RB25DET turbo fitting to R32 RB20DET

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I'll start by saying this is not the only way to probably do this, but its the method which I used, and which I found worked fairly well. So that out of the way so I don't get 'you didn't really need to do that'.. I've used a lot of words as that is how I describe things, but it's much easier than it maybe sounds.

Tools You'll need:
* Pliers
* 10mm ring spanner
* 10mm socket (1/2")
* 16mm socket (1/2")
* 24mm socket (1/2") - std, or short socket.
* 17mm ring spanner
* 1/2" Driver
* 1/2" Breaker bar
* 1/2" ratchet
* 1/2" extender
* Water/oil pan (optional)
* Coolant

Possibles:
- Manifold to turbo gasket
- Copper washers
- Turbo to dump gasket
- Oil drain gasket

Timeframe
About 4 hours off with rb20 turbo.. 4 hours on with rb25 turbo, assuming you haven't done it before. So allow a whole day. Spread out over two days, like I did, might make it a bit easier.

To Start
Here you can see everything to start with with a few things marked you'll need to know about. Make sure your car has cooled down. Its probably easier if things aren't completely stone cold though, as often while still a bit warm, bolts are easier to undo, etc.

Start by removing the standard ancillaries .. that is cross over pipe, airbox and AFM. If you've worked on your car before, changed spark plugs, etc – this should be an easy one. If you have trouble at this point, maybe its best not to attempt the rest. That's the easy part :-p



Intercooler Piping
Also remove all of you intercooler piping where it goes to your turbo outlet, and to your cross-over pipe. Probably not recommended to swap to rb25 turbo anyhow without doing FMIC first.

Remove and set aside. You can leave the rest where it goes around the front of the car in place.

Heatshield
If your standard heatshield is still in place, removing it will allow you to get access to the turbo. There are two 10mm bolts facing upwards near the dump pipe, and two down the side (quite hard to reach and fiddly to remove). You will need your 10mm spanner here.

Remove and put aside. Hey look – a turbo!



Turbo Elbow
Removing the turbo elbow allows you to reach a few things much easier. Its maybe not essential, but I think you'll find its much easier. There are 3x bolts, which can be used using the 10mm socket and an extender to get some clearance. Pull off the elbow, being careful to grab the metal gasket before it falls on the ground or gets caught up in the cross member or something.



Rubber AFM pipe / BOV return & Breather Return
This is the flexible rubber pipe that starts with your AFM, and goes to the inlet of the turbo. Also off this is your BOV return (BOV gasses recirculate by getting sucked back into the turbo), and the general oil breather. The oil breather goes up to the rocker cover and allows excess turbo oil blow-by to be sucked back into the system and thereby burnt off (supposedly). Remove the metal piping, where it is held to a bracket, by undoing the single 10mm bolt.



Reach down, and with the turbo elbow removed, you should be able to reach the main hose clamp where it joins to the turbo. Use a 8mm socket, or flathead to loosen. Once the hose clamp is sufficiently lose, you should be able to pull the whole AFM hose off, and the attached metal re-circulation pipes as one piece. Set aside.



Remove Oil feed
Start by undoing the oil feed line, using the 16mm socket and ratchet. Use the breaker bar if required to loosen it (can be pretty tight). Remove the large eye bolt. Take care to grab the copper washers (2x), or at least find out where they fall. There is one on top, and one just before the turbo.

A few drops of oil will come out, but it won't piss out as its a wiggly pipe from the block, and most of the oil will be in your sump at rest. Set aside the bolt, as you'll need that to put the new turbo on.



Remove Coolant Return
This is where you're going to start getting coolant coming out. Depends where you're doing it, but if you don't want coolant all over the ground, use the oil pan to catch any coolant as it starts to come out. Place it just under the turbo on the ground.

The water return goes to the front of the turbo, looking onto the turbo.

