Mileage and reliability.

[BigSquints25]

where is everyone on mileage with their 2.8? And have they had any problems? If so were they from the swap and missed something? We’re they part failure? Easy to fix? Are you loving your 2.8?

[DieselJeep]

Mine isn't together yet, but I look around at the Foton Tunland occasionally and that 4x4 truck claims about 27 mpg. Just a starting point. I don't expect that. After talking with Bruisers and Axis, 25 mpg is possible for my build with on-road gearing and mild off road tires. As a rule of thumb due mostly to the energy density in diesel vs gas and typical thermal efficiency between the 2 engines, a 40% increase is possible for similarly sized engines and applications. There's also another component that is often overlooked in regard to MPG and that deals with the engine size and the usable torque in your normal RPM range.

I haven't really looked into reliability of the engine in the Fotons, but there's so many variables that I don't know. There were some reports that these weren't good engines, but I've only seen anecdotal evidence from odd areas in Russia and China. DieselToys poo pooed on them and I inquired about access to a Toyota half with a D4D engine or whatever but never got a response and that swap looked too difficult anyway.

To be honest, I've only seen anecdotal evidence, these are good engines, but I believe they are a sleeved block and coworkers that have worked in shops with those style engines would have fairly lower level techs do partial rebuilds in a shift without pulling engines if they were sleeved. I've got no experience in this though for smaller engines, but we sleeve stuff in industry all the time and it speeds up major rebuilds quite often. I have been wanting to see the timing adjustment on these, which is in the rear, but when I've had timing issues it was always from worn guides, not chains or sprockets, though those were changed too. Bosch knows how to make a fuel system so I would suggest changing filters slightly more often and not messing with it. Common rail diesels often get a bad rap, but typically if they are maintained and not messed with they just keep on lasting.

I'm not sure if anyone has really looked around on Quickserve or not, but I'll try to look for some diagrams and if I see something interesting I'll let you know. I suspect these engines will be pretty good if taken care of with any regularity. There is a little valve on these things that I don't like, but they're easy enough to bypass if someone was so inclined.

[RePowerToy]

Have built many of these now and all running like champs. The aero of your vehicle and tire size will determine fuel consumption. the RePowerToy typically got 19-22 on 35” tires. The Discovery gets about the same or just under due to its weight. Working on one right now that we should clear 40 mpg when done....

These engines are built to last, are they as robust as the larger engine? Maybe, simply because it is a blanace of weight/size/ performance when building an engine. With the stock tuning or slightly over there is no reason this engine will not last the life of the vehicle, if properly taken care of. Just like any engine.
If you treat it like most owners that want 1000000 horse power from their Cummins, you will eventually kill it like any engine.

Keep in mind it’s a 2.8l engine making nearly 300 ft lbs! 15-20 years ago getting 100 ftlbs per liter was not common for a production engine. Sorry that turned into a rant, but in other words very, very reliable with over 25k miles on builds with no parts replaced!!

[BrdHntn]

Low end of the range is 24 mpg pulling grades and 70-75mph, 26 mpg on highway 60-70 mph through 5 tanks. Compared to the 22RE and swapping to a manual transmission, it's so nice having that power and not hunting gears at the slightest incline.

[DieselJeep]

I don't have my odometer yet and I've been off-road some and I've been idling a lot for various reasons and doing some sweeps checking stuff out. Estimating from Google Maps I did about 220 miles +/- 20 mi and I filled back up with 8.667 gallons. My tires are 32.6" in diameter, AX-15, 3.07 gears. I seem to have a slight leak around the tank somewhere. I suspect it's somewhere in the venting, but it's hard without dropping the tank to confirm.

Just to mention it here too. With the new tune I've had no trouble pulling up steep grades and accelerating in 5th gear. With the original tune I had to get into the throttle more and on one grade I didn't down shift but my speed dropped below 70 mph, but I didn't floor it either. I used to not be able to pull that hill at all with the 4.0L I would just drop to like 50 mph in 4th but I was afraid my old engine would explode if I shifted to 3rd and took it to the red line.

[DieselJeep]

I had a tank with half in-town driving and half towing which was mixed highway and off-road in 4x4 lo. I didn't write down the exact amount of fuel used, but I know about how much it was and on that tank I was getting 18-22 mpg. Sorry it was after an ice storm, we had no power and I needed to fill some gas tanks for my generator and just missed how much I added.

For a week I did all in town driving and the average was just over 22 mpg. I've done a few tanks mostly on the highway 60-70 and I'm getting just over 26 mpg. And that's with an awning on 1 side, a light bar on the hood, 33x10.5 KM3s, 1" BL and 2" Suspension. I talked with some guys that work at a Cummins shop and their opinion was an EGR delete would be beneficial hands down.

The place I screwed up and it still haunts me is the oil pressure sensor adapter. It was threaded into the aluminum oil cooler in a hard to reach area and the adapter kept leaking and I didn't support the area properly and stripped out the threads in that port. I did do a somewhat repair and its been fine, but very frustrating. Just install that before the engine is swapped in.

What I removed from the engine to inspect the damage and clean it up, the machining and designs for sealing seem excellent. This likely won't be a 6BT as far as leaking is concerned.

I wish this was an OEM option. That's my biggest issue. OEM can spend so much time and man power and testing to integrate something like this. They can also do it in a way that after awhile you can get parts cheap and for some of these common vehicles, parts are in stock in the town you live in.

[Sanders]

I know I'll be labeled as biased being who I am - but I too am a customer and have daily driven my personal build for over a year now and prior to that have driven test vehicles since around 2014-2015.

