As anyone who has done an engine swap probably can attest, setting the location is a juggling act balancing various tradeoffs. In this conversion we have the advantage of a relatively short engine being that it's only a four cylinder replacing a six. We also have a tall hoodline to give us good vertical clearance. The disadvantage of the FJ40 is that the wheelbase is short and in this particular combo we've added an adapter in between the trans and tcase so overall powertrain length is quite long (approximately 4.5" longer than an H55/split case combo). The rear driveshaft is going to be short, but anything we can do to keep the powertrain forward would be good.
As I mentioned above, one thing you have to plan for is mounting an intercooler for the R2.8 so knowing your radiator thickness (including shroud and fan) is pretty critical. And somewhat interestingly - the Cummins install manual recommends electric fans, though they do state a mechanical can be mounted to the engine. In the pic below I've placed the radiator in the factory mount locations to do initial measurements. The fan isn't on but I have it nearby and know that it's 3.5" thick. I'm also assuming a 3" thick intercooler which will push the whole radiator backwards so the fore/aft position of the engine needs to be able to accommodate that. This isn't the final location, the engine ends up a bit farther back than shown here.
In the tunnel area it's a fight to keep the transfer case from hitting the cross brace on the body. The pic below is a little bit deceiving, the tail shaft is just loosely stuck in the back and will end up about 1/2" further in the trans. I had another split case sitting on the floor nearby that I was using to measure off of for various clearances. My goal was to retain that factory cross brace which also serves as the mounting/sealing flange for the tunnel cover. In the finished position I'm going to need to notch out some of that front flange where you can see the spot welds, but the main beam of the brace will be okay.
This is where having an H55 instead of an NV4500 would really help. As I mentioned earlier, the H55 setup would be 4.5" shorter than this NV4500 combo since there's no adapter. I would
highly recommend anyone considering this swap go that route, in future posts you'll see how much floor and tunnel fab work is required to make this setup fit, it's no small task. We almost changed our plan in mid build here to go that route, but the owner really likes the Dodge trans and didn't want the hassle of returning parts and re-ordering things so we continued with the build.
Back to the front of the engine - a critical clearance on this setup is the right front corner of the oil pan to the front axle. The Cummins may only be a 4-cylinder but it's a wide one and this area was one I paid close attention to. If the engine is on vehicle centerline you'll quickly see that the oil pan looks like it could get hit by the differential. The first easy thing to do is offset the engine, much like the Toyota engines are from the factory. There are some things you have to watch in the trans tunnel but there's a decent amount of room so in this build I've got the engine about 1-1/8" offset to the driver's side.
Moving the engine rearward also helps, there's a step down in the diff carrier on the left side that makes a nice little clearance area for the corner of the pan. The most obvious thing you can do is mount the engine high in chassis to maximize the gap between the pan and the axle housing. I found that hood height wasn't a limiting factor, the trans became the issue. Moving the engine/trans up means more and more mods to the tunnel cover to try and clear the split case and NV4500.
The pic below is the best angle I can find but it's really hard to show this gap between the pan and axle in pictures.
Moving to the top side - with the engine up and left you have to watch the clearance to the firewall and master cylinder. The early trucks are not power brake so there's no booster to contend with but you may want to leave space for one. The R2.8 intake system is pretty big, extending out on the left side of the engine quite a bit. There are two pipes you can see below, the large one with the black mesh is an EGR pipe which can't be moved. The smaller one on the outside with the blue silicone section is actually just a water pipe that bends around the back to connect to the heater. You can see how that water pipe is getting close to the firewall in this location.
As I moved things around and juggled all the clearances I finally decided to remove the water pipe rear section behind the blue silicone hose, it simply unbolts and can be pulled off. I'll just run flexible hose from the stub that's left. We're not currently planning power brakes on this build, so I didn't test fit a booster. I think I can get one of the small diameter Supra-style ones in there if he wants to upgrade some day, but it's going to be very tight. Worst case scenario is having to do an angle booster/master mount similar to a Bronco.
So these are some of the trouble areas you're going to be dealing with on an R2.8 install. As you can imagine, there was quite a lot of work tweaking the engine location with small adjustments in all directions followed by measuring clearances. Once I found the exact spot I liked and had the engine and trans resting on solid blocks I started fabbing the frame towers to connect to the motor mounts. More on that in the next post.
