LOST JEEPS :: View topic - Ultimate fuel mileage in a CRD?

Just some thought going thru my head. But, it stands to reason if you lift a jeep and put bigger tires on it the fuel mileage drops significantly. Now with that in mind would it stand to reason there might be some increases with a lowered liberty and maintaining some original equipment sized tires? But lets go a step further than this.

-Convert to two wheel drive(less mechanical drag and less weight if you remove the front diff and related pieces.
-Lowered to reduce the frontal area(less aerodynamic drag)
-Lower numerically rear gear ratio(lower rpms at interstate speed) Factory 4.10 to a 3.55 or 3.21 is available
-Engine tune and a downpipe for more torque at lower engine speeds to go with the rear gear

I know it would be easier to buy a car to get better fuel mileage. I like to be different and experiment so initially just a rear gear change and disconnect the front drive shaft. This would be nothing more than a daily driver. I have a lifted Liberty already and its not a practical daily driver.

This would all be done on my second Liberty. Helpful input is appreciated and negative comments are not. Keep those to yourself. Thanks.

Author:	mpm17 [ Wed May 25, 2022 4:00 pm ]
Post subject:	Ultimate fuel mileage in a CRD?
Just some thought going thru my head. But, it stands to reason if you lift a jeep and put bigger tires on it the fuel mileage drops significantly. Now with that in mind would it stand to reason there might be some increases with a lowered liberty and maintaining some original equipment sized tires? But lets go a step further than this. -Convert to two wheel drive(less mechanical drag and less weight if you remove the front diff and related pieces. -Lowered to reduce the frontal area(less aerodynamic drag) -Lower numerically rear gear ratio(lower rpms at interstate speed) Factory 4.10 to a 3.55 or 3.21 is available -Engine tune and a downpipe for more torque at lower engine speeds to go with the rear gear I know it would be easier to buy a car to get better fuel mileage. I like to be different and experiment so initially just a rear gear change and disconnect the front drive shaft. This would be nothing more than a daily driver. I have a lifted Liberty already and its not a practical daily driver. This would all be done on my second Liberty. Helpful input is appreciated and negative comments are not. Keep those to yourself. Thanks.

Author:	TURBO-DIESEL-FREAK [ Thu May 26, 2022 5:42 am ]
Post subject:	Re: Ultimate fuel mileage in a CRD?
mpm17 wrote: Just some thought going thru my head. But, it stands to reason if you lift a jeep and put bigger tires on it the fuel mileage drops significantly. Now with that in mind would it stand to reason there might be some increases with a lowered liberty and maintaining some original equipment sized tires? But lets go a step further than this. -Convert to two wheel drive(less mechanical drag and less weight if you remove the front diff and related pieces. -Lowered to reduce the frontal area(less aerodynamic drag) -Lower numerically rear gear ratio(lower rpms at interstate speed) Factory 4.10 to a 3.55 or 3.21 is available -Engine tune and a downpipe for more torque at lower engine speeds to go with the rear gear I know it would be easier to buy a car to get better fuel mileage. I like to be different and experiment so initially just a rear gear change and disconnect the front drive shaft. This would be nothing more than a daily driver. I have a lifted Liberty already and its not a practical daily driver. This would all be done on my second Liberty. Helpful input is appreciated and negative comments are not. Keep those to yourself. Thanks. The two best things you can do for your Liberty CRD to increase fuel economy are... 1) Get an engine tune and matching transmission tune that are geared for economy. Green Diesel Engineering had excellent tunes until the EPA clipped their wings. I understand that Yeti tunes are very good as well. 2) Get your engine operating temperatures up higher. North American Liberty CRD vehicles are subject to politically influenced pollution control regulation that forced Daimler Chrysler to make changes to the R428 engine that are detrimental to the reliability, power production and fuel economy of the engine. One example of this is engine operating temperatures. The rest of the world gets these engines with 195 degree thermostat valves in them; we here in North America get 176 degree thermostat valves to lower NOx emission levels. The NOx levels are lower here, but at the expense of an engine that does not combust the diesel fuel efficiently. This also contributes to the engine being clogged out with pollutants because it never runs hot enough to burn some of them off.

