Tow/Haul on Truck
I'm wondering how many of you use the "TOW/HAUL" mode on your trucks. I'm assuming this only a function with newer trucks but I imagine it's a feature across the board with the various makes. I have a...
Forum Discussion
bighatnohorse wrote:Grit dog wrote:
Someone please explain the "engine brake" on the Powerstrokes. . . .
I'll give it a shot. . .
To my knowledge, the newer Powerstrokes use a Variable Geometry Turbo (sometimes called a variable vane turbo).
In engine brake mode, the turbo vanes are closed, thus choking off air flow and causing engine compression braking - thus the term "engine braking".
In exhaust braking, there is a butterfly valve used, either after the turbo or in the exhaust pipe.
http://www.trucktrend.com/how-to/engine/0705dp-ford-f350-exhaust-brake-system/
Engine braking can occur without the use of a butterfly valve.
Yes, they do have a vgt that acts as an exhaust brake. All the light duty pickups use the turbos for the exhaust brakes now. Slightly different method than a butterfly valve down stream but same effect. They both choke down the exhaust for back pressure.
I understand that part, but there were a few folks talking about an engine brake AND an exhaust brake being used on the new Pstrokes. But I think you've confirmed that they only have an exhaust brake. Thanks.
Fwiw, exhaust brakes are very different than engine brakes. They both provide re tarding horsepower but engine brakes do it via the valve train, cracking the exhaust valves open at the right time to lower cylinder pressures to aide in slowing the rotation of the engine.
