12 Valve Engine and Drivetrain Talk about the 12V engine and drivetrain here. This is for 1994-1998.5 engine and drivetrain discussion only.

mpg's on 12 valve

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Old 04-09-2008, 06:11 PM
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My 95 2wd auto gets 22 in town, and 26 on hwy trips.
My 98 4wd 5spd gets 17 in town, and 21 on hwy trips.
Old 04-09-2008, 06:27 PM
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Originally Posted by MikeR
Nope, across the board they have been less fuel efficient.
When they were coming out with the 24v, Cummins said it would be more efficient and quieter...it was neither.
I'll have to disagree with that. According to the poll I did a while back, lots of 24v's (if not more) fell in the 21+ mpg range.

https://www.dieseltruckresource.com/...t=fuel+mileage
Old 04-09-2008, 06:33 PM
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Originally Posted by sal09
im not sure on the gears but i get 22 mpg on the highway at 1700 rpm on fifth gear
you have 3.54's most likely running that rpm on the highway, i have 4.10's and at 1700 rpm im doing under 60mph. all of my highway driving is done over 2k+. my around town driving is pretty much under 2k and with my 33's and my stock auto tranny with 117k falling apart, i get around 14mpg, combined with lots of highspeed runs and having my needle on my boost gauge playing tag with the 34psi mark on my 60psi gauge. I used to see around 20mpg when tranny only had 105k and the truck was pretty much stock. so i know it is possible with a 4x4 auto with 33's and 4.10's to get decent fuel economy.
Old 04-09-2008, 08:32 PM
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about 18mpg

mostly Highway with some town and traffic, I get about 18, sometime 17.
I have a 4x4 5speed with 3.55 gears tires 265x70x17 I think. I am like at 2200 rpm on the higway in the 70 to 75 mph area. P.S. I got a stock looking muffler now, with no cat, silencer ring?

Wish I were getting like 20 or more mpg
Old 04-10-2008, 01:27 AM
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Originally Posted by wcbcruzer
The 24v's are just as fuel efficient if not a tiny bit more due to higher injector pressures, more valves, and electronic timing.
More power=less fuel plain and simple. Look at the new 6.7's I have heard only 13-15 and 10 towing 6k.
Old 04-10-2008, 01:32 AM
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Originally Posted by wcbcruzer
I'll have to disagree with that. According to the poll I did a while back, lots of 24v's (if not more) fell in the 21+ mpg range.
You must be seeing some secret info the rest of us can't see. I just read that entire thread and 95% of the 20+mpg info was posted by 12 valvers.

I've been at this many years now, and still consistantly see what I posted.
Old 04-10-2008, 01:43 AM
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I just clicked on all the screen names of people who voted in the 21+ category. Of all the voters, there were 11 more 24v'ers than 12v'ers (3rd gen included). I mean, I don't know if 12v's get "better" mileage than 24v's. If anything, they're about the same.
Old 04-10-2008, 08:30 AM
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everyone i know around here gets less with their 24's than i do with my 12. the guy i bought it off of has asked if i want to sell it back to him since he only gets around 15. only one other guy i know has a 12v and he gets 15 but he has it pumped up and it smokes a lot. that being said all of them except for 1 have manual trannys, and they seem to accelerate out of corners and around cars like they don't care fuel is 4.19 a gallon. so i think and this is only my opinion not supported by a cnn poll, but if you drive like a sausage and your truck looks like you threw a gallon of 80-90 in a wood stove of course you will get bad mileage no matter what you drive.
Old 04-10-2008, 01:31 PM
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Our is getting around 13 now with the new transmission - hope to improve how it breathes a bit with new IC boots. Of course, it NEVER gets to run empty, always has a load or a trailer on it, or both!
Old 04-11-2008, 02:50 PM
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41 MPG as I just filled up today, of course that does not nclude the WVO.
Old 04-12-2008, 11:18 AM
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I recently traded a 24 for a 12. my 24 averaged 18-19 and my new 12 is getting 12-14. I am not sure what's going on.
Old 04-13-2008, 01:05 PM
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4.10's and automatic maybe?
Old 04-13-2008, 11:19 PM
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I get 17.6 around town and 20.8 on the highway running 1800 rpm. I know I can get better, just trying to figure out what holding me back because I drive it like a grandpa
Old 04-14-2008, 08:00 AM
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Originally Posted by Kansascrewcab76
because I drive it like a grandpa
thats funny stuff right there. you never seen a grampa till you seen my buddy get up to speed, i've never seen anything like it...
Old 04-15-2008, 05:57 PM
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im getting 27mpg mostly highway some city. but i drive to save fuel, speed down hills coast up hills stuff like that. i also have a custom air dam. i love my 12v compard to my powerstroke you can just tell he torque diff. when you hit a hill, it stays right at about 65 and juggs along. I NEVER SEE OVER 2K unless i wanna burn the silt out and turn 4K


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