Autospeed said 10-12k I think they were talking if you used the RB26 head, which would obviously be more expensive and theres more to change. Still sounds high tho. Keep us posted. Ben Visconte is now running DOHC.

I am opting for a non turbo conversion due to the fact that I can register the VL as an RB30E powered car (no engineering required according to a local mechanic as it is still an RB30 and would retain the same engine number as an RB30 ) which would mean it would cost less to insure,also the fact he mentioned there are a lot of cars going around where you would never know what has been done to them (e.g. 383 C.I. Holden v8 Commodores,etc). Someone on the Skylinesdownunder website mentioned to me that top piston ring on the RB25DE pistons is narrower than the standard RB30 rings,I am planning on using the RB25DE pistons and having the block decked to bring the compression ratio up to 10.5:1. I want to know if there are any aftermarket piston rings available to suit these pistons or would I have to somehow chase up a genuine set,or could the ring groove be machined out to accept the RB30 rings? This I am sure with external mods (i.e. my single cam 3 litre already runs a 3 inch exhaust system primarily installed for turbo engine use) and a high flow air filter would be on the list,along with an air snorkel would yield around the 200 kw mark which is my desired power level,I also have to be realistic on what power I want as well. I find some insurance companies try to frighten people away from vehicle mods even if it is an air snorkel (cold air intake) and I crashed my last VL which had one,no questions were asked about it,which leads me to believe that when I was told my greenslip would be null & void if I fitted an RB30DE engine into the car that the engineer was also trying to scare the hell out of me also.

What a comment,isn't an RB30 a Skyline motor?

Quote: Originally Posted by Choice_Bro Autospeed said 10-12k I think they were talking if you used the RB26 head, which would obviously be more expensive and theres more to change. Still sounds high tho. SLIGHTLY HIGH??? Thats bloody ludacris! You can buy RB26's for cheaper than that, half that amount and less. If you pay that much for just a cylinder head swap, even an RB26 head, you are THE BIGGEST SUCKER on the planet and I guarantee you whichever mechanic did it would not be able to stand up cause he's laughing so hard that someone (insert your name here) actually forked over that much cash for such a procedure.

Quote: Originally Posted by LukeVL You can use a non VVT head and it bolts on. Do what I did and get a VVT head? No dramas. Pay someone $90 to weld up a coolant hole partiall, weld up the VVt oil ffed and re-drill oil galleries for oil feed to cam main bearing. Simple. Use adjustable cam gears to fix the VVT module or make your own adapter. None of this T-piece ****. Some people do things the hard way every time. Luke Hey luke, Does the VVT work on your engine?? So when u redrilled the oil gallery, did u drill through the welch plug on the front of the head and through the plug that devides the front cam bearing gallery from the main head gallery, then replace the front plug?? The way i saw it, if i drilled out the plug the amount of pressure in the head wouldn't be great enough to actuate the cam adjustment and with the solinoid open it would let all the pressure out of the head! So i drilled and tapped a fitting into the front of the head into the front cam bearing gallery. I've done the T-piece ****, it wasn't hard at all! I was talking to some1 else in person who had just blocked up the feed cos they thought it was connected to the main gallery, he got really worried when i told him it wasn't! He said "it's done 4000kms, hmmm better check it out..." Thanks, Darren.

Your best bet is to get yourself a whole early non VVT normaly aspirated RB25DE engine for around $1,000. This has the better 248 degree cams fitted. The later model VVT engines have shorter duration cams to meet the more recent and stricter Japanese emissions laws. The VVT is for emmissions not more power. Stock VVT cams are not good, and even worse if you disable the VVT. Please note the GTR never used VVT. The easy way is to just fit the whole RB25DE engine. This has 10:1 compression and works well, but lacks low end torque. If you put the twin cam head on the RB30 bottom end this will be far better - and you get to keep the same engine number (hint). The only disadvantage is that the compression ratio drops to about 8.5:1 which is ideal for a turbo, but a bit low for normal aspiration. You could always fit the RB25DE pistons to the RB30, but you might need to machine the dome down slightly to reduce the compression back to about 10:1. This will make the engine more lively, increase power by about an extra 5% and improve fuel economy as well. I suppose it depends on how good your RB30 is. If it needs a freshen up with new rings and bearings, I would be putting in some higher compression pistons at the same time. The RB25DE engine has been around since about 1993, (R33 Skyline) and if you wanted to buy one from a wrecker in say 1994, the conversion might very well have cost you $5,000 back then. So someone digs out an old article about this, and thinks that is what the cost is today.

