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
ShinerBock wrote:
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.
The DI gasoline engines are no longer regulated to a 14.7 air/fuel ratio nor is the compression ratio limited. Preignition can't happen without fuel being injected.
Hopefully emission equipment for the diesels will become simpler and less taxing on fuel economy but until they can get rid of the DPF and the DEF there is an efficiency tax that the diesel has to pay.
