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Rebuilding A Rb25det 4wd From A Stagea


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Now before anything, I don’t want to turbo my current block and I don’t want to sell my car and buy another and I want a 4WD car, so please don’t just clog this topic up with these suggestions.

I'm currently an owner of a 1995 R33 GTS4 Skyline and have got off my ‘P’ plates, now what I want to do is get more power from my car, after some research I want to get a turbo engine and do a swap. I also want to keep it fairly stock as it is an every day driver and don’t want to be blowing up stuff and spending heaps on fuel.

Now I have tracked down an RB25DET 4WD from a Stagea, but they haven’t got much…or any…history on it so I'm preparing myself that I may have to rebuild it.

So my questions are:

1. How much would it cost me to get someone to rebuild it? (take into account that I will give them the motor on a pallet)

2. Is there a workshop manual I can get that will take me through step by step on what to do (I'm a first year apprentice so I would like to do the work myself)

3. What else will I need for the conversion? This is the list I have so far (let me know if I don’t need items as well):

Turbo engine loom

Turbo gearbox loom?

Turbo ECU

Front and rear hubs (5 stud)

Front and rear brakes

Master cylinder and booster

Intercooler and pipes

Exhaust

Fuel pump

Clutch?

If I can get enough information on this I will be doing it and am happy to make a ‘How To’ diary on it!

So please if you can help me out I would really appreciate it!

Cheers!

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No my car is manual, is this only applicable for autos?!?

Also the motor im looking at is auto so i will be swapping out the auto front dif one for my current manual one so the gearing ratios are the same.

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if memory serves me correct the N/A gearbox is nowhere near the strength, gotta question drive shaft and so on as well.

Not a cheap conversion for the end result that's for sure.

You planning on changing brakes? (do they come 5-stud in R33?)

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I don't think you need a gearbox loom because i believe the gearbox loom is for auto's thus letting the ecu shift it up/down.

It certainly won't be a cheap conversion that's for sure. Everything else looks spot on as far as parts go. Have the engine checked you may save 6grand (minimum) if you don't need a rebuild as you said it's a daily and the rb25s aren't weak so they won't stuff up easily

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I don't know what sort of parallels there are mechanically and electrically between a 4WD NA R33 and the same era Stagea but it is worth researching and keeping an eye out for wrecked Stags in that era - donor car sort of idea .

If a donor car has everything you need to build an AWD R33 25DET then it's possibly the cheapest way of getting the bits AND it'd be a matching set from a car you can order spares for . Stags of that era may not get you four piston calipers or the discs that suit them but I believe they bolt up anyway .

Something to know early is does your R33's era Stag have a manual transmission option .

Also importantly double check the diff ratios because those for an NA R33 RB20 probably won't suit the power characteristics of an RB25DET . I think the final drive choices were 4.111 and 4.4ish .

Long shot idea but worth a few searches , cheers Adrian .

Also for kicks search prices for 33 GTR with blown engine - who knows ...

Edited by discopotato03
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I've done this conversion in a 32 GTS4. I used an aftermarket ECU (Wolf 3D 4+). The engine itself drops straight in, and bolts up to everything - gearbox, driveshafts, P/S pump, A/C compressor.

The outright majority of Stagea engines are autos - manuals are almost rare as chicken teeth. So you will need a new flywheel, and a new spiggot bearing.

The diffs in a Stagea are 4.08:1 . RB25DET doesn't need 4.375 final drive, so I ended up getting a Stagea rear diff and swapping the crown wheel and pinion over to the R32 diff housing. Also, I don't think the Stageas have any form of LSD rear, so another reason to swap the gears.

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Well i would rather not rebuild the motor, what tests can i do on it while ts on the pallet to make sure it aint a lemon.

Im guessing a compression test? what else?

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if memory serves me correct the N/A gearbox is nowhere near the strength, gotta question drive shaft and so on as well.

Not a cheap conversion for the end result that's for sure.

You planning on changing brakes? (do they come 5-stud in R33?)

He will want a GTR box

Drive line in the GTS4 is GTR so it will hold...and yes ill be doing brakes though the front hubs have to be from a GTR the calipers will be GTST

You will want GTR brakes and driveline, GTS4 stuff is weaker, get under and measure! Best way to check.

You could get a series 2 Stagea(so a NEO motor, which has GTR rods standard), try and find a manual half cut. But personally i think the cheapest option would be to grab the series 1 stagea motor(similar to the series 2 R33 but rumored to be different cams) and sort out a GTR box, then replace driveline parts as you break them :banana:

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Im pritty sure the drive line is GTR, i had it on a hoist the other day and it was massive, though i havent seen a gtr drive line i know mine is bigger than a new BMW M5's. If some one can tell me the diamiter of a gtr tail shaft then i can check it out.

Also what tests can i do to see if the motor im looking at is ok?

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your doing what I'm doing! lol, my cars going in in a couple weeks, I picked up a stagea motor and whole front cradle took it all to my mechanic he told me its pretty much a straight bolt on swap and quoted me $500-$700 labour. Your standard GTS4 box will hold no worries (as the previous owner of the stagea motor had it in his r33 gts4 with standard box and had no probs), but suiting your needs as a daily driver don't worry about a GTR box and drive shafts unless your gonna chase some big power in the future. It will hold.

Keep in mind only 5stud hubs from a GTR or stagea will fit in the front, the brake lines were a bit different as well, i had to get mine modded a little bit, everything else is pretty much straight forward.

PS. I got a spare pair of front R33 GTR front hubs for sale if interested :down:

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My GTS-4 has a Stagea RB25DET (series 1 type) and supposedly has a Stagea manual too (at least the receipt says) which is what I've been trying to work out whether I actually do have a Stag box and all the ATTESSA hardware or whether its just a standard GTS-4 box (was thinking this in regards to trying to find a Series 1 RB25DET ECU to replace the Microtech fitted).

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