Warpspeed

buying from a dealer has some advantages, you get some sort of warranty, and you can sue if the car turns out to be stolen or has serious hidden mechanical problems. You are also protected somewhat by the trade practices act. If you buy it from some dork that lives in a low rent flat, he may not be around in a few weeks. You are totally on your own. What you buy is what you get, and that might turn out real bad. If you go to see a car for private sale and you like it, but think it is overpriced, say to the seller "I have two more similar cars to inspect today, and both sellers are asking less" make a firm offer and leave your phone number, do not argue. He might call you back later after thinking about it for a while, and accept your terms if they are reasonable. I never haggle but make a reasonable fair offer and then leave.

Some of the Japanese torque control units modify the three G sensor outputs, so the ATTESSA still works normally, it is just being fooled about what the car is actually doing. I agree a permanent 50/50 full lockup of the FWD clutch is a horrible idea.

If I was a dealer, I would know what I paid for that car, and how much I need to sell it for to pay the rent and the phone bill. If some smart ass punk comes into my yard and offers me less than it cost me I would tell him to piss off and go play somewhere else. If it was a private sale, you might do a lot better in beating someone down if they are desperate. But a professional hard nosed car salesman in a car yard, I don't think so.

Well.... The thing is controlled by software, so in theory you can write a program to make it work any way you want. The difficulty is deciding what is the best way for all situations. No doubt Nissan have put a lot of work into it to suit what they consider the average driver. The average driver is not a drag racer, or a rally driver. It must also work in wet slippery conditions or in the dry, and be fairly predictable. A pretty tall order. People I have talked to that have modified the standard system say things like, yeah it's fantastic when xxx, but when yyy it really sucks. That is the problem as I see it, there is no single best all around solution, but many have tried.

Yeah, as has been said, you can tell by the smell of bullshit that the mechanic is running MEAN. He needs immediate brain surgery which is going to cost him $6,000

Individual throttle bodies give vastly improved throttle response, are much more cam friendly, and give much cleaner idle emissions. A large single throttle might give you a poofteenth more power right at the extreme top end, but is a bummer for drivability. Drag racers use large singles, road racers use individuals. Maybe all the Formula one guys are complete dummies. Maybe they should use a big single eh ? If VVT was the total answer, why did not Nissan use it on both the inlet and exhaust cams of the GTR ? They obviously have the technology to do it, Maybe they are complete dummies too ???

Steve is right, the GTR head has the same ports, valve sizes, and combustion chambers to the RB25. In other words the GTR cylinder head has no more power in it. What makes the GTR so good is the superb six throttle body induction and the twin turbos. But a Greedy inlet manifold on an RB25 would come mighty close for a lot less cost and trouble. The VVT is only there to enable the RB25 to pass idle emissions and still make reasonable power. The GTR can pass easily without VVT simply because the six throttle bodies are so close to the inlet valves. VVT is for emissions, not power !!! If you put decent cams in an RB25 and get rid of the VVT it will go much better, but it could never pass idle emissions like that. If VVT was there for top end power, why was it not fitted to the GTR ? It would have cost them nothing to add it. The obvious answer is that it was not required and adds nothing to performance.

Have a look at the two cam wheels on the end of the cams. If they both look the same, there is no VVT fitted. With VVT engines the inlet cam wheel has a huge "nose" fitted and looks quite different to the wheel fitted to the exhaust cam.

For what you are asking there are basically two different types of RB blocks, one uses the variable valve timing on the inlet cam, and the other does not. These two different blocks have slight differences in the front right hand corner, which concerns how the oil drains back from the VVT to the sump, and the nearby water passages in the same area. Very early RB25 blocks did not have VVT, and neither does the RB30, or the GTR, so heads and blocks all fit straight together. To fit a GTR head on a later RB25 VVT block requires some easy modification of either block or head. Apart from that it all goes straight together using the original 10mm RB25 head bolts. Or you can tap the block for the 12mm GTR head bolts if you want. The locating dowels are the same in all RB engines, no changes are required. Your best bet is to buy a complete RB26DETT and fit the crank, rods, pistons and oil and water pumps. But use the original RB25 block and sump. Or you could buy a blown up RB26 and just use the top half on your RB25 bottom half. You should be able to find an absolutely complete RB26DETT that has spun a bearing or has several cracked pistons (from detonation) for maybe $3,000. The top half will likely be quite o/k. After you have sold your RB25 top half to one of the RB30 Commodore guys, it should not work out too bad if you do it all yourself.

