MPG thread!

Just out of pure curiosity (boredom?) what are the other intermediates seeing for fuel economy?


I"m seeing 10-14 mpg with a TBI 258 t14 373gears and 31's. With the 10mpg on a 310mile highway trip at 75+ mph (yes im young and stupid). The 14 cruising at 45-50 under ideal conditions.

What are the rest of you seeing?

 

Right now I am getting REAL good mileage since the jeep is broke and undriveable...I;ve had the same tank of gas in it for nearly a week now. mehh(transmission is on the garage floor right now).

It is however my DD and I average between 10-13 MPG...mostly city driving.

If I keep my foot out of it I get close to 13...if I do a lot of stop and go or drive it harder than normal it sneaks back down to 10.

 

I used to get mid-teens with my '75 CJ-6, brand new. 258, T-14, 3.73s.

 

Dunno, speedo hasn't worked since I got it So I tell people about yay to there and back

 

I just took a 350 mile trip in my 72 with a 258 and 3.73s on 30s and I got 14.5 driving 65.

 

I get 16.7 going 60-65 in V8 3 speed 32" tires and 4:27 gears. This is with the MPEFI with the closed loop feedback turned on. I turn 2800+ RPMs at these speeds and am amazed I am doing so well.

I used to get 10.5 with motor-craft carb.

 

MPEFI? Multi-Port Electronic Fuel Injection?

I would like to hear more about this system you have.

 

yes do share!

 

Edelbrock pro-flo #3531 for the AMC V8. I was sold on it as completely replaced my ignition and fuel system. A buddy up the street has a stock 360, my EFI 304 "blows his doors clean off". It is completely compatible with the larger 360 and 401 versions with just a flash if I choose to go big. This was the first thing I did to my CJ in 15 years and was going to be the only thing. After I ran it and realized how this kit fixed all my pet peeves of the cold blooded, stinky, gas guzzling AMC, I decided to do a frame off resto and built a jeep around a potent little 304. I have had the kit installed since 2006, I have had to replace an O2 sensor but that is about it. I'll also mention that I used to struggle to pass the emissions laws in my state. I pass with no problems now.

Kit has dizzy, harness, pump, filter, intake, throttle body (fully assembled intake), tuner... I had to buy plugs and wires and a coil if I recall. I was not happy with the external mounted fuel pump and installed a summit racing in-tank pump for a 5.0 mustang.

 

Edelbrock is not the only source for MPI for the AMC V8s. Here's a recent thread about Custom EFI's product: http://www.ifsja.org/forums/vb/showthread.php?t=118907

 

Sounds like a great upgrade. Summit has the kit for just over $2,700. That's a bit rich for me right now. But it's good to know that it works that well. Thanks.

 

for 1200 you have a tbi system, 2700 for a High Performace system isnt a bad price.


Are any of you guys running an EGR system? Im going to try to get mine working with my tbi computer control. I'm hoping it will reduce some of the pumping losses at part throttle.

 

I figured that after 150 tanks of gas, it will pay for itself... I hope I live that long as I will always, always own this Jeep.

 

Reduce pumping losses at part throttle?????

 

energy lost to the engine having to pull air though a partially closed throttle body. It takes work to create that vacuum. By allowing some inert gas (exhaust) back into the intake manifold after the throttle It reduces the vacuum. While not changing the power output or the air/fuel ratio.

 

EGR systems are primarily an emission control device used to lower NOX emissions at part throttle, they do this by introducing exhaust gases back into the intake to lower combustion temperatures which lowers NOX. When the EGR valve opens it does change the O2 sensor voltage some and I don't think you would see any performance or fuel economy gains by having it operating. Many diesel engines use EGR systems to lower NOX also and they have unrestricted air intake systems (no throttle).

 

I'm about 15mpg...sometimes more if I'm not climbing mountain roads. It seems the T18a get's a bit better gas milage on the trail, though.

 

Last time I checked the swapped in 5.0 EFI ford was getting 12 mpg, that is with 4.56 gears and 33 inch tires. I havent had a chance to check it with the new 35's but it might inprove some as the rpm's at highway speed are now a bit lower.
Once I get the computer tuned it should improve somewhat. If not I plan oa a 21 gallon tank.
Biggest mpg problem I have is keeping my own right foot out of the throttle.