Sounds alright. But if you look closely, all the pressure for the lifters and journal bearings throughout are supplied by two high pressure galleries that run down each side of the head (on the out side of the cams). Basically all I did was get the head welded up in the corner where the dramas are, so it matches the gasket (and head) and blocked off the VVT feed in the process. No feed to the end bearing right? Well you obviously noticed the welsh plug at the front, I drilled straight in that hole, tapping into the pressurised gallery, then replaced the plug, leaving oil to flow into the bearing which was cut off. This way it gets lubed- and pressure for that matter- WITHOUT having a hose running through your engine bay. cheaper than a T-piece, safer and more reliable. Having those pipes on a high-performance engine is asking for trouble. Just watch your oil pressure gauage carefully...

Cheapest way out is to get an RB25DE from an import wreckers you can pick them up for under $1000 compared to $1200 for a det head!. Then you can use the idler and other odds and ends you will need from the RB25 engine. How can you use the computer from the RB25 on a 3 litre engine ????? Mixtures/mapping would be way out wouldn't it??? Quote: Could u PLEASE scan the article of that head conversion? lotsa ppl would be interested and it would stop ppl having to always ask about it. i can scan the article but i cant post it up (no webspace) The std DE cams would be fine, i'm doing the conversion with a turbo and a SubZero told me that the DE cams would be fine even with the turbo. They have a R33 that is RB30/25 and it pulls ultra low 10's with the std DET cams.

check the article on n/a twin cam converison at www.r31skylineclub.com they used the rb25 computer including the multicoil setup of the rb25 head. i dont understand how it would work properly either, with an extra 500ml of capacity, but hey what do i know. the std DE cams would give better off boost driveability with a turbo, or so i believe anyway. r31wagon posted a link to a great site earlier, unfortunatly that link doesnt work anymore, however this one does http://trinity.frontierisp.net.au/~rowan/twincam.htm

The RB25DE computer will be o/k. The reason is that the airflow meter measures the air going to the engine, and the computer adds the right fuel for the airflow it sees. It is important to realise that the RB30DE will not make any more power than an RB25DE, and maximum power will occur lower in the RPM range. Remember maximum power is set by maximum flat out airflow. Increasing the stroke increases the engine capacity, and torque, but it cannot increase maximum airflow. Also, if you use the stock RB25DE inlet and exhaust manifolds, and cams, the volumetric efficiency of the engine will still have similar characteristics. The mapping will remain fairly close with the stock RB25DE computer. At light throttle cruise, the closed loop oxygen sensor will correct the air fuel ratio for best economy. If you fit extractors, and big cams, then you are going to have to remap it, or get yourself an aftermarket computer.

Yep that sounds fine Luke but does the VVT actually work? If u supply power to the VVT solinoid does it affect the engine at all?? Um and i know about all the galleries in the head but they are not high pressure galleries... They are fed by two little holes in the block. If all the clearences for the lifter and cam bearings add up to just half the area of the two small feeds then the pressure in the head will only be half of the pressure in the block, if the clearences add up to the same area as the feeds there will be barely any pressure! If u leave the solinoid open it makes a drain for the oil in the head and result is no head pressure at all... What u done is fine, actually great if u don't want to use the VVT, just make sure the drain in the front cam bearing is blocked. Just looking out for ya Some original photos have not been recovered yet.

