Best Fuel Eco Engine Swap - JeepForum.com
 5Likes
Reply
 
LinkBack Thread Tools
post #1 of 32 Old 06-27-2020, 09:14 AM Thread Starter
King_Nick10
Registered User
 
Join Date: Jun 2020
Posts: 2
Best Fuel Eco Engine Swap

I recently bought a 1974 jeep cj5 to restore. I’m not looking to do any major off roading. I’m looking to put a reliable engine in it that’ll get 20-23 mpg. Any suggestions?

King_Nick10 is offline  
Sponsored Links
Advertisement
 
post #2 of 32 Old 06-27-2020, 10:00 AM
MrPeter63
Registered User
1983 CJ7 
 
Join Date: Nov 2019
Location: WOODSTOCK
Posts: 73
Thing is an engine is just that, an engine. It's gonna suck down as much gas as your foot allows it to. Getting 20-23 mpg out of a 4x4 isn't an easy task. Jeep has been trying for years and years and wasn't until the JK they broke the 20 mpg highway mark. Of course people throw on bigger tires and so much for that. It's really more the transmission, differential gearing, and tire size that will effect gas mileage then what motor you have in it. Problem with the short wheel base CJ's is you are kind of limited in what you can "make fit" without a lot of fab work, custom drive shafts, etc.. and then getting 20-23 mpg probly ain't happening..
uptillnow likes this.
MrPeter63 is offline  
post #3 of 32 Old 06-27-2020, 10:07 AM
Axhammer
Web Wheeler
 
Axhammer's Avatar
1985 CJ7 
 
Join Date: Aug 2018
Location: Moyock
Posts: 1,138
Garage
Early to mid nineties 4.0

1985 CJ-7 Red with white hardtop, 258 auto
View my Pontiac in my profile
Axhammer is offline  
 
post #4 of 32 Old 06-27-2020, 10:17 AM
StoneTower
Registered User
1985 CJ7 
 
Join Date: Jan 2015
Location: Fair Oaks
Posts: 1,645
Some of the diesel swap guys claim they get those MPG numbers. Keeping skinny street tires on your Jeep will help the mileage tremendously.
StoneTower is offline  
post #5 of 32 Old 06-27-2020, 10:40 AM
MrPeter63
Registered User
1983 CJ7 
 
Join Date: Nov 2019
Location: WOODSTOCK
Posts: 73
The 4.2, 4.0, and even the 4 cylinder that came in the TJ never got more then 18 mpg highway. Yea with the EFI set ups you can tune them, swap injectors and what not. Get a little bit more MPG out of it. but for the most part your not gonna improve it more the a MPG or two...
MrPeter63 is offline  
post #6 of 32 Old 06-27-2020, 11:23 AM
CJ7-Tim
Real Jeeps have dents
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis
Posts: 28,257
Quote:
Originally Posted by King_Nick10 View Post
... I’m looking to put a reliable engine in it that’ll get 20-23 mpg. Any suggestions?
Jeep, Chevy, or other ? Carburetor or fuel injected ?

Pretty much, 18 mpg's is about what you will get from a brick shaped 4x4.

.
“When the people find that they can vote themselves money, that will herald the end of the Republic.”

- Benjamin Franklin
CJ7-Tim is offline  
post #7 of 32 Old 06-27-2020, 11:57 AM
bob4703
Registered User
1974 CJ5 
 
Join Date: Feb 2015
Location: Easley
Posts: 2,405
Some of the suggested engines might get you in the 20 MPG ballpark, but what it will cost you to get there will eat up your savings for years.

A 74 CJ5 is geared fairly low--3.73 or lower. There are folks here who will trade higher gears for your lower ones. There is a reason they want to trade. The higher gears are anemic in their Jeeps. I'm keeping mine.

When my wife bought our 74 it needed an engine so instead of rebuilding a worn out 232 I chose to buy a crate 258. Later I bought a rebuilt ethanol gas compatible Carter YF carb for it. With some tuning for power and not economy I average 15 MPH. That's driving in town, country, mountains, some off road, but very little highway driving. If I want 20+ MPG I drive my truck, but I'd miss the fun of driving the Jeep.

-----

Paved roads are prime examples of government over spending!
bob4703 is offline  
post #8 of 32 Old 06-27-2020, 12:12 PM
Matt1981CJ7
Web Wheeler
 
Matt1981CJ7's Avatar
1981 CJ7 
 
Join Date: May 2011
Location: Elbert
Posts: 22,581
Heck, my 2015 Tundra doesn't even get 20 MPG, empty. Throw a load in it, and a few mountain passes in the mix, and I'm lucky to get 15 MPG.

I think 20-23 MPG out of a 46 year old CJ will be a difficult task with any engine.

