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Stock RB26DETT in a 1972 240z: a Beginner's Perspective


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Go to http://forums.hybridz.org/showthread.php?t=127109 for the progress forum on my project.

 

This is where I will post all the detailed final results of each step, including a parts list and total prices, no BS, of the total cost of this swap including miscellaneous parts and time spent on custom fabrication.

 

My goal is to get an rb26dett and rb25det trans into my 240z at minimal pain, cost, and downtime, which means I will start off completely stock, so the total cost will only include necessary parts and a few replacement parts, as no crate motor is perfect.

 

In case you were wondering, I bought my 240z for $2,500 and it came with a salvage title and a fresh coat of paint, but it doesn't look like it has ever been in an accident, and the only rust I've found is on the driver side kicker panel, which was covered in bondo before the paint. Not too bad of a start I think. Zero dollars going into the body that is in decent condition all around, and every penny going into the swap.

 

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The engine and trans set, which I got from a Hybridz member, was actually really convenient because he lives 20 miles away from me and cost $3,000 altogether. If it weren't for that bit of luck, I would probably be going in a completely different direction.

 

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Also, after the swap, for what it's worth, I will be selling off parts I didn't need, including my old engine parts, so if you have a similar situation you can subtract that from the total in a sense. I might be giving my l24 long block to a friend for his autoshop class to rebuild it though.

 

Ideally this blog will contain one post titled for each area of the swap and be organized and easy to follow, but we'll see how that works out. So bear with me, as this is also the first time I will have ever attempted to do a swap of any magnitude, let alone one this involved.

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  • 8 months later...

My personal website will now house all the images for this project. I'm working on organizing them into categories so that its easier to navigate.

 

http://www.davestation.com/pages/240z.htm

 

Ideally, this thread will then be organized into similar categories, not necessarily time frames, for an easy flow of the process to read through.

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  • 1 year later...

You’ve all been very helpful in my build and I know I said I was going to do a crazy writeup, but it seems that everyone is already pretty set in what they are doing and I’m the amateur asking you all the questions. Looks like I found the right forum to research for my build because there are some truly expert enthusiasts eager to help.

 

That said, hopefully I can bring a little knowledge to the table now for anyone else out there in my position that wants an overview of what is necessary for such a build and would love to answer any specific questions down the line. You probably didn’t come here to learn how to take out or drop in the new engine, and hopefully you didn’t come here to learn how to rebuild one, because that won’t be covered here. I tried to wait until I got most of the bugs out before doing a writeup, and hopefully now I’ll be able to remember it all well enough.

 

Basically my plan was to have a project car that didn’t take forever to finish (in other words a daily driver project), plus I didn’t have a bunch of money to throw at it, so I kept it as simple as possible. It also made things much easier because I’ve never done a project like this before, plus there were less points of failure to troubleshoot if it didn’t start up right away. However, that’s not to say I cut corners where possible, I just didn’t do any “unnecessary†upgrades—which I’m sure is a loose term itself—and others here will probably speculate at. Either way, I’m happy to say that it all ran pretty smoothly, didn’t completely break the bank, and now I have a very reliable rb to play with and work on in the future once I tackle the restoration of the rest of the car (I know, I did it backwards, right?), but I digress.

 

Before you embark on such a project, you should know what you’re getting into because way too many people start projects like this and never finish. I did a ton of research on this forum before even choosing an engine, let alone buying it, and even then I was surprised with all the little details I didn’t think of ahead of time. I mean, theoretically you could have every part planned out ahead of time and throw it all together in a month after you drop the engine in, but realistically this is just not possible. I went with the rb26 because I found one local that was a decent price and because I wanted the challenge along with the future possibilities. Basically I had to be sure it was worth it before I got halfway through and thought to myself, I should just get an sr20. Take also into consideration that the swap will be costly. For what it’s worth, while the car cost me two grand, the engine cost me three grand, and the swap itself cost almost as much as the two combined. And this is at a very modest swap build, when most people told me that it would cost much more. That is to say if you don’t have some of the resources I had, or are planning to do a more in-depth swap including some upgrades etc., it’s going to get pricey (I still have trouble counting where all that money went) because the bulk of the money is spent on the cheapest items—it really adds up. But now that we got all that out of the way…

