Rb25Det S2 Into R34

[nzkiwi121]

hi guys, I'm new to the forum, hi everyone :-) lol, I've got a rb25det s2 engine I wanna put into my r34 witch has a neo engine in it, was wondering am I able to use the 5 speed manual box from it and the diff and drivetrain? will be able to use the rb20det clutch I have for it on that box?

also wondering what else from the neo engine I can transfer , thanks guysguys

[luke gtr]

why do you want to put a standard 25 in place of the neo?

if its the turbo, see in the naturally aspirated thread for turbo conversion guide to NA...

[R34GTFOUR]

Everything will physically bolt up, i.e. your current clutch/flywheel combo and gearbox will bolt straight on the S2 rb25 without any issues.

The electronics will be a different issue though, you will need to run all the neo sensors/manifold etc because they will be different.

[KiwiRS4T]

hi guys, I'm new to the forum, hi everyone :-) lol, I've got a rb25det s2 engine I wanna put into my r34 witch has a neo engine in it, was wondering am I able to use the 5 speed manual box from it and the diff and drivetrain? will be able to use the rb20det clutch I have for it on that box? also wondering what else from the neo engine I can transfer , thanks guysguys

Why do you want to do it?

[nzkiwi121]

got the engine cheap so why not, ive just put the engine on, bolted up straight to the neo's gearbox and used the clutch/flywheel witch is excedy onto the s2, but ive come to the ecu loom wiring problem now, ive got a r33 loom for it, can I just take the r34 one out and put in the r33 one? what things will I have to wire up differently? thanks

[R34GTFOUR]

You'll need to swap everything over, i.e. inlet manifold, injectors, sensors etc from the R34 to the R33 engine so you can use your R34 harness

[nzkiwi121]

ohk the r34 had a rb25de neo in it not turbo if you got confused, so id have to move all the sensors etc over from the neo to the s2, the injectors wont be turbo spec would they? and would the manifold fit on the s2? after ive done all of that do I just cut the plug off the engine loom and solder on the s2 det ecu or run the neo ecu? cause they both have different plugs..

[R34GTFOUR]

Basically you need to run the ecu to match the sensors for the engine, if you want to run R33 sensors etc, then you need to run the R33 ECU which means re-wiring.

If you want it as plug and play as possible, then I would be running all the Neo gear on your S2 RB25, that way everything will just click together and it will start. I would avoid the rewiring path at all costs. The inlet manifold on the neo is interchangeable with the S2 engine, so its just a matter of unbolting everything and swapping it over.

The biggest issue you're going to have is that you're going to be running an N/A computer/injectors on a turbo set-up, which will limit what boost you will be able to run. It should run fine, but I wouldnt expect you to run much more than 10psi on the stock turbo before you ran into issues. Ideally, you would get the turbo ecu (or aftermarket ecu to suit an R34 so it was a plug n play job), upgrade the neo injectors and away you go.

Or better still, try to sell the S2 engine if you can and get a NEO RB25DET and then it will be much more plug n play.

[nzkiwi121]

ohk sweet as sounds good, apparently its running on 8psi atm so if i got it a tap for the gate i could turn it up to 10psi and see how well it goes, so im guessing if i put the neo inlet manifold on it, it will bring the injectors over as well? cause i hear the neo's are top feed ones? or bottem correct me if im wrong, also will it run the neo CAS? heard they are different on both engines?

[R34GTFOUR]

The neo top feed injectors will need to come over with the neo manfiold because the injectors/rail are to suit that manifold only. R33 injectors are side feed and the rail also has different mounting points so it will only fit the R33 manifold, which is why you will need to swap the complete manifold/injectors over from the neo.

I forgot about the CAS.... The cam key will be different between the S2 and Neo so you will need to run the R33 CAS to suit the R33 motor. Hopefully the CAS plug on the R34 harness will fit the R33 CAS (not sure on this part), however worse case senario you will just need rewire the R33 CAS plug onto the R34 harness, which should be straight forward.

