joshuaho96

Be very careful with those Mishimoto radiators, they're garbage.

We'll have to see, worst case I replace the turbos when they blow up or when the engine gets pulled again. The US tuners with dyno sheets on the GT3-SS don't have a financial interest in selling an HKS turbo over a Garrett turbo, even if they play games with correction factors and inflate numbers I'm looking for relative comparisons. The data I've seen so far suggests that worst case, it's a minor improvement over -9s in the mid-range and isn't as capable for power. Best case I'll be able to get close to the "as advertised" torque curve here with VCAM step 1B, which would really be incredible: I'm really not wedded to making a ton of power, at the end of the day this is a street-tailored car and power delivery is more important than what the number says.

Check your capacitors, could be dead ECU.

It remains to be seen what the real results are. I would really hope that for the money and with over 10 years HKS can beat a set of -7s.

It would be good to know if you've changed the final drive ratios or you're running something other than OEM tire diameter, otherwise it's not too hard to use a gear calculator to do the math and see that your dyno is sweeping from ~1500 RPM to ~7000 RPM, with boost hitting target psi somewhere around 3200 RPM. Really great results, I'm wondering if it even makes sense to go for a larger duration exhaust cam to match the intake cam as HKS recommends if this is what you got out of VCAM step 1 with stock exhaust cam.

https://www.gtr.co.uk/threads/attesa-accumulator-nitrogen-canister-change.572973/#post-5815458

VCAM step 1?

If you don't already have a factory double DIN you need a kit to relocate the HVAC unit: https://www.suncoastparts.com/product/9X6DDIN.html My experience is that the 996 is not exactly a quiet cabin, I would not mess with the speakers at all, don't be the guy that drills random holes in the chassis, there's a guide out there for how to retain all of the speakers here: https://rennlist.com/forums/996-turbo-forum/1157084-double-din-stereo-install-retaining-bose-and-most-interface-long.html

I'm not suggesting it, it could cause issues with compressor surge because the BOV doesn't see vacuum when the throttle snaps shut, and I don't know what differential pressure is required to cause the BOV to open up significantly. Personally I would just run wastegate pressure if "boost" is a big deal. A low compression N/A engine is nasty to drive.

The BOV needs a pressure/vac source post-TB so it doesn’t crack open under boost but does open when the turbo is in boost but the intake runners are in vacuum. If you disconnect the vacuum line for the BOV and cap the fitting on the intake it creates a substantial boost leak. Whether it’s enough to avoid leaking boost at all is hard to say.

I would love to buy the MHI turbo that it's based on and not pay a thousand dollars for an HKS logo, unfortunately nobody is really interested in figuring those pesky details out. Doesn't seem like anyone is really interested in small power builds these days.

My goal was to find the smallest aftermarket bolt-on twin turbo. The HKS GT3-SS is the smallest turbo out there, to the extent that it cannot sustain much more than ~1.35 bar at high RPM due to the small turbine, which basically means that it was competing with -7s and -9s. From what I've seen it is roughly competitive with -7s in terms of peak power, but is capable of delivering a lot more power down in the 4000 RPM range. -9s can deliver more peak power, but the narrower compressor map seems to affect how well they respond down low. The GT3-SS is also a pretty new turbo, came out ~4 years ago, I don't put a lot of stock into their marketing literature but they basically admit in it that they've just borrowed a turbo from a more recent engine and modified it to suit the RB26.

Decats cause tremendous amounts of carcinogenic and lung irritating gases to be constantly coming out of your exhaust, everyone in traffic will hate you, as will your neighbors. You will smell of exhaust well after you stop driving and get out of the car. Leave well enough alone.

I have to go stealth so we’ll see what the HKS GT3-SS “modern” turbos do. It’ll be the only modified part on the car.

I would be inclined to give a real answer but there's no point in answering when it's clear it's just in search of affirmation. OP probably bought an auto Skyline and is now experiencing buyer's remorse.

Not a great comparison point because it's VCAM step 2 vs step 1 but they did have an EFR7163 VCAM step 1 comparison: "The Black run is a Step 2 V-Cam with a GTX 35/82The Blue run is a Step 1 V-Cam with a EFR 7163The Orange run is NON V-Cam with our DR500s These runs were all done in 4wd with 92 octane in similar weather conditions. I tried to grab an average run from each turbo setup as not be to be misleading." Also seems like people like the G25-660 for big power which is surprising to me:

Pretty sure it’s an actual GTX3582. Dyno is a Mustang 4 wheel dyno as far as I can tell so it’s not laughably high reading. Spectrum Motorsports sells both single and twin turbo kits.

I've been wondering how they've been doing it too, they tend to get results that others don't.

It’s different turbos, supposedly same engine spec within reason. Both running VCAM Step 2 with an HKS 272 exhaust cam.

Curious to know what others think of this data point, this is supposed to be a more modern twin turbo setup for the RB26 vs a GTX3582: "More info Twins vs Single. 4WD mustang dyno, 92 octane, similar weather condtions, Step 2 V-Cam, 272 exhaust cam on both, both running metal cats.Blue run are the DR500 twinsOrange run is GTX 35/82 Again this is just more info for everyone. Each of you will have your own opinions on what setup is better. Its coming to my attention that when we post up data, that we have collected, and speak highly of our results its because we are in love with what we do! Its unfortunate that it has come across as being competetive and that is not our intent. The information is there for you to use, only if it applies to what you want to accomplish with your GTR. And yes we have watched the Motive video." Link: Looks like the turbos are made by Spectrum Motorsports in 42R configuration: https://www.spectrummotorsportssolutions.com/products/r32-r33-r34-rb26-smr600

Higher numeric final drive (shorter gears) would affect the RPM you spool by because the engine will reach higher RPMs sooner. But if you were to do a time to torque/boost measurement you would find it to be faster because the engine is getting up to an RPM where it can spool the turbo sooner. You can play games with dyno load to do this, it's effectively brake boosting.

Doesn't this imply that you would want less CR anyways? I can't imagine running rich all the time is healthy for an engine.

Yeah, probably going to just disconnect the FPCM and use the PWM controller then.

Doesn't that imply that you would have to run rich for too much of the load/RPM map? Modern gasoline is up to 14:1 CR for NA, or even as high as 16:1 for the Skyactiv-X, as high as 12:1 for turbo. I can't think of why emissions would factor into it. NOx obviously goes up with high CR, but 10:1 PFI-T is nowhere near what diesels have done for a long time now.

That is a properly buff pump but probably too much fuel pump for something making 300 kw. Something like the Fuelab 48402 seems to be what I'm looking for, around 10A draw and capable of 300 lph at 70 psi outlet pressure to be able to turn up the FPR to 3.5 bar differential pressure. I might run some experiments to see if the OEM FPCU/FPCM has the right resistances to be able to actually function as the pump speed controller, have to see what the impedances look like. Probably have to just accept that it's a horrendous idea though and just use a standalone ECU to run the PWM controller. Anyways, I don't doubt that high CRs improve driveability, I'm just skeptical that you can run high CR with low duration cams and no tricks like advanced VVT/cooled EGR/E85. I'm sure that Mitsubishi and Nissan would've raised the static CR on the 4B11T and VR38DETT to 10:1 if they could've done so while meeting power targets on pump gas. The VR30DDTT has a 10.3 CR but uses GDI and dual VVT to get there.