In my full time 4wd Disco 2 on 32" rugged terrains and 4.32:1 final drive ratio, I am consistently at 20mpg driving around town which is most of my duty cycle. I get upwards to around 23 when running highway speeds (75-80mph) but I'm also spinning more than I need to be. Our bigger and heavier 80 series sees 25mpg on 33's with 4:10's. Our little TJ is 24-31mpg on 31's and 3.73's.

As DieselJeep says above, so many integration factors play into FE. We saw a Vixen RV pulling down 29mpg with the R2.8 on last year's Cummins Cruise and he was 9k lbs spinning the engine at 3200rpm! His aero was so much better than ours that he was winning the fuel economy challenge (until the hot rod Volvo 122 came along pulling down 47mpg!).

As far as reliability, I've literally trusted my life and obviously my reputation with this engine on multiple occasions with three Ultimate Adventures, two Cummins Cruises, countless test trips, and the most important test of all - packing my family up and driving a through remote areas with no cell coverage. Videos don't do justice of what Fred Williams, Verne Simons, Christian Hazel, and now Trent McGee put this engine through. No product is without the occasional issue but that's what the 2-year warranty is for My personal Rover hasn't had any issues to speak of and I'm around the 15k mile mark

[DieselJeep]

Your posts are so informative, thanks for coming on here.

Btw I'm still on my stock 3.07 gearing on 33s (.79 5th gear). Have you all messed much with various gearing? On the highway 5th is now functional after the swap, but I've been debating 3.55 vs 3.73 for a bit more torque and so I can shift to 5th a bit sooner. I didn't know if you could chime in on this to optimize my MPG on and off road.

By the way, now that I'm running a roof rack, I try to keep it 65 mph and under on the highway.

[Sanders]

Thank you! I am trying to be more disciplined in my posting to help where I can!

In your current configuration you should be able to set a land speed record Our black TJ has 3.73's on 31's (measuring to about 32") and is about perfect. Going to a slightly larger tire for it would make it even better. My vote would be for the 3.73. This will allow you to shift into 5th sooner and you'll still have plenty of RPM left to run over 90mph if you ever find yourself needing to get out of the way of something. It's been my personal experience that FE is more about the load at any given RPM so engine speed is only part of that equation. We've observed that spinning faster doesn't always equate to worse fuel economy.

You would be sitting right around 2000 RPM at your desired cruise speed of 65 mph with ability to bump it up to around 80mph around 2400 RPM essentially matching my Rover's final drive ratio. My final overdrive is .67 with a 4.32:1 t-case/RAR drive ratio which puts me in the exact space. I've got plenty to run 80mph on the interstate all day long and it's also super peppy on the country roads running 40-60 MPH.

[hawraned]

Please post your latest experiences with the reliability of your personal R2.8 and the ones you tested for Cummins. Your last post to this thread about reliability was 10/7/2019. I would like to know what has happened in the last 19 months to your R2.8 and the ones that you have been testing.

[RePowerToy]

Welcome, not much to report on any of the engines I have installed or own. The RePowerToy broke another transmission but that was just a ticking clock. One engine with about 25k miles developed a small oil leak from the rear cam cover, just popped it off and resealed it.

Nothing really to report beyond that, engine is reliable and makes great power stock and even more with tuning!

[Sanders]

My personal rig/daily driver has been trouble free going on 3 years. I change the oil, fuel filter and air filter almost on time each time I’ll edit the post with hrs update from ecm clock.

The Cummins rigs are all in the same boat. The jeep frame is rotten and needs replaced so we’re looking for one to get it back on the road. The vehicles continue to be used for testing as well as random corporate loaners for vacation etc.

[97 TJ]

I have a 97 TJ with an AX15 and 3.73 gears with 35's that I put the R2.8 into. I average 19-20mpg. I have put about 20K on the swap. Seeing what every one else is getting for mileage mine seems a little low? Any suggestions?

[DieselJeep]

That sounds right for most 35" tires if you drive like a normal person. I would assume more highway would get you a bit over the 20 mpg mark. I'm running 33x10.5s AX-15 with newish 3.73 gears (and something wrong in the rear axle I think), 2-2.5" lift and a roof rack. I recently regeared and I'm around 20 mpg now, but a similar setup with the 4.0L I'd be getting 10, maybe 11 mpg. I might add that I drive around without the rear seats and add weight in the back to keep my springs somewhat compressed. I picked my springs based on trips where I'm loaded and on the highway some. I can choose to either be overloaded on trips or underloaded daily, I chose underloaded.

I think driving style and maybe seeing if there's anything that is not helping your aerodynamics that you don't really need could be adjusted. An aftermarket tune might help as well. It looks like the global tune (I think HD global gets 360 lb-ft) for this engine isn't what is loaded for the US market and the US regulations aren't here to make your engine last longer or use less fuel or have much affect on air quality. I wish I could say otherwise, but I look at the data and look at the recommendations/requirements and they may make claims, but they aren't true for anything but unrealistic situations that don't pertain to real world conditions and I'm not sure it's not meant to hamstring diesel to promote EV. I'm not knocking EV for the sake of diesel, but right now diesel is king and EV is quite some time away from the necessary infrastructure and development, except for the very wealthy urban population that can afford an extra toy.

[Aggie Jeeper]

i am averaging 20 mpg over 18,000 miles now. For a lifted jeep on 35" tires this is better than i ever would have expected. No issues on reliability yet too.