AussieHJCruza
Supporting Vendor
- Joined
- Jul 8, 2013
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- New South Wales, Australia
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- www.completecruisers.com.au
Apologies if I sound like a know-it all d@#*head but that advice is incorrect for a diesel. Unlike petrol engines where a lean condition leads to hot combustion, (higher Exhaust Gas Temperatures, numerically higher Air-fuel ratios) in a diesel, running rich leads to hot combustion (higher exhaust gas temperatures, numerically lower air-fuel ratios) which can lead to melted pistons and the likes. A diesel runs cooler when run lean. In a petrol engine, typical Air-fuel ratios would be in the 11:1 area with EGTs (in an aircraft engine - my only real experience in petrol engines about 815 degrees Celsius (1500 degrees Fahrenheit) whereas in a diesel (where I spend most of my time) ideal air-fuel ratios would be around the 18-22:1 mark and safe EGTs of 650 degrees celsius (1200 farenheit) which is why worked turbo-diesels like what @gbentink does (such as 1HD-Ts) run boost in the 30-40 psi area with AFRs around the 20:1 mark. This is further reenforced by the fact that most diesel engines do not have a throttle body - the airflow entering is pretty much unrestricted and the engine speed is regulated by fuel alone, whereas in a petrol, the airflow is regulated by a throttle body or carby and the fuel charge is supplied based on air entering because a lower AFR in a petrol (to a practical limit) = cool, whereas in a diesel a lower AFR (ie, rich condition) = hot which can be catastrophic.On the pump settings, white smoke can also indicate lean condition, black is a rich condition. Back it down until you see SMALL amounts of black smoke. Black smoke under heavy load is OK, but your mileage will drop off comparatively. Better to run a diesel rich (black) than lean (white). Running lean will create hot spots in the cylinder and score a sleeve in the block.
I hope this is understandable and somewhat relevant, and once again, not wishing to be a smartarse, just wanting to help the O.P. with the right advice.
Edit: Note, all EGT values given are in the exhaust manifold, not after the turbo if applicable)
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