The Other RS

Are you tired of hearing Subaru WRXs burble past? You no longer get excited about go-fast Mitsu's?

Well, take a look at this – a rare-as in Australia Ford Escort RS Cosworth. The Escort Cossie is one of the most extreme made-for-rally vehicles of all-time and redefines the term ‘hot hatch’...

Escort RS Cosworth Background

The seed for the Escort RS Cosworth was planted in the 1980s when Ford Motor Company joined forces with Cosworth Engineering to produce specialised vehicles for circuit racing and rallying. The first vehicle created through this partnership was the RS500, which was a homologation special based on the conventional Sierra chassis. This spoiler-equipped, turbocharged and rear-wheel-drive coupe made a big splash in circuit racing. Road going versions – sold only in select counties – generate a substantial 167kW.

The RS500 was followed by the slightly detuned Sierra RS Cosworth, which used a similar mechanical package to the RS500 and was initially released in rear-wheel-drive form. A constant 4WD version was later introduced - this vehicle saw some Group A rally action in the hands of drivers such as Didier Auriol. Unfortunately, the Sierra RS Cosworth had limited competitive success against the likes of the Lancia Delta Integrale.

Ford’s answer was the light and nimble Escort - but not your average Escort...

In contrast to many of its rivals, the rally-going Escort carries over very little from the bread-and-butter model – none of the conventional front-wheel-drive, transverse engine platform remains. Instead, Ford took the engine and AWD chassis layout of the proven Sierra Cosworth and draped it with a body that only looks like an Escort. This is essentially the Sierra RS Cosworth AWD crammed into a smaller package.

The Escort RS Cosworth was an extremely expensive vehicle to build. The chassis were freighted to Karmann (in Germany) for comprehensive re-engineering to accept the new high-performance driveline. Note that the only parts shared with the bread-and-butter Escort are the doors, windscreen, rear quarter windows and rear hatch. The RS Cossie is longer, wider and has a longer wheelbase than the everyday version.

The suspension geometry and layout is very closely based on the Sierra’s. The front suspension employs MacPherson struts with lower control arms and anti-roll bar. At the rear is a strut/semi-trailing arm IRS with an anti-roll bar. On paper it’s not a technical stand-out, but the awesome level of traction and grip quickly makes you forget about that...

The Escort RS Cosworth has typical AWD handling characteristics. It has mild turn-in understeer but will happily accept full power at the apex – the AWD system providing total traction. Note that Escort RS drivers often floor the accelerator before the apex of a corner – the big turbocharger fitted to early models takes a few moments to build boost pressure. Grip levels are exceptional – the standard 16 inch alloy wheels are clad in big an’ sticky 225/40 Pirelli P-Zeros.

Steering is a power assisted rack and pinion arrangement. With just 2.5 turns lock-to-lock, it’s direct, linear and has meaty weight. The ventilated disc brakes are controlled using a short-stroke brake pedal and offer excellent stopping power. ABS is fitted to road-going versions.

The body of the Escort RS Cosworth is as wild as any other production hatch in the world. The aero package comprises a front spoiler and 3-position adjustable splitter, bonnet vents, flared guards, side skirts, rear apron and a huge wing combined with a lower spoiler. Nobody can say aerodynamics were an afterthought... The front and rear spoilers are said to deliver 45 Newtons and 190 Newtons (respectively) of downforce at 180 km/h. The RS apparently has a 0.38 aero Cd – slightly higher than the basic Escort.

And what about the engine?

Well, the Escort RS Cosworth shares the Pinto-derived engine with its RS500/Sierra/Sapphire stable mates. Displacing 2.0 litres, the DOHC, 16 valve Cosworth engine has an oversquare bore and Mahle forged pistons giving a static compression ratio of 8.0:1. The crankshaft is a heat-treated steel item and the block is cast iron.

Note that two road-going versions of the Escort RS engine were produced. The first 2500 vehicles were homologation versions required for FIA accreditation and came equipped with a large Garrett T3/T04B (aka T35) turbocharger – the same turbo used on the earlier Group B RS200 rally car... Not surprisingly, this turbocharger is great for maximum power but gives terrible lag. Charge-air heat is reduced by an interesting 2-stage intercooler arrangement with a water-to-air and air-to-air core in series.

Vehicles equipped with the big T35 turbocharger use a so-called YBT version of the Cosworth engine. A brief over-boost function allows up to 1.3 Bar (19 psi) of boost pressure, settling back to 0.8 Bar (12 psi). Peak power output is 164kW at 6250 rpm and there’s 290Nm at 3500 rpm - more than enough for a 1275kg AWD hatchback...

Ford officially quoted 5.9 second 0 – 100 km/h acceleration along with a top-end of 225 km/h.

Not bad...

Later Escort RS Cosworths (which were built beyond FIA requirements) were toned down. Examples built from late 1994 are fitted with a ‘YBP’ spec engine, which uses a smaller and more responsive Garrett T25 turbocharger. The YBP engine also switches from Weber-Marelli engine management to the generic Ford EEC-IV system.

