Nissan Skyline GTR Tuning Guide

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Under the hood (stock 170 to 180 awkw)
The legendary RB26DETT lies under the hood of the R32, R33 and R34 GTR in different forms but the tuning basics remain the same. The engine is similar to that found in the rest of the nissan skyline range but it’s a more hardcore race style engine built for Group A racing in Japan. Featuring twin cams, 24 valves, solid lifters and a six-throttle inlet manifold the nissan skyline was claimed to produce 206kw in reality the actual power figure is much closer to 260kw. Induction is via twin garret turbochargers with ceramic exhaust wheels and air is cooled by a large front mount intercooler. This nissan skyline engine is said to be strong enough to support 600hp with a standard bottom end.


Engine Tuning Stage 1

Exhaust
The RB26DETT is a sweet sounding engine but very quiet in standard form and as with most factory turbo cars the exhaust causes a huge restriction. A good free flowing exhaust will have your nissan skyline sounding great, turbo lag will be reduced, and power gained throughout the rev range. 15+ awkw achievable

Start with a cat back exhaust either get a local exhaust shop to make it or buy a after market one. Either way make sure it is at least 3 inches in diameter and has high flow mufflers. This is the cheapest option and will provide good results. For better results start the exhaust from the turbo's. Dump pipes from the turbo’s can either be a 3" open bell mouth or better still a split pipe design to separate the gases from the turbine and wastegate. However if you choose split dump pipes make sure there is at least 40cm of separation before they spit pipe rejoins the main pipe. another 10+ awkw achievable


Intake
Now we have the exhaust side of your nissan skyline breathing the next step is to get more air into the engine. Either use a high performance air filter, or replace the air box with a POD style air filters. If you choose to go the POD filter route I recommend you fabricate some type of shield to keep hot air from the engine bay away from your intake. A cold air intake to the filters from the front of your Skyline will also give you a performance advantage. 5-10 awkw is achievable


Boost increase
Boost should not be increased above 1 bar with the standard GTR turbo’s because the ceramic exhaust wheels will fail if to much heat is produced. The N1 GTR is equipped with larger turbo’s with steel wheels in this case you can run 1.5 bar, efficiency runs out above this boost level. The good news is that GTR's are equipped with a boost restrictor from factory and once this is removed you can run 1 bar of boost. To do this locate the yellow banded hose which is connected to the boost solenoid, there will be a lump where the yellow band is, remove this restrictor and you will have 1 bar of boost. Alternatives include a electronic or manual boost controller.

A manual controller is very basic in its operation it bleeds off air causing the wastegate actuator to open later. The amount of boost run depends on the amount of air bled form the system. It is critical to install an after market boost gauge before carrying out this modification as the stock gauge is not accurate enough. Manual boost controllers are cheep and easy to install but they do have there disadvantages, some can cause boost spikes, and boost creep. I have also found boost tends to tail off high in the rev range.

Electronic boost controllers on the other hand use stepper motors and monitor boost about every 10th of a second because of this boost spikes and boost creep are kept to a minimum, and the desired boost level is held to redline. Electronic boost controllers are expensive and for this level of modification a manual controller will probably be good enough but better still just remove the restrictor. 15+ awkw is possible


Cam Gears
At this stage the Nissan skyline will benefit from a set new cam gears which are relatively cheap. The outright power will be increased but the main reason for installing cam gears is for a fatter torque and power curve. Upgraded cams can help reduce lag, improve mid range, and top end power. HKS, GREADY most other Japanese manufactures make cams and have proven to give good results. 10kw+ can be achieved


ECU
Nissan ECU's tend to run rich when extra air flow in introduced this hurts performance you have a few options to fix this problem. An aftermarket ECU will give good power gains and improve drivability one popular option is the Apexi SAFC (Super air flow computer). The SAFC is a piggy back to the ECU and works by tricking the ECU into thinking your engine is getting more or less air than it actually is. Tuning should be done be a professional on a dyno, this modification will fix your air/fuel ratio but you cannot change other variables like timing ect with the SAFC.

