Supertech Valve Spring Kit Nissan RB25

Supertech valve spring kit for Nissan 2.5L 24v inline-6 RB series engines (RB25DE naturally aspirated and RB25DET turbo). Available in 3 distinct configurations covering all engine build levels, from performance replacement on OEM hydraulic lifters to complete conversion to solid lifters for race applications.

Common technical specifications

• Manufacturer: Supertech
• Origin: Made in USA (San Jose, California)
• Application: Nissan RB25DE and RB25DET
• Number of valves covered: 24 (12 intake + 12 exhaust)
• Matched components supplied with each kit

Available part numbers

• SPRK-1012S-RB25 - Single 78 lbs @ 30.6 mm (OEM hydraulic lifters): SPR-TS1012-SI springs + NVG1014/T1 retainers + SS-2820-E exhaust seats + OEM intake seats retained
• SPRK-2081-RB25 - Single 85 lbs @ 30.6 mm (OEM hydraulic lifters): SPR-TS1015-SI springs + NVG1015/T1 retainers + SS-2820-E exhaust seats + OEM intake seats retained
• SPRK-TS1015-RB25 - Double 83 lbs @ 35 mm (solid lifter conversion, max lift 14.30 mm, cam base circle 20.7 mm): SPR-TS1015 springs + NVG1015/T1 retainers + SEAT-RB25-I intake seats + SEAT-RB25-E exhaust seats

Configuration selection

The choice depends on the engine build level and the type of valvetrain used:

• SPRK-1012S-RB25 (78 lbs hydraulic): recommended for light to moderate build with OEM hydraulic lifters retained. Lightly upgraded cams, street/light drift use. Moderate pressure limits cam and valvetrain wear.
• SPRK-2081-RB25 (85 lbs hydraulic): recommended for more aggressive performance build with OEM hydraulic lifters retained. Performance cams with moderate lift, higher RPM, drift/circuit. Increased pressure for better valve control at high RPM.
• SPRK-TS1015-RB25 (83 lbs solid conversion): complete conversion kit for switching to solid lifters (mechanical). Mandatory double spring configuration with specific SEAT-RB25-I/E seats supplied. Suited to high lift cams (up to 14.30 mm) with 20.7 mm base circle. Reserved for serious race builds (aggressive drift, drag, circuit, very high RPM).

Components (retainers, seats) are specific to each configuration - do not mix components between the 3 part numbers.

Hydraulic vs solid lifter difference

Hydraulic lifters (OEM on RB25) automatically adjust valve lash via an internal hydraulic system. They are convenient and silent but limited at high RPM (risk of "pump-up" preventing the valve from closing properly). Solid (mechanical) lifters eliminate this issue and allow higher cam lifts and higher RPM, at the cost of periodic cold valve lash adjustment.

Supertech is a leading American manufacturer of high performance valvetrain components, designed and manufactured in the USA to aerospace-grade precision specifications.

Application

Compatible with Nissan 2.5L 24v inline-6 engine:

• Nissan RB25DE (naturally aspirated)
• Nissan RB25DET (turbo, all versions: S1, S2 and NEO)

Important: the double SPRK-TS1015-RB25 configuration mandatorily requires a complete conversion to solid lifters (compatible mechanical buckets/shims) and appropriate cams (20.7 mm base circle). Do not install on an engine with stock hydraulic lifters. Configurations SPRK-1012S-RB25 and SPRK-2081-RB25 retain the RB25's OEM hydraulic lifters and are installable without additional modification. Best used with other Supertech RB25 components (NIVN-1052-12 intake valves + NEVI-1052-12 exhaust valves, KPR-6N-6-ST-24 keepers, VS-N6I-12 intake seals + VS-N6E-12 exhaust seals).