 

Preparation

When I received the engine, the water had been sitting for so long that it started to rust and needed to be flushed. This also meant that the water pump needed to be replaced, so if your engine was in a similar state, it’s probably best to replace the pump now that you can get to the timing belt and covers easily. I bought an rb25 water pump because they look the same except that when advertized as the rb25 pump it was like half the price. However, after installing it I quickly realized that one of the bolt holes, which was actually a slot, was off enough to cause leakage and had to be welded up. I’m still not sure if this was because the rb25s were made that way, or if the aftermarket version just wasn’t built to the same specs, so you’ll probably want to make sure you see a picture before you buy one, although in the end I still enjoyed the savings despite the minor hassle of fixing it.

 

Another thing I had to do was buy new injectors (and new plugs of course, which aren’t cheap by the way), because some of them were leaking due to the plastic tips being broken. This is probably a good time to replace them anyway. The engine had several minor bruises from shipment, so it’s a good idea to do a thorough inspection. I also had a couple crushed vacuum lines and a broken plug on the igniter box. Furthermore, the engine didn’t come with the maf’s, so I bought the oem ones to keep it simple, although I’m told there are others that you can easily upgrade to. Most of the replacement stuff is common sense, and it’s up to you what nonessential items you want to replace now while it’s easy to get to, as opposed to when it inevitably fails down the line.

 

 

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Oil Pan

 

The main concern for mounting the engine is of course the oil pan, since the rb26 was awd, and had a very stout pan incorporating the front differential. Fortunately, the rb25 pan is a bolt on, using a slightly different pattern. That said, the oil pickup will not work with this setup, nor will the rb25 pickup work, because of the bolt pattern, which I learned the hard way. You can do something elaborate like make your own pan or change the oil system, which many have done, but again I was just going for “functional.†If you plan on 1000hp, you probably want to go a different route (obviously), but for me this worked great. I cut out the area around where the original pickup mounted as well as some of the baffling, and as little of the flange as possible, and made a tube extending from the oil port to the alternative oil sump mounting pad (which was a lifesaver) that the rb25 pickup conveniently goes on. Because of my concern for an oil leak, I ended up sealing new pocket in the oil pan with tubes that go all the way through for the bolts.

 

 

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Mounting

 

In my setup I used Rick Wong’s motor mounts with supra isolators, which set the engine in the bay pretty nicely, although with a little more fabrication you could reset the mounting points to bring the engine closer to the firewall as a bonus. However, the current mount put the shifter of the rb25 tranny just about dead center in the original hole. I was able to construct a basic transmission mount that preserved the old mounting posts, but again you could move the posts for better weight distribution etc., it’s all up to you. The only drawback on my mount is that it gets in the way of the exhaust pipe, which had to run a little lower to the ground as a result. Also, it is said that old dodge mounts would work fine and actually make the engine lower, but they proved to be impossible when I tried them because the oil pan wouldn’t clear the steering rack. Note that the only way the supra isolators seem to work is if they are turned sideways, but that seems to be a moot point.

 

It should also go without saying that you will need a new drive shaft to mate the new tranny, so hopefully yours came with the yoke, because you will need it to have a custom one made. The shop I went to said it was easier to make one from scratch than reuse parts from the old shaft anyway, since both u-joints were apparently a common size.

 

There was no way to get the radiator in without removing the original fan, although I don’t know why you would keep that thing anyway. I mounted an aluminum radiator with a single puller on a homemade shroud that does the trick, it’s not the perfect size, but then those are hard to find and usually have to be custom made. I recommend getting a double pass radiator, not just for cooling aspects, but so that the inlet and outlet are both on the passenger side (this became very instrumental in the way that the engine bay was plumbed).