A better but more expensive option is the Apexi Power FC which replaces the standard ECU. Many people choose the Power FC as it’s less expensive than other aftermarket ECU's, and it plugs straight into you old loom so there is no need to cut any wires. All parameters of your car can be tuned with a Power FC but once again it should be dyno tuned by a professional. Please note the power FC.

Another option is to get your standard ECU remapped this is a good idea if your not planning future modifications. If you are however the Power FC is a better option as you will save money in tuning costs. 20+ awkw is achievable


Clutch and Flywheel
At this level of modification it’s likely that the stock nissan skyline clutch will need upgrading to handle the extra power. If you are launching the car hard (drag racing ect) the standard clutch will wear out quickly and need upgrading. Popular upgrades include the Exeedy range of clutches. Many people choose to upgrade the flywheel at the same time a lightened fly wheel will improve acceleration.


Conclusion (up to 250 awkw with stage 1 modifcations)
This completes stage 1 engine tuning for the nissan skyline GTR. Basically at this stage we are at the limits of the standard turbo and fuel systems but in terms of car modification this level of tuning is offers great value for money. Many people with these modifications with and a well sorted suspension and tyre packages have run low 12 to high 11 second quarter mile passes.

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Engine Tuning Stage 2

Stage 2 of tuning is where things start to get expensive as we need to upgrade many of the standard systems. Nissan Skyline RB engines are known for the strength and the RB26DETT is the strongest animal with regular maintenance and a safe tune 330+ awkw is possible.


Turbo Selection
Many good turbo options are available for the Nissan Skyline GTR I recommend turbo’s that will bolt onto standard manifolds, this will save time and money in the long run. Popular models include;
HKS 2510 response close to stock with slight power increase
HKS GTSS responsive turbo with max power output of around 300 awkw
Nissan N1, Garrett 2560r, HKS2530 are similar to each other, a good compromise between lag and max power, and 350+ awkw is possible.


Fuel system
The GTR fuel pump and injectors are good for levels up 265rwkw, any more than this and you are starting to push safe limits. Popular upgrades include pumps from bosch, walbro, and tomei. Nengun.com has many injector and fuel pump upgrades available for the Nissan Skyline GTR just remember to choose items which will support your power target and allow some room for future upgrades if need be.


Intercooler Upgrade
The GTR Nissan Skyline intercooler runs out of its efficiency range at power levels above 300rwkw and needs to be upgraded. Many aftermarket bolt on kits are available for the GTR starting at around AU$1000 but as with most things you get what you pay for. Be aware a small decrease in throttle response may be noticeable due to the extra piping and larger core size.


Airflow Meter's
To improve the tunability of the engine its a good idea to upgrade your airflow meter's this allows for finer tuning which will result in smoother power delivery and make it easier for the tuner to produce a higher peak power output . Popular upgrade choices include the Z32 and the Q45. The Z32 is cheaper of the 2 but the Q45 will allow more airflow. click for more information


ECU
If you have not done so already the ECU will need to be upgraded as stated before the Power FC is a popular option due to its price, ease of installation, and use. There are plenty of other options that are superior to the Power FC and allow many other tuning functions like launch control, and the ability to use a map sensor instead of the airflow meter. But the FC is still a popular and is proven to perform.


Head Gasket
Running boost levels above 1.2 may require a new metal head gasket to lower compression and improve reliability. Opinions differ on this subject so I think its best to ask you tuner.


Clutch and flywheel
The stock clutch will certainly fail quickly at this power level the hardest part is finding a clutch that will handle the power yet not make your car a pig to drive. Exeedy seem to be popular and reliable choice and while you are upgrading your clutch a lightened flywheel is well worth considering. This will help the car rev quicker but the trade off is your car will loose momentum quicker to.


Cams
At this stage the Nissan skyline will benefit from a set new cams. The outright power will be increased but the main reason for installing cams is for a fatter torque and power curve. Upgraded cams can help reduce lag, improve mid and top end power. Popular choice is tomei pon cams as they fit without modification and are proven to give good results.