Usually they're very fast and have very big turbos.
For just over 60 years now, British engine specialists Cosworth has been powering road and race cars. The company has over 176 Formula One wins under its belt but has been entrenched in all sorts of racing since being founded in 1958 by Mike Costin and Keith Duckworth. The name Cosworth comes from is a portmanteau of their names and both were formerly with Lotus. Cosworth maintained a close relationship with Colin Chapman at Lotus for a while and initially only built engines for the British road and race car makers. After that, Cosworth was best known for its relationship with Ford but has been involved in some of the most beloved car-enthusiast icons to hit the road, including cars from Mercedes, Audi, Opel/Vauxhall, and even Chevrolet.
While based in the UK for access to Europe, Cosworth also has a strong presence in the US with facilities in North Carolina, Indianapolis, and Michigan. Cosworth has also had success in Indycar racing and provided the spec engine for the Champ Car World Series in 2003.
The Sierra RS Cosworth was both the model that made it possible to own a cool Ford Sierra and made the name Cosworth a household name through three generations. It was born of Ford Motorsport in Europe who wanted something that would dominate Group A racing throughout the world. Cosworth was contracted to build and tune the Ford base engine to power it and the result was an all-wheel-drive beast with a 204-horsepower 2.0-liter inline-4 engine complete with a Garrett turbocharger and Weber-Marelli fuel injection system under the hood.
It wasn't just rallying and touring car racing where the Sierra Cosworth made its name though. On the road, it became a working-class hero for being loud, brash, and very, very, fast. Then it got stolen a lot, and the cost of insurance eventually forced a lot off the road. The Sierra RS Cosworth's influence still ripples through fast versions of cars today from the oversized spoiler on the first generation to Cosworth's spicily turbocharged 4-cylinder engine.
The follow up to the Sierra Cosworth was the more marketing-friendly Escort Cosworth. It wasn't actually based on the Ford Escort chassis though, but rather on a shortened version of the Sierra Cosworth's chassis. The Escort Cosworth became even more notorious on the streets of the UK although its success in World Rally Championship was modest. We can still find it's DNA through Ford hot hatches all the way up to the Ford Focus RS.
In the mid-1980s, Mercedes wanted to go rallying and the 4-door 190E was the most likely candidate due to its sophisticated suspension and aerodynamic body shape. Mercedes entrusted Cosworth with tuning the engine and the company built a whole new cylinder head for the Mercedes engine that used 2 camshafts and 4 valves per cylinder.
However, it was ready just as the world was watching Audi dominate the World Rally Championship with the Quattro. Mercedes did some quick thinking and came to the conclusion that, perhaps, the Cosworth powered 190E might be better suited to touring car racing. It subsequently went on to challenge BMW's M3 into the 1990s and won the German touring car series in 1991 and 1992.
The RS is Audi's highest trim level and stands for RennSport, which literally translates from German as Racing Sport. The original B5 version used a twin-turbo 2.7-liter V6 developed and built by Cosworth in the UK rather than the inline-5 design of Audi's other high-performance vehicles. It featured Audi's Quattro system and was a riot to drive and full of character. Part of that character was in how low key it was until the boost came on tap. Factory cars now don't tend to have a pronounced turbo lag which is a bit of a shame as it added to the fun factor, even though it's not ideal for performance.
Unlike the other cars so far, the Subaru Impreza Cosworth was limited to just 75 units. It was also only sold in the UK. It was almost double the cost of a standard STI and, for their money, those customers got 395 hp and 400 lb-ft of torque from the Cosworth-tuned Subaru 2.5-liter flat-4 engine. The initial response wasn't so great with complaints of it being laggy and power not coming on until 3,500 rpm. But, after the rev needle hits that mark, things got exciting quickly and showed off how important the all-wheel-drive system was. For those with the skill to keep it in the rev-range, the Cosworth Impreza had a habit of spitting itself out of corners at a remarkable velocity.
Aston Martin and Red Bull got together in a close partnership to build a lunatic level track car that could also cruise on a road. It's still in testing at the time of writing, but we got a glimpse recently with its public debut at the 2019 British Grand Prix race at Silverstone. The highlight of the Valkyrie is its screamer of a V12 engine tailored by Cosworth to, a currently reported, 1,030 horsepower. That means that with the reported weight of 2,271 lb, it exceeds the target 1:1 power-to-weight ratio that Aston Martin and Red Bull were aiming for.
The Cosworth-powered Chevrolet Vega could have been a wonderful car. It had John Delorean's hand in it and styling that echoed the 1970 Camaro. It launched with high praise from the automotive media until it became known for some large faults that included a propensity to rust, reliability issues, safety issues and durability problems with the engine. So, Chevy did the logical thing and had Cosworth build 5,000 performance versions of the 90-horsepower engine in 1975 so it could go racing. The engine with its new cylinder head made 290 horsepower and revved out at 9,000 rpm.
Unfortunately for the road cars, emissions throttling brought output down to 120 horsepower, just 10 more than the optional high-powered engine. The extra 10 horsepower cost almost double the price of a base model. That didn't stop Road and Track saying that it "goes like the proverbial bat out of Carlsberg Caverns" and praising its handling, as well as Car and Driver choosing it as one of its "10 Best Collectible Cars" for its 4th annual 10 best issue.