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Just joined - '69 Bronco

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  • Just joined - '69 Bronco

    Hey everyone -

    I just joined today while researching a R2.8 swap for my 1969 Bronco. It looks like I have a few challenges ahead with transmission adapters (currently using a ZF5), but having CAD and machine shop access as well as an engineering background, I may take this one on myself.

    Looking forward to meeting some like-minded people and playing with a new engine.


  • #2
    Looks great and welcome!!

    I have been hoping someone would build a bronco with a 2.8.

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    • #3
      Is that first pic in Moab?

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      • #4
        Originally posted by Victorino View Post
        Is that first pic in Moab?
        Longmont, CO during their annual cruise night.

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        • #5
          Pulled the trigger today. R2.8 on the way!!

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          • #6
            That is going to be so cool.

            How's that trailer/camper? What are the specs of your current engine (well engine with that trailer/camper)? I want to add a trailer for my Jeep and just wondering how they handle on-road/off-road. I'm debating an off road utility vs the off-road camper type, but I keep coming back to both. What a compromise.

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            • #7
              Originally posted by DieselJeep View Post
              That is going to be so cool.

              How's that trailer/camper? What are the specs of your current engine (well engine with that trailer/camper)? I want to add a trailer for my Jeep and just wondering how they handle on-road/off-road. I'm debating an off road utility vs the off-road camper type, but I keep coming back to both. What a compromise.
              Current engine is a warmed-over 351W. ~350HP @ 5000 rpm / 440lb-ft @ 3500 rpm However, I live in Colorado, so in the front range, engine is only making 279 HP and 360 lbft. On the mountain passes where I need the most power, its down to 245HP / 308 lbft MAX. Additionally, it sucks to hold the engine at 4000+ rpm for 10-20 minutes at a time while ascending a grade with a trailer. My 7.3L PowerStroke is only rated for 225HP and 475 lbft, 300,000 miles ago and it pulls much better at altitude.

              I love the trailer. It makes camping with the family more enjoyable since most camping is off-grid in the National Forrest. The camper isn't heavy at 2800 lbs, but presents a decent wind load at speed, so it feels heavy. The Bronco does a decent job towing it, but I have modified it with larger brakes, hydroboost, 5-speed trans and a trailer brake controller. Off-highway, the Bronco and trailer are highly maneuverable. It fits in smaller areas and covers rough terrain pretty well, albeit slowly. I have taken it to some areas where you just don't take traditional tow rigs and trailers. Cross-wind can be a handful, but we just slow down a bit.

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              • #8
                Are you planning to modify the R2.8 some for a bit more HP and torque? I went from like 220 ft lbs at 2,800 RPM to 307 ft lbs at 1,800 RPM with my swap so it's night and day. Even the V8s I've had really had to be wound up to go up hills and pull stuff. My diesels are 5th gear pullers for the most part. If I'm towing on a steep hill, I would have to use a lot of throttle to maintain speed with the R2.8 and my gearing.

                My fuel economy is easily double now and even though we've got like under $2/gal gas, it's still slightly cheaper for me to fill up now than before. But hey if fuel is cheap then great, but if fuel ever gets expensive, then I'd rather use as little as possible.

                How's your gearing for the Bronco?

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                • #9
                  Originally posted by DieselJeep View Post
                  Are you planning to modify the R2.8 some for a bit more HP and torque? I went from like 220 ft lbs at 2,800 RPM to 307 ft lbs at 1,800 RPM with my swap so it's night and day. Even the V8s I've had really had to be wound up to go up hills and pull stuff. My diesels are 5th gear pullers for the most part. If I'm towing on a steep hill, I would have to use a lot of throttle to maintain speed with the R2.8 and my gearing.

                  My fuel economy is easily double now and even though we've got like under $2/gal gas, it's still slightly cheaper for me to fill up now than before. But hey if fuel is cheap then great, but if fuel ever gets expensive, then I'd rather use as little as possible.

                  How's your gearing for the Bronco?
                  Unlikely. I have been fighting a modified 351 for 5 years now. Reliability and mileage are the main goals. The numbers say the R2.8 is still adequate for mountain towing, albeit maybe a little slower, but I doubt there will be much difference considering how much the 351 lost at altitude being a N/A engine. I was averaging 12-14 mpg with the V8 and there is strong indications that I can do better than 20mpg with the 2.8, so I plan to see a 50%+ fuel economy increase.

                  Gearing is currently 4.56 turning 37" tires and running a .0.76:1 over drive. Given effective tire diameter, I'm turning 2500rpm at 75mph right now. Too much for a 4BT, but appears to be okay for the R2.8.

                  A friend of mine has a stretched early Bronco with a stock 4BT, ZF5 and 4.10 gears turning 37s. Loaded weight is 7700lbs and he is getting 20mpg. Towing his matching trailer, mileage drops to 18-19, but he can pull decent mountain grades loaded to 10,000 lbs in 4th @ 50mph with good EGTs.

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                  • #10
                    20 mpg may be doable while towing, but I'm thinking your sweet spot would be 60 mph in OD. It'll probably be pretty easy with a tune and EGR delete, but I don't know that for sure.

                    I've only towed once so far and didn't note how many gallons of fuel I used when I filled up the next time. The loaded trailer was under 2k lbs, but I'm also a bit under geared for towing and the fill-up would have been mixed with my daily commute, lots of idling and probably a half hour or so of 4lo. Power/torque wise it was a breeze compared to even empty driving with the 4.0, but imo that engine needs a bit more torque anyway and at least a gearing change. To maintain any speed it required so much shifting and it's not like you get decent MPG for all that lack of torque, but it is/was a great motor just not quite the right application imo.

                    I think almost everything with 4lo should have 2 options at our current level of technology, a small turbo diesel for normal use or some sort of high hp V8 or forced induction gas engine for guys that like to race or do dunes or something. I'm not exactly the target market though as taxes and insurance deter me from owning a new vehicle, let alone their price tags. And plastic and vehicles that look like inflatables don't get me excited just because they have a screen that looks like the crappiest tablet screen that is PITA to use and requires updates. I do say that jokingly, so please forgive the rant.

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