GMTGTR's R32 GTR overhaul

[GMTGTR]

Grab a coffee, because this might take a while. Thanks for reading.

My transmission/clutch is starting to act up, so it seems like a good time to dig into the drivetrain to address much needed (and wanted) upkeep and upgrades "since I'm in there". I'll be doing a lot of planning to manage the overall scope, requirements, and goals of the project before I start disassembling anything. Anything I can verify ("known knowns") or proactively plan for ("known unknowns") before I disassemble will be budgeted as contingency to avoid delays or overspending. I am (was?) a project manager by trade. So why not project manage the shit out of this?

The car will be left on a battery maintainer and not driven at this time. I plan to start disassembly around January of 2024. I'd love to be completed by June of 2024, but quality of execution is my main focus. I will be doing all the labor with a friend who owned and has extensive knowledge (some dated) on skylines from working as a mechanic/track support at HKS USA and MotoRex (confirmed shit show lol).

There's five main goals (scope) for this overhaul:

1. Maximize the current setup on the car (HKS GT-SS) with a proper standalone
2. Overhaul entire suspension
3. Perform general maintenance/inspections on entire running gear
4. Modernize where prudent (R35 coils)
5. Modernize where convenient (a radio? lol)

I'll do my best to index future posts to make it easier to follow progress on different aspects with reference to project goals. Not sure how much I will document with pictures or video, I'll see how the first steps go before I commit. Aside from the financial abuse I'm about to take and the hiatus of driving my skyline, I'm looking forward to this. Looking forward to any tips or advice along the way. Thanks SAU

Edited September 24, 2023 by GMTGTR

[GMTGTR]

Here's some background on my car:

1. Two previous owners in Japan (92-16, 16-19), I'm the first owner since it was imported in 2020
2. Have maintenance documents from 1995 to 2018 (Heisei 7-30)
3. Mileage is at 84k KMs with verified odometer checks and maintenance to validate
4. It came from a contaminated region (Ibaraki Prefecture). Supposedly they test at the ports. I don't care; I'll be buried in this car.
5. Auction rated at a 4/B in 2016 and 2019

My car was imported to the US in early 2020. I bought it in Feb 2020, but I had to wait 8 months for the car to be brought to California compliance (CARB certification). 

Parts removed for California legalization process:

1. HKS F-Con V Pro
2. HKS EVC 6
3. HKS SQV4
4. Sard 800cc Injectors
5. RSR Equal Length Front Pipe (will reinstall)
6. Sard High Flow Cat
7. HKS Hi Power Catback Exhaust
8. Apex'i Intake Pods

Parts currently installed (or claimed) on the car:

1. Greddy Front Mount Intercooler with Piping (confirmed)
2. HKS GT-SS Turbos (claimed, will verify)
3. HKS Actuators (confirmed)
4. HKS Oil Cooler with Filter Relocation kit (confirmed)
5. HKS Fuel Pump, 280l/h (claimed, will verify/likely remove)
6. OS Giken Clutch, unknown model(claimed, may rebuild depending on model)
7. Apex N1 Coilovers (confirmed, will replace)
8. Cusco front and rear anti-roll bars (will verify)
9. Cusco front and rear strut bars (confirmed)
10. R32 Vspec or R33 Front Brembo Calipers (confirmed)
11. Nismo Braided Brake lines (confirmed)
12. Volk RE30s (18x9.5+22) with ContiSportContact 3 (265/35/18)
13. HID conversion in stock projector housing

Car passed CA smog in September 2022 without any changes from above.

Edited September 24, 2023 by GMTGTR

[GMTGTR]

Known issues (half of goal 3):

1. Throwout bearing (or possible input shaft bearing) is failing. Clutch still functions normal, with no issues. Noise is consistent in pitch and cadence in neutral, moving, clutch in/out. Have a video I can attach.
2. Going into 4th gear from 3rd quickly will grind slightly. I usually let off in 3rd (street car) and usually let the rpms drop until it slides into 4th without resistance now that I know. Rev matching from 5th into 4th quickly hasn't caused any issues.
3. Doesn't hold idle on cold starts. Long crank, starts up briefly but stumbles and dies immediately. Second start up immediately after will stumble a bit and then increase idle to ~2k and then settle. No issues with warm starts. If I add a slight amount of throttle, I can prevent the first startup stumble/shut off. 
4. Suspension is awful. A combination of worn out, over sprung, and too aggressive for non-Japanese roads.
5. I have a very slow drip (1-3 drops per 2 weeks) of steering fluid (red) on the passenger side of the engine bay. Not enough for reservoir level to change in 3 years.
6. Oil collects/weeps, but doesn't drip at the transmission/engine connection. No oil level movement between change intervals (5k KM).
7. Driver side mirror doesn't not fold.
8. Door strikers don't secure doors firm. Slight door noise/rattle
9. HID retrofit has a bad connection between ballast and bulb in passenger side. Intermittently cuts out from vehicle vibration.
10. One section of lighting in the gauge cluster flickers/intermittently off when parking/headlights lights are on.
11. I don't have a radio. 

