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Nissan Skyline R34 Gtt Modification/tuning Guide


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Under the hood (stock 140 to 150rwkw)

The R34 GTT replaced the Nissan Skyline R33 GTS25T and features a upgraded version of the RB25DET. The main difference is the NEO head which has a new varible valve timing system, revised cam profiles, and solid lifters. Power was increased to 206kw with more torque availible earlier in the rev range. The turbo has a slightly larger exaust housing and a nylon compressor wheel. Cooling has also been improved with a larger more efficent intercooler.

Engine Tuning Stage 1

Exhaust (around 160rwkw)

The RB25DET NEO 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 the RB sounding great, turbo lag will be reduced, and power gained throughout the rev range. The new exhaust should start from the turbo with a dump pipe either a 3" open bell mouth or better still a split dump to separate the gases from the turbine and wastegate. From here a high quality 3" high flow cat should be used, then 3" all the way to the back of the car with high flow mufflers.

Intake (160 to 170rwkw)

Now we have the exhaust side of the engine 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 filter. 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 filter from the front of your Skyline will also give you a performance advantage. 5-10 rwkw is achievable with this mod.

Boost increase (175 to 185rwkw)

In standard form the R34 runs a two stage boost control system 5psi to 4500 rpm then 7psi to red line 7000 rpm. As mentioned before the turbo’s exhaust wheel is ceramic and they tend to fail if to much heat is generated. The amount of boost you can run with the stock turbo is debatable but I don’t recommend running more than 10 psi. You have a few options when choosing to increase the boost either a manual boost controller, electronic boost controller, or a new wastegate actuator.

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 and is measured in mmg not psi or bar. 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.

A 3rd option is to install a different wastgate actuator and the good news is the R32GTST item is exactly the same as the R34 except the spring inside is set for 10psi. R32 actuators can be hard to find but I think it’s the best option for this level of modification as boost spikes and boost creep are eliminated.

No mater which system you choose the 2 stage boost control system should be disconnected. After this mod is carried out many people notice flat spots throughout the rev range this is due to the ECU seeing an increase in airflow and as a safety precaution it richens the air fuel mixtures. Many people find re-gaping the spark plugs from 1.1mm to 0.8mm fixes this problem but if it does not you need to consider the next upgrade.

ECU (185 to 200+rwkw)

As mentioned before many people have problems with flat spots and rich air fuel ratios. Even if you don’t have these dreaded flat spots 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 your engine actually is. Tuning should be done be a professional on a dyno this modification should fix those dreaded flat spots by leaning you airfuel ratio's at different RPM points.

A better but more expensive option is the Apexi Power FC which replaces the standard ECU. Many people choose the Power FC as its 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 cannot be used an automatic transmission.

Clutch and Fuel Pump At this level of modification it’s likely that your clutch and or fuel pump will need upgrading to handing the extra power.


This completes stage 1 engine tuning for the Nissan Skyline R34 GTT. 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 offers great value for money. Many people with these modifications along with well sorted suspension and tyre packages have 12 run second quarter mile passes. 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 the RB25 is no exception with regular maintenance and a safe tune 270rwkw is easily possible. Some people push the limits with 300rwkw+ but if you want an engine that will last 270rwkw is a safer limit.

Turbo Selection

There are many good turbo options available but I recommend a turbo that will bolt onto standard manifold this will save time and money in the long run. Many people in Australia have had there standard Nissan Skyline turbo high-flowed by GCG turbo’s these turbos are popular because they use a ball bearing cartridge, and everything bolts back into place. Turbo response is said to be similar to stock and power figures average around 230rwkw or up to 250rwkw with cams. Some people have used larger exhaust housings from the R34 GTT or the old single turbo 300zx and have achieved 270rwkw+.

HKS in Japan have a range of turbo's for the R33 that come with all the parts needed to bolt on. Suitable kits available from HKS at the moment include the HKS GT-RS known to make 280rwkw and the HKS PRO-S known to make around 300rwkw the GTRS is cheaper and a little more responsive than the PRO-S. Another popular choice since superseded by newer models was the 2535 which is similar to the GT-RS.

