Is 25mpg/city possible in a full size pickup?
 

Hello all. My current ride is a '95 Chevy k2500 with the 7.4 gasser/auto. This truck has been a very good truck and tows well. The down side is that it gets 10-11 mpg hwy and probably 8-ish in the city. I will be selling/trading this truck in the near future and I'm trying to plan ahead and start gathering parts for a swap. My question is; can I get 25 mpg in the city from a full size truck with some sort of diesel engine? I'm not really interested in the popular cummins swaps but I don't know what all engines are available to swap. I'm not going to hot rod the truck but it will need to be a daily driver in the city. My only requirements are that it be smooth running and not real loud. Any one have any ideas on what a good engine would be? Am I asking for the impossible? Don't hold back on your thoughts on this. My goal is to have a nice truck that gets great mileage. Thanks!!

PS.
I'm open on make and model of truck as long as its a full size 4x4.

I get 21 on good days and 19 on bad days and my truck weighs 9600 lbs

Not since the early 90s. A good running stock D250 1st Gen with a Getrag would do it driving empty carefully. Nothing since.

I have a buddy that swapped a 4BT into his 3/4 ton dodge two wheel drive. The truck originaly had a 5.9 gas engine and a NV4500. I know you said you weren't interested in doing a Cummins swap, but his truck averaged 26 on the freeway driving reasonably.

The 4bt was a route that I was interested in looking into.......until I heard/saw one running. My buddy traded around and got an old delivery type van. It had the 4tb and an automatic in it. Now I don't know alot about these engines but this thing was very rough running. I don't mean rough like it wasn't hitting on all 4 but like it was vibrating and shaking all over the place. Thats just not what I'm looking for.

You are aware that you can add a balance shaft to the 4BT? The insulators also play a big role in transmitting vibrations to the interior compartment.

Ditto^^^. Those things run A LOT smoother with a minimal amount of work and good insulators(engine/trans mounts). Add a balance shaft and have a machine shop balance the rotating assembly.

25mpg city isn't doable without an engine swap, other than the 1st gen dodges which aren't going to be anywhere near as comfortable as your 95 2500. Do you want to just swap something into your current truck or find a different truck?

The only other diesel for a swap the I know of to consider is the 2.5L I5 from the Dodge Sprinter vans. They use the 545-rfe 5 speed auto trans (same trans behind all the truck/jeep Hemi engines). It's a common rail injection system and makes plenty of power, astronomically smoother and quieter. The transmission has plenty of upgrades available but really doesn't need a whole lot, it's a good trans.

If you want a manual, I'm sure you could get a bellhousing or adapter to hang an NV4500 behind it but I don't know that for sure.

I didn't know about a balance shaft for these engines. Actually I know very little about a diesel engine but I'm trying to learn. I will be buying another truck to do this swap on. My current truck is a regular cab and I have a habit of keeping a truck for several years so I am thinking about an x-tra cab or short bed-crew 4x4. I have looked at the Sprinter engines and I saw a few on ebay but they are very expensive. These sound quite to me and seem to idle smooth but I have never driven one. This is not a swap question but Whit's post has me thinking now. Do you think a Duramax, 6.0PSD, or Cummins equipped newer truck could do 25mpg city? Every thing I read is about getting the most power and torque out of these engines but could you go the other way to get the most mpg? Sorry this is long, sometimes I start to ramble when I get going, lol.:w2:

The only way you will get that kind of mileage from any of the big three, is to put one of those engines in a very light truck. A 6bt in an S-10 comes to mind.

I agree, the only way to get better milage is to put the power of the larger diesel engines in a lighter truck body or put a smaller V6, 6bt, or 4bt into a full size truck. Changing your differential oil with a good synthetic oil reduces how hard the engine has to work to get power to the ground can help as well. You have options. The military used 4bts in their hummers for a long time and they are pretty heavy vehicles. My suggestion is a 4bt with all the balancing and such to make it a quieter, smoother ride or a 6bt which may be better but your milage will drop with it a little. :U:

Fuel milage is primarily a factor of vehicle weight and gearing. With what ever motor you choose; you will get better milage in a lighter vehicle with taller gears.
I would love to see a 6BT or D-Max in an S10 truck or S10 Blazer.

You know they did make a 4bt ISB engine for a couple of years.

I think if you could come across one of those it would run quiter and smother while also getting better fuel economy and even more power.

Just a thought if you have time to search for one in your area.

p.s I am currently averaging around 27mpg with my 97 f-150 4bt swap

I'm getting 28-30 mpg freeway on my 2wd 82 Chevy Suburban with the 6.2. It has 3.08 gearing and overdrive transmission and cruises along at 1600 rpm at 60 mph. Some of the mods I have done that increased gas mileage was headers, free flowing exhaust, ported heads and installed a timing gear. The trick to higher gas mileage on with these engines is to use the older 82-84 heads with smaller precombustion chambers, no turbo and tall gearing.