Matt


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Matt1981CJ7 is offline  
post #9 of 32 Old 06-27-2020, 01:38 PM
jeepdaddy2000
Registered User
 
jeepdaddy2000's Avatar
1971 CJ5 
 
Join Date: Jan 2002
Location: Eagle Point
Posts: 8,654
The real question is how much do you want to spend to get those numbers.





I assume your looking at highway miles, not city or combined.


A diesel swap will break 20MPG but will break your wallet as well.


The proper balance of tire size, gearing, and modern 4 or six cylinder will get you there, IF you drive 55MPH or slower.



So the offsetting question is how far will you have to drive to make up the difference in fuel cost to pay for you swap.

Paperwork will ruin any military force.
Chesty Puller
jeepdaddy2000 is offline  
post #10 of 32 Old 06-27-2020, 02:06 PM
momo2
Registered User
1980 CJ7 
 
Join Date: Jul 2009
Location: Vienna
Posts: 249
I easily get 20 mpg with my iron duke, 31 tires and a weber 32/36. I don't drive faster than 60 on the freeway though. And if i a really want to go cheap, i go with my BMW station wagon, it averages around 34 mpg even when driven really fast.

Gesendet von meinem SM-G950U mit Tapatalk
momo2 is offline  
post #11 of 32 Old 06-28-2020, 02:47 PM
agear
Registered User
1984 CJ7 
 
Join Date: May 2011
Location: norfolk
Posts: 3,471
Cummins turbo diesel
Jim1611 likes this.

1984 jeep cj7, 258 I6, rebuilt T176,rebuilt Dana 300, amc 20 , dana 30, 4.10's Trac-lok in rear , 4.10's detroit soft locker in dana 30, 2.5 inch bds suspension lift, 1 inch polyurethan body mount lift. Line ex. weber carburetor. factory tach. factory clock ,oem replacement speedomter cluster, and oil pressure gauge, factory volt gauge.
agear is offline  
post #12 of 32 Old 06-28-2020, 06:39 PM
oldschool74cj5
Registered User
 
Join Date: Jan 2017
Posts: 503
hello

mpg and jeep are 2 words that just shouldnt go in a same sentence. thats like prius and cool. just 2 words that dont work. i would do a engine swap that performs the best for what you are building it for.

oldschool
oldschool74cj5 is online now  
post #13 of 32 Old 06-29-2020, 06:25 AM
StoneTower
Registered User
1985 CJ7 
 
Join Date: Jan 2015
Location: Fair Oaks
Posts: 1,645
How much money do you want to spend


If you have the cash a Cummins R2.8 would be a nice swap.


Jump to 5:10

31 MPG highway

25 MPG City


https://shopcummins.com/products/cum...28164531421284

$7699.00

Not all that bad for a modern state of the art emission compliant motor (for smog states).
StoneTower is offline  
post #14 of 32 Old 06-30-2020, 05:20 PM
HighCountry
Registered User
1986 CJ7 
 
Join Date: Aug 2001
Location: North East Texas
Posts: 1,038
We are missing something... What engine is in the Jeep NOW? Chances are that you will be so many dollars ahead by keeping it like it was born, not to mention reliability and the ability to repair it for 'CHEAP' when/if it breaks. Just try to optimize what you have, drive it and SMILE!


Bruce
HighCountry is online now  
post #15 of 32 Old 06-30-2020, 06:26 PM
JEEPFELLER
Registered User
 
JEEPFELLER's Avatar
1977 CJ5 
 
Join Date: Dec 2015
Location: GREENWOOD
Posts: 97
Garage
I've got a Holley 390 and an Offenhauser 4 barrel intake on my '77 CJ-5 w/ 258.

This set up is the best I have tried and "messing with it" is EZ and most parts that might give a problem are locally available right then and there at the parts counter.

Prior to the Holley:

I swore I'd break the 16 MPG barrier in which 17 was always a no show and 16 was only with peak perfect factors working for me.

I was really depressed that I couldn't do better and stay really inexpensive and now I did not care, I was gonna do it no matter what price I might pay.

I had been trying like forever for better MPGs- with various carburetors along with every gimmick device available. A couple being the ole tornado over the carb, opposing magnets over the fuel line, additives, different jets, adjustments, different PCVs, you name it, I probably done it!

Normal (Grandma) regular ole driving almost consistently will yield me 18 or 18 and a bit MPG (Never have hit the 19 mark when I have checked the MPGs) Horse'n around of course will eat into my numbers alot!

I am now satisfied!

Pros: I'm still carbureted, pretty much everything works the same I just have a different carb and intake, in my countryboy rural pocket book, this seemed like an expensive endeavor.

Cons: really none----after seeing the extent of laboring and funds spent by some of the fellers on here I really think I got off still being simple and cheap!

But most of all---HAPPY!

Ain't it all pertty and stuff, sitting up in there like that?

-----JEEPFELLER
Attached Thumbnails
SHARKTEETH12wwwq.jpg  
JEEPFELLER is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome