joshuaho96

For efficiency shift based on the peak efficiency RPM, shift just past the peak efficiency point while maximizing load without encountering high load enrichment so you sweep through the efficiency sweet spot. Looking at the gearing of the GTRs it looks like you want to be shifting at 3000 RPM so you drop down to ~2000 RPM when accelerating. Hold the engine right around 50-60% throttle if this is an NA engine or right at atmospheric pressure for turbo engines for best results. For cruising pick the highest gear that doesn't have you exceeding the accelerating throttle condition. As for the best speed to cruise at, something high enough that you aren't running below 2000 RPM and something low enough that you don't exceed 3000 RPM.

Give it some more time, the US economy is currently in the process of unraveling so people are going to be unloading things they can't afford anymore.

If it felt even the slightest bit wet/slick it's oil. Otherwise that's probably soot from running rich. I would also confirm against the plugs. Running rich will turn the plugs black but it should be a dry deposit, not a wet one.

Rub the exhaust tip with your finger. If it's oily you're burning oil, not running rich.

dE2000 of 0.3 would be incredibly good across all light sources. Generally speaking just staying under dE of 1 is good enough.

This sounds like a GT-R with extra steps.

The HKS logo halves the turbo lag.

What's bizarre to me is that nobody at Nissan considered disabling the system as the car reaches the limits. The wheel sensors were all there, the lateral g sensor was there, the yaw sensor was there. Why didn't anyone write a bit more code to disable the system if any sensor value suggested the vehicle was at dynamic limits? I know the Porsche rear axle steer system has this logic present for exactly these reasons, to make the vehicle more predictable at the limit.

Is HICAS really that bad in the R33 and R34?

Definitely try GTRCanada/GTRUSA on Facebook, list with a 25-33% discount off new and someone will probably bite.

Yes, he has. But the topic is interesting beyond just helping him decide. -7s and -9s are a comparison that has been done to death. I think the GT3-SS is an interesting alternative for those that are willing to give up some of that high RPM compressor efficiency for better low RPM response. Ball bearing would help with response for that given turbo but no such option exists.

I don’t think it’s that simple. Journal bearings do have worse transient response from the oil viscosity drag but the oil film helps to dampen any imbalance in the rotating assembly. The oil flow also improves cooling and the thicker oil film also improves longevity. On the balance it looks like despite the cheapo journal bearings they’re more responsive if you can actually get the engine to flow enough at 2500 RPM. Based on the dyno charts out there a journal bearing R32 ceramic turbo can out-spool pretty much everything out there. It just doesn’t survive high boost or age. The R34 ball bearing turbo does spool faster but that tells me that it’s a second order effect on the boost curve of a turbo.

I'm not on that train. I would much prefer PRP's double VCAM if that ever makes it out of R&D, the intake only VVT even pulling the pistons for 50 degree cam advance doesn't make for a modern turbo engine response where it spools at 2000 RPM and pulls to redline. There's a significant bump again with dual VVT compared to intake-only VVT: https://www.enginelabs.com/news/spooling-up-tuning-dohc-variable-valve-timing-for-boost/ The GT3-SS is very likely just a recent single scroll turbo adapted to the RB26. Not new, but for those that want to keep the twin turbo setup instead of single it helps to modernize the engine.

This is true. When I looked it up a full kit for -9s with HKS actuators and various bits was within 400 USD of the GT3-SS. It’s definitely not a value for money choice and it’s only a matter of time IMO before someone figures out what turbo HKS rebranded this time and sells it for a solid 25% discount, maybe more. But frankly nothing about RB26s is good value for money.

-7s and -9s is a pretty simple answer. If you want more power get the -9s, they have a more efficient if narrower compressor map, especially at high boost. If you're ok with less in return for a touch better response get -7s. I agonized over this for a while but after seeing the prices for a full -9 kit vs GT3-SS I think I'm going with the GT3-SS.

