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[January 2007]
Zircotec Keeps Hot Impreza Cool
When performance car specialist Litchfield Imports wanted to make the ultimate Subaru Impreza, it turned to the best in the business. That included Harwell-based thermal management experts Zircotec.
Litchfield's Impreza Type 25 is based on the already quick Japanese-only Spec C car but features a more powerful, 2.5 litre engine co-developed with Cosworth. This produces 415bhp, rather than around 300 on the 'standard' car but it also generates more heat.
This can be a problem because of the way Subaru engine bays are laid out, says managing director Iain Litchfield. "The engine doesn't like heat. The intercooler sits on top of the engine, rather than down at the front by the radiator. This is fine when you're driving along but if you sit in traffic it doesn't get the air flow."An intercooler is a heat exchanger that cools the air compressed by the turbo before it enters the engine. Cooler air is more dense, so packs more oxygen into the cylinder, producing more power. However, the intercooler's effectiveness is determined by the difference in temperature between air passing through it and the air around it. This is complicated still further because the up-pipe that brings hot exhaust gases to power the turbo and the down-pipe that takes them away again are both routed directly beneath the intercooler. To resolve this, Litchfield, having heard about its work on World Rally Championship cars, turned to Zircotec.
Its solution was to plasma-spray a zirconia-based, heat-shielding ceramic coating on both the up and down-pipes on the Type 25. This prevents the exhausts transferring heat across to the intercooler, helping it work efficiently so the car responds in a predictable way.
Keeping the heat in the exhaust also improves the car's performance, Litchfield explains: "The more heat and energy you can keep in the system, the faster the turbo will spool up, making the car more responsive. We're finding it's bringing the turbo up to speed 300 or 400 rpm sooner, which you can really feel in the crispness of the throttle response. It's little details like this that end up making a big difference and we wanted to make sure there were no corners cut on this car."Alongside its supercar performance, Litchfield wanted to be able to offer family saloon standards of reliability. "This is a production-quality car and comes with a full warranty," he says. "It has to be much more reliable and dependable than a tuner's special that you'd spend all your weekends getting perfect. It's going to be bought by people who already own other high-performance cars. They want to be able to use it every day, do the shopping and pick up the kids but still have the performance of their 911."
To sell a product to this discerning clientele, it was important to Litchfield to use a solution that was professional looking as well as durable. "This is a 'halo' product for us, we wanted it to be as OEM-looking as possible. The coating is also much more durable than the alternatives, too. Heat shielding wraps and tapes are a 'Band-Aid' fix, they're not suitable for someone who doesn't want to spend all their time working on their car."
Building such specialist vehicles is a big step for a company that originally just imported vehicles. Litchfield says suppliers like Zircotec make the process easier. "We've been really pleased with their turnaround. The logistics of getting all the parts here at the right time can be a nightmare, so it's great to know that we can take our exhausts to Zircotec and have them back three days later, ready to go. It takes a lot of stress out of the process."
Litchfield has been so impressed by the performance and reliability benefits that the Zircotec coating has offered that it plans to use it more widely: "Eventually we hope to offer it as an option on all the cars we do."www.zircotec.co.uk
ENDS