F450 vs Ram 3500 DRW tow vehicle
So the wife and I are moving to the full time RV lifestyle. We just purchased a 42' toy hauler this weekend, with a GVWR of 20K#. Now I'm looking at a tow vehicles. I'm considering either purchasing a...
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"Tests have been conducted on Agricultural tractors by Nebraska Tractor Tests and have shown that when 1/2 of rated HP is needed a tractor will burn nearly 30% less fuel running the engine at 80% rated engine rpm vs running at full rated rpm."
The main efficiency advantage in slowing down a diesel comes from the fact that it takes time to inject the fuel into cylinder. Fuel injected after the piston has moved very far down does not get the opportunity to push the piston as hard or as far, resulting in torque loss. So basically, if you are operating near the dropoff in the torque curve there can be real efficiency gains from reducing rpm. Full rated RPM is typically near the dropoff in torque. After you are well away from dropoff there is not so much to be gained as a partially loaded diesel not have to such air past a throttle plate like a gas engine does. Not that there isn't a gain, it just isn't nearly as significant.
The main efficiency advantage in slowing down a diesel comes from the fact that it takes time to inject the fuel into cylinder. Fuel injected after the piston has moved very far down does not get the opportunity to push the piston as hard or as far, resulting in torque loss. So basically, if you are operating near the dropoff in the torque curve there can be real efficiency gains from reducing rpm. Full rated RPM is typically near the dropoff in torque. After you are well away from dropoff there is not so much to be gained as a partially loaded diesel not have to such air past a throttle plate like a gas engine does. Not that there isn't a gain, it just isn't nearly as significant.
