joshuaho96

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.

Any more than 15-20% is cause for concern. If the engine is still being broken in the rings might not seal very well but afterwards it should be 10% or less when the engine is warmed up.

I'm aware of the Midori sensor, they have more info here: http://midoriseibi.co.jp/tuning/r34/yaw-rate-sensor.html If you read the link that I put up it says this: Odd. These pages are out of the R34 GT-R Service Manual supplement. I know what I have seen on R34's. I am not aware of an early and late change, as you can see here - Yaw rate is part of HICAS. No Yaw rate in the ATTESA ETS- PRO system.

Definitely a bit of a tangent but still interesting. My source is here: https://www.gtr.co.uk/threads/handling-differences-due-to-mechanical-vs-a-lsd-r33-r34-gtr.176499/page-2 If you have some proof that the yaw sensor in question does in fact connect to the ATTESA system for A-LSD control I would be interested to learn more.

There's only two good explanations. Either they were thinking of compression tests when they said that or they're not actually as reputable as you say they are.

I was under the impression that the yaw sensor on the R34 is actually for HICAS, not the A-LSD.

I wouldn't decat a street car which is what I assume you have if you're concerned about dB limits. Decatted cars are obnoxious to be behind.

Most of them do look pretty flat but one of them looked a little suspect, I couldn't tell if it was just the lighting or something else. I do agree the TR14 connections look pretty nasty.

The photos aren't super useful unless you are taking macro shots of each capacitor in good lighting. The tops of the capacitors should all be perfectly flat. If you see any bulging replace all the capacitors as a preventative measure. You could meticulously check the resistance of each solder joint to see if you have a bad joint somewhere.

If you got water into the electronics you won't be able to repair it most likely. You can try cleaning the corrosion off the board but usually the corrosion etches away critical connections.

Another thing to consider is capacitor rot on the ATTESA-ETS control unit. Crack open the controller and inspect visually and nasally. If you can smell ammonia you have some bad electrolytic capacitors. If you can see bulging or leaks on any of the capacitors you need to replace them. Pretty much every one of these 90s cars is due for new capacitors in pretty much every board after 25-30 years if they've been driven regularly.

https://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/technical-talk/techart-18-30071600.html Gasoline went unleaded in the 70s, no reason to look back. Arizona E85 may be inconsistent but it's nothing a flex fuel sensor can't deal with. Ethanol blends vary between E30 and E85 at the pump depending upon season as ethanol doesn't want to start in the cold and evaporative emissions are harder to control. Leaded gas is nasty stuff. Lead is a potent neurotoxin and when you burn leaded gas it's being spewed into the air in a form that is easy for the body to intake. There is a lot of research out there that strongly correlated a crime spike in the 1970s and 80s to leaded gasoline. General aviation is the only major consumer of leaded gasoline at this point and it's only because the engines they run were originally certified on leaded gasoline and the aviation industry is extremely conservative. They still use magnetos and carbs. An RB26 is designed to run unleaded fuel and not designed for leaded fuel at all. So why bother with the thing that's more expensive than ethanol mixed with mogas when lead poisoning is a real risk and lead could damage the engine in unexpected ways?

I wouldn't run 100LL on any reasonably modern car engine. Even if you decat the O2 sensors will foul, the lead oxides will foul up and corrode exhaust valves and spark plugs. Just way too much effort for an especially toxic blend of gas when E85 is cheap and is comparable. Water/meth is complicated but if you're willing to spend a lot of time and effort on making it work then it's great too.

91 AKI Canadian is equivalent to 95 RON. 93 AKI is equivalent to 98 RON as you have suspected. I believe that 91 octane in Arizona, California, and Nevada is so exceptionally bad that many tuners have special maps to dial back the timing if you plan on using gas in those states.