New Geely 1.5-litre 4-cyl Hybrid Engine Boasts Over 40% Thermal Efficiency!

Until recently, Chinese carmaker BYD’s Xiaoyun engine series stood as most thermal efficient mill in mass production with a claimed rate of 43%. Now, it seems they’ve been dethroned by rivals Geely and their new BHE15 Plus 1.5-litre 4-cyl mill that boasts a higher thermal efficiency rating of up to 44.26%.

Before we digress, here’s a quick way to grasp thermal efficiency – it essentially the amount of energy an engine can extract from fuel. The average thermal efficiency for any regular combustion engine ranges between 20% to 30%. However, in recent times, the likes of Hyundai, Toyota, and GAC have already built engines boasting 40+% thermal efficiency.

Back to Geely’s latest mill, it employs the Miller Cycle but much of its high thermal efficiency stems from other tech employed in the BHE15 Plus. It includes enhanced tumble ratios, high compression ratio, increased height-to-diameter ratio, as well as a high-pressure fuel injection suite rated at 350 Bar.

Produced en-masse now in China, this new mill is set to power things like the just announced Galaxy L7 plug-in hybrid (PHEV) model we reported on earlier. In this model, Geely touts that the mill can deliver an average fuel economy figure of 5.23 litres/100 KM on top of peppy performance – 0-100 KM/H in 7.5 seconds, 200 KM/H V-max.

Besides the Galaxy sub-brand, Geely is widely expected to field this new mill into its other brands too such as Lynk & Co. However, in the case of Proton, it’s likely that the national carmaker – who has a partnership with the Chinese giant – may not receive this highly efficient mill just yet.

To be clear, no existing Proton models – either native (Persona, Iriz, Exora, and Saga) or Geely based (X50 and X70) – are primed with any mills form the BHE15 family, from which this latest BHE15 Plus unit derives from. Instead, Proton is set to receive Geely’s 1.5 TGDi mild hybrid (MHEV) units that we’ve detailed in this prior post of ours.