Ford Ranger or S-10 + 4BT Cummins + ZF 5-speed (gasser version for lower first) + GV overdrive unit + Ford 9" rear with 3.00 gears + good tuning + smart right foot = every bit of 25 mpg and probably much more :yeah:

Just my opinion...:w2:

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F-150 ex-cab short box would probably work too

well guys there are a few trucks with monster mileage that I can think of...a 4BT and a 600hp 50mpg 12V I think from the diesel power mag site. thats just to name a few. If you throw a 4bt with any kind of power in a moderately light vehicle there is almost no reason to get less than 25mpg imo.

oh and sorry the 12V 50mpg machine was 700hp

2007 Dodge Ram - Cummins Diesel Engine - Diesel Power Magazine
take a gander at this

and here is the Bronco I was thinkin of
1966 Ford Bronco - Photos - Diesel Power Magazine

There are quite a few high mpg machines out there even some with big power numbers

Answer is still no - not without extreme modification. I don't believe the OP was going for engine swaps and resto-mod conversions.

I disagree... Mileage has a LOT to do with driving style. If one were to obey all the tips and tricks to "hypermileage" then it might be possible.

What the reality is, it's probably not very possible for a "practical everyday" fullsize to make 25+ mpg...:nope:...not without some good modification, like NadirPoint said

You'd have to do a 4 cylinder diesel swap into something like a Ford Ranger to get that kind of mileage. I'm sorry but IMHO there's no way in hell you'll ever see 25mpg from a fullsize pickup truck in city driving. The old 6.5 Chev half tons were pretty good. IIRC my uncle's 94 was getting about 19mpg city and ~29mpg highway. I haven't seen a single full size pickup truck do better than what his truck did...

Oh, sorry - you ARE looking to do an engine swap! :ouch:

Still not thinking it's possible. The problem is with a 3+ ton vehicle it just takes too much energy to start and accelerate. In "city" driving you are assuming alot of starting and acceleratring, where the most fuel is consumed in any type vehicle.

The reason the early manual 2wd Dodge Cummins trucks were so good is because they had the right combo: Relatively light (for the 3/4t class) with a very efficient drivetrain in 5sp trim. But that peak 25mpg number is a "highway" number.

That's what I'd be driving if I wanted a dedicated tow vehicle or DD for the street. Add 4x4, weight goes up, mpg goes down.

I completely agree! My 82 Burb 4x4 gets high 20s as well and is a sure starter. I just don't understand why more people won't consider this swap, since these engines are incredible in my opinion. Hell, even the old HMMVs ran them...

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In fact, I am thinking of replacing the 350 in my 89 GMC 4x4 with a 6.2 for the economy and coolness factor. Then I will have only one gasser in my fleet to worry about poor mileage.

could add CNG to it and run on that too. alot cheaper than fuel.

However there are fewer units of BTU in LPG so you will use more.

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And fewer yet in CNG.

My opinion here..
 

You gotta be more clear here. Are you swapping or trading this truck? In answer to your first question, that answer would be a highly unlikely. There may be engines that would get you that mileage but they wouldn't be good to drive let alone tow with. 25MPG city is not a realistic expectation from anybody for a full size 3/4 T truck. I would challenge anyone that makes that claim to back it up with fuel tickets reflecting miles and gallons. Not the display numbers. In answer to your second question, any of the big three engines are potentially a "good" one. They all have good records overall. In answer to your third question, not the impossible, just the improbable given todays engines. Someday we will probably be there if the country isn't bankrupted first. There are many that claim that kind of mileage, few can prove it with fuel tickets and odometer readings.

My Bronco weighs exactly 5100 lbs on the scale with the '91 6BT in it and C6 auto/1200 rpm billet converter. I'm only averaging about 20-22 mpg with it, but I still need to tweak some stuff. I wish somebody made a 3.00 gear set for the high pinion D44 front axle, because the stock 3.50s and no overdrive are a limiting factor on my highway mileage. My truck still gets better mileage than my girlfriend's stock Liberty, so we always take my rig to save some fuel. haha!

I'd say an 03 or 04 2 wheel drive regular cab, manual with 3.42's swapped in would be a fairly easy way to get a real 25 mpg. Maybe ditch the tow mirrors and add a dam on the front bumper and I bet you would be right there without having to drive too careful.

my buddy has a 93 chevy crewcab dually running 19.5's with a cranked up 4bt in it, and he gets 27mpg out of it. not as fast as my truck but I get 19-21 out of my truck with a 6bt.