The YBP engine generates a healthy 305Nm of torque which can be accessed at just 2750 rpm. This gives the car a much livelier feel than the previous model. Interestingly (despite the smaller turbocharger) the engine is said to produce more power than the earlier YBT version – 169kW at 5500 rpm. Note that peak power is achieved at lower revs – the small turbo engine starts to run out of puff toward 6000 rpm.

The only visual differentiation to the earlier model is a HTT (High Torque Turbo) badge on the front doors.

The Escort RS Cosworth is a pretty raw vehicle to drive. This was, after all, built as a homologation special - it was never going to be a mass produced vehicle with millions of dollars spent on NVH... Inside, the cabin is a conventional Escort dashboard with sports instrumentation – a 270 km/h speedo, tacho, volt meter, oil pressure and boost pressure gauge. A 3-spoke leather wheel comes fitted as standard while air conditioning, a sunroof, power windows and mirrors, heated seats and leather trim were available as options.

In its first year of production (1992) almost 3500 Escort RS Cosworths were sold. However, production gradually fell away until it was axed in 1996. A total of 7145 examples were built, making this hot Escort a true collector’s car.

Motorsport Version

So how far removed from the road-going Escort RS are the Group A rally cars of the ‘90s?

In short, a long way!

The competition-spec engine is built with aftermarket forged pistons, the cylinder head is modified and fitted with bigger valves and custom camshafts are used. The static compression ratio is said to be around 8.5:1. A magnesium sump (providing 8 litres capacity) and twin pump fuel delivery system are incorporated. Boost pressure peaks at approximately 2.5 Bar (36 psi) drawing through the mandatory 34mm FIA restrictor. A bigger air-to-air intercooler is installed in the centre of the nosecone along with an intercooler water spray and water injection system. Anti-lag systems were used for some events.

Output is a politically correct 300hp (224kW) – a bit conservative given Ford quotes 0 – 100 km/h in the 3 second range on gravel...

Early Escort RS rally cars used a 7-speed non-sequential gearbox. However, during 1997, a new X-Trac gearbox was employed featuring a pump that circulates fluid through a dedicated radiator. The clutch is dual-plate carbon and driveshafts are titanium. Front and rear differentials are electronically controlled and front-to-rear torque split can be adjusted in-cabin. The centre diff is disconnected when executing handbrake turns.

The braking system employs two master cylinders, front discs up to 378mm diameter with water-cooled 8-pot calipers, adjustable bias and no vacuum assistance or ABS. Steering is non-assisted and 2.4 turns lock to lock.

The suspension layout is loosely based on the original layout with altered geometry and fully adjustable ride height, damping and alignment angles. The later WRC version of the Escort switched from rear struts to a multi-link set-up. Eighteen inch magnesium wheels were used for tarmac events.

Competition vehicles are fitted with a structural roll cage and the body is seam welded and strengthened in various strategic locations to enhance rigidity. The fuel tank is relocated inside the cargo area. Competition weight is around 1230kg.

The Escort RS Cosworth campaigned in the world rally championship until 1998, achieving eight wins under the Group A formula and two more wins under WRC guidelines. It was then replaced by the Focus.

A Local Example

Nicholas X of Sydney owns this magnificent red ’93 Escort RS Cosworth running the standard YBT ‘big turbo’ engine.

Nicholas has previously owned a BMW M3 and Subaru WRX and says he wanted an Escort RS since he first saw one. So when a 78,000km example came up for sale about 12 months ago, he didn’t hold back – there are only about twelve in Australia and the owners tend to hold on to them tightly...

The car – which was originally imported and ADR’d by a now-defunct company in Western Australia - came into Nicholas’ hands with what appears to be a Graham Goode Racing entry-level upgrade. A full-length 3 inch exhaust, Group A injectors and a larger fuel pump are the most obvious additions. Nicholas says the car was running extremely rich when he purchased it, so he handed the car to Silverwater Automotive Services (SAS) for a custom retune.

And the result?

A solid 141kW at all four wheels on a Dyno Dynamics chassis dyno – without touching boost pressure! Nicholas says it’s certainly a faster car than either his WRX or M3...

The car is also fitted with Eibach lowered springs and Koni adjustable dampers. These enhance road holding in conjunction with the 18 inch Compomotive Motorsport wheels wearing 225/35 Falken FK451 rubbers.

Nicholas says he’s more than happy with the car’s performance and will now focus on some body detailing. At the time of writing, a pair of quad-lamp headlights was going on and there were plans for a respray and new badges.

And, no, Nicholas won’t be selling the car in the foreseeable future. When you own such a collectable car with shattering performance, why the hell would you?!

Contact:

SAS
Silverwater Automotive Services
02 9748 1300
info@silverwaterauto.com.au
www.dynotuning.com.au