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Hey guys, I'm extremely keen to build a 25/30DE, I know it's not turbo, but there seems to be a hell of a lot of info in here and thought maybe someone would be able to help out.

Am I right in assuming you can't use the stock ECU from the 25DE for an NA 25/30DE?

Also, How would I be most likely (and cheaply, but reliably) able to get a high CR, like 10.5 or 11:1?

Cheers, John.

  • 2 weeks later...

Thats cheap dude. Very tempting. if only I wasn't broke...

You can disable the VVT - I did. I have adjustable cam gears in stock at work which delete the VVt. All you have to do then is get the head welded to fill in the hole, and block off the unused oil feeds in the front cam journal. The high pressure oil galleries in the head that feed the buckets and the other cam journals feed the end one too if you drill it. It takes a little messing about, but worth it. VVT sucks. get some good cams and leave them in one spot.

Don't say this won't work, cause I have done it.

Just a note on radiator and heating issues in general on an RB30DET from personal experience...

I've been running one of these for almost 3 years now with about 1 bar, and a big front mount IC in front of none other than the standard RB25 radiator that came with the car originally. I have had absolutely no overheating issues whatsoever. The temp guage did not budge from the original point after the conversion, nor does it move under the most sustained and abusive of engine treatment possible on the road, even on 40 degree days with the AC on and no AC auxilliary cooling fan, which had to be removed to fit the IC. This is also confirmed with the PowerFC temp display. So, if anyone is concerned, don't bother with changing or upgrading radiators.

Another thing about the conversion that I hardly ever see mentioned....

The additional height of the block. When I test fitted the engine, the crossover piping just rubbed on the hood lining. The BOV was in complete contact with it. This could have been the result of slight displacement of the piping from the different turbo fitted. Maybe that is why this hasn't been mentioned so often. Leaving it this way would have resulted in the lining being ripped to shreads, and consequently giving the game away. Additionally there was no way the aftermarket strut brace originally fitted could fit. It would hit the throttle assembly. The solution was to make 10mm thick adaptor plates that fit between the engine mounts and the block They have 4 coutersunk allen bolts that attach the plates to the original engine mount holes on the block. The plates then have 4 new holes drilled and tapped about an inch directly ABOVE the other 4 holes, which the engine mounts then bolt to. Effectively once installed the engine is lowered about an inch, bringing it back into line, allbeit still slightly higher than the original. The crossmember does not allow further lowering without maintaining some sump clearance. The holes in the crossmember that hold the rubber mount pad that the other end of the mounts bolt to need to be elongated outwards to accept the new engine mount positions, which now splay outwards that little bit further. Bear in mind the original strut brace could still not be fitted without hitting, although a different design may be OK.

The block to gearbox brace also needed to be slightly relieved to clear some obstructions. From memory, I think it was the drivers side one fouling on the steering rack or lines, but I may be mistaken. I defintely needed to relieve at least one of them.

This is all straighforward, but it did make the conversion slightly more than just a bolt-out-bolt-in affair in my case. Maybe this all makes sense to someone who has had this issue...

I forgot to mention that the radiator fan shroud also needed to be slightly relieved as the fan is now also about an inch lower....

Phantom,

Did you modify the standard RB30e's main oil feeds to the head. From memory they are definately sized different. This is one thing I have not looked in to.

The engine is getting built up as we speak, so I have to get my arse in to gear and let him know.

Joel,

Didn't do any mods to any oil feeds. All I did was screw a grub screw into the VCT supply hole in the head to block it off,and fed it externally via another fitting screwed into the side of the head. The only gallery type mod I did was enlarge the front water gallery on the block to more closely suit the 25t head with a standard head gasket.

Its going to take around 3 weeks to build / wait for parts.

The engine builder said the cranks/blocks are perfect.

I asked about oils. He said for general street use a good correct viscosity engine oil. Penrite, Penzoil, Mobil 1, Castrol etc. It doesn't matter if its not Synthetic, but must be friction modified.

For Race use a good synthetic oil.

BUT he said when I start using a oil make sure I keep using the same oil and not flick from one to another due to different addatives & cleaning properties. Because its turbo oil & filter every 5000k.

Hi Joel, you know that you have to run the engine in using mineral oil, never synthetic. We use the cheapest Castrol GTX, it's 100% mineral oil and runs the rings in very well. We change the filter fairly quickly, around 4 to 500 k's to get rid of any crap left over from the machining. Then at 1,000 k's change the filter again and the oil to synthetic as the rings should be run in well and truly by then. We use Castrol Formula R Synthetic 10W60 from then on.

yeah there is still the two theories of whether it's better to baby it for the first few 100km's or just rip into it right from the start. I'm not gonna do either i think... i'll load it up, but i won't rev it too hard for too long or screw in too much boost. Also no constant revs (freeway driving)

my car has been tuned mildly and with little timing to produce 355rwhp at 12.5 psi at 6400rpm. in an r32 it spins the wheels in every gear, except 5 not game to try but im sure it will. I'm very happy with the conversion, and hope to post some more power figures soon when it reaches over 400rwhp.

my car has been tuned mildly and with little timing to produce 355rwhp at 12.5 psi at 6400rpm. in an r32 it spins the wheels in every gear, except 5 not game to try but im sure it will. I'm very happy with the conversion, and hope to post some more power figures soon when it reaches over 400rwhp.