[nzkiwi121]

awsome man thanks a bunch, ill end up doing the swap over this weekend and ill let you know how we get on

[nzkiwi121]

hey man we just took the intake manifold off the neo and found out the bolt patterns are different on the neo one compared to the s2 engine? and the injectors from the neo wont go into the s2 manifold either cause like you say they are different...what have I done wrong here? like you say they are interchangable but they arent witch is wierd, is it a different head on it maybe?

[R34GTFOUR]

The only thing I could potentially think of is the N/A Neo head is different - which would strike me as odd..

The r33 na and turbo heads are idential, same bolt pattern and fully interchangeable.

The R34 GT-T head is a different set-up to the R33 heads, however the manifold bolt pattern (both inlet and exhaust side) is the same as the R33 heads so the manifolds are definitely interchangeable.

I've swapped all of the above over before, but must admit I've never touched an N/A Neo head before - I would have assumed that the N/A Neo head would have the same pattern as the turbo one because thats what it is like on the R33 engine... and its unlike Nissan to develop a completely different head.

Unfortunately, if the n/a neo manifold wont fit on the S2 engine, then its no longer a simple bolt in excercise with the gear you have..

I would still steer away from running the R33 gear and re-wiring your R34 to suit but thats me.

If it was me, I would look at three options:

-try to track down a standard turbo neo manifold for cheap and bolt that onto the S2 engine.

-If you can't get the stock manifold or if they want blood money for it, then buy an aftermarket top feel fuel rail and fuel regualtor so you can run the top feed injectors on the S2 manifold. A nice rail is around $180, $50 for fittings, then $150 for a regulator - so budject around $400.

-Replace the inlet side altogether with an aftermarket set-up. Get a new Greddy "style" manfold (or the genuine version if have the $$), get an aftermaket fuel rail and regulator to suit the top feed injectors for an R33 manfiold. This will cost anywhere from $700-$1300 depending if you get the genuine greddy gear or not.

[nzkiwi121]

hey man, ive got a picture of the intake manifold bolt pattern, ive been doing some research and as far as ive got is thinking this engine may not be a rb25 but a rb20....it has red temp sensor on the radiator hose, looked up the CAS model number and its saying its an rb20 one...but it seems to be running indivdual coilpacks and I know the rb20's never had these, ive attached pictures of it, see what you think...

[R34GTFOUR]

Yup that's definitely not an RB25 - the biggest give away is that it has no "bulge" on the timing belt cover where the inlet cam is - that's where the VCT should be. No VCT - no Rb25

I wouldn't be putting that into an R34. Sell it and get the right one.

[nzkiwi121]

hey man ive just ran the head and block numbers, the head has 08U writtten on it witch is the r32 rb25de head and it has 75T on the block witch is a r33 rb25det, so I do indeed have a rb25det in there, question is can I still run the rb25 neo ecu with it? cause it looks like its running the rb20 injectors etc...witch are top feed anyway

[R34GTFOUR]

I wonder what has happened to this engine and where it has come from...

Is it a R32 RB25de that someone has just bolted a turbo onto or is it actually an R33 RB25DET that someone has removed the stock head and put a R32 RB25de head on it (if so, why - doesn't make sense??)

Anyway.. it all comes down to the head as that will dictate what manifold you can use and in turn what injectors/ecu/wiring. If its a R32 RB25de head then the inlet pattern is different again to the R33 25 manifolds so you're going to run the manifold that came with the engine as your R34 also wont fit (as you now know). The injectors that came with your "new" engine should work,because if they are R32 RB25de injectors they should be high impedance so your stock ECU should be fine. Basically, you will want to try and swap as many sensors etc off the R34 to the new engine so you keep it as "plug n play" as possible. You may need to rewire a few to suit if some of the sensors that aren't compatible (i.e. CAS, possible injector plugs). You also wont be able to hook your VCT up either because this engine doesn't have it.

I would still be opting out and look at selling the engine and getting the NEO RB25, but if you're up for a challenge and a bit of work theres no reason why you couldn't get this engine going in your car.

Good luck!