Full-Flow Boost Control in a Lightweight 60mm Package
Serious boost control starts with a wastegate that can handle the pressure. The HKS GTII 60mm External Wastegate (14005-AK001) delivers full-flow bypass capacity in a compact, lightweight package, purpose-built for high-displacement engines running aggressive boost targets. Its stainless steel lower body and anodized billet aluminum upper case combine heat resistance with a clean, professional appearance that stands out in any engine bay.
Compact Design Without Sacrificing Flow
The GTII 60mm is approximately one-third lighter than the original HKS GT Wastegate, tipping the scales at 1,509g (roughly 6 lbs) compared to the previous generation’s 2,246g. Despite the reduced size, the 60mm stainless steel valve maintains the same lift amount and flow characteristics as its predecessor. The result is a wastegate that fits in tighter spaces without compromising the performance tuners relied on from the GT series. Part number 14005-AK001 uses V-band clamps on both the inlet and outlet flanges, allowing for a clean, serviceable installation that can be positioned in virtually any orientation.
Key Features
- 60mm stainless steel valve with full-range spring kit included
- Base boost pressure range: 8.5 to 29.9 PSI (0.6 to 2.1 kgf/cm2) across four spring combinations
- Stainless steel lower housing with anodized billet aluminum upper case (alumite finish)
- V-band clamp connections on inlet and outlet flanges for tool-assisted quick service
- Four springs included (two pre-installed): Blue/Pink, Blue/Green, Blue/Red, Blue/Yellow
- Special spring-installation tool (SST rod, slider, collar, parallel key) included
- 1/8 NPT boost control port for direct EVC or VBC boost controller connection
- Fluorosilicone rubber diaphragm for heat and chemical resistance
- Approximately 2/3 the weight of the prior HKS GT Wastegate generation
- Compatible with optional 4-bolt adapter flange for legacy bolt-on wastegate manifolds
- MPN: 14005-AK001 | Part: 14005-AK001 | HKS PN: 14005-AK001
Boost Pressure Spring Settings
The 14005-AK001 ships with four color-coded springs that can be combined to achieve four distinct pressure bands without a boost controller. Spring combinations are as follows:
| Springs Installed | Pressure Range (kPa) | Pressure Range (PSI) |
|---|---|---|
| Blue/Pink only | 58.8 to 98.1 kPa | 8.5 to 14.2 PSI |
| Blue/Pink + Blue/Green | 88.3 to 127.5 kPa | 12.8 to 18.5 PSI |
| Blue/Red + Blue/Green | 127.5 to 166.7 kPa | 18.5 to 24.2 PSI |
| Blue/Yellow + Blue/Red + Blue/Green | 166.7 to 205.9 kPa | 24.2 to 29.9 PSI |
For pressure settings above 29.9 PSI, use in conjunction with an HKS EVC (Electronic Valve Controller) or HKS VBC boost controller.
What’s Included
- 1x HKS GTII Wastegate Assembly (60mm valve, 14005-AK001)
- 4x Color-coded wastegate springs (2 pre-installed)
- 1x Inlet base flange (V-band, 90.8mm)
- 1x Outlet flange (V-band, 58.4mm)
- 2x V-band clamps
- 2x Plug SUS PT1/8 (boost port plugs)
- 1x Hose fitting 6mm
- 1x Spring installation tool set (rod, slider, collar, parallel key, bolt)
- 1x Installation manual
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 14005-AK001 |
| Valve Diameter | 60mm |
| Base Boost Range | 8.5 to 29.9 PSI (0.6 to 2.1 kgf/cm2) |
| Max Valve Lift | 15mm |
| Inlet/Outlet Flange Type | V-band (G-coupling) |
| Inlet Flange Size | 90.8mm V-band |
| Outlet Flange Size | 58.4mm V-band |
| Boost Control Port | 1/8 NPT |
| Valve Material | Heat-resistant stainless steel |
| Lower Housing Material | Cast stainless steel |
| Upper Case Material | Anodized billet aluminum (alumite, purple) |
| Diaphragm Material | Fluorosilicone rubber |
| Weight | 1,509g (approx. 6 lbs) |
| Fitment | Universal (external wastegate, fabrication required) |
| UPC | N/A |
| Brand | HKS |
Installation Instructions
- Select the desired spring combination based on your target base boost pressure using the spring specification table above.
