Maruti Suzuki Scores Hit With Clean-Sheet Diesel

MUMBAI – Maruti Suzuki circumvents technical issues with Fiat and a business dispute that led to its break with Volkswagen as its engineers design a small diesel engine from scratch.

The result of the 5-year, Rs9 billion ($140 million) effort is the DDiS125, a 2-cyl., 0.8L diesel mill that powers the Celerio premium hatchback but can be fitted in the No.1 Indian automaker’s other small cars.

Maruti had been using 4-cyl., 1.2L diesels built by Fiat in five of its models. But the Italian automaker could command high prices because it was supplying seven automakers with engines for 18 car models, with six more on a waiting list. The Fiat engine also was costly to Maruti because its standard size forced the Indian automaker to reconfigure the engine housing in several of its cars.

Meanwhile, Volkswagen, which held a 19.9% stake in Maruti Suzuki parent Suzuki, objected to the Japanese automaker’s purchase of Fiat diesel engines without its consent. Suzuki denied that claim.

Volkswagen contended the deal violated its 2009 agreement with Suzuki to cooperate on developing small, fuel-efficient cars for emerging markets, with VW providing the smaller automaker with access to technology in exchange for Suzuki’s small-car expertise.

The dispute went before the London Court of International Arbitration, which last month ruled Suzuki had violated the agreement but also allowed it to buy back Volkswagen’s stake. Suzuki last week paid VW an estimated $3.8 billion as the partnership was dissolved.

The DDiS125 diesel designed by engineers with Suzuki and its 32-year-old Indian joint venture has strengthened the popularity of the Celerio, which has been among the country’s top 10 sellers in six of the 18 months since the gasoline-powered version launched.

Growing Versatility While Cutting Weight, NVH

The engineers were tasked with developing a low-maintenance engine with high fuel efficiency, compliant with current and future emissions standards and able to fit in Suzuki’s full range of small cars.

They responded with a powerplant making 48 hp, 92 lb.-ft. (125 Nm) of torque at 2,000 rpm and delivering fuel economy of 64.9 mpg (3.6 L/100 km), which Maruti Suzuki claims is the Indian market’s highest.

The diesel weighs just 198 lbs. (90 kg), achieved by using an aluminum engine block and lightweight components. A counterbalance shaft normally would be needed to curtail noise from the block, but that would have increased the overall size of the engine. The solution was to increase the height of the block.

To curb vibration, the engineers chose a compression ratio of 15.1:1 instead of the usual 16.5:1. To compensate for the power deficiency resulting from the lower compression, two fixed-geometry turbochargers were used in place of a costlier variable-geometry turbo. This achieved comparable performance within the available budget and size of the engine block.

Supplier Bosch helped in replacing a common-rail fuel-injection system and air-to-air intercooler by developing a reservoir of air, again saving both space and money. A double camshaft with 2-valve arrangement was used in place of a single cam, and a high-pressure fuel pump meters fuel injected into each cylinder.

A belt drive for camshaft is relatively quiet, but wear and tear is high and frequent replacement is required. The engineers instead adopted a chain drive that requires more lubrication but uses less-expensive, more effective mineral oil in place of synthetic oil.

To contain costs, 97% of the DDisS125’s parts were locally sourced.

“We have developed a compact engine with excellent fuel economy,” says C V Raman, executive director-design  development and engineering for Maruti Suzuki. “It was tough to meet the requirements of containing emissions (and) noise, vibration and harshness – but we have met them. We have made the small car fuel-efficient with a green engine. And there is no lack of power.”

The diesel optimizes tuning both for hot and cold weather as well as variations in fuel quality. “There is no loss in drivability or durability, efficiency or performance,” Raman says.

The engine is slated for use in Maruti Suzuki’s forthcoming first light-commercial vehicle codenamed Y9T.