70mph, the new 55mph...

[comptiger5000]

I'm sorry, but 33hp per 1000 pounds isn't necessarily enough. To achieve this AND gain efficiency, this would mean my 4000 pound Jeep would have a 2.5 or 3 liter engine. In other words, it would have way too little torque, and would be a nightmare to drive. The 4.0l 6 cylinder (195hp / 230 tq) is underpowered in these things on the highway. Around town, the power isn't a big deal. However, at 60, it has to downshift, so it's no longer turning 1800 rpm, but screaming 2800, to maintain speed on a hill. However, my 5.9L V8 (245hp, 345 tq) with the same gearing has no trouble churning up that hill (and even gaining speed if desired) at 1800 rpm in OD with the TC locked. I've pulled hills around town at 1100 rpm at 37-38 mph in OD with the TC locked. My instant mpg reads about 9-10 doing this. With the smaller engine (4.0), it reads about 8 instant mpg turning 2000 rpm in 3rd (TC unlocked unless you manually lock out OD, then it locks in 3rd) on those hills around town.

[Christ]

Originally Posted by comptiger5000

I'm sorry, but 33hp per 1000 pounds isn't necessarily enough. To achieve this AND gain efficiency, this would mean my 4000 pound Jeep would have a 2.5 or 3 liter engine. In other words, it would have way too little torque, and would be a nightmare to drive. The 4.0l 6 cylinder (195hp / 230 tq) is underpowered in these things on the highway. Around town, the power isn't a big deal. However, at 60, it has to downshift, so it's no longer turning 1800 rpm, but screaming 2800, to maintain speed on a hill. However, my 5.9L V8 (245hp, 345 tq) with the same gearing has no trouble churning up that hill (and even gaining speed if desired) at 1800 rpm in OD with the TC locked. I've pulled hills around town at 1100 rpm at 37-38 mph in OD with the TC locked. My instant mpg reads about 9-10 doing this. With the smaller engine (4.0), it reads about 8 instant mpg turning 2000 rpm in 3rd (TC unlocked unless you manually lock out OD, then it locks in 3rd) on those hills around town.

Gearing makes more of a difference here, as well as the fact that you're using an auto trans. The trans downshifts way before it actually needs to, in almost all applications.

IMO, it shouldn't downshift until you're at ~80% throttle and still decelerating. I used to remove kickdown cables and levers and just downshift manually for this reason.

Anyway, climbing that hill has everything to do with torque production at the RPMs you're afforded.

I have 265 lbft of torque at 2,000 RPM in my F150, and in 5th gear at 1,000 RPM, I'm ~32 MPH, IIRC.

Today, I climbed a 4% grade for over 1,000 vertical feet in 5th gear at 70% throttle, vehicle speed ~28 MPH, which is = ~900 RPM.

At one specific corner, I slowed down to ~20 MPH, which is ~500-600 RPM. If I go any lower than that, I'm still not lugging, but oil pressure starts to drop off, and I don't like that. After the corner, I never downshifted, just put it back to 70% throttle and went back to ~30-32 MPH until I got to the top of the hill.

This is in my '96 F150, carrying about 800lbs of crap in the bed, including a motorcycle and set of 30x9.5-15LT rims and tires.

Vehicle speed vs RPM vs load vs scenario makes a huge difference in whether or not you can do certain things. Believe it or not, if I'd downshifted to 3rd, I'd likely have had to slow down, because at ~3k RPM, I have nearly no torque (comparatively).

This isn't particularly the case for your 4.0, but that auto isn't really helping your case.

[MadisonMPG]

Originally Posted by comptiger5000

I'm sorry, but 33hp per 1000 pounds isn't necessarily enough. <snip>

That's why you have a manual 6 speed. Jeeps (at least the old ones) aren't meant for the highway and should honestly not have an OD. The 33hp /1000lb thing comes into play when you are talking about things that belong on the road.

[cfg83]

99LeCouch -

Originally Posted by 99LeCouch

Driving the speed limit around me is passe. People get mad if you're going the PSL and holding them up. Many times people have whipped around me, only to get stopped at the next red light, or cluster of cars further up the interstate.

If they want me to go faster, then they should pay for my gas and whatever fines/increased insurance/new car I'd need after going faster.

Yeah, I've tried to think of a pithy bumper-sticker in the vein of "will speed for gas money".

CarloSW2

[Christ]

Originally Posted by cfg83

99LeCouch -



Yeah, I've tried to think of a pithy bumper-sticker in the vein of "will speed for gas money".

CarloSW2

LOL. I like that one.

[roflwaffle]

Originally Posted by Old Tele man

...my "point" was GASOLINE is tangible, while TIME isn't.

Only if someone is using tangible strictly in reference to being able to touch something.

[gone-ot]

...got a spare "minute" to lend me?

[Christ]

Originally Posted by Old Tele man

...got a spare "minute" to lend me?

I think I've lent you enough minutes for comments like this... :P

(I keed.)

[roflwaffle]

Originally Posted by Old Tele man

...got a spare "minute" to lend me?

Sure! Anyone can have 60 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

[IsaacCarlson]

I like my 1991 F-250....LOADS of torque down low and good gearing to go with it. The first three gears are towing gears and the other two are MPG gears. I decided to use synthetic oil to help with the lower oil pressure when driving in town. Like Christ, I run LOW RPMs. I can run around town in 4th gear all day and shift to 5th if I am doing 30+. If I have a load of wood I run the gears out a little more to get the oil pressure up.

I am just itching to get the TCC lock put in the olds.....it has a LOAD of torque down low too. Hardly ever has to downshift to climb a hill. If I could keep it locked up in all gears but 1st I would be very happy.