Reinforced valve spring kit Nissan VQ35DE VQ35HR

€1,238.15 (tax incl.)

Reinforced kit of 24 valve springs for the Nissan VQ35DE and VQ35HR 3.5 V6 24V engines.

Brand: SUPERTECH
Engines: VQ35DE, VQ35HR (350Z Z33)
Springs: double
Contents: springs, titanium upper retainers, lower spring seats

Nissan engines covered

This kit is made for the 3.5 litre 24-valve V6 engines VQ35DE and VQ35HR of the Nissan 350Z (Z33), coupe and roadster alike.

The double springs in the kit replace the factory ones and arrive with their own retainers and seats; the original collets are still used for fitting.

SUPERTECH reinforced valve spring kit

After the lobe has passed, the spring pulls the valve back against its seat. As revs climb, the valve's mass resists: without enough load it bounces, closes too late and may hit the piston. That is valve float.

This kit gathers 24 double springs: 311 N on the seat at a height of 36 mm, then 832 N when the valve is open 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-TS1015-N352-24	SUPERTECH	Double	Outer 27.5 / 20.0 mm Inner 20.0 / 15.2 mm	311 N at 36 mm	832 N at 10 mm		15.5 mm	24 springs, 24 titanium upper retainers, 24 lower spring seats

Valve spring kit fitting details

Part	Nissan original	Reinforced spring kit
Spring	13203-AL611, 13203-CD000, 13203-AC700, 13203-JK21A	Kit specific (double)
Retainer	13209-6N200, 13209-AC700	Kit specific (titanium)
Spring seat	13205-53Y00	Kit specific
Collets	13210-53Y00	Original kept

The SUPERTECH kit contains 24 double springs, 24 titanium upper retainers and 24 lower spring seats; the original collets stay in place.

Installed height is taken with the valve closed: it is the gap separating the lower spring seat, the spring's support, from the upper retainer. The 311 N load is correct at 36 mm only. A larger gap, after machining the valve seats for example, makes the spring lose load with every extra millimetre, at the pace of its rate, as the table shows.

	SUPERTECH
Installed height	36 mm
Seat pressure at this height	311 N

Technical guide

Our brands

SUPERTECH has been building valve gear for motorsport in California for upwards of three decades. The wire of its springs combines chrome, silicon and vanadium, and every production run then undergoes ultrasonic, X-ray and laser examination, one after another.

How to choose

With firmer springs the valve stays pressed on the cam up to far higher revs: the limiter can be raised, a sharper camshaft fitted or boost pressure increased without fearing bounce. This kit holds 311 N on the seat at 36 mm, as the previous table states. The chosen camshaft must never lift the valve beyond 15.5 mm, the maximum net lift of these springs.

Criterion	Key point
Choosing the pressure	The 70 lbs mark corresponds to the seat load, or 311 N. To decide, compare three figures: your camshaft's lift, the revs you aim for and any forced induction. When one of them rises, the load has to rise too, provided the lift stays within the kit's limit. There is no need to look for more than necessary, since springs that are too hard wear cams and followers ahead of time.
Single or double spring	Two springs sitting one inside the other equip each valve here; they split the effort and calm each other down, whereas a lone spring would resemble the factory layout more closely. The kit comes complete with upper retainers plus a lower spring seat for every spring.

When reinforced springs become necessary

More cam lift than standard
Rev limiter well above stock
Forced induction added, or boost raised
Cylinder head built for circuit or rally use
Worn factory springs, or float noticed in the upper revs

Compatible vehicles

Model	Engine code	Power	Years
Nissan 350Z Coupé (Z33) 3.5	VQ35DE, VQ35HR		2002-2008
Nissan 350Z Roadster (Z33) 3.5	VQ35DE, VQ35HR		2003-2007

OEM part number (valve spring): 13203-AL611, then 13203-CD000, 13203-AC700 and 13203-JK21A

Important: this kit concerns the Nissan 350Z (Z33) fitted with the 3.5 litre V6 VQ35DE or VQ35HR. The 370Z's VQ37VHR and the VQ40DE are not covered. One set of 24 equips a complete engine.