Author:	mpm17 [ Thu May 26, 2022 9:08 am ]
Post subject:	Re: Ultimate fuel mileage in a CRD?
The two best things you can do for your Liberty CRD to increase fuel economy are... 1) Get an engine tune and matching transmission tune that are geared for economy. Green Diesel Engineering had excellent tunes until the EPA clipped their wings. I understand that Yeti tunes are very good as well. 2) Get your engine operating temperatures up higher. North American Liberty CRD vehicles are subject to politically influenced pollution control regulation that forced Daimler Chrysler to make changes to the R428 engine that are detrimental to the reliability, power production and fuel economy of the engine. One example of this is engine operating temperatures. The rest of the world gets these engines with 195 degree thermostat valves in them; we here in North America get 176 degree thermostat valves to lower NOx emission levels. The NOx levels are lower here, but at the expense of an engine that does not combust the diesel fuel efficiently. This also contributes to the engine being clogged out with pollutants because it never runs hot enough to burn some of them off.[/quote] Thanks Turbo Diesel Freak. This is the type of information I was looking for. I'm familiar with GDEs wing clipping. I'm in Alabama so no emissions testing for me. I'll probably get a set of cables and appropriate software and load one of the available free tunes if they are still available. Already have the EGR delete so I'm ready for the CEL to go away. Did not know about the thermostat temps differences. I'm about the open up the top of my lifted Liberty and will plan to replace the thermostat while I'm in there. Thanks again for the information.

Author:	user113 [ Thu May 26, 2022 11:44 pm ]
Post subject:	Re: Ultimate fuel mileage in a CRD?
Go with the skinniest original sized tires to maximize MPGs, or even a slightly larger diameter tire in a skinnier size. Either way run them at the max psi to reduce rolling resistance.

Author:	TURBO-DIESEL-FREAK [ Fri May 27, 2022 7:56 am ]
Post subject:	Re: Ultimate fuel mileage in a CRD?
"Thanks Turbo Diesel Freak. This is the type of information I was looking for. I'm familiar with GDEs wing clipping. I'm in Alabama so no emissions testing for me. I'll probably get a set of cables and appropriate software and load one of the available free tunes if they are still available. Already have the EGR delete so I'm ready for the CEL to go away. Did not know about the thermostat temps differences. I'm about the open up the top of my lifted Liberty and will plan to replace the thermostat while I'm in there. Thanks again for the information." mpm17: Don't rush out and get an O.E. thermostat so fast... perhaps you are unaware that they are a throwaway assembly where the thermostat valve is encased in a cheap cast aluminum housing. You do not get a choice of opening temperatures for the thermostat valve inside as the aftermarket largely avoids thermostats like this. You are essentially forced to accept the 176 degree Fahrenheit E.P.A. mandated thermostat valve. I sent you an e-mail message with an alternative you may be interested in. Best regards. Jeff Bauer

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Author:	2prong [ Sat May 28, 2022 2:38 pm ]
Post subject:	Re: Ultimate fuel mileage in a CRD?
Would love to get the alternative info you emaild mpm17 too tdfreak! Thanks!

Author:	mrhemi [ Mon May 30, 2022 7:05 am ]
Post subject:	Re: Ultimate fuel mileage in a CRD?
I have put over 150000 miles on one of my CRDs with the mods mentioned above. It consistently knocks down 33mpg (Can) on the hwy. with the cruise set at 77mph (125kph). Range is good for nearly 700 km per tank.

Author:	TURBO-DIESEL-FREAK [ Tue May 31, 2022 2:45 am ]
Post subject:	Re: Ultimate fuel mileage in a CRD?
2prong wrote: Would love to get the alternative info you emaild mpm17 too tdfreak! Thanks! I just sent the same e-mail to you that I sent to mpm17... verbatim. BOTH the e-mail messages are from the LOSTJEEPS.com online forum website; the e-mail address should read Administration@lostjeeps.com. Both e-mail messages to you and mpm17 have the following words on the subject line... JEEP LIBERTY CRD ENGINE THERMOSTAT You should both reply directly from your e-mail address to my e-mail address, (INTCOMBUSTION2@hotmail.com). No sales are to be conducted through LOSTJEEPS.com as I am not an official vendor.

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