Jump to content
SAU Community

Recommended Posts

Engine is out for a chassis refresh, I've been going in circles for the better part of a year now trying to figure out what turbos to select. Power goals are basically nothing to write home about, probably ~280-300 kW to the wheels on an honest australian dyno, wouldn't be surprised to get 280 kW on California 91 AKI (~95-96 RON AUS) but a good amount more if I go E85. To make emissions testing simpler it has to be a bolt-on twin turbo setup, doing anything else is going to be problematic. Most important to me is response at 3000-3500 RPM and the shape of the power curve, I don't want the turbo to choke the engine at 6000 RPM with 2000 RPM left to go or a turbo that takes until 4000 RPM to really get into the torque. In practice from what I've seen the R34 GT-R stock turbos are as responsive as it gets for stock mount twins, but I'm pretty sure those are ceramic turbines that can't take much more than 1 bar of boost or any mistreatment. I'm planning on running VCAM to try and compensate for the loss of the ceramic turbine. 

Should I get -7s? -9s? HKS' GTIII-SS turbos? Hypergear T25 high flow with BB CHRA? I've seen evidence that the GTIII-SS is really, really good for mid-range torque with VCAM but it still feels like a gamble, Garage Yoshida seems to suggest that it still feels lazy compared to -7s due to the bush bearing. -9s are supposedly just a little less responsive than -7s but with more favorable efficiency for high boost. GTIII-SS is supposed to be more response than -9s in the low/mid range, but boost tails off at high RPM from the small turbine so it can't sustain much more than 1.2 bar or so. The hope is with enough work the engine will feel more like a more modern engine in power delivery with VCAM and the right turbo choice instead of a more distinctly early 90s turbo power delivery.

Link to comment
https://www.sau.com.au/forums/topic/480670-best-bolt-on-twins-for-rb26-~300kw/
Share on other sites

It sounds like your in California? 

If you wanted the car to be street legal and have a single turbo, what would that involve? I'm guessing it's not as simple as having the car certified by an engineer? (sorry if this is a dumb question, I'm over in Aussie land and not familiar with your processes)

3 hours ago, Murray_Calavera said:

It sounds like your in California? 

If you wanted the car to be street legal and have a single turbo, what would that involve? I'm guessing it's not as simple as having the car certified by an engineer? (sorry if this is a dumb question, I'm over in Aussie land and not familiar with your processes)

You would have to get engineering certification for the kit, which basically requires you to do a test of the emissions of the car stock on the FTP-75 (ADR 27 cycle with an extra warm start repeat after a 600 second cooldown), US06, and SC03 drive cycles using 11.5 AUD/L certification fuel. This is easily like 4000-5000 USD. Then you have to modify the car with the specific part/kit you want to certify. You are not permitted to do things like use end user programmable ECUs, usually this means you're limited to the factory ECU. For R33 GT-Rs this is a huge headache because you can't easily remap the ECU, I don't even think you can buy new Hitachi H8/534s anymore. You must follow all of the relevant emissions regulations around PCV, evap control, and retain full functionality of the onboard diagnostics system from the original ECU. Once you've modified the car you then repeat the same emissions tests that were requested by the California Air Resources Board engineers and send that data to them. You also need to send detailed engineering drawings, specs, etc to them so they can understand exactly how the part is made and how it differs from the OEM part. You're only allowed a small deviation from stock emissions, basically to account for measurement error. In this case it would be the car post-emissions compliance for import. The cost of this is insane, it only makes sense if you can amortize over a bunch of different vehicles. You're probably easily looking at 10k USD per "item" if everything goes mostly right, there's no single vehicle certification process. 

In theory whatever the car has on it when it passes the original import emissions compliance testing/modification is "certified", but a condition of initial registration is another emissions inspection after you receive emissions compliance. You can't just take it to any emissions tester, it's a state "smog referee" that will look at the car and expect it to basically be stock. So if you roll up with a single turbo swap it doesn't matter if you've passed the nightmare FTP-75 test + evap test, they'll fail you and send you away when they see that the intake isn't stock and lacks a CARB EO number.

Personally I care about improving fuel efficiency and emissions where practical but I'm not rich enough to put down 10k just to prove that R35 injectors are in fact better atomizing than the OEM 440cc injectors. Or that a bolt-on turbo won't have any impact on emissions if constrained to the same mass flow rates as the OEM turbo on the OEM tune. Or that hot film MAFs are in fact better than the OEM hot wire MAFs. Or that a simple change to the twin turbo piping has no impact on emissions. The list honestly goes on and on. But the onus is on you to prove it through the same tests that the OEMs have to do to certify entire engine/transmission pairings.

