RB25 turbo conversion this weekend

[nedb]

Hi all, as the title says i'm swaping my RB20 turbo on R32 to the RB25 this weekend.

I know its a straight bolt on but I'm just wondering if there is anything else i might need for this conversion. So far i've got the turbo and the pipe going to the intercooler.

I've never done this before so i got limited knowledge about it but my mate, a mechanic, will be helping out. But i dont want to get cought up missing something in the middle of conversion as it will be long weekend and no places selling parts will be open.

So if anyone has any ideas it will be very apreciated.

Also, if anyone knows of any DIY manuals for this type of conversion i'd be very greatful.

Thanx.

[BHDave]

It really is a straight bolt up.

My only problem when i did this conversion was the compressor outlet pipe (which you have) that i had to fabricate on the day as the rb25 one is different from rb20.

Get a gasket kit from gcg which included a new turbo flange gasket, oil drain gasket and dump pipe gasket and some new washers for the oil and water lines incase you drop one when playing.

Probably be handy to have some new bolts, studs and nuts for the dump too just incase one decides to snap on you.

Take your time and you'll have no problems. And use the rb20 actuator rather than the rb25 one as it will hold a bit more boost.

I did the conversion in a day including the fabrication of the outlet pipe taking it really slowly.

[cul202]

Seeings as you've got the RB25 compressor pipe all should go to plan. But, if you have a very early R32 like mine ('89) the water lines may (& I say may) be different. The core on my stock turbo had smaller banjo bolts requiring RB25 water lines (40 or 50 bucks from JustJap). It could just be that I got an SII/R34 style turbo though.

You have to tap in a connector for the pressure hose to the actuator as it fits different from R32 to 33. We put mine at the bottom of the compressor pipe. This is the only mod that had to be done. Everything else bolts straight up.

.

[nedb]

It is an 89 model so i'll make sure i get the water and oil lines of the rb25. Someone suggested using the Pirtek lines as its easier to fit them as they bend - any ideas on that?

I've also heard that intercooler piping doesn't mach, 2.5" from turbo into 2" intercooler piping. Is this true?

Hopefully the conversion will be done tomorrow - can't wait. :burnout:

[BHDave]

Yeah, it'd be easier but you're up for 100 bucks per line

factory ic piping is near enough to 2.5 inch anyway so you shouldn't have a problem

[nedb]

Ok, the conversion went according to the plan, so I decided to write up a basic DIY info.

Make sure you get the water lines and bolts with the turbo as they might not mach up as in my case. The new turbo needed the bigger bolts than the original RB20. Also, you’ll need the intercooler outlet elbow pipe as the original is slightly different.

It took me and my mate around 9 hours but that included taking lunch break and a lot of smoke breaks and also sourcing the new water lines and some tools we didn’t have. Also, it included the change of engine oil and filter and new coolant. Realistically you need about 6 hours taking it slowly.

Be prepared to loose all the coolant once you undo the water lines of the turbo, it happened in our case. I’m not sure about the engine oil as I drained it before taking off the oil lines, but might as well be prepared for that too and change it as well at the same time.

First you need to remove the intercooler pipes so you can get to the turbo. Then, undo the dump pipe and then undo the turbo and the water and oil lines.

Once we had undone the turbo bolts we couldn’t get the turbo out until we took the exhaust manifold off. So undo the manifold and the turbo should come straight out. Be patient with the bolts and make sure you have WD40 at hand.

Swap the actuator from the old turbo to the new as it holds higher boost (9 psi as opposed to the RB25 6-7 psi). Install the new water lines in the engine bay. The oil ones should be the same. Put the turbo back into the bay and connect the rear water line as it will be much harder to do it later. Put the exhaust manifold back on and use some Maniseal on the gaskets. Bolt the turbo back on the manifold and connect the rest of the lines. Bolt on the dump pipe. Reconnect the intercooler piping, and inspect everything. Add the oil and add the coolant. Make sure you fill up the radiator and have the engine running with the heater on full blast till the thermostat opens and let the coolant in, then fill it up again. Inspect for any leaks under the car. Go for a test drive.

The only other thing that needs to be sorted out is the little hose coming off the actuator. Instead of installing it on the intercooler end of the turbo as on the RB20 turbo you need to install it into the intercooler pipe as the RB25 turbo doesn’t have the nipple for it.

I can’t confirm the performance of this turbo yet as I haven’t connected the hose yet and on my test run it hit about 18 psi, so I’m taking it slowly not till I get this done.

I’m looking for a self-tapping nipple to connect the hose to the pipping.

The above is only my view of the installation, and someone else might have a different or better view.

Search words: rb20 rb25 vg30 turbo upgrade conversion option.

Just an update: I ended up using one of the hoses running of the plenum and Ting into it for the wastegate actuator. With this turbo the car made 168 rwkw on 14 psi with a few other basic mods.

Edited January 9, 2006 by nedb