lever. Clutch, brake and throttle control were likewise all mechanical, and aside from (unassisted) steering the only other driver control was (mechanically operated) brake balance.

Instrumentation was a combined water temperature and oil pressure gauge, plus a rev counter. Of course, while all cars used a specified tyre, each driver could make basic chassis setup adjustments, so race engineering came into the equation. Cars were bought outright at a cost of £17,400 with a maximum of one additional (fully prepared) engine per competitor at a cost of £3900. At today’s prices that equates to £44,500/£10,000.

The UK’s respected Motor Sport magazine reported of its inaugural season, “Mechanically and financially, the tightly controlled formula worked beyond expectations.” In addition to national series in the UK and Germany, there were series in Ireland, Benelux and Scandinavia, and there was also a Euroseries. The 1988 Euroseries was won by Mika Hakkinen, who of course rose to Formula One and went on to become the 1998 and 1999 World Champion.

From 1990, there was also a Nations Cup whereby two drivers teamed up to represent their country. By then, the category was so strong that 25 countries were represented in that inaugural single-event contest. The 1992 running was won by the Netherlands, with one of its two drivers being Jos Verstappen, father of the current World Champion Max.

Close racing for the revived Formula Opel/Vauxhall single-seaters

The category was overseen from GM’s European motorsport HQ in Ruesselsheim, near Frankfurt, Germany. In 1989, Dr Fritz Indra was in charge, deputising as manager of GM’s European motorsport operations. He had started his career working on Niki Lauda’s Formula Vee car and had subsequently worked at Alpina-BMW then Audi before joining Opel.

At Audi, Dr Indra had been deeply involved in four valve per cylinder r&d work. After moving to Opel he became a senior member of the team that was working on the naturally aspirated 2.0 litre I4 C20XE ‘red top’ double overhead camshaft 16-valve production engine. Developed with motorsport in mind, this initially powered the 1988 Opel Kadett GTE and Vauxhall Astra GTE roadcars.

“The C20XE was the most efficient roadcar engine of its type at that time,” remarks Peter Hass, who had joined Opel in 1980 and headed its customer support for motorsport throughout the FOV period. “The C20XE was an exceptional roadcar engine, and in the early 1990s Spiess built a Formula Three version, which was the best of its day for the series.”

The brand new C20XE was chosen as the engine for FOV. It was based on the ‘Family II’ iron block, aluminium head, belt-driven overhead camshaft I4 that, introduced in 1979, was the backbone of GM Europe’s petrol cars through much of the 1980s. The C20XE head featured a 46o included valve angle. It had been developed in conjunction with Cosworth, which cast it using its Coscast process.

A later version of the head was developed in conjunction with Lotus, but that did not come along until 1994 and it was not used in FOV. The category’s initial Lotus label suggested there was some involvement of the marque, whereas in fact it was name-checked purely for marketing reasons. At the time, GM owned Lotus but it sold it in 1993, after which its branding was removed from FOV.

The C20XE had a bore and stroke both of 86 mm for 1998.2 cc. The valve diameter was intake 33 mm, exhaust 29 mm with lift of 9.5 mm. For FOV, it was modified from production specification only in respect of lubrication, induction, ignition and fuel systems to allow it to be mounted in a single-seater chassis (as an unstressed member). A suitable dry-sump system was designed by freelance engineer Mike Mills working in conjunction with Swindon Engines in the UK. The sump, including attendant pumps, was then manufactured in Germany by SHW, a major supplier of pumps and other production car components to Opel.

While fuel injected and run by a full engine management system in its roadcar applications, FOV initially specified carburettors and a distributor to save cost and to aid the scrutineering process. Thus for FOV the C20XE was equipped with twin Weber 40 DCOE Type 151 side-draught carburettors having a modified bypass system and with jetting free. The engine then had an ignition box that imposed a 7100 rpm rev limiter cut. A spec exhaust system had to be fitted for FOV complete with a 100 dB silencer and a catalytic converter.

Normally the coolant system thermostat was removed and engine temperature was adjusted via tape on the sidepod-located radiators. The racecar was equipped with a production-style starter motor driven by an external battery.

Stock components

The cam timing had to remain stock, and access by FOV competitors to components between the sump and cam cover was barred by four official seals. The ignition box was also sealed. Engines were built from production-line components at Ruesselsheim and were then shipped to customers after dyno testing had been carried out on behalf of GM Motorsport by KST Motorenversuch, a German powertrain testing specialist located near Mannheim.

The C20XE is little modified from stock for Formula Opel/Vauxhall

The essentially unmodified C20XE FOV engine retained the stock compression ratio of 10.5:1, and was raced using a super unleaded fuel of RON 99.5. It was capable of a Formula Three-rivalling 165 bhp but all engines were shipped within a 3 bhp range averaged at 158 bhp at 7000 rpm (tested complete with the exhaust system). Maximum torque was 155 lb-ft (210 Nm) at 4700 rpm. A 1988 post-season track test by Motor Sport magazine reported, “The engine proved so flexible that we could afford to run in fourth and third from low revs [2500 upward] and still find rapid response. Of course, it works best if kept between 4000 and 7000 rpm.”

