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Most efficient driving speed?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=51&t=4823
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Author:  eyehatetofu [ Thu Apr 08, 2010 10:31 pm ]
Post subject:  Re: Most efficient driving speed?

2400 RPM's

79 MPH

17.5 MPG

Author:  Sharon [ Sat Apr 10, 2010 3:18 pm ]
Post subject:  Re: Most efficient driving speed?

Well i do play with the speed and see what is the best speed and rpms. with my liberty which is a CRD i get it up to around 65 and she shifts in to 5 gear lockup 2 and then set cruise and i drop her to 58-59 mhp she purrs at 1625 rpm the mileage just climbs. Now i did have the speed calibrated when i put the lift and the bigger tires on so i know that is wright. I do use the gps and check mileage and speed just to make sure. I guess with the full skids (maybe they help with less turbulance on the underside) and the SP diesel progamer on FE which is the fuel economy mode i do run 44psi in the tires filled with nitrogen. I have Goodyear Wrangler Silent Arnor tires. Now at 72 mph at 2000 rpm i was getting 34 mpg. Let see i was using Amsoil Cetane booster and fuel conditioner too. With the CCV disconected that really does help i think that added about 4 mpg just by itself but i left the MAF conected. i just did not want to deal with the CEL light. I figured the the EGR could open and Close but at least it was not getting all dity because the CCV was disconected.

Sharon
Best MPG so far is 38.5

Author:  CATCRD [ Thu Apr 15, 2010 6:42 pm ]
Post subject:  Re: Most efficient driving speed?

Sharon wrote:
Sharon
Best MPG so far is 38.5


Is that number from hand calculating after filling up the tank? Or just from watching the EVIC? You can't believe the EVIC, especially if you have a power module plugged in.

Author:  Boiler [ Fri Apr 16, 2010 1:09 am ]
Post subject:  Re: Most efficient driving speed?

I'm still baffled. I've got new U-joints, full syn all around, new autolite platinums last fall (old were clean), amsoil air filter, only engine and TC skids in steel, gas tank and radiator in aluminum, no rear bumper fascia at the moment, basically NO extra payload besides me.

When it was bone stock with no skids at all, premium touring tires, and no lift (and no rack) I got 17 or so on highway trips that used the full tank basically without stopping. In town I was getting 15.5 or so. Now with lift, rack, duratracs, and partial weight on skids I'm getting about 16 on the highway trips and 14 on my half limited access, half in town commutes. I do typically drive with all four windows open about 2 inches.

Even when I was bone stock I always complained about my engine braking. I'll drop from 70 to 40 faster than gentle brake riding, even down gradual hills. I also get lots of downshifting on hills / overpasses / 3 degree slopes in the road, and I always have. I used to have brake squeaking but that is gone since I had them redone this winter...well, I think it is gone, I have ceramics now so maybe they're just not making noise.

I'd love to find more things to check / clean / grease and find why my milage is so terrible. When I was bone stock I'd get an extra 1/2 mph if I kept the rpms under 2000 all the time, so very gradual accelleration.

I need to try LTT's cold air, but beyond that I think there is a problem.

250 miles when my dummy light dings that I'm nearly out of gas, or thereabout. Usually I get 240 to 260 on 17.5 to 18.5 gallons of gas. And yep, I've checked my odometer with my GPS, it is about 3 miles per hundred off. So add 7 or 8 miles to my tank count.

Finally, I typically drive 45 in town and 63-67 at 1900-2000 or so RPMs on my 4 lane commute. I do run a lunchtime or after work errand in town about every day, and sit in a drive through idling about 3 times a week. What I'd give for 20 mpg. :cry:

It doesn't sound like that much, but 5 mph is 100 miles more driving per tank. Thats a TON.

Author:  Daksport [ Sun Apr 18, 2010 1:33 am ]
Post subject:  Re: Most efficient driving speed?

How hard do you accelerate from a stop???

