Re: [A/S] Stick shift for towing?

["Jim Dunmyer" <jdunmyer@xxxxxxxxxxx>]

Woody,
 Although a Diesel has much more compression than a gas engine, it has
little compression braking because of the lack of a throttle butterfly. The
piston simply "bounces" on compression, so no work is being done to amount
to anything. With a closed butterfly, the gas engine is TRYING to pump air,
but can't, so has quite a bit of resistance/back pressure.

Point of information: a "Jake Brake" (brand name) works on the exhaust
valves of the engine, I believe that they open the valves just about the
point of maximum compression (TDC on the compression stroke). They're very
noisy because of that. The "exhaust brakes" that are used on light-duty
diesels in p/u trucks are a simple butterfly in the exhaust pipe, just after
the turbocharger. If used with an automatic, special provisions must be made
to keep the torque converter clutch locked, or you'll get very little
braking effect, and a VERY hot transmission. That's why some truck
manufacturers void the tranny warranty if you add an exhaust brake.


<<Jim>>