Sik32,

How much of an improvement is the low end torque compared to the ol' RB20?

Huge difference that slaps a big grin on your face?

I'm not talking about once on boost, more so the accelerating off boost torque (1000rpm-2000rpm) when you first take off from the traffic lights.

Well the Rb30 is all built... but omg she’s a sick little girl.

Few things on my part that are bad at the moment... old fuel (2month + old optimax)... so going to dump the fuel and get some fresh stuff in there.

My oil line to the head I don't think is getting enough oil to it... It’s fairly thin... I assumed that that the line to the head had to be 1-2mm thick... But I guess its not... Just a restrictor that has to be there. So I'm going to get Enzed out to make up a line for me.

Also using old plugs (well done about 20K - so going to get some new plugs for it)

It barely idles, when the accelerator is depressed it has a horrible sucking sound from the pod doesn’t rev and almost dies (eventually does) and generally sounds like crap.

Next it is going off to a mechanic if the above does nothing for it.

Anybody got any advice for me as to what it may be if it’s not those things? Has good compression don't have an exact measure going to get a compression tester onto it.

Hi riceline,

Sorry to hear about your malodies :(

Personally, I dont think fuel is going to 'age' and 'go off' significantly in two months to the point that it effects engine running....something else is wrong here.

For my external oil feed to the VCT I used an off the shelf copper line kit with a modified fitting, as used to connect oil pressure guages. It's also is quite thin, I suspect in the 1 to 2 mm ID range (1/8 th inch OD). I've done about 60,000km with it and haven't had any problems.

I'd start with the obvious....check ALL hose connections thoroughly for leaks. I'd also suggest new plugs as a start, the least you can do on a new engine after all that effort!! Failing that it may be an electrical problem. Check for spark. I'd also give the AFM a check to see if its giving an appropriate output. This sounds similar to what happens if you disconnect the AFM whilst running, or if its faulty. I've had a previous bad experience with a fuel rail that was delivered complete with injectors to an "injection specialist" (I use the term very loosley!)for cleaning. Upon return and installation, it all went south. To cut a long story short, the morons didn't lubricate the o-rings on the side feed injectors prior to re-installation. When pressed in, the o-rings were torn causing fuel to continuously leak into the engine whenever the fuel pump was running causing extremely rich and bad running....

The only other suggestion I would make is try to solve this issue VERY quickly. If the engine is new, ie new rings/bore/hone ring seal problems may occur down the track if the engine is run for extended periods like this. It doesn't take much...

Yes the motor (botom end) has been all rebuilt.

Crank - Cleaned, Balanced

Rods - Cleaned, Polished, Balanched

Pistons - Cleaned, Polished, balanched With new rings

New Bearings (Main and Rod)

Block - Honed, Chemical Clean.

Sump from the 25T is on there bolted up no probs. Degreased and cleaned before put on.

Head from the 25T is on. New Exhaust studs (2 of wich broke but were fixed) and taped for the oil feed to the head. Original oil feed to head blocked with Plastic Metal epoxy. The fuel rail and injectors were not touched at all during the whole time. They were left in the head at all times.

The line from the block is running from the oil filter assembly.. As you probaly know it T's out.. one end for the oil filter, One for the sensor and the other end is welsh plugged. Enginers put in one of the oil line fittings in there for me. I have included pictures of the oil feed.

The engine bolted together with no real problems accept that the engineers put the tensioner stud about 1cm to far along. but the belt still feels firm. Could use a little more tension but its not enough to stop it from idoling properly ( I think) And one bolt in the water pump does not line up.. So have to take that all off to fix that up and realign it (going to get a Rb30 water pump rather than use my rb25 one)

I have pulled the coil pack's out of the motor put the plugs in them and cranked it over.. They all fire But I am going to get a set of new ones as well. As well as geting some fresh fuel in there (just incase)

There seams to be a noise coming from the front of the head So that was my reasoning for asking about the oil line needing to be thicker for more oil to get in? As you will see in the pictures the size of the oil line is not very thick.. But I think I am using the same stuff as you.

I have not checked the AFM (I don't know how to) What I am going to try though is some break cleaner over it see how that goes.

The cam timing im not 100% sure how to check... From the TDC mark on the crank to the TDC mark on the head I counted 52 teeth.. Apparntly that is the correct amount?

Im not driving the car or anything like that.. just trying to get it to idol nicely before I go doing anything else with it.

Any further advice would be great!

Thanks for your help guys.

Im not sure if this question has been covered but from what i remember you can not put an older engine into a newer car legally due to adr and emission laws. If this is the case how did the some of you manage to get it all passed through the road transport companies.

Thanks

Harun

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