Anything is possible, but..... The 4WD blocks are different to RWD blocks. The 4WD has the front diff mounted in the sump, and the sump and oil pan rails are further apart and quite different on the 4WD blocks. If you really want to fit an RB25DET it would have to be from a Stagea 4WD. Or you could use a non turbo RB25DE block from an R33 GTS-4 which is also 4WD. While you can put an RB26DETT into a GTST, by butchering the sump a bit, it would be pretty difficult to go the other way. There is a company somewhere in NZ which makes an adapter plate to fit the 4WD sump to "normal" rear wheel drive RB engines. Guys that fit RB30 blocks to GTRs use this plate, or have to make up something similar themselves. Apart from the oil pan rails the RB25 and RB26 blocks are pretty much identical. Cranks, rods and pistons can be swapped either way, and drop right in. You can build up an RB26DETT using an RB25 block for a GTST and all the GTR bits. This keeps the old RB25 engine number (hint) and the original skinny sump.

Mr Skyline, Saying someone has made 504Kw is one thing, but you cannot make that sort of power with a totally stock engine, no way. Highly modified Skyline GTR engines with the four valve DOHC head are reputed to be now capable of over 1,000Kw, so what ? The fact is, the DOHC head is a much better basis to begin from. From there you can spend insane amounts of money, but the DOHC will always beat the two valve for any given budget. I have never heard of anyone with a GTR fitting the VL cylinder head because it is somehow better. Have you ?

The DET head completely standard will flow about 30% more, but fitting it will reduce your compression ratio slightly too, so the power increase is not quite that much. As a straight swap on an RB30 block it is a very worthwhile modification. Saying that the two valve E head can be ported to reach the same flow is probably true, if you want to spend the money. Getting all of that 30% would not be a cheap job. A quick port clean up and match will only get you typically about 5%. Extensive porting done properly with larger valves is going to cost you far more than the DOHC conversion. Best bang for your buck would be a DET head with aftermarket camshafts. If you still want more, get that ported. If it is n/a a set of RB25 pistons will increase the compression of that RB30DE to about 10.5:1 which is ideal with big cams fitted as well. It is probably too much compression for the stock cams. If turbo, the 8.5:1 compression is ideal with the standard RB30 pistons.

D/ Let the moron go past. Many times times in situations like this, I have noticed the moron rapidly gaining on me from behind at illegal speeds, was in an unmarked car, and wearing a police uniform. They just love to drive fast themselves and bait people.

How could everyone already be using them, they have only been available for about a couple of weeks ???

Hey Sydneykid, I have lived in some pretty small flats at various times, but living in a post office box would be far too cramped for me. Let's be honest guys, young blokes like fast cars, and they like to drive them flat out from time to time. The trouble is that they are at some time going to lose control. It is one thing to frighten yourself to death by spearing into the weeds backwards in a Datsun 120Y flat out at 80Kmh, and quite another to hit a steel pole sideways at 200 Kmh. I was young once, and I used to thrash around, made lots of noise, hated the cops, had a few accidents too. As you get older you DO slow down and think a bit more about what you are doing. You can still thrash a low powered car, but the accident might then only be a little one. Put a P plater in a boosted GTR, the eventual prang is going to be far more spectacular. Allow young guys into high powered cars, but only after say two years of unblemished driving in a low powered car. That is, no speeding fines, and no prangs. It might take a long time for some to reach two straight clean years. It would have been pretty tough going for me when I first started driving.

They are still made by Garrett, but Honeywell now owns Garrett.

The original power curve is smooth as a babies bum, showing good tuning. The modified power curve is ragged, and it looks like it is having a heart attack. If that is the best they can do, no thanks. That is a bloody disgrace, If I had tuned it, and saw that power curve posted on the internet, I would die of shame.

I managed 12. Screwed up on the year Alfred Buchi patented his turbo, and the AVNT actuator. I actually have a Garrett VNT turbo fitted to my Ford Laser at the moment, but have never heard of AVNT. Must be something pretty new eh ?

There probably is a specification around somewhere for minimum oil flow, but I have no idea what it is for ball bearing turbos, probably not very much. The old sleeve bearing turbos that are oil cooled need half a gallon of oil per minute at fast idle (full oil pressure). But these sleeve bearing turbos use oil for cooling as well as lubrication. They usually have two 1.0mm restrictor holes in the front thrust bearing. It is quite easy to disconnect the oil return to the sump and measure the actual flow into a container. Too much flow is not a good thing for two reasons. It steals oil from the rest of the engine, and lowers idle oil pressure, and all that oil has to get back out again. If it cannot escape easily, it is going to find its way out past the seals as has already been mentioned. Ball races only need to be wet with a thin oil film, they don't need to be drowned in oil. The water in the bearing housing will carry away all the heat. I doubt if oil starvation is ever going to be a problem, unless there is a total blockage. But too much oil is probably a worse enemy.