 

That said, with the mounts I used and the moderately sized fan, there was no way to use the original harmonic damper, so I got the overly nice ATI one. I even tried to machine down the stock one to save money, but the flange is a lot thinner than it looks and the whole thing came apart. There are cheaper ones on the market for sure, but most of them don’t really do any vibration dampening, they are just a belt wheel. The ATI one does the trick even better than the stock one, and while it is still bulky because it has room for the power steering belt, it is small enough to fit (the add-on a/c driver that comes with it is removable).

 

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Air

Intake is self explanatory by the pictures, and is one of the most customized aspects, so there’s not much to go into here. I will say though that unless you require cold intake, the way I mounted the maf’s was about as simple and functional as it gets.

 

 

 

For what it's worth, my intercooler is a 3†by 31†core, said to be 35†wide overall, but it had straight inlets, and I needed some pretty tight 90s to get it to fit, so I cut them off and welded on cast 90s (tighter radius than mandrel bent tubes). Overall it was a tight squeeze to get the inlets through the holes in the radiator wall while clearing the hood hinges and the hood itself. Some people are able to find intercoolers with the 90s already installed, or they make their own caps and move the inlets etc. to fit a large intercooler. The 35†one was fairly simple in the end, you just have to be careful in your measurements. The size is a bit of an overkill, but I’m planning on turning up the boost down the line anyway, and there’s almost no such thing as too big regardless.

 

 

Welding a flange for the bpv on the tube nearest the intake plenum was also fairly convenient. Since I kept the original computer (an aftermarket management would make this even simpler if it used map sensors), I didn’t want it to blow off, so I routed the bypass back to the intake through a couple homemade tubes. If you haven’t figured it out by now, having the ability to do your own welding makes things a whole lot simpler (and cheaper) on a build like this. The bpv crosses the top of the radiator and turns down to the chassis line, then tees off into the custom intake (similar to the stock one but more condensed and straight) to the front turbo and up to the stock intake tube of the rear turbo (I cut the inlet of this tube shorter to fit the maf and air filter near the shock tower). The bpv also has a reference line to the manifold (a small vacuum tube extending forward from the aac) so assist in opening when the throttle closes, but this may not be necessary if your blow off pressure is set properly.

 

 

 

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Fuel

Fuel is also pretty simple overall. I used my original gas tank and just plugged off all the emissions nonsense, plus made the supply port a little larger and fed to an external pump mounted on the underside of the toolbox. It did have to be isolated to get rid of the horrible whine it was making, but this can easily be done and most of the noise is gone. At first, I mounted the fuel filter conveniently to the differential support, but when I got the r200 upgrade, I had to move it next to the fuel pump and make a custom bracket. I believe I used the original supply line as the new return line and installed a marine grade fuel hose for the new supply, but it’s all up to you. In fact if you spring for the bent stainless lines that many people buy, they will likely be bigger as well. To facilitate the plumbing in the engine bay, I got rid of the supply tube that runs the length of the fuel rail towards the front of the car, and just braised on a nipple at the firewall side with a right angle for the supply line to connect to.

 

 

