Back in 2019 Maruti Suzuki introduced its own diesel engine, a new 1.5-litre motor, on the Ciaz sedan in the Indian market. Before this, the brand had been using (Fiat) FCA’s diesel motor, a 1.3-litre unit which led the brand to where it is today. However, the engine deal from FCA was an expensive one and after 12 years the brand finally had to chance to make its own diesel engine. Upgrading the 1.3 DDiS was also an expensive affair for the brand so much so that Maruti Suzuki planned to develop a new diesel engine on its own. And this gave birth to the E15A, a 1.5-litre 4-cylinder oil motor.
Essentially the E15A engine was supposed to be two E08A engines which was a twin-cylinder diesel motor that was sold with the Celerio. The two 800cc diesel engines were joined together and the displacement downsized to make the E15A. However, even for a less experienced diesel engine manufacturer, Maruti Suzuki’s E15A diesel engine was not only smooth but also offered ample performance, thanks to the expensive dual mass flywheel and use of light weight material in its construction.
So why did Maruti Suzuki discontinue such a good engine at the turn of the BS6 era? The E15A which made its debut with the Maruti Suzuki Ciaz and then employed on the Ertiga was killed saying that the demand for diesel engines had dwindled and BS6 norms that were tighter than before made the cost go up increasing the price gap between diesel and petrol cars. Also, petrol engines had become more efficient and the price between petrol and diesel fuel was also not much. However, Maruti Suzuki had invested over 5 years and INR 1000 Crore in development costs just to run the engine for 1 year, so what happened?
According to a media report, the E15A engine cylinder head featured an integrated exhaust manifold. This was done not only to save weight but, the head also integrated water jackets to cool the exhaust gasses improving efficiency. But this is a problem with the diesel engine, which already runs cooler than the petrol and this could lead to a problem of over cooling if the exhaust manifold is integrated with liquid cooling system.
What happens is, the hydrocarbons in the diesel exhaust are passed through a DPF (Diesel Particulate Filter). This filters the unburnt hydrocarbons before it reaches the environment. However, this process can happen only if the hydrocarbons are in the gaseous state. Under 180-degrees Centigrade, the hydrocarbons become liquid and are unable to pass through the ultra-fine channels in the DPF.
This complicates further during the regeneration process. The DPF is exposed to temperatures of around 1000-degrees C to burn off the soot into harmless ash. But if unburnt fuel is trapped in the DPF and it combusts, the temperatures can rise up to 1300-degrees C which can harm the ceramic based substrate in the DPF. In addition to this, lighter vehicles with a large diesel engine, do not heat up the motor compounding the problem of over cooled exhaust gas as the engine load is less.
Will Maruti Suzuki in the future redevelop the E15A for the Indian market? The question remains.
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