Warpspeed

Hi hippy. I am interested in this as well. The first thing is to ensure your engine is in good mechanical condition, do a compression check. Second thing is make sure it is tuned properly, and that everything is working. When was the last time you changed the spark plugs ? is the oxygen sensor actually working ? Third, look at the whole car. Tyre pressures o/k, handbrake not dragging ? do you carry around a lot of heavy junk in the boot that you dont really need? Lastly and most importantly is how you drive it.

Sil8ty has raised a few points. A standard GTR with standard cams does not make best power between 8500RPM and 9000RPM. The factory rev limiter is set to 8000RPM or just above. The Nissan engineers designed the GTR to be a docile machine with a lot of power. The standard GTR cams are very mild in both lift, duration, and valve action. This is to enable the stock valve springs to last the life of the car. Max rated factory power is at 6800RPM by the way. New aftermarket or reground cams are expensive. Lots of GTR owners replace their cams, so there are a lot of secondhand stock GTR cams available really cheaply, typically $250-$300 per pair. For this reason only, I suggested it might be worth a try. Anyone who thinks that Nissan really screwed up with the valve timing, will probably get ten percent more power by being smarter than the Nissan engineers. For the rest of us, there may be a few Kw to be had right at the very top end in a modified engine, or with a stretched timing belt. This is not going to be cheap power though, unless you already have the adjustables, or can get them for nothing. Standard GTR cam lift is about 8.2mm as I remember, the Japanese cam grinders offer cams with lifts up to 9.7mm as a drop in replacement. Beyond 10.5mm, head machining and special valve springs are required. I have seen cams quoted with 11.3mm lift. Mechanical lifter cams have long ramps at the beginning and end of the lift curve. The opening ramp ensures the first bit of lift slowly and gently closes up the tappet clearance before the valve is rapidly accelerated off its seat. The closing ramp is to stop the valve being violently dropped onto the seat as the cam lobe pulls away from the tappet. The ramps reduce both noise and mechanical shock in the valvetrain. Hydraulic cams do not have these ramps. The whole valvetrain is kept solid by oil pressure in the hydraulic lifter. The cam lobe is in full control of the valve motion at all times, so acceleration away from, and onto the seat can be quite rapid, and without shock. You can fit a mechanical cam into an engine with hydraulic lifters without any problems. Putting a hydraulic cam ino a solid lifter engine is a very bad idea. So yes, GTR cams can be used in an RB25.

Yeah INASNT your right. A GTS-4 plus a GTR front cut will easily get you the most bang for your buck. The great unwashed, and the ignorant, will probably think the -4 on the end stands for 4 cylinders, Hehehe.

You could always give it to the local fish and chip shop. They need batteries as well.

I have seen gearboxes go for about two grand. then you need a clutch, flywheel, lots of small parts. You need to fit a clutch pedal. It sounds like a heap of real expensive trouble to me. I am waiting to buy/import a manual. They do not cost any more to buy, so why bother.

I have been looking for one of these myself for a couple of months, they are a rather rare beast. There are two that I know about, PVAs car, and another for sale in Adelaide at the moment. Standard they are certainly no rocketship, but have a lot of good features that come standard. It would be rather easy to add a turbo (or two) and end up with a rather quick car, for around half the cost of a GTR. If you buy a GTSt, it would be just about impossible to fit 4WD or ABS onto it later. Smoking the tyres and sliding around all over the place may be fun, but it is neither fast nor safe, particularly in the wet in my opinion.

I believe that the low RPM switching point is purely emmission related, they also do some shifty things with the ignition timing as well sometimes. Remember the original designers get all worried about things like catalytic converter temperatures and so on. None of this is performance related, at least not in the sense we mean performance. The upper switching point is the one you should be most interested in, the amount you gain will not be huge. In fact if it switches right at the crossover point you will never be able to pick where it has changed, because the power should be identical at that point.

I believe the ECU turns a solenoid valve on or off, which in turn diverts engine oil pressure to the VVT mechanism through drilled passages in the head and cam. I am not familiar with exactly how Nissan do it exactly, but all the other systems that I know of, retard the cam at Idle to reduce valve overlap, for lower emmissions at high manifold vacuum. At some low RPM above idle say 1,500RPM? the inlet cam is advanced. This increases overlap, and gives earlier inlet valve closing, good for mid range torque. At some higher RPM the inlet cam is again retarded, this gives later inlet valve closing, and better high RPM torque. On a lot of engines this might be around 4000RPM for example. What you do is run the car on the dyno in both positions, and arrange for the VVT to switch over where the power curves cross over. This will give you the best everywhere. If you fit a slightly longer duration cam that has both the overlap and the late inlet closing features together with a bit more lift, and no VVT, then you will get more torque everywhere, but it will probably not then pass a full formal emmissions test. Hehe.