Hass says, “We didn’t have a specified number of kilometres running for an engine [until a rebuild]. It was just that if a team said they would like another engine – and sometimes a team would take an engine only for one race before they said it wasn’t any good – we would test it again. And if it was good, which was normally the case, we just put it back into the system.”

A ‘Mark Two’ FOV car was introduced in 1993. This had mostly subtle changes, and on the powertrain side added a third gearbox option, this one from Drenth and following the pattern of the existing options. Reynard continued to manufacture the spec chassis until the mid-1990s, when after it had completed 201 cars the contract was switched to Schubel in Germany. Finally, Vortex Motorsport took over and by 2000, the last year of FOV, it had taken total production to 269 cars.

The Mark Two car had introduced a production-based engine management system. This ran a conventional port injector for each cylinder and distributorless ignition with those and the normal sensors as per the stock C20XE. The (mechanically operated) throttle body was taken from the Opel Omega (naturally aspirated) 2.6 litre V6 production engine.

The ECU was sealed, with competitors unable to access the software and having to use an EPROM map devised specifically for the formula. The mapping was undertaken by KST, and the system was used without the production car knock sensor owing to the vibration associated with the racecar. Care was taken not to enhance the performance of the engine, which was still shipped at the nominal 158 bhp.

With its mapping, KST strove to maintain the existing power curve. However, there was widespread opinion that the new injected engine was stronger at low revs, with the carburettor engine perhaps having a corresponding edge at high rpm. The injected engine was certainly easier to drive at low revs. Hass recalls that a driver could need some psychological help to cope with the tricky characteristics of a carburettor engine at low rpm!

On balance, neither option was found to give a clear-cut overall on-track performance advantage. However, the injected engine was a lot more userfriendly, with the engine management system accounting for changes in altitude and ambient conditions where the carburettor engine user had the burden of making jetting corrections race to race and even hour to hour. “A carburettor engine is much more complex to set up,” notes Wilco Ibes, who was closely involved with the race engineering of FOV cars at the time.

Engine components

In 1994, GM replaced the C20XE with an evolutionary engine model. Following this change, with FOV wishing to continue with the established unit, engine build was moved away from Ruesselsheim and was split between Irmscher in Germany and Swindon Engines in the UK. Both companies were C20XE competition engine specialists (in 1992, Swindon Engines had famously prepared a reverse-head version for the British Touring Car Championship).

FFR-FOR series competitors get ready for the off at Hockenheim

Throughout the life of FOV, all engine components remained unchanged aside from a switch from forged to cast pistons made to the stock unit purely for reason of cost. Of the 500 or so engines prepared through to the end of FOV in 2000, most came from Ruesselsheim.

“The number of engines that came from Swindon or Irmscher was not really big, because the teams were using their engines for so long and the series went down a bit in the late 1990s,” recalls Hass. “So the changing of engines [for new ones] was not so frequent at that time – some of them were running more than 20,000 km. “Even after 20,000 km [still sealed] an engine could be in really good condition and there was no loss of performance.

We actually found engines were growing in performance after the first 500- 2000 km. This production engine was gaining about one or two horsepower from running in a bit. “In the early days, some [FOV] pay drivers would want to put into their contract that they wanted a new engine, but the team boss would advise them not to do that because the engine gets better if it’s been running a bit. I recall one driver who insisted on fitting a new engine and went about a second a lap slower than before!”

No further cars have been constructed since FOV’s final season in 2000. However, the many remaining examples from the 269 production total have seen diverse competition, especially as the C20XE is straightforward to take up to a 240 bhp level, Ibes notes. Hillclimbing is a popular application, and cars have been raced in open formula spheres such as Monoposto in the UK and even the European BOSS GP single-seater series.

These days there is a strong following for the original formula car in the FFRFOR racing series, which since 2017 has been part of the AVD Historic Race Cup. FFR caters for Formula Ford 1600, Zetec and 2000, whereas FOR is exclusively for revived Mark One and Mark Two FOV cars, strictly to original specification.

FFR-FOR holds races in Germany (Hockenheimring, Nurburgring), France (Dijon), Belgium (Spa-Francorchamps), the Netherlands (Zandvoort) and the Czech Republic (Autodrom Most) and caters for budget-conscious career-minded drivers racing alongside enthusiasts. Generally, competitors get two 20-minute practice sessions and two 20-minute races at each meeting. Although no new cars have been produced since 2000 there are plenty of good refurbished examples. FOR accepts engines prepared by any builder so long as they respect the original carburettor or injected specification. In some  instances that involves detuning an engine that has been modified for other forms of motorsport.

Ibes, who now organises the FFRFOR series, notes that all the original engine parts are still widely available. He reports that a ‘new’ engine for the series can these days be bought for less than €6000, around half the inflation-corrected cost of a new engine in 1988.

Although it isn’t feasible to centrally dyno test and seal such refurbished engines, FOR’s scrutineer carefully checks each one for conformity. If any competitor is thought to have somehow gained an engine advantage then they will be protested and as a consequence their engine will be tested. That is rare though.

Indeed, such is the mileage of these engines that some current FOR competitors still use original sealed engines to no competitive disadvantage. “Provided the user doesn’t over-rev the engine or do something silly like forgetting to replace the oil, this engine – which is very robust and reliable – will provide year after year of cost-effective racing,” Hass concludes.