Cos I Can

It’s a Cosworth, right? Nope, this started life as a bog-stock 2.0 GLS. It’s not a Cossie; it’s a … Cos I Can
Words: Dave Smith, photography: Darren Woolway

You can’t really call a Sierra Cosworth a sleeper, can you? Certainly not the original three-door with it monster spoilers and whatnot, though the later Sapphire four-door saloon might be able to sneak up on the unwary. So that’s all this is, right? A Saffy Cosworth with some big wheels on? Hardly. As far as we’re aware, the employees of Messrs Costin and Duckworth have never clapped eyes on this car, and these days it moons at mere Cosworths as it flies past them…

This car began life in 1992 as a 2.0 GLS; near the top of the range, but hardly an explosive powerhouse. “I’ve always loved speed,” says owner, Mike Perrott, from Gravesend. “I’ve had Cosworths in the past, and before I bought this 12 or 13 years ago, I was driving a TVR Cerbera. I was just about to buy a house and couldn’t afford to run the TVR, so my dad, Denis, said we should build a car, and suggested a Sierra – they’re nice, practical cars and were cheap to buy then.

“I didn’t want to start with a Cosworth because, when I came to insure it, I’d be insuring it as a modified Cosworth, so we looked around for a good, standard shell and found this one in Orpington. It was a solid, rust-free, well-looked-after car and, being the GLS, had ABS and rear disc brakes already.

I drove it around for three weeks while I sold the TVR, then the project took off. First, we took out the original 2.0 DOHC engine and manual ‘box. Dad had a spare 3.9 Rover V8 – he’s got loads of stuff that he’s accumulated along the way, and whenever he upgrades, I get the hand-me-downs! – which we craned into the engine bay. This was all done at the side of the road outside the house in Croydon. We started it up on a Holley carb with two exhausts sticking straight up, just to run the cam in.

“I used a Cosworth radiator, which put the pipes in the right place, and a Cosworth T5 ‘box. Dad’s friend cut the back off a Rover auto bellhousing and made a plate to take the T5, and it dropped straight onto the stock mount on the crossmember. Then we bolted the turbos on! They’re 2WD Cosworth T3s with 360° thrust bearings, bought from a guy in Kew Bridge, running at about 14psi.

“I ran it like this for a while on the stock Sierra diff and brakes, but they just couldn’t cope, so I fitted AP Racing 330mm discs up front on Cosworth hubs and Gaz coil-overs all round. The engine doesn’t weigh much more than the a Cosworth lump so I could use standard spring rates, and I fitted poly-bushes all round. This was still all done outside in the street – it was hard graft, but once it all started coming together the project really got rolling. I’ve since upgraded the rear discs with a set of 280mm Alfa Romeo discs that I bought from Beaulieu.

“I dropped the original 7” rear end and replaced it with the Cosworth crossmember for the 7.5”, but Quaife said they wouldn’t warranty a 7.5” diff to take the sort of power I was talking about, so I fitted the differential section from a Jaguar with 2.88:1 gears. The halfshafts are different lengths, but I wanted to keep the Cosworth CV joints, so I made up some spacers and used the shorter shaft on what used to be the long side, and had to order a shorter one for the other.

“I spoke to a company in Wallington about making me a stainless exhaust, and they said they could, so we towed the car to them on a rope behind dad’s Sierra… in the snow. We got there and they said, ‘Oh, sorry, we thought it was a standard Cosworth. No, we can’t do that,’ so we put it back on the rope, towed it home again and decided to make our own. I ordered two Cosworth downpipes, 2.5” out of the turbos, and made a full stainless system with X-pipe and side-exits ahead of the rear wheels.

“I had a set of 18” wheels on it that I’d imported from the States, but then I bought a set of Mercedes SL500 18” wheels from Essex swap-meet – two 10” rears and two 8.5” fronts – and decided I was going to make the car take them, which meant cutting the arches. At another meet, I got a pair of second-hand BMW E36 front wings and thought I could let the arch sections into the Sierra wings, but the second-hand wings were a bit scabby so I went to Euro Car Parts and bought four new pattern E36 wings! To get the rear wheels on, I had to shorten the back doors by an inch, push the rear bumper back, stretch it out at either end and make each arch three or four inches wider. At the front, I had to push the Cosworth bumper forwards an inch and a half and stretch it out at either end, too – fitting the bumper is a two-man job now, but it’s not glaringly obvious. I ended up with 20×10” Mercedes wheels from America, which needed spacing out 20mm at the rear and 15mm at the front to clear the inner arches.

