R34 Engine Build Advice Needed

[jimmyjam]

Hi all,

I need some advice, recently I bought a R34 GT-T Skyline. The Neo engine is nice and has some mods Power Fc, bigger turbo etc, but i am chasing more power.Fortunately I also have a R33 RB25DET engine i had built for my non-turbo R34 Skyline sedan (my daily). Yes that's two R34's, i have a problem .

However costs for the engine build went a lil out of control (they always do) and instead of a basic rebuild i now have a built RB27DET ready to drop in a car.

Anyways i have decided to ditch the daily driven non-turbo R34 sedan and put the built engine in my new R34 GT-T. Now I know the Neo engine already in my new car has GTR rods, N1 oil pump? solid head etc all from the factory, however this built RB27 is a little more serious. The problem is the RB27DET engine has a R33 spec head on it.

I really want to put my built engine in my R34 GT-T, how do i overcome any potential wiring issues? will the R33 RB27 fit up to the R34GT-T gearbox? Will the Neo spec Power Fc work with the R33 RB27? Has anyone tried this before?

Please help

[GTSBoy]

Many people have put the older shitter 25 into R34s, and yes there are a few things you need to sort out. Some of these depend on whether the R33 engine is S1 or S2. I am no expert on the PFCs, so I can't tell you if the Neo spec one is flexible enough to overcome the few differences in sensors. Keep in mind that the R34 also has traction control which is tied up with the ABS and the TCS will chuck a spaz when bits of the system are pulled out. Your Neo spec PFC will run the TCS (I think), but not when the TC throttle is removed, which is what happens when you switch out the engine.

The gearbox stuff is all fine. You may need the original R34 flywheel to go with the R34's clutch (which is opposite actuation to the R33 type).

[jimmyjam]

Many people have put the older shitter 25 into R34s, and yes there are a few things you need to sort out. Some of these depend on whether the R33 engine is S1 or S2. I am no expert on the PFCs, so I can't tell you if the Neo spec one is flexible enough to overcome the few differences in sensors. Keep in mind that the R34 also has traction control which is tied up with the ABS and the TCS will chuck a spaz when bits of the system are pulled out. Your Neo spec PFC will run the TCS (I think), but not when the TC throttle is removed, which is what happens when you switch out the engine.

The gearbox stuff is all fine. You may need the original R34 flywheel to go with the R34's clutch (which is opposite actuation to the R33 type).

Thank you GTSBoy that was informative. So if i change out the Power Fc to a R33 one would that make life easier or is there a way around the ABS TCS issue whilst retaining the 34 Power Fc?

[GTSBoy]

Can't tell you. Just don't know.

The main thing you don't want is for the ABS to stop working (unless you just don't care). If you put the R33 motor in you simply won't have TCS anyway, so you won't care about that one. So the main options I can see happening are;

1. You put in the R33 motor with the R34 PFC. You get no TCS (no surprise), but somehow the ABS keeps working. Win.
2. You put in the R33 motor with the R34 PFC. You get no TCS (no surprise), and the ABS shits itself too. Lose, unless you don't care.
3. You put in the R33 motor with the R33 PFC. You get no TCS (no surprise), but somehow the ABS keeps working. Win.
4. You put in the R33 motor with the R33 PFC. You get no TCS (no surprise), and the ABS shits itself too. Lose, unless you don't care.

Obviously there's not a lot of difference between the 1st 2 options and the 2nd pair. The only difference is that option 3 is possibly less likely than any of the others. But the relative probabilities are a mystery to me!

Oddly enough, if you were crazy enough to try it, it would likely be possible to retain the TCS throttle and R34 crossover pipe on the R33 motor, neatly sidestepping this issue. But it's not what most people would do!

[chiksluvit]

Bolt the r34 TB on the r33 manifold? That'll solve half of the wiring problems

[jimmyjam]

Thanks again GTSBoy I like your lists

I have a FFP that i was hoping to use for the R33 Engine. Would the R34 throttle body fit?

A R34 Neo manifold wont fit, correct?

Are most other sensors between R33 and R34 RBs inter changeable or better still will most of the sensors just plug in to the R34 loom?

Alternately i could get a haltech or some other modern wire in ecu but i would like to use the PFC i have if possible. I also have a spare R33 loom if need be. I am just looking for the most effective simple way to do this..