- Using the included SST (special service tool) rod and slider, compress and install the chosen springs into the wastegate body. The order of springs (top or bottom position) does not affect function.
- Weld the included inlet base flange (90.8mm V-band) to the exhaust manifold wastegate outlet. Ensure the flange face is square and clean for proper sealing.
- Weld the included outlet flange (58.4mm V-band) to the exhaust dump pipe or downpipe. Route the dump pipe to an appropriate exit point.
- Mount the wastegate assembly to the inlet base flange using the 90.8mm V-band clamp. Torque to 3.9 to 4.9 N-m (0.4 to 0.5 kgf-m).
- Connect the outlet flange with the 58.4mm V-band clamp. Torque to the same specification.
- Connect the boost control port (1/8 NPT) to a boost controller solenoid, EVC, or VBC controller using the included 6mm hose fitting. If running base pressure only, install the included PT1/8 plugs.
- Route and secure all boost control lines away from heat sources. Check for leaks under pressure before full-load operation.
Frequently Asked Questions
What is the difference between the HKS GT and GTII wastegate?
The GTII series is approximately one-third lighter and significantly smaller than the original HKS GT Wastegate while maintaining the same valve lift amount and flow characteristics. The GTII also uses V-band clamps on both flanges, improving serviceability over the bolt-flange design on older models.
Does the 14005-AK001 include the mounting flanges?
Yes. The wastegate ships with a 90.8mm V-band inlet base flange and a 58.4mm V-band outlet flange, both of which are designed to be welded to your exhaust manifold and dump pipe respectively. V-band clamps are also included.
Can I run higher boost than 29.9 PSI with this wastegate?
The spring-only base pressure tops out at approximately 29.9 PSI. For boost levels above that, an HKS EVC or VBC boost controller is required to regulate actuator pressure above the spring preload.
What flanges are compatible with this wastegate?
The 14005-AK001 uses V-band (G-coupling) flanges on both inlet and outlet. HKS also offers an optional 4-bolt adapter flange for tuners who want to use this wastegate with older bolt-pattern external wastegate manifolds.
Is this wastegate compatible with any vehicle?
The GTII 60mm is a universal external wastegate. It requires custom exhaust manifold fabrication with the correct V-band outlet flange. It is not a direct bolt-on for any specific vehicle without fabrication.
How do I change the spring combination?
Use the included SST (special service tool) comprised of the rod, slider, collar, and parallel key. This tool compresses the spring sufficiently to swap combinations without risk of damage. Full instructions are included in the installation manual.
What boost controller is recommended with the 14005-AK001?
HKS recommends the HKS EVC (Electronic Valve Controller) or HKS VBC for use with the GTII wastegate to achieve boost settings above the mechanical spring range.
Is the upper aluminum case durable under high exhaust temperatures?
The upper case (alumite-treated billet aluminum) is isolated from direct exhaust gas contact, which is handled by the stainless steel lower housing. The fluorosilicone rubber diaphragm is also rated for high-temperature operation, making the assembly suitable for demanding track and competition use.
What does the hose fitting include?
A 6mm hose nipple fitting is included and threads into the 1/8 NPT boost control port. This connects to standard boost controller vacuum lines.
What is the torque spec for the V-band clamps?
The G-coupling (V-band) clamps should be torqued to 3.9 to 4.9 N-m (0.4 to 0.5 kgf-m) for the 58.4mm connection and approximately 6.9 N-m (0.7 kgf-m) for the 90.8mm connection.
WARNING: This product can expose you to chemicals including lead and its compounds, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, visit www.p65warnings.ca.gov.
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