This has been done before by many people. The way they do it is as you suggest. Cut all the GTST runners off straight, just before the injectors, and either weld on the GTR plenum direct, or better still, weld on a flat flange plate, and then bolt on the GTR plenum. There will be quite a bit of grinding and matching because the runners DO NOT LINE UP perfectly. GTST runners are almost evenly spaced, the GTR plenum has the runners spaced in three pairs to suit the three twin throttle bodies. Every runner needs to be moved sideways a small amount. This is not obvious just by quickly looking, but if you look very carefully you will see what I mean.

Sweetr33, sounds like you have a plan. Fitting the GTR plenum just by itself will probably make the engine feel a bit soft down low, and might be a disappointment. But if it is just the very first step in a long range plan that you have worked out, it is probably a pretty smart move.

Oh golly, what a bun fight......... My take on it is this. Multi throttle bodies will give you two things, better transient throttle response, and better cleaner idle with large overlap cams. None of this is going to show up on a dyno at wide open throttle(s). On the road it might feel quite different, and that is where the advantage lies, not on the dyno, or quarter mile times. For sheer balls to the wall top end horsepower, a single throttle body can be made as large as you want to make it. Throttle response and drivability will not improve. Drag cars have single throttle bodies, and the road racers keep the individual throttle bodies. What do YOU want to use YOUR car for ? As far as inlet manifolds go, what else are you going to do to the engine, and what is most important to you ? Long intake runners are a definite advantage for low end and mid range torque. At stock and moderate boost levels they are NOT restrictive as Sydneykid keeps on telling everyone. Air distribution is excellent. If you are planning absolutely massive boost and radical high Rpm power, something else might work better. The GTR manifold was designed for less restriction, but it also is going to have less low and mid range torque because of much poorer cylinder filling off boost. That DETT engine relies totally on boost pressure to make it go. I would bet that with stock boost and stock single turbo, an RB25DET will have reduced low and mid range torque, and it will not have the same top end power as the GTR simply because the stock turbo will run out of flow. Although I have not actually tried this myself. It probably will work better if you are planning to upgrade everything else along with the intake manifold, the engine will then take on a completely different character. At stock GTR power levels the factory GTR manifold will have near perfect air distribution. The Nissan engineers made it that way by putting in all those ridges, steps, and curves. But if you start increasing the air velocities greatly above what it was designed for, it will all start to go wrong, and the rear cylinder runs lean. That is where all this nonsense started, guys start running 20+ psi and complain the stock manifold is rubbish. Well, maybe, but it was never designed for that. Decide what you want it to do, and design it to do that job.

The needle might turn into a blur, and you will hear the dreadful noise, the engine might not not be terribly happy either abut the rapid pressure fluctuations. The effects can vary quite a lot from hardly noticeable to turbo end engine shattering violence. It all depends on how bad the surge is. All turbos can surge if the compressor flow drops below a certain value. As lithium says bigger and bigger compressors surge at higher airflows. There is a myth that huge compressors will force more air through the engine. It simply is not true. If the engine has 10psi boost with a small compressor, and you fit a humongous compressor wheel that also makes 10psi boost. The engine just sees 10psi and flows EXACTLY the same amount of air. It might be more efficient at the top end, but if you have a decent intercooler, that does not matter either. Suppose the air going into the intercooler is 120C and 50C coming out. You fit the monster compressor wheel and the air going into the intercooler drops to 90C, and the air coming out of the intercooler to 47C. Hardly worthwhile doing. If it also now surges, you have wasted your money on that "hi Flow"compressor wheel.

Joel is spot on. Have a look at the Mazda Miller engine, it will amaze you. Although supercharged not turbocharged, this engine has a static compression ratio of 10.2 :1 and runs 18 psi boost from the factory. And they don't detonate either. The reason being the inlet valve closes 72 degrees after BDC. The piston is almost half way up the bore before the inlet valve closes, meaning only half the actual piston stroke compresses anything. Think about it. If the theoretical compression ratio is 10:1 and if only HALF the stroke length is used it would only actually be 5:1. It is not quite that low, but you get the general idea. It is not that simple because of con rod angles and piston motion, but late inlet closing does reduce compression. The cranking pressure with a compression gauge will give a pretty good idea of this effect as well. As Joel says, some of the normally aspirated racing engines run 16:1 compression ratio, but the cams are pretty extreme too. With a turbo, what stuffs things up is exhaust back pressure, which is nearly always more than boost. On a stock factory engine it might be twice boost pressure. If you have turned up the boost yourself it might be closer to three times boost pressure. A large overlap cam simply is not going to work with a small turbo. Small turbo, small cam. Big turbo big cam is the general trend.

There is an article in Autospeed "Godzilla Tamed" which includes a circuit diagram and an explanation of how the thing works. You can download it, but if you are not already an Autospeed member, you will have to cough up $6.00 for the article: http://www.autospeed.com/A_0060/P_1/article.html