Edited September 24, 2023 by GMTGTR

[GMTGTR]

Gripes about my car (majority of goal 5):

1. I don't have a radio.
2. The center console surround is a cheap fake carbon fiber part.
3. ABS Brake line holder/clips are colored BLUE.
4. I have the slightest passenger dash bubble.
5. Trunk mat is beat up.
6. My Tommy Kaira Shift knob doesn't fit. It's a M10x1.25 (same as my old Evo X), but the threads on the shifter are M10x1.5 (verified). WTF?
7. Lettering on my AC buttons is partially worn off.

Edited September 24, 2023 by GMTGTR

[GMTGTR]

(Shit, I just realized that you have time limits to edit on this forum. My bad. I was trying to placehold posts to break things up and put in order. Oh well.)

Ok, so onto the fun part of the project. Goal 1: Building the drivetrain to maximize the (hopefully still installed) HKS GT-SS turbos.

While F-Con V Pro tuned, the car felt great. Somewhere in the high 200kw to low 300kw range. I only drove the car once like this and it was over 3 years ago, so that's my best guess. 

I don't have a true power goal in mind. I'd like to get my car roughly to original level (~300kw/400whp) or higher with E85/flex fuel(~350kw/470whp) if that's reasonable on these turbos. 

One small side note: The more stock appearance the engine bay is, the better for California. The laws are bullshit, and I'd rather avoid as many hassles as possible.

Here's the breakdown of the engine/power related (non-maintenance) plans so far:

1. Engine block: Leave unmodified
2. Engine head: Verify if HKS cams
   1. If HKS, try to verify profile and add adjustable cam gears
   2. If stock, leave unmodified/maybe adjustable cam gears
   3. MAYBE, VCAM Step 1 if budget permits
3. Intercooler: Leave Greddy Front Mount with Piping
4. Intake: Leave stock airbox. Install upgraded air filter.
   1. Install AFM delete for MAP sensor/tune
   2. If stock airbox limit is reached, reinstall Apex'i Intake Pods
5. Turbo Inlet Pipes: Leave stock if possible
   1. Correct me if I'm wrong, but I don't think these need to be upgraded ever on stock location twins?
6. Blow Off Valves: Leave stock if possible
   1. I'm under the impression that the stock BOVs are fine for sub-370kw/500whp goals? Correct me if I'm wrong.
7. Intake Manifold: Leave stock
8. Injectors: ID1050x or ID1300x (suggestions?)
   1. I'd like to keep duty cycles below 80% on E85 with ~20-22psi
   2. Stock fuel pressure if possible
   3. Don't need a bunch of headspace. If I go bigger than GT-SS (much later), it'll be a mid-frame single, so it'll be replaced.
9. Fuel Rail: Stock
10. Fuel Lines: Stock
11. Fuel Pump: FPG In-Tank Surge Tank Kit with 1x Walbro 450
    1. Twin pump setup for futureproofing
    2. Overkill for a street car at 500whp/370kw?
12. Coilpacks: R35 Retrofit
13. Spark Plugs: BKR8EIX or BKR7EIX?
    1. I'll be running E85 a majority of the time
    2. Usually do 1 tank per 6 weeks
    3. Adding fuel stabilizers if E85 sits too long
14. ECU: Up to the tuner really. If I had a choice, Haltech.
    1. Will install supporting sensors as needed
    2. MAP tuning, so AFM Deletes as mentioned above (Intake line 4)
15. Exhaust manifolds: Whatever is on it. Assuming stock
16. Turbos: HKS GT-SS
    1. Will visually confirm
    2. If stock ceramics, will buy GT2859R-9
17. Turbo Outlets: If turbos don't need to be changed, leaving whatever is on it. I'm guessing it's HKS Outlets based on previous exhaust mods.
    1. If turbos need to be removed, whatever fits a RSR equal length front pipe (70mm x2) best? Suggestions?
18. Front Pipe: Reuse RSR Equal Length Front Pipe, 70mm x2 - 80mm x1
19. Cat: Berk 3" 240cell count
    1. Not flashy, looks oem/basic which is a bonus for me
20. Catback Exhaust: Fujitsubo Legalis R (type Evolution)
    1. Pretty quiet and not as flashy as canister mufflers
21. Did I miss anything? Suggestions greatly appreciated. Thanks

Edited September 24, 2023 by GMTGTR

[GTSBoy]

3 hours ago, GMTGTR said:

Placeholder Post (I'm really really sorry MODS)

It's a waste of time. You can;t go back and edit posts after they're a few hours old. You're going to have to ask a mod to paste into it.

