Jump to content
SAU Community

GTSBoy

Admin
  • Posts

    19,017
  • Joined

  • Days Won

    313
  • Feedback

    100%

Everything posted by GTSBoy

  1. Nah, it's not the reduced knock margin. It is a direct mechanical effect of having to initiate the combustion earlier, while the piston is still rising, which starts to exert combustion pressure on the rising piston earlier, making the rest of the engine work harder to finish driving the piston up to TDC where the combustion pressure stops being a negative and starts being a positive. Your modern engine that only needs ~10° to make MBT doesn't waste the other 10 or so degrees of crank rotation. That's almost all of it. The difference in knock margin might go either way. Remember that modern engines to which you are currently comparing the long tractor engine (the RB) are now running super high compression, direct injection, tricky cam control and maybe even cylinder pressure sensors. You're not comparing apples with other fruit. It's apples and sea weed, or some other evolutionarily primitive vegetation. And remember, squish only really comes into play at the very end of the stroke. It certainly does good things, but it is not the biggest contributor to what's going on. It is quite possibly much less important in 4 valve head than 2 valvers also, because there is so much less squish available to a 4 valve anyway.
  2. Johnny's just upset because he sees that he's spent mutliple BMW money on his dirty Datto over the years and wishes he'd put the money into a stocksbro business prior to the market explosion and then he'd be rolling in BMWs, dead hookers and coke.
  3. Oh, and only having done this task yesterday, I've now driven the car ~60km since, and while it is hard to avoid placebo effect and confirmation bias, I reckon that some annoyances I had with the way the car has been behaving have improved. Which....kinda makes sense, I guess. If the bushes were really stiff and resisting rotation, they would have been contributing to the effective wheel rate. And if it was more so on one side (which it was, because one side was worse than the other) then.... you might imagine that the additional rate would be asymmetric, and potentially even different between compression and rebound. And so... the car has been twitchy at higher speeds - like freeway on ramps. It really shouldn't be. The wheel alignment is good and there are no (other) known problems elsewhere in the suspension. But at 90-100 on a long sweeping ramp, tiny steering wheel motions would make it feel like it wanted to rear steer. Quite nervous. At lower speeds it would heave about in a manner that it didn't use to. Didn't want to put power down, etc etc. Now...seems to behave better. Am going to have to concentrate on the various corners where it has exhibited weirdness, on the rare occasions when I can get a decent run at them without Methanial getting in the way in his D-Max/Ranger/LDV Van/etc.
  4. Water's still going to come in without the side hatch being refitted.
  5. I was only moderately grumpy. I was in fact quiet happy that there weren't still stock bushes in there, because that requires more effort to get them out. They were SuperPro, so definitely zincish. It is very much like the coating wasn't done properly. They were almost certainly of the vintage where the supplied lube with such things was that black messy crap. Some lithium based horror. They have since moved onto the silicone&PTFE greases which are much more sticky and water resistant. I shall have to mark my calendar to have a look at these in 5 years' time.
  6. Well.... yes and perhaps no. It depends on what you mean by "spool". For most of us, the point that we would describe as where the turbo is "spooling" is the point where the wheel speed gets high enough for it to start making some boost. This is coincidentally around about the point where it starts making noise - hence the "spooling" sound. If that is what you mean, then no - the wastegate should still be shut at this point. The boost will still be way below the point where it should start opening. If, on the other hand, you mean "spool" as "reach full boost", then yes. At the point where the boost has reached target, then boost control has already started. The wastegate is already open, and has been for some time. Some short time, definitely, but still, some time. If you have no boost controller - just the wastegate actuator connected to the boost source, then you have a mechanical system working as a pressure balance. There is pressure on one side of the wastegate actuator's diaphragm from the spring, and pressure on the other side coming from the boost measurement location (the "source"). This is not a digital thing. The wastegate does not stay shut until the boost pressure reaches the spring "pressure". The spring will start to compress as soon as you start to apply any pressure onto it. This can be controlled somewhat by adding pre-load into the spring, but you cannot add enough preload to make it into a digital switch behaviour. The wastegate will crack open and start to leak exhaust out (and therefore not though the turbine) well before you reach the target boost pressure. Electronic (and some mechanical/pneumatic) boost controllers will act to prevent the boost source applying pressure to the actuator until just before you reach target boost, thus preventing the wastegate from creeping open. And some boost controllers will apply boost pressure on the spring side to further push it shut. And this can be be necessary because the exhaust pressure in the manifold also pushes on the wastegate valve and tries to open it and you cab get it leaking even without it being connected to the boost source.