Probably. As you said at the start, people have put n/a cams into turbo engines and said it went better, but who knows ? Someone somewhere must have tried GTR cams in an RB25DET by now. There are so many GTSTs and so many spare GTR cams around.

I am new to this myself, but am trying to learn all I can. From what I have been able to find out the cams in RB20 RB25 and RB26 all fit, there is no problem there. Some versions of the RB25 (only) come with VVT which is an oil pressure activated helical spline arrangement on the inlet cam only. The VVT cams themselves are different on the drive end, as is the special drive pulley that incorporates the VVT mechanism. I have been told that a non VT cam with its standard drive pulley will drop straight into the head with no other changes. Also an exhaust cam which has the drive tang that engages with the cam position sensor will fit into either the exhaust side or inlet side. An inlet cam can only be used as an inlet cam because it has no drive tang. I have not actually tried any of this myself yet, so cannot absolutely guarantee this is correct. But I have been interested in it for a while, and nothing I have been able to find out contradicts.

Thanks for the info ph1. I notice that the data you have is for R32GTR, and is undoubtedly correct. The cams I have measured are probably R33GTR, and from what I hear R34GTR are different again. My information comes from firstly my own measurement on a cylinder head with degree wheel and dial indicator, Julian Edgars book, and also an article that I cannot now find, in one of the car magazines. While the published info can always be suspect, it all agrees exactly , with what I have measured myself. I have seen aftermarket 254 cams advertised, but am not aware that 250 or 252 cams were also available. The aftermarket cams also usually have higher lift and more agressive profiles, even though the seat to seat timing may be the same or only slightly different. Sil8ty. A lot of people are replacing the stock cams in their GTRs with aftermarket cams, and so there are plenty of stock GTR cams available at bargain prices. It is extremely difficult to predict how much if any improvement you will get, without knowing what cams you already have in the engine. Maybe you could borrow a set to try ? Also GTR cams are mechanical lifter cams, RB20 and RB25 have hydraulic lifters. You can put a GTR cam in the other RB engines, but you cannot put a hydraulic cam into a GTR. But then why would you want to ! The GTR cams are actually quite mild as far as lift and valve action go. Looking at what some of the Japanese camgrinders are offering as replacement cams for RB20 and RB25, apparantly standard valve springs are o/k up to about 9.2mm lift. The GTR cams are less than this so should go in without any spring related problems.

I have a GTR cam right here, and I measured 250 degrees duration at .012" lift. This is about where the end of the ramps would be. I have also seen this figure published. I believe this is an R33 GTR cam (not absolutely sure though). What exactly do you have there, because I am extremely interested.

The variable timing on the inlet cam is put there so that the engine can meet emmissions and still make reasonably good all around power. The actual valve timing is quite restrictive, but am unable to give the exact cam duration figure (actually I would love to know) of the VVT inlet cam. If you remove the VVT and fit a suitable fixed inlet cam the engine will run better everywhere if emmissions are of no concern. What cam is best for you depends on what you have, and what you wish to achieve. The n/a inlet cam is I believe 240 degrees duration. I know for sure that the GTR inlet cam is 240 degrees duration, so this is probably a good choice for a mild street engine with stock turbo. If you overcam the engine you will lose power, particularly on the inlet cam. You can run a larger exhaust cam than inlet cam, and this will actually give you a better power gain. The standard GTR exhaust cam is 250 degrees.

Why dont you two guys get together and just swap exhausts ? Turtles three inch system would go o/k on a GTST, and Rs73s system would probably be about right on an n/a, reasonably flow and reasonably QUIET. Save both of you heaps.

One other thing to watch is the two idler rollers on the cambelt. If you are on your second or third timing belt, it may be time to replace the belt tensioner and idler bearings as well. If one of these fails, the belt will break or come off, and you will then be in real trouble.