Bolt the r34 TB on the r33 manifold? That'll solve half of the wiring problems

[chiksluvit]

http://www.sau.com.au/forums/topic/402704-rb25det-neo-throttle-body-change/

R34 TB should fit on r33 manifold so that'll solve tps and keep TCS

This is if u don't go FFP

R34 TB won't work with FFP simply because of lack of space

Other issues I can think of are:

IACV, but I think you can rewire it

CAS

Maybe other sensors eg the map sensor but I don't think r34 PFC uses that as reference like stock ECU

Tbh I don't think it's that hard providing that you keep the stock plenum, or use the r34 plenum on the r33 head? (Not sure if it fits)

Even better swap the head around, then put that hybrid turbo motor into ur r34 sedan

[jimmyjam]

http://www.sau.com.au/forums/topic/402704-rb25det-neo-throttle-body-change/

R34 TB should fit on r33 manifold so that'll solve tps and keep TCS

This is if u don't go FFP

R34 TB won't work with FFP simply because of lack of space

Other issues I can think of are:

IACV, but I think you can rewire it

CAS

Maybe other sensors eg the map sensor but I don't think r34 PFC uses that as reference like stock ECU

Tbh I don't think it's that hard providing that you keep the stock plenum, or use the r34 plenum on the r33 head? (Not sure if it fits)

Even better swap the head around, then put that hybrid turbo motor into ur r34 sedan

Thanks chiksluvit,

I have been toying with the idea of doing the head swap as solid lifters would be nice.. However there is a smaller cc in the neo head apparently which may cause a lift in my CR. also it would be a shame to waste a brand new head gasket then have to buy 2 more. Its a relatively simple job to rewire the cas is it not?

[GTSBoy]

If the cas needs rewiring, yes it's not hard.

Neo head on old 25 block will be too much compression.

[chiksluvit]

Depends on what piston you've got now and whether you've dropped the compression on the current build

[GTSBoy]

Does anyone drop compression these days? If I was building a motor I'd be giving it the highest cr I could make work with e85.

[chiksluvit]

Sure, but there were no specifics on the 2.7l build, so thought I'd put it out there and let him decide

[iruvyouskyrine]

The gearbox stuff is all fine. You may need the original R34 flywheel to go with the R34's clutch (which is opposite actuation to the R33 type).

Nope, won't need to change flywheel.

Differences in the loom between R33 S2 and R34 is;

CAS wired exact opposite (180deg)

TPS is different

IACV plug is different

And the ECU plug pinout is completely different.

GTSboy' list is good, I would put the 2.7 in the 34, keeping the 34 loom and PFC, and doing appropriate wiring loom mods. They are not hard.

[iruvyouskyrine]

Disclaimer, I don't gives a shit about ABS or TCS, so decide if you do and go from there.

[jimmyjam]

The engine is 2.7 due to GTR crank and Rods.. Oversize pistons bored out block.

Nope, won't need to change flywheel.

Differences in the loom between R33 S2 and R34 is;
CAS wired exact opposite (180deg)
TPS is different
IACV plug is different
And the ECU plug pinout is completely different.

GTSboy' list is good, I would put the 2.7 in the 34, keeping the 34 loom and PFC, and doing appropriate wiring loom mods. They are not hard.

iruvyouskyrine i agree the list GTSBoy made is good .. i would prefer to keep R34 PFC and i am not to concerned about TCS etc is there a link or can you shed more light on what needs to be swapped on the ecu ?

[KiwiRS4T]

Measure your new cylinders and calculate the CR with the Neo head. Using the Neo had would be my choice unless the CR is 11:1 or something untunable.

[gtr jet]

11:1 with low boost on E85 would be interesting to see.

[jimmyjam]

I'm not looking to run E85. Just pump fuel/street car on a relative budget (im at uni)

Neo head would be ideal but it is the more costly way to do this.. If it is possible to use the R33 head with out too much stuffing around thats what i will do.. I have done plenty of engine/gearbox conversions in Silvias just a little unsure of how this will go in a R chassis.. Does any one have any links or info regarding the wiring side of the R33 engine into R34 chassis?

11:1 with low boost on E85 would be interesting to see.