Rolling resistance and driveline efficiency?

[CanMan]

This thread is:

 

[RCP Phx]

:roflmao:

No... but I think we should all do that so we don't have to drill anymore for oil...

And judging by your first post, you're one of those who didn't read the thread

:cheers:

You called in sick to work today,didnt you!:roflmao:

 

[CanMan]

You called in sick to work today,didnt you!:roflmao:

Thats some funny sh!t.

 

[ECKSJAY]

:roflmao:

No... but I think we should all do that so we don't have to drill anymore for oil...

And judging by your first post, you're one of those who didn't read the thread

:cheers:

I read the thread and I think you're wasting your time.

 

[PurpleCherokee]

Looks like someone else is asking the same question.

Synthetic fluids are a great example of what I'm talking about but I, along with most others, are already running them.

I thought that this was interesting: "...mopar already has a higher efficiency automatic; the 45RFE and its derivative, the 545RFE that I've seen claimed at 17-20% loss (80-83% efficient)."

I have no idea where the AW4 would lie. But then again, we've got transfer cases to deal with too.

Another example (though I don't know if they are made for an XJ, except for the universal stuff like u-joints, wheels, and tires) would be lightweight driveshafts, axles, wheels, and tires. Maybe higher efficiency wheel bearings and/or u-joints? Simply higher quality materials with more precise tolerances? A lot of this stuff could be customed by someone and it would probably cost an arm and a leg and may not be nearly pheasable.

 

[asp]

Listen closely...

AERODYNAMICS MATTER VERY LITTLE AT LOWER SPEEDS.



-Austin

Not only that, but there's a LOT more involved with XJ fuel efficiency than aerodynamics. Aerodynamics are a big factor ON THE HIGHWAY but certainly not the only factor and certainly can't be used as a blanket statement as to why XJ's don't get the best gas mileage.

ANY VISCOUS LOSSES SUCH AS BEARING DRAG, ROLLING RESISTANCE, AND AERODYNAMIC EFFECTS ARE ALL SOMEWHAT MINOR AT LOW SPEEDS ARE MINOR COMPARED TO ENGINE EFFICIENCY.
BETTER FLUIDS WILL IMPROVE LIFE NOTICEABLY BUT INCREASE PERFORMANCE LITTLE.

BY THE WAY, I'M TYPING BIGGER THAN YOU.

 

[Ba-Riedo]

BY THE WAY, I'M TYPING BIGGER THAN YOU.

:laugh2::laugh2::laugh2::laugh2::laugh2:

 

[PurpleCherokee]

ANY VISCOUS LOSSES SUCH AS BEARING DRAG, ROLLING RESISTANCE, AND AERODYNAMIC EFFECTS ARE ALL SOMEWHAT MINOR AT LOW SPEEDS ARE MINOR COMPARED TO ENGINE EFFICIENCY.
BETTER FLUIDS WILL IMPROVE LIFE NOTICEABLY BUT INCREASE PERFORMANCE LITTLE.

BY THE WAY, I'M TYPING BIGGER THAN YOU.

Not anymore you're not

And bearing drag isn't a viscous loss, but at slower speeds, rolling resistance and kinetic friction are your main sources for driveline inefficiency, NOT aerodynamics. Not only that, but they're the only elements that we can do sh*t about lol. There's not much you can do about driving a brick besides try to improve it's efficiency in other ways :guitar:

 

[redriverhugh]

light weight works, samuri,s get good mileage, put your xj on an extreme diet. Maybe cut most of the sheetmetal off, put a tube frame in and lose all the glass except the windshield and front side windows, lose the doors, just make a light door frame and skin it with thin aluminum. Doesn,t sound to practical though it might be fun. Where I live the cops would prob take it off the road the first time they saw it.

 

[asp]

Not anymore you're not

And bearing drag isn't a viscous loss, but at slower speeds, rolling resistance and kinetic friction are your main sources for driveline inefficiency, NOT aerodynamics. Not only that, but they're the only elements that we can do sh*t about lol. There's not much you can do about driving a brick besides try to improve it's efficiency in other ways :guitar:

bearing drag is a viscous loss. a viscous loss is one that increases with speed. bearing drag increases the faster you spin it. i've taken a class or 5 on this. :lecture:i'm a senior in mechanical engineering right now...:read:

something to help the cause would be to pull the front driveshaft though...

 

[Deadman 94 xj]

This thread SUCKS

 

[PurpleCherokee]

bearing drag is a viscous loss. a viscous loss is one that increases with speed. bearing drag increases the faster you spin it. i've taken a class or 5 on this. :lecture:i'm a senior in mechanical engineering right now...:read:

something to help the cause would be to pull the front driveshaft though...

Ya know, it's funny you say that cause in about 5 minutes I'm puttin mine back in lol. I just got back from autozone to get a set of u joint straps that I somehow lost when I took it out. I didn't notice anything at all without it and it's startin to get nasty out and I'm tired of driving a 2wd jeep. As far as the viscous thing I've never heard of it referred to as that but I believe ya. But that's just all the more reason to upgrade your bearings right?? And as far as upgrading would you agree with better materials and smaller tolerances?

 

[asp]

yeah better materials and tighter selection tolerances will make a bearing smoother and all that jazz, but all the bearings like unit bearings or carrier bearings or stuff like that isn't really available in "smooth rotating" options. if anything better fluids (gear lube, motor oil, etc) will help but even that won't do much. the thing is that the xj produces too much power for low speed operation. because it's not using all of the power it produces, it becomes inefficient...

moral of the story:
if you want good gas mileage go buy a honda.

 

[PurpleCherokee]

the thing is that the xj produces too much power for low speed operation

Which is where gearing comes in. Seems to me that in terms of fuel efficiency, the XJ has too much torque for low speeds and not enough horsepower for high speeds. I just find it hard to believe that with all of the advances in engines in the last 10 years, that the drivetrains haven't advanced much at all, beside maybe simply better manufacturing or higher quality materials.

 

[igotanxj]

bearing drag is a viscous loss. a viscous loss is one that increases with speed. bearing drag increases the faster you spin it. i've taken a class or 5 on this. :lecture:i'm a senior in mechanical engineering right now...:read:

something to help the cause would be to pull the front driveshaft though...

So what exactly do they teach you how to engineer in mechanical engineering??? I'm thinkin about switching my major. They teach you how to build cars? Or just a bunch or random mechanical stuff?

 

[asp]

mechanical engineering is so much more than cars, but cars happen to incorporate all aspects of mechanical engineering. i've learned metallurgy, thermodynamics, manufacturing processes, automatic controls and system dynamics, component design, assembly desgin... i left stuff out from that list too... and we get machine shop time for a few of the classes. it's pretty cool, but it's a lot of work. what school are you going te be doing this at?

 

[5spd_xj]

nerd. :read: :looser:


jusssst kidding.

 

[PurpleCherokee]

Way to chime in on the driveline efficiency w/the 5 SPEED

I'm guessin you gave up a long time ago on mileage though right?

 

[asp]

Way to chime in on the driveline efficiency w/the 5 SPEED

I'm guessin you gave up a long time ago on mileage though right?

him and i both have 5 speeds.... if you drive a 5spd right you can get better mileage than with auto.

nerd. :read: :looser:


jusssst kidding.

which one of us has a cool job? hmm?

any bets on how long till this thread gets locked?

 

[5spd_xj]

5 SPEED. well going with all the *gay* comments describing this thread... no surprise your jeep is an auto....

oh, and it's purple?