A six cylinder direct-injection diesel engine of 105 mm bore was modified for heat insulation and turbo-compounding. The insulation was provided by entirely eliminating cooling water and replacing major hot parts with the ones having air gap or ceramic insulator in their structure.
The engine was run with three different fuel; Diesel fuel with 52 and 30 cetane number and coal derived fuel, SRC-II. Due to the elevated temperature of combustion chamber in the insulated engine, ignition delay was significantly shortened and helped to burn the low cetane fuel. The engine could run with SRC-II, cetane number less than 10, though the rate of pressure rise was excessive at light load.
Cylinder liner temperature was almost 400°C and way above the empirical limit for conventional water cooled engine but the engine could complete a couple of 250 hour durability test.
Combining with turbocompound system, the heat insulated engine was concluded to be a very viable approach for the high thermal efficiency and crude fuel acceptability of future engine.