No it doesn't work and you don't want it to. The VVT gear works on a double helix, (Just two bumped together) and when twisted in opposite directions, tensions the thread and holds the gear in place. At solenoid switching, the oil pressure is set to the right amount to slide another helix and release the first two. I haven't tried to figure it out and don't really want to. The main things are that Nissan engineers are a bunch of incredibly smart guys with plenty of decades of experience behind them. Tryinbg to duplicate their work with oil pumps and pressures different to theirs (Original RB25DE) and different computers etc is near impossible to achieve their result. You are best off taking it off and getting cams made to suit your engine and don't shift around at 5000 rpm or whenever it works. How did you put the VVT head on your block? The shape is not the same as RB30 and oil would contaminate the water etc. I'd like to know, it sounds like you've done a good job if it works. Is that your calais in the pic? It looks sweet. Do you circuit in it?

The VVT system has a nasty very short duration inlet cam, and works as follows: At idle the inlet cam is retarded, this removes all valve overlap and allows a good clean low emission idle. Just above idle at about 1500 RPM the ECU advances the inlet cam. The earlier inlet valve closing increases low RPM torque. At about 4000 RPM the inlet cam is again retarded, the later inlet valve closing increasing high RPM torque. The ECU has an output which switches at the two selacted RPM points and operates an oil pressure solenoid. As Luke says, the Nissan guys are smart. This horrible system was designed to get the engine to pass strict emissions laws. You certainly do not want it on your engine if you have a choice. If you buy an earlier RB25DE head without the VVT it will fit straight on your RB30 block, and have some decent cams already in the head. These are the longest duration factory RB cams available. You can get a whole motor for $1000 dollars, a reground inlet cam costs about $650. Why bother with the VVT head at all. If you already have one, sell it to someone else, and buy either a non VVT head, or a GTR head.

I really don't think it's all that complicated, i don't mean the actual mechnisim, i mean the operation. there's 1 solinoid, u either apply power to it or u don't... I'd really dought if it is PWM'ed. I dought u would have to have the right oil pressure for it to work either, just have enough pressure to operate the mechinism, there's no maximum? I am only guessing though, i could be wrong, but i'm going to try it anyway! As for the VVT being a complete waste of time, i don't think so, the factory cams may be crap but with the right cam it would have to be better, not max power but through the range. I'm aiming for an engine with a very wide power range like 2000-6000rpm thats why i'm using twin turbos sequentially spooled up the same setup as a supra. None of this boosting at 5000rpm crap, thats pointless... Luke, I could have had the head welded like u to match the water gallery but i'm also using a RB25DE VVT head gasket as the cylinder water jacket holes are all even where the RB30 gasket holes get larger from front to back. So the gasket doesn't line up with the block... I tapped a thread in the oil gallery and pulgged it. As yet i haven't done anything yet but i was planning on bronsing or silver soldering a small piece of steel to the side of the block and getting the top machined. Yep that my calais, i'm just getting into circuit racing, had 3 races. It's awsome fun.

I read posts all over the net were people say to get rid of the Variable Valve Timing. I can say from my own experience with this engine that VVT makes a big difference. We all know that advancing the valve timing of the inlet cam will give the engine better bottom end power, Guys will RB30E's tell you that one tooth ( about 4deg) gives it a big bottom end lift and that they don't rev the engine that hard so they don't miss the top end , Well I can say that with my RB30DE ive advanced the inlet timing about 6 deg ( the VVT cam pulley has adjustment, but its behind the pulley) for great low rpm torque and then to be able to have the VVT work to retard the cam 20deg ( think its 20 crankshaft degrees, 10 cam degrees) to improve the top end is worth every bit of trouble you have to go to keep the system. My engine pulls strongly in from 1500 to 7100rpm, something that I don't think it would do as well, with out the VVT. I'd just like to add that people seem to miss the point of VVT, yes it has been used lately to meet the demands of tighter emission laws, but as guys would say, "get rid of that EFI and put a good 4 barrel on it", guys are saying the same about VVT now, because they don't see or maybe haven't worked with it to see the true picture. At low rpm the air speed through the port and valve is slower, so we try to have the valve reach its point of maximum lift at the same time the air speed reaches its maximum speed, for the best volumetric efficiency. But as rpm increases the air speed falls behind the increasing engine speed and torque drops off, but if we retard the inlet valve timing we can match the maximum valve lift point to the maximum air speed which is now later in the cycle, this will increase torque at higher rpm. So as you can see the engines torque can be increased over a much wider band (and torque times rpm equals HP) with the use of VVT, for any reasonable cam used. Steven