  7. I recently discovered that I could not remove the outer bolt on one of my rear UCAs. Looked like it was seized to the crush tube. It wasn't all that long since I had last had that arm out (I dunno exactly, but certainly <2 yrs), so I was a bit surprised. I thought I had stock bushes in the rear knuckles, so I ordered some new PU bushes and resigned myself to having to do some dismantlery....and some butchery. It was clear that the seized bush was going to need to have the bolt cut out of it and then possibly some more brutality after that. Upon getting the 3x arms on each side disconnected from the knuckles (with the exception of the seized one, of course), I discovered that I had in fact put PU bushes into the knuckles when I did the subframe conversion about 12-13 years ago. So, I say "Oh, good, I might not have to swap any of these others out". We set to work butchering the bolt out of the seized arm. Stainless blade in a big-arse Milwaukee recipro made short work of it, and also damaged the arm, which added a welding and grinding and painting step to the whole exercise. During the butchery it became clear that the bolt was not just seized but bent. Head scratching ensued, as it is hard to understand how that bolt could get bent. I did suffer a broken (stock) toe control arm on that side a few months ago, and drove some miles with some significant rear wheel self steer and lack of control, which probably was the cause. But it's still hard to understand how it would bend that bolt, rather than just bend the arm. But here's the start of the real discoveries. The crush tube was rusty as all shit. I mean seriously rusty. A little on the inside, contributing to the tube seizing to the bolt (along with the bend). But the outside had at least 2-3mm of compressed flaky iron oxide jammed in between the parent metal and the PU bush. This one was brutalised and still took some effort to get the PU off the crush tube. So I thought I'd inspect the others more closely. The one on the tension rod adjacent the bent one was first. I had to use a 2-jaw puller to get the crush tube out, and it took some effort. It came out looking like the first one. All 6 of them were the same, except for one that looked not too bad. Had some corrosion on it, but was mostly OK. There was also a significant amount of corrosion on the inner surfaces of the knuckles. They took some convincing with pointy tools to let go their grip on the inside of the holes they were in. There was no sign of the original (SuperPro) lube anywhere. I and my bro-in-law have never seen any crush tube end up looking like this. It was seriously like the car has spent time putting boats into the water at the boat ramp. So, it seems like the PU might have been bonded to the steel on both sides, which would have to make them work more like stock rubber bushes (where arm deflection results in twist inside the rubber). Despite this, I have never had cause to believe that they were so tightly bound up. The suspension moved up and down much as you'd expect. The car never made any noises in those bushes that would have led me to believe there was a problem. Maybe the rusty interfaces actually were "sliding". Anyway, lesson learnt. Even quiet, non-troublesome PU bushes should be inspected every now and then!
  8. Wait until @Lithium posts a compressor map and tries to explain what's going on. There is a strong possibility that the OP lives in a digital world and is not comfortable with analogue machines. A turbo is just about as analogue as it gets, with plenty of non-linear behaviours added in on top. Most of us who think we know how they work are actually only getting by on 2nd and 3rd order mental models that abstract away from the actual physics and bring it back to the sort of kindergarten level concepts we can hold in our heads. This is important when you need to hold 10 such concepts in your head at the same time. You need to reduce the complexity of the individual concepts to allow them to be simultaneously held and manipulated. Too much complexity in the base models makes it very difficult to make them work with each other mentally.
  9. Yep. >10 posts required. Prank can relax that for individuals when required.
  10. They do that at random every now and then, with almost no detectable cause. Mine has done it a couple of times (over 25 years!!). Never worked out why.
  11. It is completely normal. Your original understanding is what was wrong, not what you see in the charts.
  12. Much less twat-tastic. CF wheels are too garish for civilised use.
  13. They should do. I have S14 (or something S chassis, anyway) driveshafts in my R32 (because my diff flanges have 3x2). They're the right length. When you go looking for R32/3/4 driveshafts (for turbos), they're all the same thing, so are the same length. So there really shouldn't be any reason why those cheapies from JJ won't also fit an R34. R32/3 NA should also be the same thing. The (3x the price) D-Max ones are uni-fit. They have 5x1 and 3x2 bolt holes and say they cover all the cars. So that would also suggest that they are all the same except for the flanges. And in that case, the flange goes both ways. I'd be buying the D-Max ones if I ever have to replace a shaft. Because that will open up diff options without needing to juggle shafts also. Juggling shafts is gay.
  14. Unless there's something particular about the Greddy manifold's injector holes that I'm not aware of, those injetcors look to be totally wrong. They would absolutely want to be spaced up to get those long snouts out of the runner. Which, I think, is not usually the way that that problem is solved. I think the problem is solved by using the correct injectors, which would be much more like what Andrew posted.
  15. If you really want squish back, you can have it put on the piston (at least to some extent).
  16. Impressive. He's very very smooth.
  17. One small step for an R31...one giant leap for a submarine?
  18. Integrated (probably) Power Distribution Module Body Control Module
  19. Mount phone/gopro/whatever under the guard and do a short drive. See if the noise is much louder when up close to the suspension.
  20. Stock less likely to carry one like that than urethane, but still can, especially if the bolts are not as tight as they should be. If it's making that much noise you should be able to use a hose as a stethoscope> stick one end in your ear, crouch down and wave it around the various possible noise makers and get someone to lift the front end at the guard lip.
  21. Broken actuator rod. Could be one of a couple of them broken. Or, it's locked and the central locking actuator is broken/stuck or the actuator rods between it, the lock and the key barrel are jammed or broken similarly. You'll probably need a locksmith/mechanic who is experienced with using slim tools to reach down next to the window glass to manipulate the mechanism. That's assuming that it is not so severely jammed/broken that nothing useful will move.
  22. Suspension bush. Got urethane bushes in the upper arms?
  23. There are fixes for this. In industry we use compressed air for everything. It is frequently wet, and many things cannot tolerate it. So there are various forms of driers available that you can install. The simplest option for something like this would be a dessicant drier. Much cheaper to replace some silica gel than actuator cylinders.
  24. Lunchtime walk: Lou Reed, Zeppelin, King Missile, Church, QOTSA, Machine Gun Fellatio and Alabama Shakes.
×
×
  • Create New...