Get the 24mm socket in there, and either use the ratchet or breaker bar (probably breaker bar is necessary here). There should be enough room to get it in there from the top. You're going to find this is VERY tough to get off, and is a very stubborn bugger. Put your whole weight behind it, and it should finally crack.

You can see this below....



As you losen it, you'll find the seal is broken with the feed, and that's when the coolant starts piddling out everywhere. Again, there are two copper washers, so either grab them before they fall, or make sure you can see where they fall so you can pick them up.

At this point, I wouldn't completely loosen off this feed, but let it gradually empty as much as possible from the block while you do the other things.

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Dump Pipe Removal
Its quite likely you've already removed your dump pipe in the past for an aftermarket jobbie before you are attempting the rb25 swap. Therefore, the bolts should be much easier to get off that second time, and less chance of snapped bolts. Use the 1/2" sized socket (yes they are 1/2" for some reason) and ratchet to remove the top 2 (these hold the heatshield bracket in place as well – remove), and also the two side ones.

Climb under and undo the bottom two nuts with a spanner. The dump should now be free to move around, and ready to slide off the back of the turbo when you pull the turbo forward.



Turbo Oil Drain
Its time to loosen the oil drain hose/pipe closest to the turbo. You'll have to get under the car to do this. Use a 8mm socket or philips head, to loosen the nissan factory hose clamp sufficiently. This will allow you to pull the turbo up, and the oil drain will pop out from the hose.



Remove Turbo to Manifold Nuts
These are the 4x main bolts which bolt the turbo to the manifold. They have a locking tab mechanism, to keep the bolts from loosening. Use a flat head screw driver to lever back the tabs. I'm not sure if this is normal, but mine were almost finger tight after that (I used a bit of WD40 10 mins before – that might have helped). Use a 17mm socket to undo all 4.

You will probably need a 17mm ring spanner to do the bottom two.



Now with dump loose, top oil feed, and front water feed loose, this should allow you to pull the turbo forward from the manifold.



Remove Coolant Feed
Now that you can slide the turbo forward a bit, you should be able to reach the coolant feed, which sits behind the turbo, facing it from the guard.



Again, this requires the 24mm socket.. You can try and remove it whilst the turbo is still in the car, but I simply found this impossible, no matter how much force i put on it with the breaker – I was only going to break something else. So this called for plan b.. that was to remove the whole line from the car with it attached to the turbo.

To do this, you'll notice the line goes back towards the block, and around the back. Use a 10mm spanner to undo the first mount point. Then, go around to the other side of the car, and undo the one where it attaches to the back of the engine. This is again, a bitch to get to, but with a ring spanner, you should be able to undo it. Use the pliers to pull back the clamp. And gradually wiggle the metal of the hose.



This for me, was not easy, and much swearing! Took probably 15mins just to get this off.


Remove Turbo(!)

Now all should be clear to remove the actual turbo! Wrestling it out of the engine bay is not as easy as it might seem as there is not much room, near the strut tower, etc. I found that I pretty much had to undo the power steering reservoir (3x 10mm bolts) and push it to the side, to give me enough room to get it out.

You may have to bend (slowly!) the oil feed piping out the way, and also the coolant lines to be able to get things off.

It's not easy, but first of all pull it up, so that the oil drain pops off the bottom hose (remember you undid the bottom clamp right?).

Pull it, or use a large flathead to pop the dump off the exhaust threads, so the dump should sit "floating" there.

Gradually tild, twist, riggle, and move the old turbo, until the stubborn bugger comes out. Be careful not to destroy, kink, or bend the water feed line, or you'll need a new line made up. It will get in your way :-(



Hopefully, after much swearing, the turbo will come out as one unit. This will leave you with one empty side of the engine.



Transference
Now that you've removed the old turbo, its time to transfer a few things across, depending on what you got on your rb25 turbo.

The main one of these is the turbo actuator. The RB20 one is stock at 10psi, and the RB25 one is stock at 7psi. This allows you to run 10psi stock like the old rb20 turbo, and means any boost controller or bleeder has to work a bit easier to build higher boost (with less chance of it dropping off at high PSI). Just unbolt the old one, and swap them across. You'll work it out fairly easily. It's not mandatory, but not a bad idea.



