diesel truck help can't decide what to get

[egon]

FWIW, a Jacob's engine brake closes the exhaust valves and the compresion stops it .

Isn't "Jake" brake an acronym for the real words which I can never remember? [img]/forums/images/icons/grin.gif[/img]

Egon [img]/forums/images/icons/grin.gif[/img]

[Bird]

I guess it might be an acronym, but I just always thought it was an abbreviation or slang for "Jacobs".

[Pat]

Egon, The '97 and on (don't know when they changed it) auto tranny in the Dodge/Cummins would break lock on the converter when coasting (especially in 4th). This is not a good thing to do when using an exhaust brake as then the brake slows the engine only but since the engine is not connected to the rear wheels it provides no actual brakinig to the truck.

I had to go after market/third party supplier to remedy that.

I don't think I will be getting a new truck any time soon unless I win the lottery and the odds on that are really slim since I don't buy tikets. I think my wife expects the '97 truck to outlast me. I told her it only has to outlast her and then I can buy a new one.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] Actually what the Jacobs system does is open the exhaust valve at the top of the compression stroke to take away the "spring" effect that the compressed air would impart to the piston after it passed top dead center. Near the top of the stroke, the exhaust valve pops open and poops all of the trapped air into the exhaust manifold. [img]/forums/images/icons/crazy.gif[/img] With the Jacobs system you get the grade retarding effect of the compression stroke without the corresponding effect of that compressed air on the power stroke. [img]/forums/images/icons/crazy.gif[/img]

[egon]

A little more info on the exhaust brake for the Dodge.

web page


And this site for the heavy duty brakes:
web page

Egon [img]/forums/images/icons/grin.gif[/img]

[Pat]

tbolt, a good description of a system that automatically shifts to the lowest gear available without overspeeding the engine. If this system is in use on a gas engine it will give good engine braking. If it is in use on a diesel (big rig) without either variable valve timing (compression release braking) or an exhaust brake such as is used on diesel pickups, then it will not do much for you.

Downshifting a diesel without an engine brake system gives you a lot more RPM and very little braking effect.

P.S. I envy the newer Dodges with the tranny mods stock to support an exhaust brake.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[Bird]

I haven't driven one of the Duramax trucks, nor the later model Dodges, but that Freightliner FL60 with, I believe, a 300hp Cat engine and Allison that I drove for a week was one of those that downshifted as it slowed. That thing was great to drive.

[tbolt]

I don't know how it all works but it does slow you down
(a great deal) I have electric trailer brakes but this really helps by itself. Maybe some other Gm owners have a better explanation of how it works, all I know is that it does work.

[hudr]

Pat, regarding my experiece w/ gas vs. diesel and one out-coasting the other. My thought process was skewed from the beginning. I wasn't comparing apples to apples. In other words, diesel w/ manual and gas w/ auto, P/U to car, weight diff., etc. I did a little research, sat down and went through the 4-stroke process and decided I shot from the hip a bit on my original posts. [img]/forums/images/icons/grin.gif[/img]
Not the first time I have engaged mouth before brain. [img]/forums/images/icons/grin.gif[/img]
Also, looking at a couple of your other posts, I agree about the trannies on most diesel p/u's. I know my 6.5TD Chevy needs another gear between 2nd and 3rd and Dad's old 92 Dodge Cummins doesn't shift where I think or how I think it should (feels like every other Chrysler auto I've driven, slushy). Anyway, thanks for helping to put me straight on all that. [img]/forums/images/icons/grin.gif[/img]

[Pat]

hudr, None of us were born knowing all we know, we had to learn it sometime A_N_D we are all friends here. If friends can't help, debate, tweak, bedivil and otherwise enjoy each other then somehow we just aren't doing it right.

Now when do you suppose someone with marry an Alison to a Cummins in a one ton. (Or a Chinese truck, a Won Ton)

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]