Ah. I see you worked it out.

54 minutes ago, GMTGTR said:

(Shit, I just realized that you have time limits to edit on this forum. My bad. I was trying to placehold posts to break things up and put in order. Oh well.)

Edited September 24, 2023 by GTSBoy

[Duncan]

So, if you have GTSS turbos and a 300kw goal, you really don't need anything except the fuel pump, injectors and tune (and depending on ECU, swapping the AFMs for Z32 or nismo ones). And 3" exhaust from the dumps back.

You should check the rb26 dyno thread for GTSS results because I'm not sure, but I think they will be OK for 300kw at about 20psi, anything over that they will start to choke anyway. You are unlikely to need e85 and preparing for it requires a bit of cost (new fuel lines, e85 pump, e85 injectors), plus it is no good in irregularly driven cars because of how it pulls water into the oil.

[Duncan]

Sorry, if should add, 300kw is a bit of a sweet spot for these cars in terms of not having to change much. When you get to 350-600 you have to change a heap more, and when you want to go over about 600 the sky is the limit on cost.

Depending on the clutch, you might need to change that to a better single plate if it can't hold the power (you will probably find out, or not, on they dyno)

[GMTGTR]

2 hours ago, Duncan said:

So, if you have GTSS turbos and a 300kw goal, you really don't need anything except the fuel pump, injectors and tune (and depending on ECU, swapping the AFMs for Z32 or nismo ones). And 3" exhaust from the dumps back.

You should check the rb26 dyno thread for GTSS results because I'm not sure, but I think they will be OK for 300kw at about 20psi, anything over that they will start to choke anyway. You are unlikely to need e85 and preparing for it requires a bit of cost (new fuel lines, e85 pump, e85 injectors), plus it is no good in irregularly driven cars because of how it pulls water into the oil.

Thanks for the input. I should have been more clear, I was expecting to hit just under 300kw with pump (95ron) and 350kw with e85/flex fuel at similar boost with better timing/cooler temps/etc. The upgrade to the fuel system was two-fold, size up to run E85 with safety margin and to replace old equipment for safety/upkeep since I don’t know how old these components are.

As far as the hydroscopic nature of E85, I was planning on using fuel stabilizers if the tank lasts over 6 weeks and fill the balance with standard 95ron. I don’t drive far distances, but a majority of my driving is through urban streets and mountainous areas. I think last time I check, I was averaging 8-10 miles per gallon (3.5-5.5km per liter). So figured the increase rates of e85 will empty quicker.

Is there something Skyline specific related to the fuel system that is different from other vehicles? My friends with other platforms(evos, stis, supras, s13s, m2/3s, etc.) don’t seem to have an issue with stabilizers and blending from time to time on non-daily cars.

While my mechanic does have the tuning license for the F-Con, it’s quite pointless to use that piggyback with the current standalone offers/support in US. I would like the safeguards that modern standalones provide.

[GMTGTR]

2 hours ago, Duncan said:

Sorry, if should add, 300kw is a bit of a sweet spot for these cars in terms of not having to change much. When you get to 350-600 you have to change a heap more, and when you want to go over about 600 the sky is the limit on cost.

Depending on the clutch, you might need to change that to a better single plate if it can't hold the power (you will probably find out, or not, on they dyno)

Yeah, I was planning on staying a safe margin away from a gearset change (more on the transmission in a later post) and needing a full bottom end rebuild. Maybe on the next phase much further down the road I can shoot for a higher ceiling. 

As far as use case and driving behavior, the car is just a weekend cruiser/spirited canyon driving. No launches ever, nothing past the top of 3rd gear, and I let the rpms fall before engaging the next gear. I enjoy carrying speed through the corners and rolling on the throttle much more than banging gears, so I figured my transmission and related components should hold up at 350kw levels. Let me know if I’m crazy or bound to kill 3rd gears?

[Duncan]

You'll be fine with the standard gears at around 350kw, if you are kind to gearboxes. I've been racing on a standard box for years at around that level, including standing starts etc. I've worn a few out (synchros and bearings) but nothing broken

[r32-25t]

For what your trying to make all you need is exhausts, pods, turbos, injectors, fuel pump, clutch, cam gears and an ecu with a wideband and flex sensor and then bobs your mums brother she’s done. If you want a little more throw some drop in cams into it. Anything else is a waste of money 

[GMTGTR]

15 minutes ago, Duncan said:

You'll be fine with the standard gears at around 350kw, if you are kind to gearboxes. I've been racing on a standard box for years at around that level, including standing starts etc. I've worn a few out (synchros and bearings) but nothing broken

That’s great to hear. Thanks for confirming for me.