Intercooler Upgrade

The standard R34 Nissan Skyline intercooler runs out of its efficiency range at power levels above 200rwkw and needs to be replaced by a larger front mounted intercooler. GTR intercoolers are a popular choice but custom piping will be needed in order for it to fit. Many aftermarket bolt on kits are available for the GTT these days starting at around AU$500 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. You may notice a small increase in power with this mod before upgrading your turbo as airflow will increase and the air will be denser.

Fuel system

If you haven’t done so already the fuel pump will need to be upgraded. Second hand GTR pumps are a popular option as are new pumps from bosch, walbro, and tomei. The GTR and Tomei pumps are a direct fit. You may also install a fuel pressure regulator to increase fuel pressure.

Standard injectors will also need to be upgraded at this stage. You can either have your standard injectors high-flowed, or buy after market ones from Nismo or Performance company's. I recommend you use injectors that are a direct replacement and don’t require any modifications s to fit.

Airflow meter

To improve the tunability of the engine its a good idea to upgrade your airflow meter 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


If you have not done so already the ECU will need to be upgraded even with a SAFC or similar the stock ECU will not do the job. 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 or Cam gears

At this stage the skyline will benefit from a set new cams, cam gears, or both. 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.

Big thanks to Squeak from http://www.skyline-owners-club.com


  • Like 2
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Definately will be.

Im currently looking for a GTT, and was doing some research and came across this information aswell.

So i hope this helps other GTT owners aswell.


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this is absolutely awesome for a new GTT owner like me...

great info on steps to take to mod the car right... thanks! i will be working my way through stage 1 for sure, i already had a pretty good idea of all the steps (am doing my full exhaust first currently) but all of that just clarifies it for me and fills in any minor knowledge gaps i had aswell...

no plans on stage 2 for me that is getting serious and won't get through stage 1 for a while, so we'll just see how badly the bug has bitten once im done with stage 1 ey... damn $$$$$$$$$$$$

Edited by vudoo
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  • 4 weeks later...

Awesome post!

My GTT has run 196Kw atw in on the dyno with the intake, exhaust, intercooler and electronic boost control mod (Apexi AVC-R). Can't wait for the ECU mod!

On another note you mentioned it is recommended that one should upgrade to an aftermarket boost gauges. Does anyone know what size and/or brand will fit into the standard cluster on top of the dash? I'm not one for gauges bolted everywhere, not to mention they are construed as being illegal.

Any help appreciated.

Cheers SPR34.

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  • 1 month later...

Thanks mate,

I dont care if this was posted in the past or a cut & paste. The point is it is a great guide for those unsure of what to do first before simply upgrading their turbo and potentially blowing their engine without the proper preparations.

I've found this useful and thankfully have already done most of the required upgrades previously. I've currently got a Dual Stage Blitz Electronic Boost Controller and mite sell mine for an Actuator so i cant possibly get defected for that.

Got everything required for Stage 1 - 2 (Blitz Intercooler, Full 3" exhaust without Cat, made a huge difference, Pod Filter, except for computer tune/ecu, Some Japanese Fuel pump system & Extensive Suspension work)

I think I will work on the head gasket next.



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  • 6 months later...
  • 1 month later...
  • 1 year later...
  • 2 years later...


I have just finished stage one on my R34 GTT the mods I have are high flow apexi pod with a heat cover custom made, GTR intercool, spite fire coil packs , .8 copper plugs , 3" custom made dump pipe to a high flow cat then a apexi 3" with a duel tip running at just under 12psi

At this point I was getting 180.7kw at the wheel I got a nistune done and am getting 205.4 kWs at the wheels with much smooth drive and faster response time

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  • 1 year later...

I was told that the best thing for me to do was get a hi flowed turbo, nistune/powerfc, intercooler, 20psi, Bam awesome daily driver. (Have exhaust already)

Also I don't think a pod filter does shit? except make a louder intake noise. I prefer to keep my airbox and just upgrade the filter :)

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to make use of high flow you will also need an upgraded fuel pump. 20psi will definitely need bigger injectors too.

pod filters are worthless unless you box them and feed with cold air. the standard airbox is good for lots of power.

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