The ideal vehicle

[comptiger5000]

Plus, engine braking (with DFCO) saves money in the form of brake pads.

[TimG]

Bicycle Bob-

Saab experimented with variable compression about ten years ago. I thought it was a great idea, maybe it's time is come.

Saabnet.com Press: Saab Variable Compression Engine

Tim G

[dcb]

Originally Posted by comptiger5000

Plus, engine braking (with DFCO) saves money in the form of brake pads.

I would happily change 20 sets of brakepads than one clutch

[jamesqf]

Originally Posted by Old Mechanic

3. Deceleration Should not exist.

I see you live in the flatlands. Come over here where we've got mountains, and I dare say you'll change your mind.

Beyond that, you need deceleration for proper handling, as for instance when entering curves.

Of course it'd be advantageous to somehow fake the deceleration with regen, but you still need it, and at least the level of control over it that you get from downshifting, to have a driveable car.

[comptiger5000]

DCB - If you can rev-match the downshifts correctly (regardless of auto vs manual), clutch and/or transmission wear is minimal. Technically, if with enough practice, its possible to downshift without the clutch.

When I need to slow down getting off the highway on a short ramp (and traffic won't allow me to coast down enough before the ramp), I downshift to 2nd for more engine braking. My family members all give me strange looks when I shift down, then hit the gas to rev-match while I'm waiting for the tranny to shift. After some practice, I can get the rpm almost dead on every time, eliminating that typical clunk/jerk felt when downshifting an auto.

[dcb]

But you are now spending gas to slow down with the revmatch, lol

[comptiger5000]

Technically, yes, but it's still minimal, and more than made up for by the time spent in DFCO while slowing down, vs letting the engine run at idle fuel down the ramp, as the RPMs may not be high enough to kick it into DFCO.

Of course, EOC would be better, but I won't subject my auto tranny to the lack of lube without the engine running. So in my case, if it wouldn't have gone into DFCO otherwise, it saves me a little gas, or if it would have, it's a crapshoot, as the gas wasted on the rev-match is balanced out by the reduced brake pad wear.

[dcb]

cmon, I thought jeeps were toads? Most Popular Toads

worryin about a 12 year old auto, lol. Drive it into the ground and put a stick in there mr modder

[comptiger5000]

I would LOVE to put a stick in this thing.

However, it is expensive, and requires a lot of custom fab work, although it's been done a couple times before. If it was a 6 cylinder, it would be much easier, as the first 2 years (93-94) were available with a 5 speed. However, the V8 version of this thing never came with a stick. It requires fitting a transmission that was never meant for this vehicle, custom tranny mounts and crossmember, custom shifter, ECU swap from a dodge pickup, etc. Total cost is about 1500+.

And, if I really wanted to do a good stick setup, I could adapt a Viper 6 speed to the engine, although that would have even more cost (2500+), as I'd need to re-gear the axles from 3.73 to 4.56, as the Viper tranny has such tall gearing through the whole range. Without a gear change, I'd be lugging 1320 rpm at 60, making 6th gear unusable except on dead flat ground. Also, the lower gears are pretty tall, so I'd have no power off the line in 1st. Currently, I turn a little over 1800 rpm at 60.

With the viper tranny and 4.56 axle gearing, I'd turn just over 1600 at 60. I could even go as far as the axles will support, to 4.88, giving me a bit over 1700 at 60. That would probably be my best option, as I would drop my crusing RPMs a bit, but not enough to worry about lugging, or having to downshift a lot on the highway (it never does with the current auto). And, I'd have plenty of power in the lower gears.

Basically, for this vehicle, I can put A LOT of gas in it for the cost of a stick conversion. When I go away to college in the fall, my goal is to hit 22mpg on the trips between there and home. After college, I fully intend to buy another vehicle and retire this one from DD duty.

And just think: If I drove like a normal, inefficient driver (hadn't found this site, and learned about DWB, etc), I'd probably be getting 9 - 10 mpg in my current cycle. On this tank, the computer is saying 13.3 so far, as it's vacation week from school. More or less the same driving, including the short trips. However, it excludes the really inefficient drive to and from school (lots of short roads, up/down hills, only 2.5 miles, etc). But, regardless of the gas mileage, I love my Jeep . Plus, my auto is in pretty good shape and shifts great with 102k miles on it. Rest of the Jeep runs well too.

[dcb]

ok, but it is still a toad, no? if you can tow it behind an rv you can eoc all day.