“I removed the stripes, shaved all the handles and fitted remote control poppers, then we sprayed the whole thing ourselves. I originally fitted a full Cosworth interior, but then I went for Sparco seats, didn’t like them, so went back to Recaros. I started bidding on some seats from a Focus RS that was being broken, having been wrecked with just 2,000 miles on the clock. I won the auction, then found out that the auction was for the whole interior! I sold the door cards, console and other bits, then fitted the RS front and rear seats in the Sierra. I did the armrests and rear door cards in black with blue stitching to match, but I’ve yet to get around to doing the front door cards.

“Then, one day, I blew through a piston whilst racing an R6 motorbike – I was pushing him along then, suddenly, smoke everywhere! So I upgraded to a 4.6 V8, which was a drop-in job because they’re all but the same externally, but with this engine I got the wasted-spark ignition. It uses Range Rover coil packs, a Ford EDIS8 controller, and an MSD ignition unit as well. We also got Holley Pro-Jection fuel injection, so I fitted lambda sensors and two wideband gauges in the car; left and right. That’s how we tune it – I drive it, and Dad sits in the passenger seat watching the gauges and the adjustable boost controller gauge, tweaking the map to suit.

“I also fitted the taller fifth gear from a Mustang T5 in the Cosworth ‘box. This gives it 41 or 42mph per thousand revs in fifth. It used to do 175mph in fifth before, when it was just 33mph per 1,000rpm. The standard Sierra speedometer needle used to jump around because the cable to the ‘box had to twist through some odd angles, so I replaced the speedo with an Auto Meter Cobalt GPS speedo and got rid of the speedo cable altogether. I have matching Cobalt tachometer, fuel level and temperature gauges, all in the stock Sierra binnacle. There’s a Pioneer six-disc head unit with screen, screens in the back, plus three amplifiers, two 12” subs in the boot and four 6×9” speakers in the rear shelf.

“The intercooler is a bespoke piece made by Pace – I had to make a model out of cardboard for them to work from. There are two inlets and chambers at the bottom, meeting in a single chamber and three inch outlet at the top. It’s thin – only 25-30mm – and very efficient, and it’s made a massive difference. I did fit nitrous, too, but I only used it once. I flicked the switch, put my foot down and blew all the pipes between the turbo and intercooler off!

“It’s nice to drive, comfortable, with power steering and modern comforts. I did have a full roll cage, but ended up cutting the front part out because my girlfriend didn’t like it. I left the rear part in, though, because without it, the body twists so much that the bootlid moves to the right and chips the paint. It’s heavy at the rear because of the Jag diff and all the stereo gear, but off the line it just sits down and goes, it’s ballistic. It’s all torque. I’ve taken it to Santa Pod a few times, just to tune in the Pro-Jection, and just rolling off the line it ran 13.2. It should easily be a 12-second car, but those low-profile tyres are so hard that they spin easily – it’ll spin them into third gear.

“I might fit forged pistons and connect the nitrous back up, and I’ve got a T56 six-speed to go in, but I don’t use it loads any more. I have a MkI Cortina with a Zetec engine, and dad and I are building a Dorset now. Plus, I’ve spent enough on the Sierra that I don’t want to park it anywhere. I really didn’t want it to get to that point, I just wanted it to be fun, but it all adds up. I still love it, though, and still love driving it, it’s such an animal. Ferrari 430 and Audi R8 drivers, they don’t like you pushing them along on the motorway…”

1992 Ford Sierra Sapphire 2.0 GLS

  • Rover 4.6 V8
  • Holley Pro-Jection fuel injection
  • Twin Cosworth T3 turbochargers
  • Pace 2-into-1 intercooler
  • Dual Cosworth fuel pumps; second rpm-activated at 3,000rpm
  • MSD/Ford coil pack ignition
  • Cosworth radiator
  • Electric fans, two Spal and one Kenlowe
  • Stainless exhausts with X-pipe
  • Cosworth T5 manual transmission
  • Jaguar IRS diff section
  • Cosworth halfshafts and hubs
  • AP Racing 330mm front discs
  • Alfa Romeo 280mm rear discs
  • Cosworth power steering rack
  • Gaz coil-overs all round
  • Polyurethane bushes all round
  • Mercedes 20×10” wheels
  • 285/25R20 tyres
  • Cosworth front bumper
  • Ford Focus RS seats
  • Auto Meter gauges
  • Pioneer ICE

Thanks to: “Thanks to my dad, Denis. He’s phenomenal, you couldn’t have anyone better working on your car. My dad even built my garage for me, but it’s his domain…” (We’ll be hearing more about Denis and his cars in a future issue… DS, SM)