GTSBoy

https://www.sau.com.au/forums/topic/480462-rb25det-neo-compression-test-reference/

A. Done pre-NCOP. B. or, not driven on the street. C. or, no f**ks given, drive it on the street anyway. There are plenty of f**kwits around.

Is that better than an RB20 camshaft?

No electric diff in R32. But, I had forgotten that the floor & gearbox mounts were different also! One more shell difference to add to the list.

Oh, I'm not arguing against putting a bigger core in it, or otherwise improving the cooling power. Go for your life on that. Just pointing out that I don't think a half second of continuing temperature rise after you back off is all the fault of the "slow" IAT sensor.

Crack temp and hold temp are not the same thing. There's a whole mass and energy balance thing going in between the engine dumping heat into the oil and the cooler dropping it out. Just because the TS cracks at 70 does not mean that the cooler has any hope of holding the oil at that temperature. The factors at play are the "effective HTUs" of the core, which is comprised of the oil temperature and the cooling power of the ambient air flowing across it (more oil T drives HTUs up, less oil T drives HTUs down, likewise, more and colder ambient air flow drives HTUs up and vice versa). Against an ambient air T of, say 35°C, you only get ~half the HTUs out of the core at 70°C oil T as you would with 100+°C oil T. So even though you may see the 70°C crack T as being horribly low, it actually gives quite a soft start to the cooling power, which ramps up as the oil gets hotter (both because the TS opens more and as the hotter oil drives more heat transfer out of the core).

Well, it's as fast as you're gunna get, isn't it? It is always going to lag the real temperature if that happens to be changing as boost increases, intercooler heats up and rpm is changing by several hundred per second. As long as +/-10°C isn't going to kill anything, you should be OK. And....another significant factor. The intercooler stores heat. When you load it up under a boost run then back off, the heat in the cooler transfers into the air coming through. You have a lot less air coming through when you back off, so it is reasonable to expect the core to drop a bit more heat into each unit of air and thus raise the temp of that air up very close to the core's temp, for those first second or so after you come off the hammer.

Old 2nd hand turbos are a risk. That turbo could be fine, or it could be f**ked. If it's f**ked in a way that you can't tell before you install, then you waste all the money spent on taking the car apart and putting it back together. Doubled, because you have to put the original turbo back on. If it is f**ked in such a way that it dies 10 minutes or 10 weeks down the track, it's the same, but worse, because you could be out on the highway somewhere, stuck in the snow. It's your gamble. You're probably more likely to blow up your original turbo though! There are many people around the world that can highflow a stocker. If you were in Oz I would have recommended that you contact Hypergear in Melbourne. You could still get a turbo from him, even from Japan. Have a look at their site. There are many options on the site - can be confusing. Just contact them direct if you want to go down that path and need help. https://hypergearturbos.com/product/nissan-rb25det-turbocharger-standard-high-flow-service/

Let me know if you want contact deets.

The chassis rails are different at the front. Not at the rear.

I don't think he was recommending the GTRS. That is also a very very old turbo. I would suggest that he is recommending a high flow. Where are you located?

LS3.

Squirt with spray can of teflon lube.

Front subframe is completely different. 4WD subframe will not bolt into RWD chassis. Rear guards are, or course, different. Fuel tank is different.

Yeah, once I heard rifling I assumed that the spiral shape was important to your thinking. The three big issues at hand are; oil viscosity/surface tension, qty of oil that needs to go down, qty of gas that needs to come up. I strongly suspect that cross sectional area is the king, assuming that the three main factors are essentially fixed for any given engine & operation thereof. Therefore I wouldn't expect to be able to pull too many tricks with the shape of the hole (which is essentially what any little keyway/slot runnign down one side of it would be). And further, narrow slots don't play well with movement of oil. Surface tension will hold a liquid in a narrow slot against gravity. So t probably wouldn't drain any better anyway. And then, if you just make the slot "not narrow", ie make it a bloody great wide slot, then it just comes back to extra cross sectional area. And possibly with the bad addition of sharp corners to create stress raisers. We're probably better off just agreeing to add big fat sump breathers and drill out the oil drains only if forced to (although, it's a bit late once the engine is running!)

Well, for a circuit engine, you're probably right. Uh. maybe. But probably not. If you want to try to use rotation to generate centrifugal forces to keep the oil on the outer and gas up the centre then you'd really need to get the oil spinning before it enters the drain hole. Like a cyclone (you know, particle or droplet separator). That way the oil will spin out against the side and sort of stay there. But I doubt that there's a lot of benefit. Certainly not gunna be easy to do either, given cast iron, etc etc. Better to just do all the actually easy stuff.

The thread may well be outdated relative to stupid power levels. The engine builders would rather an engine that has oil breathing problems than one that cracks the block, so are being (possibly excessively) conservative. The simple fact remains that more open area is required for gases to go up and oil to go down. However you achieve that is however you achieve that. I have no doubt that many have implemented the vents without drilling the block, which may well prove that you don't need to drill the returns. I don't have much skin in the game, but I think if I was building a moderately serious engine, I would drill the returns out as much as I thought they could take, and put stiffness back in via other means if I was aiming for more power than is actually useful.

If you think about the violent thrashing of broken parts between the cam lobe and the valve while it's all flailing away at "over rev" speeds......

Is it too simple to say "import wreckers"?

I'd be surprised if drilling the drains out would significantly weaken the block. Yeah, sure, when pushing to really big power figures you probably need every little bit of material you can get, but by then I'm sure you're in need of a half grout fill and so on anyway.

Interested to know why you would panic. What do you know about it that I don't?

Are you still speaking in English?

Yes. It would be trivial to do it on any version of HICAS. All you would have to do is trigger a fault by interfering with any of the sensors that the HICAS CU wants to see working. The steering angle sensor would be the obvious one. HICAS will go into "fail safe mode" when faulted. Meaning it won't do anything. I did it on my R32 because I had no steering sensor. I pulled the smaller of the two plugs out of back of the HICAS CU and it put it into failsafe with no dash light (because the dash light is run from that plug!). I claim credit for discovering that hack, more than 20 years ago. But, it is just f**king stupid. Take off and kill HICAS from orbit. It is the only way to be sure. Anyone who wants to keep HICAS working doesn't drive their car hard enough.

OK, so, in the same conditions, I have seen my oil temperature go to 120°C. Do you see me panicking?

Yeah, where's the problem?