FBO TO BUILT (ALPHA 9)
After driving my FBO GT-R for 6 years, with no major issues, I’ve finally decided to move on to the next level and upgrade my factory turbos, and rebuild the engine and transmission. (Project start date: April 3, 2021).
Now, before you consider the next parts for upgrades, you need to research and understand more about the factory R35 engine internals and transmissions’ safe power levels. Speak to shops, and join forum discussions.
If you’re not sure where to start, I’ve written a full detailed section with my suggestions (not recommendations) on what you should be expecting. Turbos or Short Block upgrade? –> HERE
TURBO UPGRADE
My goal is to add more WHP, while making sure it’s safe on my internals/trans. The factory turbos at the FBO level, maxes out at 20psi. As the factory turbos max out at 20PSI, the obvious solution is to get bigger turbos. There are many turbo options in the market to go with, I personally love AMS Performance’s quality, and chose to go with their Alpha 9 GEN II turbos (most refer them as Alpha 9+).
AMS hasn’t released spec details and differences between the Gen I and II. Only that they spool faster, at around 2,800rpms, and makes more top end power.
SHORT BLOCK UPGRADES
Factory rods handle up to 600whp/600wtq. So in order to be able to use the added power and boost from the bigger turbos, you would have to upgrade the factory Rods, Pistons, Studs, and Bearings. Many aftermarket shops offer a 3.8L crate upgrade with those parts.
I went with the AMS 3.8L Race, which will be built by MC Performance, including some additional parts:
-AMS Spec Extreme-Duty JE Pistons w/ skirt coating
-AMS Spec Extreme-Duty Manley I-Beam rods
-Connecting rod, main & thrust bearings
-Boost Logic 625 Head studs (not AMS)
-OEM Head Gasket kit
-OEM Oil Pumps
CAMSHAFT UPGRADE
The bigger the turbo, the longer it would take to spool. This means that reaching the optimate power point will be on the higher RPM range.
To fill that torque gap (LAG) down low from the bigger turbo, you would want to upgrade the factory camshafts and valve springs. Cams increase the duration and timing of the valve openings during the engine stroke, increasing horsepower and making your car accelerate more quickly. I chose the GSC Power-divisions S1 Cam (billet). I also replaced the OEM cam sprocket.
Adv Duration 264 deg
-Intake: 222 deg @0.04″ / Lift 10.5mm
-Exhaust: 220 deg @0.04″ / Lift 10.3mm
Other Cam options: Kelford B2 & Tomei PonCams
FUEL SYSTEM UPGRADES
Upgrading turbos require a better fueling system, and also depending on what gas you will be using. Regardless of gas options, you would need a Twin Pump fuel syst (inc. fuel lines)). If you’re moving from FBO and will be running pump gas only, then your current injectors (1100cc or 1300cc) will be sufficient. If you plan to run ethanol, you would need bigger injectors (1700cc).
For now, I’ll be running pump 95 Ron, and occasionally C16 race fuel (117 octane). I’m going with a custom fuel system built by MC Performance, paired with Twin Walbro 525lph pumps.
TRANSMISSION & CLUTCH UPGRADES
The factory clutch will start slipping over 620wtq. Unless you plan to do all the above upgrades, and limiting your tune to 600wtq, factory clutch would be fine… but on borrowed time!
For my power levels, around 760-860 whp, I was advised to go with the Dodson Superstock clutch kit with an added 8th, not 7, for more durability, built by MC Performance. The shop will be using Dodson Motorsport clutch plates and parts. My clutch baskets are still OEM, and won’t need to be replaced.
I replaced the 1st gear & input shaft with the DMS Extreme Duty kit, and was hesitant between keeping the stock 2-4 gears (keeping in mind that 4th has been the most failed gear). The shop is confident, and experienced with R35s, including the owner who will be mimicking his own daily R35 build to mine. *Note: going for a full gearset is another $7k-$8k… if you have the budget, go for it. I’ll probably do it sometime in the future, just for piece of mind.
I replaced the factory clip on the 4WD Gearlock with the DMS Heavy duty, for added safety, as the factory clip on the 4WD gearlock is known to fail and come off, which actually happened to me post build and damaged a few other parts. Make sure you get that part, even if you’re stock or FBO.
Few months later, I had a sudden loss of 1st & R gears with a P2715 CEL code, which refers to Pressure Control Solenoid D failure. It actually turned out to be from the 1/R Shift Fork. It had minor scrapes on the edges, which was probably causing the issue hooking onto those gears. I replaced that fork with the DMS Heavy Duty Billet 1/R.
(Check my guide details: How to fix or temporarily resolve issue)
Current Clutch Capacity & Touchpoints set to: +2, +2, -2, -2
TUNE: REFLASH TCM
when upgrading to any power level over 600whp/600wtq, your clutches will start to slip. You will have to upgrade your clutches, and your gears (depending on how and where you’ll be driving). By doing so, your tuner will have to “Reflash TCM”, so re-calibrating your transmission/clutches (gear re-learning), and adjusting clutch capacities and touchpoints.
I’m on Cobb with a custom tune (38B0B stock style LC5 V103 Map), and had to upgrade my AccessPort to the TCM Flash version (AP3-NIS-006). For details –> HERE
E-Tuned by MC Performance KSA & Kanoo Performance Bahrain, so the car has not been on an actual dyno. The tune is based on actual Dyno’d cars in Bahrain. 4 Maps: 2 on 95 Ron pump, and 2 on C16 Race fuel.
E-Tune Estim.
95 Ron-Low Boost: 750whp/740wtq @ 21.8psi
95 Ron-High Boost: 750whp/740wtq @ 26psi
C16 Race Fuel-Low Boost: 860whp/850wtq @ 28psi
C16 Race Fuel-Hight Boost: 860whp/850wtq @ 32psi
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MAJJ GARAGE 