You can also transfer the oil drain if you're missing one, as the rb20 and rb25 are exactly the same. Do the gasket if possible , especially if the old one is perished.

MAKE SURE THE RB25 TURBO HAS THE CORRECT ELBOW! If you don't have that, you're going to have to redrill the stock RB20 one to fit, and its not ever going to be a good fit, and probably restrictive. These also can be a real #$%#$ to track down on their own, and can be costly too (as people know they are hard to come by).

Ok, now you have nice RB20 actuator on your RB25 turbo, its time to get to work installing it.

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Nipple
You may have noticed, the rb20 turbo has the nipple for the wastegate line direct to the compressor housing. Turbo reaches XX psi, wastegate opens, gasses pass into exhaust.

The rb25 doesn't, and relies on you t'ing the wastegate up to the outlet, preferably as close as possible to the turbo outlet itself. Depending on your piping setup, you may have a nipple in your piping simply blocked off – easy, don't have to do anything. If not, you'll have to tap into your piping a standard nipple.

You'll need to drill the piping, and then get the nipple (these can be purchased from supercheap or repco for a few bucks), welded in there, or if you can thread your piping, you can screw it in tight. Just make sure there is no leak, and that it can't pop off under boost.

Here you can see the nipple I have screwed into my existing piping. Done.



Fitting Back...
Fitting back is essentially the same process as putting on... but will still take you 3-4 hours, as still is unfortunately fairly fiddly.

Firstly remove the water line from the turbo.. (this might not be easy, even off the car, you may require a decent vice.. and probably the breaker bar).. and bolt the line back into its usual position.

Remove the elbow from the rb25 turbo, but bolt on the actuator as discussed above. This is required as the elbow will simply get in your way again when putting it on.

Getting rid of things in the way...
You will need to remove firstly the power steering reservoir, as that will get in your way. You do not have to remove it, just remove all bolts, so you can maneuver it on the line.

Also there is a large metal can (I think its a resistor pack), just near there, which will also get in the way and make things much more difficult. Unplug that, and then unbold and remove the whole bracket assembly.



Maneuvering into place
Squeeze the turbo back from where the AFM used to be... in roughly the same angle you pulled it out. Again, with the elbow removed, it will be much easier (if not required) to get it into position.

You may have to bend the top oil feed a bit out of the way, it is flexible, but bending it too much and forth will result in metal fatige and eventually snappage. So be careful!

Now make sure that your water feed is pointing the right direction towards the turbo, and the front one is also nearly in place.

Once it all looks roughly aligned, slide it back onto the manifold.



Make sure the manifold gasket is sitting between the bolts in the correct position, so that its sandwiched in there... To be honest, I would use the old copper gasket if it is not too stuffed as that is a nice piece of work. I bought a new aftermarket one for $20 but was a piece of crap, and barely more than tin foil if you ask me (lets not name the company, but it was a large turbo seller).

Shove it towards the manifold and use a couple of the nuts to hold into place, whilst you maneuver other things around to fit on.



At this point its probably a good idea to get under the car and jam the end of the metal oil drain, into the rubber coming from the block. You don't necessarily have to tightened it at that point, just so its aligned.



Now I recommend doing the line banjo bolts in the order below.... But it may be possible to do it in a different sequence if you have an easier way.

Water outlet Banjo Bolt
This is the front one as you face the guard. This one will be easy to get on. Its essential you use the copper washers on both front and back of the metal line, otherwise you will get leakage and it will all have to come off. Again, new copper washers are recommended, but make sure you get copper or good quality, or at worst use the old ones.

I am not sure the correct torque on it, but 'as tight as buggery' was good enough for me.

Now this one took me nearly 40mins on its own, and really started to annoy me. Washers kept slipping off, or the banjo wouldn't tighten properly once I thought was 'aligned'.