There are rocks out there big enough to smash windscreens, it happens all the time. A similar sized rock would not do your intercooler a whole lot of good either. If the mesh is the same colour as the cooler, you will not be able to see it except up real close.

Well, I dont actually have a Skyline, so the running costs are zero. It does not take up any room, requires no maintenance, or make any noise at all. The Skyline that I do not yet have is the perfect car.

Yes that is now. I can remember when a new R32 GTR cost over 100 grand, and an import 80 grand. They have come down a little bit since then. The R34s are still current, wait a year or two. It will make a huge difference. Your savings go up, the price comes down. You will have one a lot sooner than you think.

The 2JZ-GTE is 3 litres, it has the same 86mm bore as the RB26, but the stroke is 86mm. Sort of like an RB30DET. If the bore is the same in both engines, the valve and port sizes are most probably also the same or very close. I have no idea what a 2JZ-GTE costs, but I doubt if it would be all that cheap either.

Seems to me you need some accurate monitoring equipment to do some testing if you are going to seriously modify your car. But unless you are trying to diagnose a problem having your car look like the flight deck of an aircraft is just a wank. I have several pressure gauges with large scales that can be used to measure: Fuel pressure, oil pressure, boost pressure, exhaust manifold pressure, and exhaust pipe pressure at various points. A homemade water manometer is also useful for measuring low pressures in the induction system. A digital thermometer with remote readout is absolutely vital. An airflow meter is a handy thing to have, and so is a sound level meter. A multimeter is very good to have, as is a compression gauge and timing light.

Well, the Laser aint no GTR thats for sure, BUT it is a lot of fun on few dollars. My car has a bit of a history, bought it brand new in 1985 for $3,100. I got sick of working on cars, having things blow up and fall off, swore I would never modify it. Drove it stock for ten years. Finally the engine needed a rebuild, so I put in a Jap import turbo motor. WOW from about 55Kw to 110Kw instantly. The thing smoked the tyres, torque steered, and was an absolute deathtrap in the wet. Realising I probably had only months to live, I bought a Laser TX3 4WD turbo. The thing had the same engine but was a complete slug. It was a lot heavier and nowhere near as much fun. Five weeks after I bought it someone did me a favour and stole it, wrapping it around a tree and writing it off. It was uninsured. I brought the wreck home, still have it in fact. Pulled out all the 4WD bits and put them into the original Laser. Now the really interesting thing is that both cars were parked side by side, but the red one with the mags, and the TURBO 16V 4WD stickers got stolen. Not the plain white one with plastic wheel trims. I learned something from that. Also the original 4 door Laser fitted with all the 4WD bits turned out 110Kg lighter than the 2 door TX3. It certainly went a lot better with less weight. I learned something from that as well. Over the years it has had several different turbos, was fitted with a supercharger at one stage. It has even had both a supercharger and turbo fitted together. I learned something from that as well. Turbos give plenty of top end power, but superchargers give enormous torque throughout the range. Combined with the traction of 4WD in a light car, it is an absolute rocket from a standing start. No big clutch slipping revs or wheelspin, just let out the clutch normally and nail it at perhaps 1500 RPM. So my next project is going to ba an R33 GTS-4 fitted with a SUPERCHARGED RB26. As far as I can find out it has never been done before. And it is going to remain completely stock on the outside, skinny wheels, no wing and all.

My contribution.

Around Christmas time is a good time to be a buyer in the private car market. It is not very nice, but a lot of people get retrenched, and others are real short of money around this time. Something will come up when you least expect it. So just be patient for a while. I have been looking for an R33 GTS-4 n/a myself for a couple of months now. So far only three have surfaced, two are autos, and the third has a GTR body kit that I particularly do not want. It is almost out of rego and the guy wants 19K which is a bit much, plus the car is over in Adelaide. Being three times your age, my situation is a little different. I want a stock plain wimpy looking basic skyline with all the GTR bits hidden underneath.

From your last post I gather you plan to replace the rear muffler. I would leave it right where it is for the moment, and add a second chambered muffler halfway down the pipe. Putting an offset chambered muffler right at the back is not going to give you the sound reduction you need. It will work far better closer to the engine. You can try it right at the back, but I dont think you are going to be happy with it.

Thats the whole point Duncan. Pick up a real low cost n/a now, lose nothing when he resells it in twelve months, maybe even make a few dollars. A year from now his parents will be a lot less frantic about the whole thing.