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Electrical

Well this is probably the section people are most afraid of. If it’s any consolation, I figured it out with little automotive electrical experience. You will absolutely need the engine wiring diagram. There are countless pages on how the computer is wired along with the color coding of the wires, plus there are a few tables on which wires are for what. Since I had the original wiring harness, I was able to work the wiring out fairly easily. The harness obviously comes with way more than you need, and is a little too long, but I just bundled up some of the excess in some spare room on the driver’s side of the bay and reused the firewall seal that was already glued on by enlarging a hole already in the firewall right were the wires needed to go. To this day I’m not sure what all the wires do, but trying to get crazy with it would just be overwhelming. Focus on what you need to wire to make the engine turn-key. Much of the wiring that is integral to engine function is already mounted on the engine via subharnesses that plug into the main harness that connects it all to the brain. Just be sure and do a lot of planning, taking notes, and writing down what wires need to go where by listing all the wires from the original diagrams you will need to extend to the chassis wiring, before you touch anything, or it will all be a mess. Plus, if most of it is planned out in advance, running the wires and making nice bundles will be much easier than if wires are thrown about one at a time. What you likely don’t have, are a few necessary relays and fuses, as well as the injector resistor pack that got cut off when they ripped it all out of the donor car. I got a nice little fuse box that had slots for several fuses as well as a couple commons and battery posts, plus some relays for the ignition, fuel pump, and fan that I just mounted on the firewall. After that is all taken care of, you can figure out how to wire up the gauges, which should be the easy part. I had to buy a 240sx temp sender that fit the rb engine but had the same range output as my stock gauge. On a side note, I had to put in a new oil pressure sender (a 240z one--same threads as the jdm) because my old one didn't work for whatever reason, perhaps it didn't like the sinthetic oil. Some other things had to be rewired, like the neural and backup switche on the trans, the boost controller that was cut, the alternator and starter wires to the battery and key, etc. Going into intense detail on how to wire it all up would probably be fruitless because your setup won’t be exactly like mine, and it won’t make any sense until you actually start physically putting it together anyway. If you have any other questions you can try to sort my other thread or just ask me specifically, or obviously any of the people here that know more about the subject.

 

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Miscelaneous

Now you may be thinking that this short little writeup, and believe me it is relatively short, makes it sound easy, but there are an innumerous amount of things to do that don’t fit into one of the above basic categories, and I’ll try to think of as many of them as I can here, mostly through commented pictures.

 

The throttle cable had to be custom made and the linkage to the pedal be slightly modified. This is a very simple design similar to what it looks like most others are doing.

 

 

 

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There are a few routes for the speedo. There seems to be a way to get a mechanical drive, or otherwise use an adaptor, to use a mechanical gauge, although it would have to be calibrated, and since I left the original transmission mounting posts, a bulky mechanical drive and stiff cable would interfere (it actually broke off shortly after installing it). Thus, an electrical gauge is required. Of course an alternate tach is also required, and most tachs will need a gmr pickup because they aren’t made for distributorless ignition and several attempts to use the signal from the ecu have failed. The speed signal from the ecu is even more useless because no speedo will be able to interpret it.

 

 

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I bought new oem heater hoses and cut them down into slightly different shapes to meet the new engine, it’s in the same general location fortunately.

 

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A vacuum canister is a good idea in order to support the brake booster since the engine sees a lot more positive manifold pressure with turbos. This seemed like some sort of name brand I bought off ebay fairly cheap, although many people make their own.

 

 

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The exhaust I didn't really want to deal with. I took it to a shop and got a 3" custom made y-pipe and magnaflow straight through muffler installed. It sounds really good in my opinion, which really raised my opinion of magnas because I was worried it would sound like a rat rod or something. I didn't even think to get a chrome tip welded on though, and in retrospect I'm not going back to the same guy again because the welds looked pretty amateur for the most part.

 

 

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As far as tuning goes, I don’t think there are a whole lot of options on the stock ecu. Nissan Datascan with the BlazT cable is nice because you can monitor engine parameters and use it to troubleshoot to a limited degree, but there aren’t really any adjustment functions. I’ve read that the stock ecu, at least the one I have can’t be chipped, but roms can be downloaded and installed. It’s just heresay at this point though, I haven’t done much research on the matter.

 

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Summary

 

Well this writeup is nowhere near complete, but perhaps I'll think of more to add as my memory comes back or I find more pictures in the lost archives. Hopefully though, if nothing else, this writeup was inspiring and gave you some ideas of what to do on your project, or at least areas to explore and questions to ask. Of course the story is far from over. Now what I should really do is start another thread on the journey to restore the rest of the car mechanically as well as stylishly. It will have to be a living story though, because that process undoubtedly will never come to an end.

 

Cheers!

 

Dave

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