R2.8 Cummins Build

[BugoutJeep]

I have been following your build and was curious if you would be willing to take some measurements for me. I am wanting to do the conversion in my LJ but am planning on the third link on the front suspension coming pretty far up. I'm worried about it hitting the oil cooler and have not found anyone that makes a cooler relocate yet. Do you have measurements or would you throw a tape on the distance between the frame and the cooler. Also wondering where the bottom of the cooler approximately lands vertically in the frame rail. Is it about in the middle, even with the top, or closer to the bottom. Thanks

I will take some measurements, but it will probably be next week.

I have been told that a guy busted his oil cooler assembly, because he didn't have enough bump stop. Currently I've got excessive bump stop, because I haven't made time to optimize my clearances and I want to change up my fenders and do everything at the same time.

A remote cooler might be a cool thing, because it is crowded in this area. My cooler leaks, because I hastily overtightened my oil pressure sensor adapter and then tried to up the thread size and went to a tapered thread, but that didn't work either. Of course it leaks less than the crankcase breather. I do know that my upper control arm is closer than I'd prefer for comfort to the cooler and the diff is directly beneath it. I think it's closer to the bottom of the frame as well.

I wonder if you can talk with a builder and get a custom upper arm. That being said there's a lot of builds with a bunch of flex that have used the R2.8, so maybe talk with Axis and share your concerns, because they are doing this on much more modified rigs. However, Monday or Tuesday I should be back to the house and around my garage, if I can remember. I'll be there briefly today, but I get side-tracked easily and often.

 

[jeepin05]

I talked to Axis about it and he sent me some pictures of one they are working on that is going to be set up pretty close to what I'm thinking. It all looks pretty tight with everything. I worry especially with speed that it all could be a little to tight. If that pumpkin touches that cooler a little to much it turns into a pretty expensive mistake ha.

 

[BugoutJeep]

I talked to Axis about it and he sent me some pictures of one they are working on that is going to be set up pretty close to what I'm thinking. It all looks pretty tight with everything. I worry especially with speed that it all could be a little to tight. If that pumpkin touches that cooler a little to much it turns into a pretty expensive mistake ha.

Yeah that aluminum is crazy soft, trust me. And others have busted theirs. It's a good engine swap, if there's something else you can do to make clearance.

What axle are you running? Will a Johnny joint be what's going to hit the cooler?

 

[jeepin05]

I'm still assembling parts and what not but planning on using rock jock 60 up front. It would most likely be the joint, I am pushing the front axle forward so it is possible it could actually be the arm. That is why I am trying to get as many measurements as I can. If the 2.8 won't work I will go with an ls3. Depending on which engine it will change my gear ratio decision. Just want to order the axles with the right ratio. Might have to bite the bullet though and get them mocked up and possibly switch gear sets.

 

[BugoutJeep]

I'm still assembling parts and what not but planning on using rock jock 60 up front. It would most likely be the joint, I am pushing the front axle forward so it is possible it could actually be the arm. That is why I am trying to get as many measurements as I can. If the 2.8 won't work I will go with an ls3. Depending on which engine it will change my gear ratio decision. Just want to order the axles with the right ratio. Might have to bite the bullet though and get them mocked up and possibly switch gear sets.

Maybe talk with rock jock about relocation and/or maybe get a custom arm to clear for the r2.8. Both these engines would be awesome, though my preference goes to diesel, but I go slow.

Are you going with AC? Just to mention that AC for the R2.8 requires another bracket, so add $3k to the build.

 

[jeepin05]

I have looked at that, that dam bracket is expensive. I go slow and fast, need a little of both. I figured I could get speed out of some gearing. Use a 6L80E and probably 4.88 in the axle with 40's and thought it might work good. Sometimes it's all a crap shoot till you get it together and see if it works. I prefer diesel as well but also know it isn't the end all.

 

[BugoutJeep]

Well after my regear I've been having a weird issue in the rear end. I thought for a bit the noise had something to do with the suspension, but I very slowly worked through my issues, I think I finally fixed the noise as I didn't have enough carrier preload in the rear axle.

It's nice being able to have my Jeep back. For a bit I had to drive it without being able to fix it because I had to fix my truck and also had to help my dad work on his roof (fun summer work). And then I had so much work to do on the farm and was doing a lot of towing so the Jeep had to just sit while I drove the truck.

Finally got a weekend free so I tore back into the rear axle and when getting ready to pull the diff to setup the rear pinion again (I thought maybe I had a bad pinion bearing, because I sourced one locally based on physical dimensions and maybe it was damaged during setup/install, that was my working theory). In any case as soon as I pulled the diff straps I could tell the diff needed very little effort to remove it, so I ended up adding .004" of shims, adjusting for proper backlash and reassembled and so far I've done several launches in different fashions and no more "pop/gear crunch" sound.

I even had time to install my upper door adapters for my trail doors and I'm just tickled to be back in the Jeep and not sweating every inch I travel and I can drive to work in the morning with the uppers and then remove them during the afternoon for the perfect Jeep weather. The 3.73 gears with 33s (well closer to 32s with my speed/rpm calculations) are a big improvement to the 3.07s, though some max MPG is probably not attainable with my current setup. But I was getting 11 mpg with 29" mud tires and no rack before the build so low 20s mpg with mud tires and roof rack and the ability to maintain highway speeds has me pretty excited.

I'll have to get a few more trips to verify my MPG, but I'm not expecting much more than about 20 mpg. The highway probably has my RPMs too high to get into the mid-20s, but when I'm loaded down for trips, I'll be getting better mpg and performance compared to the 3.07s. The 3.73 boost is a bit more fun too so I've been driving a bit more like a normal human being as well that doesn't get passed as often. It's really got me thinking about getting a mild tune to open this engine up the way it was meant to be tuned. The world tune is for 360 ft lbs, but the EPA is for 306 ft lbs, which isn't insignificant also sometimes MPG improves with a proper tune.