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DOHC Cylinder Head Conversion Kit for L-6 Engines (2026 Model)View larger

NISMO

240z 260z 280z Fairlady Z S30/S31 DOHC Cylinder Head Conversion Kit for L-6 Engines (2026 Model)

Nissan Motorsports & Customization Co., Ltd. (Headquarters: Chigasaki City, Kanagawa Prefecture, President: Yutaka Sanada, Abbreviation: NMC) will release the "DOHC Cylinder Head Conversion Parts Kit for L6 Engines 2026 Model" as a new product under the NISMO brand.
(Orders will begin in January 2026, and shipments will begin in spring 2026.)

More details

£29,999.00 (VAT incl.)
£24,999.17 (VAT excl.)

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This product is a DOHC cylinder head conversion kit for L-6 engines, newly designed based on modern technology, which combines high thermal efficiency with a compact combustion chamber and excellent environmental performance. It also features a newly designed reinforced silent chain, a rare addition to the tuning industry, specifically designed for this kit. It not only improves strength and durability, but also maintains quietness inside the vehicle when driving around town.

This parts kit is designed as a tuning material that allows for a high degree of freedom in tuning, and is aimed at engine tuners who are well versed in L-type engine tuning. To install it on a vehicle, in addition to assembling the cylinder head using this product, all work is required, including modifying the lower parts, selecting and procuring intake and exhaust parts, assembling the engine, procuring the parts necessary for installation on the vehicle, and setting it up after installation on the vehicle.

In the NISMO prototype, the bore diameter of the L28 engine block has been increased to φ89mm, achieving a maximum output of approximately 300PS, a maximum torque of approximately 300Nm, and a maximum rotation speed of 7,500rpm.


Main features of this product:The ultra-compact combustion chamber with a small four-valve angle and ideal combustion performance with high tumble port flow in the cylinder have been optimized for the L-type engine. Furthermore, analysis tools for racing engines have been applied to optimize the engine to maximize power output across the entire range.
The reinforced silent chain has a 6.35mm pitch on the primary side and an 8mm pitch on the secondary side, making it capable of withstanding high loads caused by changes to cam profiles and valve springs. The head tensioner, various sprockets, block tensioner, chain guide, etc. have also been designed specifically for this kit. The silent chain system is easy to maintain and can be set up relatively easily.
As options, we offer a single item of semi-machined camshaft material (unprocessed profile), and parts for installation on the Fairlady Z (S30/S31) (engine mount bracket kit, oil pan kit, intake manifold kit, exhaust manifold).
*These optional parts are only available to customers who purchase the "DOHC Cylinder Head Conversion Parts Kit for L-Type 6-Cylinder Engines (2026 Model)."


specification:
Cast aluminum DOHC 4-valve
direct acting valve
Valve clearance adjustment: Inner shim type
Cam drive: Two-stage silent chain system



"DOHC Cylinder Head Conversion Kit for L-6 Engines (2026 Model)" Main Components
part
Applicable
Cylinder head body
Combustion chamber diameter Φ89mm, combustion chamber volume 35.1cc (machined combustion chamber), valve angle INT 15°, EXH 12.5°
Cylinder head bolts
Dedicated stud bolts and nuts
Front cover
Machined aluminum
Rocker cover
Machined aluminum (no surface treatment, no paint), with the first NISMO logo
camshaft
φ28mm, cam profile 66°, lift amount 9.75mm (common part for INT/EXH)
valve
Intake valve: Nissan genuine part (KA24DE) (valve head diameter Φ36.5mm) stem diameter Φ7mm
Exhaust valve: Nissan genuine part (KA24DE) (valve head diameter Φ31.2mm) stem diameter Φ7mm
valve spring
Dedicated valve spring
Valve lifters
Nissan Genuine Parts (VR30DDTT), Retainer: Nissan Genuine Parts (RB26DETT)
Crank sprocket
Special tooth profile for silent chains
Cam sprocket
Dedicated teeth for silent chains, valve timing adjustable type (common part for INT/EXH)
Timing chain
Dedicated silent chain Primary side: 6.35mm pitch, Secondary side: 8.0mm pitch
Chain guide
Special chain guide with resin pad
Water Outlet
Dedicated products
Ignition coil
Nissan genuine parts (CR14DE)
Complete set of bolts required for installation
 
*The lower parts are not included in the kit.
*The fuel supply system is not included in the kit. It is compatible with both injection and carburetor.
Reference information:

NISMO prototype engine specifications (excluding DOHC conversion kit)parts
Specifications Overview
Cylinder block
N42 block bore diameter enlarged to Φ89mm
Upper deck surface ground to 0.1mm (to ensure surface roughness and flatness)
crankshaft
Prototype fully machined crank (stroke 79mm, journal diameter Φ55mm, pin diameter Φ50mm narrow metal, full counterweight, single key)
Connecting rod
CP-CARRILLO Chromoly H-Beam Connecting Rod for Nissan L6 Engine (Part Number: DA-L16>-65235S)
piston
Prototype forged piston (compression height 35.46mm, pin diameter Φ21mm, flat crown surface + valve recess)
Piston rings
KA24DE (E25) genuine piston rings (TOP 1.2mm, 2nd 1.2mm, OIL 2.5mm)
Main Metal
Aftermarket narrow metal
Connecting rod metal
Aftermarket narrow metal
head gasket
Aftermarket Nissan L6 engine metal gasket
(t=1.2mm, gasket bore diameter Φ90.5mm)
oil pump
L20ET genuine oil pump (3mm shim added to relief spring)
Oil pump drive gear
Prototype reinforced gear (drive side and driven side)
Damper pulley
ATI damper characteristics tuned product
throttle chamber
JENVEY TBS45i (Φ45mm x 6)
Air Funnel
JENVEY AH45X60 (L=60mm)
Fuel injector
Nissan Genuine Parts (16600 AA500)
Fuel pressure
regulator
NISMO variable fuel pressure regulator (22670 RR710)
Spark plug
NISMO Iridium Spark Plug (22401 RN010-8)
Crank angle sensor
NISMO prototype crank angle sensor and cam angle sensor
ECU
LINK G4X FURY
engine oil
NISMO Competition Oil Type 2193E (5W-40)

NISMO prototype engine main specificationsType and number of cylinders
Inline 6-cylinder
Valve mechanism
DOHC (chain drive)
Cylinder bore x stroke
Φ89.0mm x 79.0mm
Total displacement
2,949cc
Compression ratio
12.3:1
Maximum power
Approximately 221kW (300PS)
Maximum torque
Approximately 294N･m (30kgf･m)
Maximum rotation speed
7,500 rpm
fuel supply device
Multiport Injection
igniter
Direct ignition
Fuel used
unleaded premium gasoline
 

Optional Fairlady Z (S30/S31) parts:

When installing this product on a Fairlady Z (S30/S31), the engine mounting angle has been changed by 24 degrees compared to the standard S30/S31 to ensure space for the intake system accessories. (The standard S30/S31 is tilted 12 degrees to the right, while this kit is tilted 12 degrees to the left.) For this reason, we have prepared a special engine mount bracket for the S30/S31 to set the angle, and a special aluminum oil pan to avoid interference with the suspension members by setting the angle.

The aluminum oil pan has an integrated gusset structure where it is fastened to the transmission, increasing fastening rigidity.In
addition, an oil pan baffle plate (with rubber flap) and a dedicated oil level gauge are available to prevent a drop in oil pressure due to uneven oil levels when driving on a circuit.

In addition, an intake manifold and a special exhaust manifold are also available.
However, there are no optional transmissions available to pair with this. You will need to manufacture or procure a transmission for the engine tilted 12 degrees to the left.

Fairlady Z (S30/S31) mounting parts (optional)part
Applicable
Engine mount bracket
To change the engine mounting angle, tilted 12 degrees to the LH side
Oil pan
Transmission fastening gusset integrated structure, aluminum casting, oil pan capacity: 5.1 liters, oil pan baffle plate and flap included
Oil strainer
Dedicated products
Intake manifold
Compatible with 45mm port diameter
multi-port injection and SOLEX/WEBER carburetors.
Carburetor mounting angle: 2°
Balance tube
Compatible with brake master valve, with negative pressure outlet for pressure regulator, and PCV valve
Exhaust manifold
SUS304 steel 6-to-2 equal-length exhaust manifold (primary Φ45mm, secondary Φ50mm), with A/F sensor boss x2, with NISMO first-generation logo
*We have not confirmed installation on vehicles other than the Fairlady Z (S30/S31) (such as the GC10). Please consult with an engine tuner regarding installation.

Sales volume:
300 sets of the "DOHC Cylinder Head Conversion Parts Kit for L-6 Engines, 2026 Model" will be produced. *
The release date, price, and specifications for sets 301 and beyond have yet to be determined.
*Due to limited production, orders will only be accepted if the customer specifies the vehicle in which this product will be installed and then
requests installation from an L-engine engine tuner.
 Manufacturer's suggested retail price:
DOHC Cylinder Head Conversion Kit for L6 Engines (2026 Model)

Optional parts
: Camshaft semi-finished product material 
, engine mount bracket kit 
, oil pan kit 
, intake manifold kit 
, exhaust manifold

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