Edited by joshuaho96
7 minutes ago, JGTC said:

What mods are currently done to the car, and what mods have you already bought to go into the motor?

Engine is 100% stock, just noticing some oil on the compressor outlets so given the mileage of the car it's probably a good idea to replace the turbos. 

  

16 minutes ago, GTSBoy said:

Sounds like modifying a GTR in California is just one of those things that you simply should not consider.

Depends on your risk tolerance I suppose. Once the car is registered your average smog shop doesn't really know what they're looking at, just have to pass a 2500 rpm tail sniffer test.

Edited by joshuaho96

Laws aside, plenty of people running straight pipes, full decat, the works. So I’m not too worried about a bolt-on turbo getting noticed in an emissions check.

So should I do -7s? -9s? Is there some mythical BNR34 turbo that isn’t ceramic turbine?

5 hours ago, joshuaho96 said:

Laws aside, plenty of people running straight pipes, full decat, the works. So I’m not too worried about a bolt-on turbo getting noticed in an emissions check.

Well... what are your thoughts on a single turbo setup, having everything that can be anodised black (painted whatever) everything is black black black and very factory looking... once it's on e85 emissions are easy... 

What's the worst that could happen?

8 hours ago, Robzilla32 said:

Just get -9s.

I get 360 awkw on e85 @ 20 psi with decent mods.

Maybe that's the answer in the end, feels like it at least.

5 hours ago, Murray_Calavera said:

Well... what are your thoughts on a single turbo setup, having everything that can be anodised black (painted whatever) everything is black black black and very factory looking... once it's on e85 emissions are easy... 

What's the worst that could happen?

Probably not wise, the other minor detail I didn't mention is that if you get pulled over by a cop that wants to give you a hard time you get sent back to the smog referee. Then it's a scramble to put everything back to what looks like stock. 

5 hours ago, GTSBoy said:

Sounds like every broke arse Skyline & Silvia owner over here for the last 25 years.

Here I believe it mostly relates to the belief that Skylines are often used in street racing. These days the people who can afford to run a Skyline GT-R are not going to be racing them on the streets.

-7s seem to peak around the 17-20psi mark, and -9 seem to breath around the 20-24psi mark (+2-3psi respectively for E85).  If you are going VCAM, -9s would be my choice to have the best balance of response and overall output.

My understanding is the HKS GTIII-SS is the updated version of the GT-SS which was based of the Garrett -9 unit.  The HKS unit would be my choice.

This was my mod-list to support my -9 build, it all adds up when you are starting from scratch and want to support the turbo set up as much as possible.

https://www.sau.com.au/forums/topic/93880-rb26-turbo-upgrade-all-dyno-results/page/31/?tab=comments#comment-7779972

Head / Turbo 

- Garrett 2860-9s - fitted with HKS oil feed restrictor banjo bolts

- Garrett 1bar actuators

- Tomei dump pipes

- Standard cast manifolds - Port matched to turbos

- Tomei Poncam Type A - lifter shim clearance within OE spec

- Jun adjustable cam gears (OR gears modified to be adjustable) - set to 0deg/0deg

ECU/AFMs

- Apexi Power FC

- Apexi analog boost controller

- Nismo AFMs

Cooling

- Plazmaman Pro Series 76mm intercooler

- Koyorad 48mm aluminium radiator

- Trust 13 row oil cooler with filer relocation kit

Exhaust / Intake

- Amuse R1 Titan Extra cat-back exhaust 90mm

- Apexi Super Catalyzer Cat - 80mm

- Mines Pro front pipe (2 x 70mm into 80mm)

- Nismo inlet piping

- OE Airbox with Nismo panel filter and snorkel

Ignition / Fuel

- Sard 650cc top-feed Injectors

- Splitfire coilpacks

- Wiring specialties coilpack harness

- Walbro 460lph fuel pump

- Denso iridium spark plugs

 

Edited by JGTC
1 hour ago, JGTC said:

-7s seem to peak around the 17-20psi mark, and -9 seem to breath around the 20-24psi mark (+2-3psi respectively for E85).  If you are going VCAM, -9s would be my choice to have the best balance of response and overall output.

My understanding is the HKS GTIII-SS is the updated version of the GT-SS which was based of the Garrett -9 unit.  The HKS unit would be my choice.

This was my mod-list to support my -9 build, it all adds up when you are starting from scratch and want to support the turbo set up as much as possible.

https://www.sau.com.au/forums/topic/93880-rb26-turbo-upgrade-all-dyno-results/page/31/?tab=comments#comment-7779972

 

I'm definitely going to try and get all the supporting mods in to make sure the engine can perform well. I was thinking of getting the HKS GTIII-SS because of this chart:

image.png.5bcf57db8d32e70ba41d67683b8419eb.png

I don't mind that at the end of the chart the GTIII-SS isn't much to write home about, what interests me is the pretty ridiculous amount of torque it puts out by 3300 RPM. But maybe this is just what happens when you're loading up the engine on the dyno from like 1500 RPM? But even -9s from the same tuner with VCAM Step 2 doesn't make ~213 whp by 3300 RPM, and it appears to also start from 1500 RPM:

image.png.3bf0640bb79e870e4be6924aff02d16e.png

Kansai Service put out a little blurb from their testing of the HKS GTIII-SS, personally I don't know how much stock I put into it but it suggests a decent mid-range bump, just not as good as what UP Garage is seeing:

image.png.7d24ce6604b9b4cb228ce15e600d34d7.png

But the GTIII-SS is a journal-bearing turbo and more than a few people have mentioned that it's not as responsive because of it. So not sure what to do here.

Edited by joshuaho96

For anyone curious, I ended up going GT3-SS because the turbine a/r is 0.54 which is closer to the OEM turbine a/r of 0.49, multiple tuners that have tuned both GT3-SS and GT-SS in the US have mentioned that the GT3-SS trades power for low/mid torque compared to the GT-SS with a 0.64 turbine a/r. The goal has always been street-oriented so fingers crossed I don't regret paying way too much for a Civic Si turbo with an HKS stamp on it. I'll try and update with dyno results once I get it in.

On 25/06/2020 at 9:02 PM, Robzilla32 said:

Just get -9s.

I get 360 awkw on e85 @ 20 psi with decent mods.

Man I’m putting -9’s on in 3 weeks and hoping for 300rwkw. 360 is awesome robzilla. What injectors and fuel pump?

14 hours ago, joshuaho96 said:

fingers crossed I don't regret paying way too much for a Civic Si turbo with an HKS stamp on it.

A little too late my friend, you will be paying way too much for everything during the life of owning this car like the rest of us!

Edited by TXSquirrel

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • See if you can thermal epoxy a heatsink or two onto it?
    • The other problem was one of those "oh shit we are going to die moments". Basically the high spec Q50s have a full electric steering rack, and the povo ones had a regular hydraulic rack with an electric pump.  So couple of laps into session 5 as I came into turn 2 (big run off now, happily), the dash turned into a christmas tree and the steering became super heavy and I went well off. I assumed it was a tyre failure so limped to the pits, but everything was OK. But....the master warning light was still on so I checked the DTCs and saw – C13E6 “Heat Protection”. Yes, that bloody steering rack computer sitting where the oil cooler should be has its own sensors and error logic, and decided I was using the steering wheel too much. I really appreciated the helpful information in the manual (my bold) POSSIBLE CAUSE • Continuing the overloading steering (Sports driving in the circuit etc,) “DATA MONITOR” >> “C/M TEMPERATURE”. The rise of steering force motor internal temperature caused the protection function to operate. This is not a system malfunction. INSPECTION END So, basically the electric motor in the steering rack got to 150c, and it decided to shut down without warning for my safety. Didn't feel safe. Short term I'll see if I can duct some air to that motor (the engine bay is sealed pretty tight). Long term, depending on how often this happens, I'll look into swapping the povo spec electric/hydraulic rack in. While the rack should be fine the power supply to the pump will be a pain and might be best to deal with it when I add a PDM.
    • And finally, 2 problems I really need to sort.  Firstly as Matt said the auto trans is not happy as it gets hot - I couldn't log the temps but the gauge showed 90o. On the first day I took it out back in Feb, because the coolant was getting hot I never got to any auto trans issues; but on this day by late session 3 and then really clearly in 4 and 5 as it got hotter it just would not shift up. You can hear the issue really clearly at 12:55 and 16:20 on the vid. So the good news is, literally this week Ecutek finally released tuning for the jatco 7 speed. I'll have a chat to Racebox and see what they can do electrically to keep it cooler and to get the gears, if anything. That will likely take some R&D and can only really happen on track as it never gets even warm with road use. I've also picked up some eye wateringly expensive Redline D6 ATF to try, it had the highest viscosity I could find at 100o so we will see if that helps (just waiting for some oil pan gaskets so I can change it properly). If neither of those work I need to remove the coolant/trans interwarmer and the radiator cooler and go to an external cooler....somewhere.....(goodbye washer reservoir?), and if that fails give up on this mad idea and wait for Nissan to release the manual 400R
    • So, what else.... Power. I don't know what it is making because I haven't done a post tune dyno run yet; I will when I get a chance. It was 240rwkw dead stock. Conclusion from the day....it does not need a single kw more until I sort some other stuff. It comes on so hard that I could hear the twin N1 turbos on the R32 crying, and I just can't use what it has around a tight track with the current setup. Brakes. They are perfect. Hit them hard all day and they never felt like having an issue; you can see in the video we were making ground on much lighter cars on better tyres under brakes. They are standard (red sport) calipers, standard size discs in DBA5000 2 piece, Winmax pads and Motul RBF600 fluid, all from Matty at Racebrakes Sydney. Keeping in mind the car is more powerful than my R32 and weighs 1780, he clearly knows his shit. Suspension. This is one of the first areas I need to change. It has electronically controlled dampers from factory, but everything is just way too soft for track work even on the hardest setting (it is nice when hustling on country roads though). In particular it rolls into oversteer mid corner and pitches too much under hard braking so it becomes unstable eg in the turn 1 kink I need to brake early, turn through the kink then brake again so I don't pirouette like an AE86. I need to get some decent shocks with matched springs and sway bars ASAP, even if it is just a v1 setup until I work out a proper race/rally setup later. Tyres. I am running Yoko A052 in 235/45/18 all round, because that was what I could get in approximately the right height on wheels I had in the shed (Rays/Nismo 18x8 off the old Leaf actually!). As track tyres they are pretty poor; I note GTSBoy recently posted a porker comparo video including them where they were about the same as AD09.....that is nothing like a top line track tyre. I'll start getting that sorted but realistically I should get proper sized wheels first (likely 9.5 +38 front and 11 +55 at the rear, so a custom order, and I can't rotate them like the R32), then work out what the best tyre option is. BTW on that, Targa Tas had gone to road tyres instead of semi slicks now so that is a whole other world of choices to sort. Diff. This is the other thing that urgently needs to be addressed. It left massive 1s out of the fish hook all day, even when I was trying not too (you can also hear it reving on the video, and see the RPM rising too fast compared to speed in the data). It has an open diff that Infiniti optimistically called a B-LSD for "Brake Limited Slip Diff". It does good straight line standing start 11s but it is woeful on the track. Nismo seem to make a 2 way for it.
    • Also, I logged some data from the ECU for each session (mostly oil pressures and various temps, but also speed, revs etc, can't believe I forgot accelerator position). The Ecutek data loads nicely to datazap, I got good data from sessions 2, 3 and 4: https://datazap.me/u/duncanhandleyhgeconsultingcomau/250813-wakefield-session-2?log=0&data=7 https://datazap.me/u/duncanhandleyhgeconsultingcomau/250813-wakefield-session-3?log=0&data=6 https://datazap.me/u/duncanhandleyhgeconsultingcomau/250813-wakefield-session-4?log=0&data=6 Each session is cut into 3 files but loaded together, you can change between them in the top left. As the test sessions are mostly about the car, not me, I basically start by checking the oil pressure (good, or at least consistent all day). These have an electrically controlled oil pump which targets 25psi(!) at low load and 50 at high. I'm running a much thicker oil than recommended by nissan (they said 0w20, I'm running 10w40) so its a little higher. The main thing is that it doesn't drop too far, eg in the long left hand fish hook, or under brakes so I know I'm not getting oil surge. Good start. Then Oil and Coolant temp, plus intercooler and intake temps, like this: Keeping in mind ambient was about 5o at session 2, I'd say the oil temp is good. The coolant temp as OK but a big worry for hot days (it was getting to 110 back in Feb when it was 35o) so I need to keep addressing that. The water to air intercooler is working totally backwards where we get 5o air in the intake, squish/warm it in the turbos (unknown temp) then run it through the intercoolers which are say 65o max in this case, then the result is 20o air into the engine......the day was too atypical to draw a conclusion on that I think, in the united states of freedom they do a lot of upsizing the intercooler and heat exchanger cores to get those temps down but they were OK this time. The other interesting (but not concerning) part for me was the turbo speed vs boost graph: I circled an example from the main straight. With the tune boost peaks at around 18psi but it deliberately drops to about 14psi at redline because the turbos are tiny - they choke at high revs and just create more heat than power if you run them hard all the way. But you can also see the turbo speed at the same time; it raises from about 180,000rpm to 210,000rpm which the boost falls....imagine the turbine speed if they held 18psi to redline. The wastegates are electrically controlled so there is a heap of logic about boost target, actual boost, delta etc etc but it all seems to work well
×
×
  • Create New...