The quickest way imo to make or break your mpg's is acceleration. If you accelerate hard from a stop light (3000+ rpm before gear change) your mpg's will drop like a rock. A good steady acceleration keeping your motor down to max 2500 rpm while accelerating will definitely help improve your overall fuel economy.

As well, when traveling on the highways, keep the windows closed. When your driving in excess of about ~50 mph if I recall correctly the open windows cause more drag and kill your fuel economy more than running the AC. Windows open in town is alright.

Author:  stoutdog [ Sun Apr 18, 2010 11:47 am ]
Post subject:  Re: Most efficient driving speed?

Daksport wrote:
How hard do you accelerate from a stop???

The quickest way imo to make or break your mpg's is acceleration. If you accelerate hard from a stop light (3000+ rpm before gear change) your mpg's will drop like a rock. A good steady acceleration keeping your motor down to max 2500 rpm while accelerating will definitely help improve your overall fuel economy.

As well, when traveling on the highways, keep the windows closed. When your driving in excess of about ~50 mph if I recall correctly the open windows cause more drag and kill your fuel economy more than running the AC. Windows open in town is alright.

x2: Accelerate like you have an egg under the pedal. Keep the rpms down and the pedal pressure gradual.... In my CRD, I have no problem keeping up with traffic while keeping the rpms at or just under 2000RPMs

Author:  long_tall_texan [ Sun Apr 18, 2010 12:35 pm ]
Post subject:  Re: Most efficient driving speed?

Anyone got HP and Torque curves? Can figure it out from there. viewtopic.php?f=4&t=51955

Author:  Sharon [ Thu Apr 22, 2010 7:00 pm ]
Post subject:  Re: Most efficient driving speed?

My computer in the jeep has always been right on with calculating on a calculator, i do use the gps for the miles though becuase the miles rack up less for some reason on the odometer but no complaints to dealer becuase i rather show less then more. Which for some reason it is about 5 miles per 100. I drive easly and steady to a speed where she locks up in hi and then lower the speed to just before she drops into 4th. I get somewhere between 22 / 24 city / highway mix. I was wondering if anyone has tried a HHO generator on there CRD yet and if does increase the fuel mileage.

Author:  tommudd [ Fri May 14, 2010 4:01 pm ]
Post subject:  Re: Most efficient driving speed?

Can't say anything else, North of Toledo in Michigan, shows average MPG and had cruise on at 79 MPH
Image

Author:  jnaut [ Sat May 15, 2010 1:10 am ]
Post subject:  Re: Most efficient driving speed?

At 84000 miles on my engine, I can still squeak over 20mpg on an all highway trip going around 70mph. In town, not so great, I'm averaging between 14.5 and 16mpg. See my sig. Top of graph is 22mpg, each line down is by twos. Graph covers about a year of fillups. Year total average is 16.03mpg. Mostly in town driving.

Author:  TDiRooster [ Thu Sep 09, 2010 9:19 pm ]
Post subject:  Re: Most efficient driving speed?

Ex - If the posted speed is what you are driving, and you avoid sudden stops or rapid accelerating, you can post consistent mileage, you can exceed the maximum of each fill-up, this has worked in the past and is working in the present, and of course if you drive a green vehicle your driving style will be rewarded almost instantly.

Author:  CRD Joe [ Thu Feb 07, 2019 9:01 am ]
Post subject:  Re: Most efficient driving speed?

BVCRD wrote:
CRD Joe wrote:
I set the cruise at 57-58 around 1750+ RPM and at that I can get in the mid 30's on the highway.




How are you able to stay at 1750 rpm at 57-58 mph? At 60 mph, locked up in 5th gear, I am turning 1700 rpm. At 59 mph, the tranny downshifts into 4th, and the revs go higher, like over 2000 rpms.


Ive got a Green Diesel trans chip. My trans shifts up to 5th at 58mpg and I can drop down as low as 55 before it shifts down again. Here is a dash pic of a LONG trip I took down to Az from Eastern Washington. It worked out to just past 40MPG.

Image

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