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HKS has developed a turbo to suit specific engine characteristics, the GTII Turbo
The first in the GTII Turbo range is this stock replacement type sports turbo kit for Lancer Evolution IV~IX
This turbo is 100% original design, reverse rotation ball bearing turbo
I'll now explain the features of this GTII turbo for 4G63 Engines
Compressor wheel and housing optimisation
Firstly, this compressor wheel
To match the 4G63 engine, the exducer diameter is 74mm with inducer dia 52mm.
This is an approx 10% increase over stock.
The compressor blade design is also original to HKS to best suit the 4G63 engine
The compressor housing is also optimised to match the compressor housing
Scroll cross section is made to be as circular as possible
and the diffuser radius is maximised for maximum efficiency
Exhaust side emphasises quick spool and stable boost
Next, is the exhaust wheel
This has 60mm inducer and 54mm exducer, approx 10% larger than stock.
Designed specifically for the 4G63 engine
Twin scroll exhaust housing is used to improve low rpm boost
Swing valve diameter is 42mm for stable boost control
Increased spring rate on actuator for high boost compliance
Next is this actuator
This has also been designed specifically for this turbo
The feature of this is the spring found inside here
By using a stiffer spring, it can handle high boost levels
The rod is turn buckled to allow length adjustments whilst fitted to the car
Further, you can see from looking at the back of this actuator
It is strengthened to protect the spring and rod from breakage
and rust which can be commonly seen on EVO models.
ball bearing design for maximum response
Next is the centre housing
That is this section of the turbo
HKS GTII turbos use a ball bearing design, following on from the traditions of the GT turbos.
Ball bearing design offer less rotation resistance compared with floating metal type turbos
This can help turbo spool and also throttle response
Here we will show you the difference between a ball bearing type and floating metal type design
floating type (stock) vs Ball Bearing (GTII)
The GTII 7460R on the dyno
Let’s run a power check on this Evo 9, fitted with HKS' latest turbo, the GTII
This car is equipped with HKS cams, pistons and con rods
This is so that we can extract the full potential from the GTII turbo
This GTII turbo targets a max power of 450+ps
so the engine is strengthened to withstand this
Of course, being a stock replacement type turbo, it can be very effective even with a stock engine
First we will check the power at 1.5Kg/cm² where it is most efficient
At 1.5Kg/cm² boost, power was 435.5ps
torque was 53.9 Kgm
Next is a power check at 1.2Kg/cm²
At 1.2Kg/cm² boost, power was 397.8ps
torque was 43.2 Kgm
Next is at 2.0Kg/cm² Boost
At 2.0Kg/cm² boost, power was 459.8ps
torque was 57.9 Kgm
Comparing the graphs with the same car equipped with a stock turbo
You can see the GTII is able to out perform at all rev ranges
Conventionally, when a larger turbo is fitted
Peak power is gained at the sacrifice of low rpm response
However, this GTII turbo is able to overturn these conventions and outperform the stock turbo at all rpm
This is the result of applying the know how that HKS gained from many years of development of the 4G63
Opinion from a racing driver, Nobuteru Taniguchi
I've just tried the new turbo from HKS
It's easiest to feel the difference at low rpm
A larger turbo car would naturally give more power from mid-high rpm
But this turbo is good from the very bottom
Normally when a turbo is changed, you loose that bottom end feeling
but this turbo is very quick to respond and it can sometimes surprise you
From there, it continues to perform al the way up the rev range
making it very easy, comfortable and fun to drive
There is almost no turbo lag which can be felt on most turbo cars
For those of you who are worried about loosing low rpm response by changing turbo
This turbo will perform better at low rpm and is great all the way to the top
I'd very much recommend it!
This turbo was designed with the hope that people can enjoy their 4G63 further
We hope that you get the opportunity to try out the HKS GTII turbo!