87calais - be careful who you talk to and who you get advice from, not everyone has the knowledge and experience of a genuine motor builder, performance workshop or 'Turbo expert'. They may be right some times, but you never know who just opened a shop one day and started making fast cars - without ever being even a mechanic. Ask their previous customers how many times their cars have blown up and how much it cost them. Don't afraid to ask of their experience either. Just be careful... Back to the VVT: How do you guys know where the VVT unit will place itself when you first start the engine. You can take a punt and say it will stay where it is, but how do you know? I moved it with a spanner and vice and the thing moved (by memory) around 30 degrees. The oil pressure thing, well thats how the whole deal is operated. If you don't have enough at any point, it may not complete its movement or jump, I'm not sure cause I don't know EXACTLY how it works. And when you get it to work, either by RPM switch or programming, at the end of the day, the cams are not suited to a 3 litre engine with your exhaust mods, or turbo mods or intake or all. You will make more power with no VVT and different cam specs. And I know you guys will say that cams are expensive, but We can re-grind them, which isn't bad and just requires some spacing for correct valve operation. Don't worry! I'm gonna hit up my boss tomoroow and see if I can make a program for the CNC to grind RBXXDE and DET billet steel cams! A bit of testing, especially during our shop move, but I'll see. Keep yas posted. [/quote]

Quote: Back to the VVT: How do you guys know where the VVT unit will place itself when you first start the engine. You can take a punt and say it will stay where it is, but how do you know? * The VVT unit is held in the retard position internally by a diaphragm spring. *Oil pressure shifts the VVT actuator to the advance position. *Power to the solenoid will close it cutting off the oil drain from the unit making it advance. Quote: The oil pressure thing, well that's how the whole deal is operated. If you don't have enough at any point, it may not complete its movement or jump, *As the VVT has a large piston area, only a small amount of oil pressure is needed to shift it. *The small oil holes in the unit and oil galleries dampen its movement stopping it jumping. Quote: I'm not sure cause I don't know EXACTLY how it works.And when you get it to work, either by RPM switch or programming, *The R33 i tested was retarded at idle or any time the throttle was closed regardless of rpm. *just off idle it advanced (power to solenoid) *And stayed advanced till it reached 5400rpm. *5400rpm its retarded. Quote: at the end of the day, the cams are not suited to a 3 litre engine with your exhaust mods, or turbo mods or intake or all. *This maybe true, but for me the cams seem to work with my 3ltr very well. Ive advanced the inlet cam 6 degrees from std and changed the VVT shift point to 5000rpm, which suits it better. Quote: You will make more power with no VVT and different cam specs. *Yes you will make more power with different cam spec's BUT you will have it over a bigger rpm range with VVT. Steven Some original photos have not been recovered yet.

how do you advance the cam timing

Quote: Originally Posted by RACEY VL how do you advance the cam timing The VVT cam pully is adjustable from factory, just remove the pully, loosen the 4 bolts and move the pully on the center! Thanks RB30-ZED, i love u man.... :P The results u've posted is pritty much what i thought and hoped! The VVT is very much worth keeping! Just 2 Q's, What ECU r u using? And how did u supply oil pressure to the front gallery? Thanks

Thanks Twinvl, Im using a complete Holden system of a VP V6, so parts are cheap and it runs the Holden coil packs. I rewrite it with Kalmaker ( www.kalmaker.com), a very flexible system that allows you to change over 300 variables. It will also data log and run dual ignition and fuel maps. Ive had it running on a Nissan L28 and now my RB30DE. Other guys have covered this but, you need to run a oil line from a t-piece at the oil pressure switch up to the front of the head. Drill and tap in to the gallery, fit a 90 deg fitting to run the hose up to. Now you have to block the original entree to the gallery in the face of the head to stop oil going straight in to the water gallery, and that's it. Steven