Reinforced valve spring kit Nissan SR20VE P12
Reinforced valve spring kits for the Nissan SR20VE P12 2.0 16V engine.
- Brand: SUPERTECH
- Engine: SR20VE (P12)
- Springs: double
- Contents: springs, titanium upper retainers
The Nissan engine covered
These kits are made for the second-generation SR20VE, known as the P12: a 2.0 litre four-cylinder with twin overhead camshafts, 16 valves and variable valve lift, fitted to the Primera P12 (HP12 saloon and WP12 estate) from 2001 to 2005. Its valve stems measure 5.5 mm, and the titanium upper retainers supplied in the kits are made for that stem size.
The first-generation SR20VE, with 6 mm stems (Bluebird U14, Primera P11), is a separate case: its retainers differ from those in the kits, which therefore do not apply to it.
SUPERTECH reinforced valve spring kit
A valve spring shuts the valve after the cam and keeps it in contact. At high revs a spring lacking firmness lets the valve bounce on its seat and close late, risking a hit on the piston; extra stiffness cures it.
At an installed height of 37.5 mm, the two kits give 369 N and 512 N at the seat, or 801 N and 1010 N opened by 10 mm.
Valve spring kit technical specification
| Part number | Brand | Springs | Outer / inner Ø | Seat pressure | Open pressure | Rate | Max lift | Kit contents |
|---|---|---|---|---|---|---|---|---|
| SPRK-2035-2022-P12 | SUPERTECH | Double | Outer 30.0 / 21.8 mm Inner 20.5 / 15.5 mm |
369 N at 37.5 mm | 801 N at 10 mm | 41.8 N/mm | 17.4 mm | Springs, titanium upper retainers |
| SPRK-H1022D-P12 | SUPERTECH | Double | Outer 30.0 / 21.8 mm Inner 20.5 / 15.5 mm |
512 N at 37.5 mm | 1010 N at 10 mm | 49.8 N/mm | 15.7 mm | Springs, titanium upper retainers |
Valve spring kit fitting details
| Part | Nissan original | Reinforced spring kit |
|---|---|---|
| Spring | Kit specific: SPR-2035-2022-P12 and SPR-H1022D-P12 (double) | |
| Retainer | Kit specific: RET-NSR20VE-T55 (titanium) | |
| Spring seat | Original kept | |
| Collets | Original kept |
Each SUPERTECH kit brings together the double springs and the titanium upper retainers; the original lower spring seats and collets stay in use. On kit SPR-H1022D, net lift only increases if the seating of the inner spring is machined.
Valve closed, installed height is the gap between the lower spring seat, where the foot of the spring rests, and the upper retainer that caps its head. Both kits are quoted at 37.5 mm. Every millimetre of height added, for instance by skimming, costs a stiff spring more load than a soft one; the table alongside gives the reference for each kit.
| SUPERTECH | |
|---|---|
| Installed height | 37.5 mm |
| Seat pressure at this height | 369 / 512 N |
Technical guide
Our brands
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SUPERTECH, a Californian firm that grew out of motor racing, has supplied valvetrain components to competition engine builders for three decades. Its springs, wound in a steel alloyed with chromium, silicon and vanadium, are inspected by ultrasound and then X-ray before shipping. |
How to choose
With firmer springs the valve stays pressed on the cam far higher in the rev range: the red line can be pushed back, a more aggressive camshaft fitted, or turbo pressure raised, without the bounce coming back. Camshaft lift has to stay below what the kit allows, 17.4 mm for the first and 15.7 mm for the second.
| Criterion | Key point |
|---|---|
| Choosing the pressure | In the original name, the pounds (lbs) stand for the seat load: 83 lbs equal 369 N, 115 lbs equal 512 N. The 83 lbs kit, less firm, allows 17.4 mm of lift; the 115 lbs kit, firmer, is limited to 15.7 mm of net lift but holds high revs better. Before deciding, measure camshaft lift, note the target rpm and the boost pressure; an excessive load is pointless and tires the camshaft lobes and the rest of the valvetrain. |
| Single or double spring | Both kits rely on double springs: two nested springs spread the effort and damp one another, which suits high revs, where vibrations matter most. The upper retainers are titanium, and the original lower spring seat stays in place. |
When reinforced springs become necessary
- Camshaft lifting the valves higher than stock
- Maximum rpm raised noticeably
- Boost added or increased
- Head reworked for circuit, drift or rally
- Springs tired out, or valves floating at high rpm
Compatible vehicles
| Model | Engine code | Power | Years |
|---|---|---|---|
| Primera (P12) 2.0 (HP12) | SR20VE | 2001-2005 | |
| Primera (WP12) 2.0 (WHP12) | SR20VE | 2001-2005 |
Related products
Cylinder head off? Inspect the inlet and exhaust valves, plus guides and valve stem seals: all of them work in the same conditions as the springs.
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Brand
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ReferenceSPRK-2035-2022-P12
