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Ford Sierra Cosworth

Sierra Grande Published: 25th May 2011 - 0 Comments - Be the first, contribute now!

Ford Sierra Cosworth

Fast Facts

  • Best model: RS500
  • Worst model: Anything badly modifi ed
  • Budget buy: Sierra Sapphire
  • OK for unleaded?: Yes; use superunleaded
  • Will it fit in the garage? (mm): L4460mm x W1720
  • Spares situation: Generally good
  • DIY ease?: Most jobs are OK
  • Club support: Excellent
  • Appreciating asset?: Yes, steadily
  • Good buy or good-bye?: Good buy
Engine is based on Pinto block – usually durable if looked after and modifi ed properly Engine is based on Pinto block – usually durable if looked after and modifi ed properly
Pedigree was top class Pedigree was top class
Cabin is typically Ford friendly Cabin is typically Ford friendly
Lovely touches were unique to the RS such as the alloy wheels, rear spoiler and the interior in particular – check against brochure to see what remains! Lovely touches were unique to the RS such as the alloy wheels, rear spoiler and the interior in particular – check against brochure to see what remains!
Lovely touches were unique to the RS such as the alloy wheels, rear spoiler and the interior in particular – check against brochure to see what remains! Lovely touches were unique to the RS such as the alloy wheels, rear spoiler and the interior in particular – check against brochure to see what remains!
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Forget that Lotus Contina - it’s spiritual successor with the Cosworth connection is more rapid, refined and realistic

Pros & Cons

Great to drive, fast, practical, easy to run, well supported, surprisingly good value still
Lots of rubbish cars about, theft rates high, too many crash repaired examples on sale

If motorsport improves the breed, welcome to one of the best and most highly developed road cars ever made. Indeed, whether or not you believe the motorsport maxim, this truly is one of the all-time great road racers, just as happy to blitz the Nurburgring circuit as to cruise down the high street. When it comes to versatility, few cars can match the be-winged Sierra. This year marks 25 years of the Sierra RS Cosworth – that’s right, it’s a quarter of a century since this bespoilered hatch was unveiled, and while the car was guaranteed to become a classic from the minute it was first shown, it’s been through plenty of lows in the meantime as well as lots of highs. In 2010 the Sierra RS Cosworth is defi nitely on a high once more, and if you reckon now is the time to track down a good example of your own, you’d better start your search now – and be prepared to pay for a good one.


In group a trim they kicked out 500 BHP!

The Cossie ‘Jellymould’ came about because Ford had to produce 5000 road-going examples of its Group A-homologated Touring Car; when unveiled in 1985, every superlative under the sun was thrown at it. Here was a genuine 150mph car that was pretty inexpensive, practical, easy to maintain and capable of being tuned to give ridiculous amounts of power. The world would never be the same again. If the stock Sierra Cosworth was rapid, the evolutionary RS500 of 1987 was even more so. Hand-built by Tickford, just 500 were made, most in black. Still using the same Pinto block fi rst seen in the Cortina, with its larger turbocharger and intercooler, twin injectors per cylinder, pressurised oil cooling for each piston and larger capacity oil and water pumps, power grew to 224bhp – raising the top speed in the process. There were also larger ducts in the front bumper, to feed air to the brakes and intercooler, while aerodynamics were sharpened up courtesy of a front splitter and extra spoiler on the tailgate. The three-door Coswor th Sierra’s lifespan was brief but glorious; by the time production was wound up in December 1987, 5542 examples had been built, including the RS500s. However, that wasn’t the end of the line, because in 1988 Ford introduced the Sapphire RS Cosworth saloon in rear-wheel drive form; a more luxurious and refi ned and certainly not so extrovert performance tool. That survived for just a year because by 1990 there was a four-wheel drive edition of the saloon that meant that the car gripped as well as it went. The Design Council praised the Cosworth Sierra for its sheer value at under £20,000 when a rival BMW M5 cost 35 grand! Production lasted just two years though before it was effectively replaced by the Escort RS; essentially a Sierra with the more modern, trendier ‘winged‘ Escort bodyshell.


Even in standard 204bhp guise, as originally unveiled, the Cosworth Sierra is seriously rapid a quarter of a century on; it’ll do 0-60 in 6.2 seconds and top out at 150mph. The 224bhp RS500 is even faster; it can serve up 153mph, although its 0-60 time is the pretty much the same. Only the best of today’s GTis and sports saloons can stick with a well tuned out Cossie. As you’d expect of such an old-school boosted car, the turbo’s response isn’t instant, although it’s a lot better than many of its contemporaries. The power delivery isn’t entirely linear or smooth either, but the many upgrades available tend to even things out a bit, if done properly. That said, the Pinto-derived engine always feels coarse when extended. The three-door hatch was offered with rearwheel drive only, and while there’s plenty of grip if you’re having fun on a dry road. When things get greasy you can oversteer all over the place, without really trying. Folklore has it that most of Ford’s press fl eet was soon wiped out! The later four-door saloon Sapphires addressed the problem, fi rst by a not-so sensitive chassis then by adopting four-wheel drive; it’s a system that works brilliantly because you can turn up the wick and still get the power down when you want to really use it, in safety. But it’s not just about the pace on offer; the Cossie is a car that handles honestly and a good driver will fi nd it satisfying to master one. It helps that the car is so light; the standard Cossie tipped the scales at all of 1217kg, which is seriously trim for such a large car. The low kerbweight helps with the Cosworth’s agility, but so does the direct steering; there are just 2.4 turns between locks.

Many cars have had fresh (non-standard) bushes fi tted which typically fi rm up the ride a bit. These, combined with the stiffer suspension that’s usually installed can make things a bit uncomfortable on the UK’s broken roads, but if you can fi nd a car that’s still reasonably standard you’ll enjoy a ride that’s surprisingly compliant for such a hard-core machine. The brakes are more than up to it for road use. What’s really impressive though is how the Sierra doesn’t dispense with practicality for such Ferrari-matching pace; you can do all this with the family on board, complete with their luggage as if it was a 2.0 LX and expect the same user friendliness behind the wheel and easy ownership in the workshop. Naturally with its Ferrari pace on Fiesta-sized bills the press loved the Cosworth, especially its horse power, if not the the ‘hoarse power’ as Car put it. But, refi nement aside this monthly called the handling ‘marvellous’ in the dry at least and claimed: “Ford has done a fi ne job of turning the Sierra into a road racer” although it thought the big wing look of the original was all wrong. “Most people do not wish to display their purchasing power and yen for speed quite so crassly,” it commented. Styling apart though, the critical monthly rightly predicted: “For all its faults the Cosworth is a wonderful machine, and in years to come people may marvel that such a car was ever produced.”


Usable Cosworths start at £6000, with nice examples fetching half as much again; the best cars are currently worth around £15,000. The RS500 is a different ball game; equivalent values are £12,000, £18,000 and £25,000+. The 52 white RS500s (plus four prototypes) and 52 Moonstone cars are worth a small premium over an equivalent black example. Originality is desirable up to a point, but cars that have been sympathetically upgraded are worth at least as much as a car to factory spec. The Cosworth’s value and desirability has led to plenty of fakes being sold as the real thing. All genuine cars will have a factory-fi tted tilt/ slide sunroof; if you’re at all suspicious either walk away or get advice from the RS Owners’ Club. Although you have to be very careful when buying, the Cossie is still an amazing performance bargain – that’s only set to increase in value.


You’re highly unlikely to fi nd a Cosworth Sierra to factory spec; virtually all cars have had upgrades to the brakes, suspension, wheels and engine by now. If done properly these should enhance a car’s desirability, not diminish it. And that’s the key – some upgrades aren’t done properly, so establish who has done any work. A stronger head gasket is a must, even if the engine hasn’t been uprated, although it’s easy to
realise 270bhp just by tweaking the ECU. Cosworth had trouble keeping power down, so a remapped ECU ups the bhp by 35 per cent or so. If you want a reasonably reliable 330bhp, more turbo boost plus a remapped ECU are the way to go; opt for more power than this and reliability plus tractability start to be compromised. The trouble with many mods was over-fuelling, washing the bores of their lubricating oil so causing bore wear. Other worthwhile changes are the adoption of a front strut brace (but not a rear), larger discs and callipers (which mean bigger wheels and hence reprofiled wheelarches) and stronger suspension bushes. While you’re at it, Koni or Bilstein dampers with dual-rate lowered springs are worthwhile – but don’t go for coilover shocks unless you don’t mind your spine being shattered. And have the chassis geometry checked and set up, it could well be out – perhaps due to a bent chassis.

