
Originally Posted by
Brian Hjelm
Chews bloody fuel. What BS. My 4BD1 County averages 24.1 mpg in inner city stop/start use, and 29.6 highway laden, upwards of 600 kg. in & on it, plus me & the cook. It will cruise happily at 105-110kph in fifth, and 120 if pressed. One of the reasons the Aus. Army selected them was cold start capability in extreme cold conditions. Waiting for glow plugs to warm up whilst being shot at is a bit of a turn-off. Also, a well proven fact is that big capacity naturally aspirated slow revving engines live longer than tiny highly pressurised ones. Big bore slow revving American engines and power trains are the choice of the outback trucking industry, unfortunately without turbocharging they are too heavy to make 600hp, otherwise nat. aspiration & mechanical injection would be the choice of outback operators. My experience with turbocharged and supercharged race engines is that you reach a point of diminishing return, where more boost is producing insufficient power to justify the added unreliability, problems, and expense. what we found with the turbo Offys was that increasing the boost pressures over the already very high figures only pumped more heat into the engine. We were already using high fuel flow rates and latent heat of evaporation (methanol blends) as part of thecooling system. For an outback vehicle the KISS principle should be first and foremost in the designers mind.
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