Product Overview
These GR Yaris valve springs are Kelford’s most aggressive valvetrain upgrade for the Toyota G16E-GTS engine, built for professionally prepared race engines running high boost and sustained high RPM. The KVS264-X Extreme kit sits at the top of Kelford’s G16E-GTS valve spring range, designed for builds that have already outgrown the standard KVS264 kit.
Why the factory springs aren’t enough
The factory valve springs on the GR Yaris and GR Corolla G16E-GTS engine are a known weak point once you move past mild tuning. As boost climbs above roughly 1.6 bar, or power passes around 340hp, the stock springs can no longer control valve closing speed at high RPM. The result is valve float — the valve fails to seat properly between opening events — which costs power, damages the valvetrain, and in worst cases causes valve-to-piston contact. Kelford developed this Extreme GR Yaris valve spring kit specifically to remove that ceiling for serious builds.
What makes the KVS264-X different
Unlike the standard KVS264 kit, the -X Extreme version uses higher seat and open pressures across the board — 125lb seat pressure on the intake (versus 100lb on the standard kit) and 258lb at full lift. This extra clamping force keeps the valve under control at much higher RPM and boost, which is why Kelford rates this kit to 65psi and 11,000rpm when matched with a suitable build. The beehive spring profile itself is inherently lighter than a conventional dual/triple spring setup, and pairing it with titanium retainers cuts reciprocating valvetrain mass further still — meaning the valve can open and close faster with less risk of float, without adding unnecessary load on the camshaft lobes.
Do I need these valve springs?
If your G16E-GTS is running a 62mm+ turbo upgrade, drag-spec or high-lift camshafts (Kelford’s 267 series or higher), and you’re targeting boost levels or RPM ranges beyond what a mild Stage 1 build would see, this is the kit designed for you. If your build is closer to stock turbo, mild boost increase, or Kelford’s Stage 1 camshafts, the standard KVS264 kit is the correct — and more cost-effective — choice.
Installation notes
Professional installation is strongly recommended. The OEM spring base must be removed and replaced with the base supplied in this kit before the new springs and titanium retainers are fitted. Getting installed height and coil bind clearance correct is critical to how these springs perform, so this is not a job to rush through without the right tools or experience.
Technical specifications
| Spec | Intake | Exhaust |
|---|---|---|
| Seat pressure | 125lb @ 35.0mm installed height | 110lb @ 36.7mm installed height |
| Open pressure | 258lb @ 12.0mm valve lift | 232lb @ 11.5mm valve lift |
| Coil bind (solid height) | 22.0mm | 22.0mm |
Fitment: Toyota GR Yaris and GR Corolla, G16E-GTS 1.6L turbo engine.
FAQ
What boost can these GR Yaris valve springs handle?
Up to 65psi and 11,000rpm when matched with a suitably built engine, turbo, and camshaft combination.
Do these valve springs fit the GR Corolla as well as the GR Yaris?
Yes. Both cars share the same G16E-GTS engine, so this kit fits either.
What’s the difference between the KVS264 and KVS264-X?
The standard KVS264 is rated for builds up to roughly 1.6 bar boost and 340hp. The KVS264-X Extreme kit uses higher seat and open pressures (125lb/258lb vs 100lb/198lb) to control the valve at significantly higher RPM and boost, for fully built race engines.
Do I need to change my camshafts to use this kit?
Not necessarily, but this kit is matched to Kelford’s higher-lift camshaft options (267 series and above). If you’re running factory or Stage 1 cams, check with your tuner whether the standard KVS264 kit is a better match.
Can I fit these myself?
It’s possible with the right valve spring compressor tool, but professional installation is recommended to guarantee correct installed height and coil bind clearance.
Does this kit include the spring base?
Yes — a new base is supplied and must replace the OEM base as part of installation.
