Block Coolant Head Coolant Ignition Timing

Baseline Metal 180 180 Std.

Metal 220 220 Std.

Baseline Ceramic 180 180 Std.

Hot Ceramic 250 Air Std.

Hot Ceramic 250 Air -6

Hot Ceramic 250 Air +2

engine tests were conducted at speeds of 1400, 1700, and 2000 rpm for loads of 33, 66, and 100 percent of full power. The all-metal engine was first baseline tested with 180 and 220°F coolant temperatures at the standard injection timing of 12.5° BTDC. The engine was then insulated and tested with 180°F coolant temperature to see the effect of the insulated engine surfaces on engine performance, emissions, and combustion without the added variable of increased coolant temperature. High temperature engine tests were then conducted with the insulated engine by replacing the cylinder head coolant with a regulated supply of compressed air. Air flow through the cylinder head was adjusted to maintain a measured maximum firedeck temperature of 900°F. This temperature could not be achieved at some part-load conditions. The cylinder liner remained cooled with ethylene glycol at 250° F for three reasons:

1. Cooling the cylinder liner resulted in improved engine durability by maintaining an oil film on the cylinder to maintain the baseline air-fuel ratios. The full-load air-fuel ratio was 25:1. The exhaust gas back pressure was adjusted to maintain an intake air manifold pressure to exhaust manifold pressure ratio of 1.0. The intake air temperature was held constant at 180°F for all tests. Valvoline TurboGard 5 oil was used for all engine tests at a temperature of 250°F.

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