GTSBoy

I'd put a dollar on a dead output transistor in the ECU.

Did you clear the original code? Won't go away immediately.

I thought the intent of the thread was "optimisaton" anyway.

Yeah, but apropos of nothing this thread was still a huge WTF. Now it has more than nothing.

Yes, apropos of nothing this post is an huge WTF.

Do we know that it is a Blitz? OP just said "return flow".

17 psi at lower revs (and hence power output) = less air flow than 17 psi at higher revs (and hence power output). Pressure drop goes up with the square of flow rate.

This caused by this It's a simple fix. And then add more boost.

No. It is not that simple. What pressure difference between the plenum and the combustion chamber are you using to drive that flow? 100 kPa? 200 kPa? 300 kPa? 400 kPa? 500 kPa? There are people running that sort of boost on spark ignition engines. Each one of those larger numbers will mean more flow through the valve. It is not as simple as you seem to think it is. It's not even that simple in an NA engine where most people assume that you can only have almost exactly 100k kPa pressure drop across the valve, because there are many things you can do to get much better volumetric efficiency at certain points in the rev range. It is certainly even possible to get >100% VE on a stock head with the right cams and some intake tuning. Boost is the great ruiner of your theory. Not enough flow? Just add more boost.

What was "true" for Jap tuners who couldn't deal with the ITBs in the 90s was never really true at all. And what is that number? What boost are you chucking at the head? Air flow keeps going up with more boost. The limits turn up elsewhere (mechanical limits in the bottom end, detonation limits from the fuel, etc etc).

To be fair, this is a bit of a nonsense because if you're changing cams and therefore able to consider valve springs, then you can add enough spring to overcome any float issues that might be caused by high boost levels and you can run as much boost as the rest of the engine can handle. So, if you have tough enough rods, pistons and oiling, ability to run to very high revs (from the cams and springs) and sufficient fuel quality to handle the boost, you can just keep cramming more boost in and making more power. If it were an NA engine then the question might be more meaningful. But the native flow capability of the head is not really the limiting factor until you have gone all the way out into rocket science territory with other parts of the engine.

Or, you could just, you know, call XForce and ask them? Otherwise, in the absence of off-the-shelf systems, you can just buy some XForce (or whatever brand takes your fancy) mufflers and get your local exhaust shop to make something from scratch.

No, I didn't mean stock. I meant if you put rally suspension on them. Perfectly possible on an STi. Perfectly stupid on a Skyline.

To be fair though, that's mostly because the Toyota twin system is actual aids with all that back to back sequential bullshit. There are few options to improve it and many things to not want to keep. By contrast, at least the Nissan system uses 2 actual identical looking and reasonably normally specced turbos. So there are options and therefore reasons to allow the inertia (of staying twin) to prevent the tear-it-up-and-start-again approach from being the first option.

The connector in the photo is on the other side of the car. See the heater fan blower housing in the photo?

In the speedo head. It's all in the speedo head.

Yes, well, the numbers for the 3076 do seem unrealistically high. That 640 engine HP is what? ~360 kW at the rollers? Are they assuming ethanol?

Nah, just unlock the original and merge threads.

MAGA in a single image.

How is this even a question? Of course it will fit.

There is circuitry to take the AC signal from the sender and make the needle move. That appears to be working. There is other circuitry that takes the AC signal from the sender and transmits it as the PWM signal on the bis. That could be borked. It happens.

Turbo choice 4, on a VR38

So, we're not talking about wheel speed here. VSS is on the gearbox, not a wheel. The VSS sends an AC signal to the speedo head, where it is converted to a PWM (square wave) 0-5V signal that the ECU, HICAS, TCU, etc all read on the vehicle bus. If you want to measure the presence of that signal at the ECU it is best done with a scope of some sort, rather than a multimeter, as you won't reliably see it with a meter. The speedo head might be faulty.

Don't touch what you don't have to touch.

Yeah, so it's not the injectors. It does sound as though it is completely f**ked. There sounds to be bottom end bearing noise, but there also sounds to be lifters with waaaaaaay too much clearance in there. Take it apart.