In the end, I found the best approach was to, again, leave the exhaust manifold bolts right at the end of the thread. This allows you that little bit more room to get a spanner or the 1/2" ratchet in behind there.

Again, I had to really bend the oil line right out the way to get enough room to tighten.

The main problem is that there just isn't much room, and as you are reaching behind the turbo, and hand is not in a natural position, its really hard to apply enough force on it. Anyhow, I did manage to get it on using my standard 1/2" socket driver, but it will take you a while and much swearing.

Make sure you also do the same copper washer method, one behind, one in front of the line 'eye', or it will leak coolant.

Once its finally on, tighten again pretty damn tight, and prey that it is tight enough when the car is running.

Oil feed
This is the easiest one, and may as well leave till last. Bend back into alignment, if you've had to bend it out the way for the above. Again, copper washers vital.. Tighten hard.

Dump pipe
Make sure your dump pipe gasket is correctly seated behind the turbo, and align the dump back onto the turbo studs.

Oil drain tighten
Get under the car and tighten up the hose clamp to the oil drain. Here might be wise to replace the fairly dodgy / old nissan items with proper hose clamps.

One last check before tightening everything
This is your chance to make one last check that everything is into place, before tightening everything properly. If you have forgot a copper washer, something is not in place correctly, its all going to have to come off. This would not make you happy.

If you are ready go for it! Start with the turbo to manifold nuts, remembering to put back the alignment brackets behind. Once tight, use some pliers to press the brackets onto the nuts to hold them into place (during heat expansion nuts can slowly work lose, this helps prevent this from happening somewhat)

Then do the nuts and bolts for the turbo to dump pipe, making sure the gasket is in there.

AFM hose
Put this one back on before you put the turbo elbow back on, for easier access to the clamp screw.

Turbo Elbow
Put this back into place and tighten, remembering this also has a metal gasket.

Now is not a bad idea to connect a hose to the actuator, ready to connect to your piping when that goes back on, and the rubber nipple. As once the airbox is in place, can be difficult to reach down there and get it on that easily.

The rest
The rest is fairly easily, just the usual fiddly stuff. Make sure you bolt your powersteering reservoir back to the strut tower, and that resistor thing is plugged back in.

I would recommend leaving off the heatshield for first week or so, so you can check all the lines day to day and see there is no leakage.

Giving it a test
Make sure the outlet from the actuator is connected to your piping niple (this should give you a nice safe 9-10psi).

Now its all back together, it's time to take it for that first nervous drive. DON'T boot the hell of it right off the bat, because if you've stuffed something... vvvshh .. It is also a very bad idea as the coolant and oil would not have had time to correctly lubricate the turbo, which will mean a quick exit of a turbo wheel.

First just take it in small steps, pump the accelerator a little at idle. Check for abnormal noises or sounds. Then go for a spin, again, not even boosting it to positive boost right away. Checking like before.

Now you can gradually start to give it some boost.. around 1-2psi.. back off.. then around 4-5psi.. then if you're brave give it a full 10psi, and prey its all ok. Don't give it a complete flat chat... but hey, its your turbo.

Bring it back to your place, and check it over.. mainly checking for any fluid leaks from incorrectly tightened lines.

After that it should all be fine, and after a while you can look at putting the heat shield back on (this does make a massive difference to underbonnet temps).

Where from here?
It's definitely not a good idea to raise the boost up too much past the 10spi until you change to/have aftermarket management. I've found its fine on hot days (around 30) without audible pinging, but leaning it out anymore results in pinging. It needs a professional tune!

Remember if you are running a standard rb25 turbo, any more than 14psi is probably not good for the lifespan of the turbo, although most report that up to 16psi is probably ok, due to the smaller capacity 2L (instead of 2.5) putting less strain into it.

Top power expected is around 180-90rwkw (depending on dyno), with a meatier mid range. This will give you enough to best the same r33 with equivalent mods, but its no match for pretty much any other aftermarket turbo you can care to name.

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