What To Look For

  • While corrosion can be an issue, crash damage has killed most Cosworths. An HPI history check is essential (01722 422 422,, and so is a thorough inspection of the car’s structure and panels. If there’s any hint of missing seam sealer or ripples in the innerwings, be very wary.
  • Serious corrosion anywhere points to poor crash repairs. However, minor rust is quite possible in isolated areas; it shouldn’t have spread though. The key areas include the joint where the front wings meet the slam panel, plus underneath the rubber trim inside the tailgate. Also, don’t overlook the metal behind the windscreen washer bottle, in the engine bay.
  • The boot floor can also corrode, as well as the double-skinned rear chassis rails; the latter may be seriously awkward to fi x, while inspections are tricky because the affected area is hidden by the beam axle. It’s the same with the inner wings and suspension turrets; don’t underestimate the cost and diffi culty of repairing these areas correctly. However, at least the sills are easy to repair if rusty, as they’re single-skinned.
  • The 2-litre twin-cam is unstressed when standard, but most cars have been uprated. As long as things have been kept sensible, there’s nothing to worry about; start fretting when the 330bhp safe limit has been breached.
  • RS500s have a much stronger block, but cars that have been tuned to give much more than 430bhp will probably suffer reliability issues before long; if the engine isn’t standard, establish who has done the work.
  • Even standard powerplants suffer head gasket problems because of corrosion. If the engine runs hot and loses water for no apparent reason, the head gasket has blown. Unusually, a blown gasket with this engine doesn’t lead to mayonnaise on the oil fi ller cap, but it will pressurise the cooling system. To check for this, remove the header tank cap when the engine is up to temperature; major bubbling means trouble ahead. The gasket’s weakest spot is at the back of the block, on the offside; once it has blown, your best bet is to fi t an upgradedgasket that won’t breach so easily. A £105 Group A item is best; a specialist will charge a not unreasonable £350 to fi t it.
  • If there’s mayonnaise on the oil fi ller cap, it’s because the cylinder block or head has cracked – which means you’ll need to source a used engine (YB block) to slot in. Bank on paying£1500 for a serviceable unit, or £3000 for a stronger RS500 item.
  • If there’s lots of blue smoke coming from the exhaust, the bottom end may be worn; a full rebuild is £1500-£2500. Blue smoke can also mean the turbo is on its way out, but this can also lead to white smoke from the exhaust; if in doubt, get a specialist to take a look. If the turbo does need renewing, a used unit is £150, a recon £350, while new ones are £700.
  • Piston slap is common, because of the gudgeon pin’s poor design – there’s nothing to worry about as long as the noise disappears once the engine is warmed up. If there’s misfi ring, it’s because the phase sensor in the distributor is starting to break down. It’s easy enough to fi x though; a new sensor is just £35.
  • Any car that’s been tuned will need servicing more frequently, check there’s a stack of service history with it – especially plenty of oil changes (3000 miles is a good pit stop).
  • The Sierra’s transmission is durable, but even in perfect condition the changes are notchy; the first sign of trouble is baulking when changing up from third to fourth. It’s possible to live with that but when third gear breaks altogether you’ll have to get your wallet out. Rebuilding the gearbox costs £350-£500
  • If the car has been caned constantly, the diff may also be on its way out. These aren’t weak,but will take only so much abuse before failing; rebuilt units cost £450, used £250.
  • Clutches last 40,000 miles even with some occasional abuse, as long as they don’t have to transmit any more than 330bhp. Easy to fi t, and cheap too at £150,
  • More problematic is a worn propshaft centre bearing. These are unavailable new, so ifthere’s a vibration that you can drive through, expect to pay £40 for a used prop soon.
  • Feel for play in the steering, as there’s a rubber bush in the universal joint that connects the rack to the column. The bush gets cooked by heat, and once it’s gone you’re stuck because it’s an MoT failure point and new ones aren’t available. If you’re lucky you’ll chance upon a used one for £50, but don’t count on it.
  • Like most Fords with track control arms, the bushes contained within aren’t up to the job. They wear quickly, so it’s best to fi t polyurethane items at £60 for the whole set, including the anti-roll bar mounts. If the bushes have worn out, there’ll be vibration under braking and the steering will be vague.
  • Few Cosworths are still on their original suspension. First make sure that’s what fi tted isn’t shot (doing a bounce test on each corner is essential), and also check that any aftermarket parts aren’t horribly mismatched to produce weird handling characteristics. Other than this, there are no likely problems.
  • Most Cosworths have aftermarket wheels fi tted, which is fi ne if they fi t properly. Check there’s enough inner wheelarch clearance and ensure there’s no uneven tyre wear.

Three Of A Kind

BMW M3 E30
BMW M3 E30
While later M3s were rather civilised, this fi rst of the breed was a road racer, barely changed from the Group A touring cars seen on track. Early cars featured a 192bhp four-pot, but by the end there was 235bhp on tap with the Evo edition. At fi rst therewere two-door saloons only, but convertibles were offered too later on. All M3 E30s were lefthand drive.
Lancia Integrale
Lancia Integrale
An evolution of the Delta HF Turbo, which was front then fourwheel drive, all Integrales hadpower going to each corner. Early editions had eight valves but from 1989 there were 16-valves; all Integrales featured a turbocharged four-cylinder engine and LHD. Pick of the bunch is the Evo 2 of 1993, but they’re big money these days, so an Evo 1 is a good substitute.
Mercedes 190E 2.3-16
Mercedes 190E 2.3-16
While the Mercedes 190 was a worthy but rather dull small saloon, it was transformed by Cosworth, which fi tted a fettled 16-valve 2.3-litre engine – which later grew to 2.5 litres. It was all done in the name of motorsport of course; this was another one of those Group A racers. Hmm, a family car turned into a Group A racer by Cosworth – does that sound familiar?


The Eighties are coming back into fashion in a big way, and cars like the Cosworth Sierra are seriously in demand. The thing is, buyers want a healthy dose of originality; with so many cars upgraded quickly after they left the showroom, many original parts have disappeared; any car that’s ex-factory will always be highly saleable. It’s crazy you know – Lotus Cortinas sell for huge sums yet the Sierra with that same Cosworth connection still sells for relative pennies yet has to be the better car - doesn’t it? Cheap Cosworths won’t continue for long and we can see this fantastic fast Ford soaring in value soon. Deservedly so.

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