VCAM should be pretty reliable, it's literally just the Subaru EJ25 AVCS bits with some fittings to get it on an RB intake cam. If your pistons have valve relief for high lift cams then they should work with 50 degree advance. Don't buy the hype from HKS, you can fit either your own cams to the VCAM system with some modification or regrind the cams to get the desired profile. If you want to save some coin in return for some labor you can buy the step 1 system, pop off the metal block that they use to keep it within 30 degrees of cam advance and regrind the cam to your desired spec. Or replace entirely. Here are some dyno charts for VCAM: Step 1 VCAM with -5s vs stock with catback, no VCAM: Blue is Garrett 3582 with step 2 VCAM, Orange is stock with catback: More dyno charts here: https://www.facebook.com/upgarage/photos/?tab=album&album_id=2754286177933791 As for whether you should pick VCAM or single, I would say both? But it's big money to do that. If you want to know what the benefit at the top-end will be, get an adjustable intake cam and fiddle with the timing and see what timing gets you the best top-end. That will be your peak power. Fiddle with it again for best low-end response. Do that for every RPM and load combination and you end up with what a VCAM can do for you.

You are correct that the GT-SS and GT2859R-9 are the same turbo, I never argued that. I'm just looking at the data that I can see and making assessments from there. As far as turbo spool goes the GT3-SS with VCAM step 2 looks like this vs stock: The -9s with the same VCAM step 2 looks like this compared to stock: This is from U.P. Garage in Washington. Maybe the guy has a vested interest in selling HKS turbos? What stands out to me is the GT3-SS is pushing 10 psi by 2500 RPM while the -9s/GT-SS are closer to 3000 RPM. The huge overboost from like 3000 RPM to almost redline is maybe overselling the capability of the turbo but clipping the boost to be 1.3 bar flat would just flatten the torque curve even more. He also had some other neat charts like this VCAM step 1 stock ceramic vs GT3-SS: This one shows to me that the stock turbos ultimately build boost the fastest, so if the power goals are maybe 250 kw then stock turbos are as good as it gets.

If you want the absolute fastest spooling bolt-on twins the best are still the stock ceramic turbos. With the ceramic turbine. The R34 ball bearing ceramics are the fastest spooling of the three gens. If you want more power and more durability the GT3-SS is the next step up. It spools faster than the -9s despite the journal bearings but you give up high-end power, an honest 300 awkw should be possible with good fuel and tune. If the engine flows enough at the midrange it will be a better option than -7s which trade a little bit of top end for not much faster spool. -9s are going to deliver more power than GT3-SS and if you don't have a VCAM step 2 or step 1 with 50 degree advance the RB26 just doesn't breathe enough for a really substantial difference in spool vs a GT3-SS. Beyond that just go single turbo. Honestly the only reason to stay with bolt-on twins is to avoid getting defected and to have a well-understood setup that tuners have done many times over the decades.

Has anyone actually done a BSFC map of the RB26? I'm sure it's going to be ugly but curious to know what the ideal operating points are.

Sometimes the oxidation/cracking is on the inside of the lens for whatever reason. If that happens it's easier to just replace the lens with new if possible.

Doesn't Behrman make a kit to fix those? Or is it only for the GT-R trims?

I would go look up the LS2 coilpack recommended voltage vs dwell time spec. Then if you know the base dwell time for a given voltage then you can convert from the raw 0-255 values to milliseconds.

I would check when you can in Nistune to see the AAC Valve live value at warm idle, make sure you have some range both above and below or you might have idle issues. As the documentation suggests you want to change the dwell vs voltage values and not much else. In theory you could probably leave them stock but you won't realize the benefit from them.

Generally speaking you should only adjust the idle adjustment screw if you have Consult readout to log the AAC valve duty cycle. I believe recommended target is 35-40% in warm idle.

The ECU sets the idle target. If you haven't disabled this function in consult the ECU will be fighting you the whole way. The manual spec is 950 so it will open up the AAC and adjust timing to get to 950 rpm.