I forgot to mention the clutch comment. After more research, the full face twin OS Gikens are uncomfortably close to the power levels I may be hitting. So unless someone convinces me otherwise, I’ll probably opt for the Nismo twin, likely competition spec.

Edited September 25, 2023 by GMTGTR

[GMTGTR]

23 minutes ago, r32-25t said:

For what your trying to make all you need is exhausts, pods, turbos, injectors, fuel pump, clutch, cam gears and an ecu with a wideband and flex sensor and then bobs your mums brother she’s done. If you want a little more throw some drop in cams into it. Anything else is a waste of money 

Thanks for the input. I think my above parts list breakdown is extremely close to this. I do have a few questions if you don’t mind:

1. Do I need pods for this lower level? I’ve seen several people running the stock box with aftermarket filters. I do have a set so it’s not problem really, but if it’s preference or extremely minimal impact, I’d rather keep a more factory looking engine due to law enforcement hassles.
2. I think the only things I listed beyond the parts you mentioned are the coil packs and spark plugs. I just figured that these were a small investment/insurance to prevent any dyno day mishaps and the likely age of the components would make these prudent upgrades. Your thoughts?
3. I think my car has hks cams installed. I also assume that it has cam gears if they went though the hassle to install cams. I will visually verify when I start disassembly.
4. For my power level, is there a reason to go for 1300cc injectors or run a higher IDC on 1050s?

Thanks

 

Edited September 25, 2023 by GMTGTR

[r32-25t]

Coils are a probably going to be needed just due to yours being old and worn out, a trigger kit is always nice insurance as well but not required.
 

1050s will do the trick 

[Duncan]

You can get there with the standard airbox, no problem, and injectors you need 550ish for PULP but larger is fine

[r32-25t]

On a 32 I keep seeing standard air boxes become a restriction at much over 300kw, the later ones are great 

[GMTGTR]

15 minutes ago, r32-25t said:

Coils are a probably going to be needed just due to yours being old and worn out, a trigger kit is always nice insurance as well but not required.
 

1050s will do the trick 

Thanks, I was planning on writing about the cam/crank trigger kits when I go through the maintenance/upkeep area for timing related servicing. 

1050s it is. 

15 minutes ago, Duncan said:

You can get there with the standard airbox, no problem, and injectors you need 550ish for PULP but larger is fine

10 minutes ago, r32-25t said:

On a 32 I keep seeing standard air boxes become a restriction at much over 300kw, the later ones are great 

This isn’t the first time I’ve seen comments like these. I’m pretty sure both are accurate in their own expectations. Because this is an easy swap, maybe I just try both while on the dyno and see how much power/characteristic difference there is. EZPZ

[GMTGTR]

Ok, here's the breakdown on the transmission/drivetrain plans for supporting my power goals (Goal 1):

NOTE: Service of these components will be a different section. This is just for upgrade related scope.

1. Transmission: Stock
   1. While I don't need a gearset based on my power and driving needs, the exchange rate for USD to JPY is tempting me to stash a rainy day OS Giken gearset/input shaft/center plate (~$3k USD). Very much a "Nice to Have"
2. Transfer Case: Stock
3. Front Diff: Stock
   1. I think a front LSD might be too much for a street/cruiser build. Open to opinions though.
   2. While I get clunking at low speed, I'm pretty sure it's only from the rear. 
4. Rear Diff: Stock
   1. If budget permits, I may look into a 1.5way lsd. "Nice to Have"
   2. At low speeds while turning, I get a lot of clunking from the diffs. More clunking than I've had on other factory LSD vehicles (Z32 TT, Evo X). No wheel hop, but its definitely jerky if not smooth on throttle/clutch, so I'll inspect if it's aftermarket.
5. Clutch (push): As mentioned earlier. I don't know the exact clutch in the car. I will wait to remove the transmission before I make a final decision.
   1. High likeliness I replace with a Nismo Coppermix Twin, comp spec.
   2. Convince me to rebuild the OS Giken if it's  STR or GT twin vs option 1. I'm open to it.
6. Driveshafts: Leave stock
7. Axles: Leave stock

Like always open to feedback where you see appropriate. Thanks

[Duncan]

2 hours ago, GMTGTR said:

This isn’t the first time I’ve seen comments like these. I’m pretty sure both are accurate in their own expectations. Because this is an easy swap, maybe I just try both while on the dyno and see how much power/characteristic difference there is. EZPZ

To be fair, the answers aren't exactly contradictory, you can make over 300kw with a full standard intake (I do, on the race car at high boost), but it could be causing some restriction. High boost (18psi on N1 turbos, >300kw) needed a swap from factory to 550cc injectors, low boost 250kw I just got there on stock injectors 440cc

In your case, I would keep the factory intake as living in the state of california is known to cause cancer and you probably don't need the attention