Engine/Transmission (1998.5 - 2002) Lower fuel economy for 24V VP44 truck doesn't make sense...

[Hohn]

I've thought this through, and I can't figure out why the VP44 trucks can't get or be made to get better mpg than a 12V truck.



Higher injection pressure-- favors 24V



Centered fuel injector-- favors 24V



More airflow-- favors 24V



variable timing- STRONGLY favors 24V



Higher compession ratio of ETH-- favors 24V





Yet, we know that 12Vs generally get better mileage! If the retarded stock timing is to blame, then a box like an EZ should restore that economy, shouldn't it? Yet that doesn't seem to happen.



Marco has successfully hacked the ECM for more spoolup and better response. Part of this is timing manipulation, or so most of us believe. Retarded timing= better spoolup on the bottom.



So why can't someone develop a box that allows you to adjust the timing with a simple knob??



Jacobs electronics makes such a box for gassers-- you can tweak your timing while going down the road. Others make variable ignition retards for nitrous use, which allow the driver to tweak on the fly... .



Sorry to ramble, but I just can't make sense of the lower 24V fuel economy, and I think the variable timing should REALLY help, but it doesn't seem to... .



Justin

 

[Tcolesanti]

Maybe its because they put out more power stock out of the same amount of cubic inches??? More power=Less mileage??? I don't know I am ramling as well.

 

[dacook]

I thought they got about the same. I get 20-23 driving 60-72 on flat land.

no clue to answer the question. What milage do you get?

 

[Tcolesanti]

I got anything from 19. 4 to 23. 5 empty bobtailing from Houston, TX.

 

[rmackay1]

I'm getting about the same as you guys, which I think is impressive

 

[mcoleman]

Same here mileage wise. Buddy of mine has 2 2wd rigs and the 24 valve one beats the 12 valve on mileage at every fillup.

 

[SEmerson]

After mods my 12v gets better milage than my 24v too. I beleve this to be becouse of emisions. Look how the 4. 5 get really poor milage.

 

[Hohn]

OK, is my assUmption that 24Vs get better mileage invalid? I've always been told that 12V tend to get better mileage. Some 12Vers have reported up to 27mpg best.



I'm not complaining, as my 24V gets amazing mileage for what it is. I ususally get around 20 in the interstate, driving fast with WOT passes.



Best was 24 babying it. This, in a 7000# 4x4 pickup.



I'm curious if guys running aux trannies report higher mileage when empty cruising on the hwy. .



Justin

 

[mhenon]

24V vs 12V

I thought the earlier, 1st generation (12V)trucks, were a little lighter than the 2nd gen rigs. This would account for any mileage increase if there really is one.

I couldn't be happier with the mileage my 24V gets. I've just started using Stanedyne fuel additive, full time, and it looks like my towing mileage may have crept up somewhat.

Overall... no complaints on the mileage of the 24V.



Mike

 

[wtfd6]

rear diff ratio makes a big difference. my 4. 10 ratio only gets me 14. 5 mpg city/highway. 16 on the highway. ive known guys with 3. 54s that got 22-24 mpg. wish i got that.