rpm when towing
When towing with my ram diesel how do I tell when I should downshift. it seems to tow so easy, but slows when going uphill at 60 what should my rpm show.
Forum Discussion
4x4ord wrote:
Torque comes from the amount of energy in the way of fuel that can be burned in an engine per revolution. Larger displacement yields more torque. Higher boost pressure ... more torque. Diesel needs more air to properly burn than does gasoline so more energy can be burned into a set volume of air if gasoline is used as the fuel as opposed to diesel.... therefore gasoline has a higher potential for making torque than does diesel. You are right that the use of an engine has a lot to do with its design. It won't surprise me if the newer gasoline DI/turbo engine technology and the fact that gasoline requires less restrictive measure to be used to meet emission requirements causes engine builders to turn toward designing gasoline engines to be favoured over the diesels for towing.
What each fuel does outside of the engine is one thing. How each engine uses that fuel is another. Gasoline engines are regulated by air and add a certain amount fuel to stay around a stoichiometric air/fuel ratio (14.7:1) while diesel engines are regulated by fuel and uses all the air available to burn lean most of the time. The more air you add to a diesel engine, the more efficient it becomes. The more air you add to a gasoline engine, the more fuel it consumes to stay around stoich. This is one of many reasons why diesel are way more efficient than gas engines under load and are used for towing applications.
Yes, with the same compression ratio gasoline engines would be more efficient, but I don't live in unicorn would-a could-a should-a world so I go by what the real world has. Diesel fuel itself allows for much higher compression ratios making the diesel compression ignition more efficient at utilizing more out of a drop of fuel than spark ignition.
I disagree on the emissions thing. As technology increases, I see less emissions devices on future diesels. Cummins has already deleted the EGR on their current ISL engines and only utilizing SCR making the engines more efficient and better performance. they already have plans to do the same for other engines on their line up including the ISB 6.7L.
