Quote:
Quote:
Originally Posted by DieselCAR View Post
The VW TDI turbo diesels cut injection quantities to next to nothing when in gear going down hill - (with your foot off the accelerator). Even more efficient than coasting out of gear with the engine idling.
It seems that there should be some way to use this same technique in your truck when there is no demand on the engine.
UFO -
Actually it's not more efficient than coasting with the engine on, there is significant engine braking that costs momentum when the fuel is cut.
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Maybe this behavior is unique to TDI's. On a significant downhill grade I can shift into 5th and have very little engine braking effect - and the electronics basically cut off fuel to the engine. When the RPM's get down to around 1250, the controller starts feeding fuel to the engine again.
So implementing this behavior electronically, or some type of start/stop technology, when the engine has no load should be beneficial.
Even better of course would be some form of regenerative braking. This is where even a small battery pack might be very useful - in helping to keep the start/stop or electronic injection from needing to cycle as frequently.