Reinforced valve spring kit Honda R18A R18Z

Honda engines covered

This kit is made for the R18A and R18Z, 1.8 litre four-cylinder engines with a single overhead camshaft, 16 valves and i-VTEC timing, found under the bonnet of the eighth, ninth and tenth generation Civic as well as the Stream, FR-V, Crossroad and HR-V.

Other Honda engines, the K20 and K24 included, are not covered on this page: their springs belong to other kits.

SUPERTECH reinforced valve spring kit

A valve that closes again must settle back on its seat without the slightest hesitation. At high revs a spring that is too weak lets it bounce and shut late, with a risk of touching the piston; a raised load cures this failing.

At 41.15 mm installed height the kit quotes 302 N at the seat and 743 N at 10 mm lift, with 14.2 mm net lift.

Valve spring kit technical specification

Valve spring kit fitting details

The SUPERTECH kit brings together the single spring, the titanium upper retainer, the lower seat made for the R18 and the KPR-5.5/7A-ST collets.

Measured on a closed valve at rest, installed height spans from the bottom seat bearing the spring to the top retainer pinned by the collets; this kit gives it as 41.15 mm. The higher the rate, the faster the load melts away if that height grows by a fraction of a millimetre, so the kit reference is repeated in the next table.

Technical guide

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SUPERTECH, a Californian maker born in the paddock, has fitted tuned engines with springs, retainers and valves for thirty years. Each spring, coiled from highly alloyed steel wire (chromium, silicon, vanadium), undergoes ultrasonic and radiographic examination before it ships.

How to choose

More spring load lets the valve cling to the cam profile beyond what stock allows: raising the rev ceiling, fitting a sharper camshaft or, on a boosted R18, adding turbo pressure then make sense. This single kit serves road, circuit and rally cars. The spring's maximum net lift is 14.2 mm; the camshaft must lift less, with clearance in reserve. Excessive load gnaws at lobes and rockers for no gain, so look for the right value and measure installed height on the head before the final reassembly. A well-chosen load also protects the valvetrain as a whole, from rockers to guides, over many seasons.

When reinforced springs become necessary

• Camshaft with more generous lift than stock
• Red line moved beyond the original
• Turbo fitted to a standard R18
• Head reworked for track or rally use
• Aged springs, valves floating at high revs

Compatible vehicles

Related products

Head off: take the opportunity to have valves, guides and stem sealing examined, inlet side and exhaust side alike. The parts chosen for this engine: