GTSBoy

Spray carby cleaner around every place where air could leak in until you find it.

@Duncan is being a grumpy old man. He's not wrong, but if you want to get more power and make it nicer to drive, put a single on it. Having seen your intro thread now though, I would suggest perhaps not bastardising the car.

Yes. It's probably dirty and jammed so that it can't close down far enough. Block off the air pipe that goes to the IACV and see if the idle speed crashes. Otherwise just do the usual clean it out thoroughly thing.

Switch globes, use multi-meter. All the things you should do to diagnose minor electrical problems.

Perhaps that's not the question to ask. For any given power level the single will smack the twins senseless. More response, more area under the curve (from the single). So you could put a "smaller" single on and shoot to max it out at less than 400rwkW (say, aim for 350) and enjoy life a lot more. No. See 1. First question though would be "what fuel?" You can push smaller turbos to more power using E85 than you can on 98. E85 allows higher boost, which causes higher air temps at the same compressor efficiency and pushing the boost higher usually reduces efficiency when you're aiming for the top of the compressor map. The recommendation will be for a T3 or T4 twin scroll housing and proper divided manifold and wastegate arrangement. Have a look at the various RB25 & 26 turbo upgrade threads stickied on here to see what people are achieving. The options range from GTX3076, through GT3576 or GT3582, to G30-550 or 660, and BW EFRs like the 7670. There's a lot of size difference across those ones I've listed, and not all are available with divided housings, etc. And that's ignoring Precisions and all the off-brand stuff.

The timing is likely at zero because the ECU is (probably) pulling al the timing out to control idle speed, which would imply a problem with the IACV. 875 rpm is too fast for 81°C coolant temp, which tends to support the theory.

Didn't you ask this question in another thread yesterday and get told "most likely no"?

Put it in the cooler pipe. In a 4" inlet it is worth HUUUUUGE power (in terms of how much air mass flow it will take to saturate it) and even though the card type AFMs are more resistant to reversion, hectic flutter will make tuning harder.

I think the largest RB30 is either 3.6 or 3.8, but it really doesn't matter because you are talking pure drug money at that point and would be better off with a Barra.

Yeah, nah sweetheart. We'd be talking about $20+k of work here and it still probably wouldn't work.

Oh, and the 2nd one appears to be the solenoid on the idle control valve.

The first one is a solenoid valve for switching a vacuum source on and off. It may or may not be supposed to be connected to the FPR vac source. It probably shouldn't. You should look at the RB30 engine manual's relevant page for the vaccum line system.

I wasn't aware of that one.

I would say that that is a hard no. The shapes and sizes of the intake and exhaust ports are quite different, and you don't necessarily have the room to hog out the (small) exhaust ports to approach the size of the intake ports because the water jackets are quite close to the exhaust port walls. Then you would have to look at whether it would be possible to fit intake sized valves where the little exhaust valves come from (which would require removing a lot of metal and you'd probably face a similar problem with water jacketing there) and then you'd have to close up the inlet valve holes to take smaller valves. Just use a 1JZ.

If that means <2500rpm and no load at all, then you could get away with it. Still not a great idea.

But in a good way this time, right?

I wasn't going to say anything about that.

Generally, yes. But there are no "rules" here, as different things can happen to any engine. But I simply cannot think of anything that would cause all 6 cylinders to drop compression by about the same amount while sitting doing nothing. The sort of sludge hardening stuff I mentioned earlier seldom occurs evenly across an engine. I am going to put $10 on it being something else. Maybe something messed up by the workshop.

You can spooge the thermostat gasket, but it will seal with just a paper gasket. After all, cars have all done that for the last 100+ years. Cam seal corners and half moons all much the same. Not required, but a little can prevent later weeps developing.

Yes. Gold standard for OG COVID-19 turns out to simply be not good enough for Delta. Given the civil disobedience quotient of Sydney appears to be even worse than the more bogan infested parts of SEQLD, just plain dumb luck does seem to cover it for last year. Too many households in SW Syd full of people with inherent distrust of any government, coupled with many illegal visa overstayers causing unwillingness to expose households to inspection by any level of authority, etc etc = recipe for Delta strain explosion. The cases that make the news, like the 3 (different!!) sets of removealists doing the wrong thing, and in some cases not having enough English to make it believable that they're able to drive around the country unsupervised, the stupid hotel room and beach parties etc etc, all make me glad to live where I do. I was in several Teams meetings with clients and suppliers from QLD, VIC and NSW during the week. In all of them it was brought up by the other parties that we were in SA and how lucky we were. I made quips like "yeah, we're in the promised land" and in all cases There were pained grimaces from the other end. I suspect it Gladys B hadn't spent the last 18 months climing up Morrison's arse crack, maybe the eastern states wouldn't be in quite the shitstorm that they're in now. Oh well, you live and learn, right? Or maybe you don't. We're yet to see. WA and SA may also have been lucky. But then, luck is usually associated with other good things too. Our lockdown approaches are basically "take no prisoners" and so they only have to last a week.

The rest of the country is currently discussing digging a trench around the NSW border and towing the whole f**king mess out into the Pacific to drown.

I'd also like to point out that ~120 psi comp readings, like your first set, if accurate, are quite low and probably low enough to explain the low power on their own. My 25Neo measures ~175-180 psi (with only slightly higher stock compression than a 26)

I would leave it forever.

This is bullshit of the very finest sort. Take the car to a more intelligent workshop. Compressions may decrease while a car is sitting if some grunge built up somewhere hardens and perhaps stops valves from seating properly. Or the rings might get sticky in the grooves. But that sort of thing isn't usually permanent. It should come good after a brief run. It is far more likely that the compression tester is reading low. Even if it is the same compression tester. There are so many "mechanics" that simply have no f**king idea that the performance of their test gear can change and that they need to keep it calibrated if they are going to trust their measurements. This aligns with what I just said, although I would hope and expect it to be much faster than a couple of weeks. One good drive should do it.

Corners of cam seals under the cam covers. Little squidge of goo there helps to prevent leaks. That's about it.