Nissan L24 Specifications
| Engine Model: Nissan L24 |
| Engine Type: 4-cycle inline 6-cylinder SOHC 12-valve liquid-cooled gasoline |
| Total Displacement: 146.1 cu.in (2.39 L) |
| Rated Engine Power: 130-151 Hp (97-113 kW) at 5600 rpm |
| Fuel System Type: Twin or single carburetors |
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The Nissan L24 is a 2.4-liter inline-six
gasoline engine and one of the most historically significant powerplants
ever produced by Nissan. Introduced in 1969 for the legendary Nissan S30
Fairlady Z / Datsun 240Z, the L24 played a central role in establishing
Nissan as a serious global performance manufacturer. It combined
reliability, smoothness, and excellent torque delivery with the
refinement typical of six-cylinder engines. The L24 also powered the
Cedric, Gloria, and other high-end Nissan models in Japan and abroad.
Built on Nissan’s robust L-series architecture, the L24 features a
cast-iron block, an aluminum overhead-cam cylinder head, a durable
timing-chain drive, SU-type Hitachi carburetors, and strong internal
components. This engine became famous not only for its smoothness and
drivability, but for its durability under motorsport conditions -
including circuit racing, rallying, and endurance competitions. The L24
paved the way for larger L26 and L28 engines that would later power the
260Z and 280Z.
Today, the L24 remains highly desirable among classic-car enthusiasts
for its rebuildability, parts availability, mechanical simplicity, and
long-term reliability. Its combination of torque, smoothness, and
period-correct character makes it an iconic classic engine.
The Nissan L24 is a straight-six, water-cooled, four-stroke gasoline
engine with a displacement of 2393 cc, or approximately 146.1 cubic
inches. Bore is 83.0 mm (3.27 inches), and stroke is 73.7 mm (2.90
inches), making it an oversquare design that promotes smooth, high-rpm
operation and responsive performance.
Compression ratio varies by year and application, generally between
8.8:1 and 9.5:1. Output specifications differ slightly by region, but
power production is 130 to 151 Hp (97 to 113 kW) at 5600 rpm. Maximum
torque ranges from 201 to 210 Nm (148 to 155 lb-ft) at 4400 rpm. Idle
speed is usually set around 700 to 800 rpm. The firing order is the
standard inline-six sequence: 1-5-3-6-2-4.
The L24 block is cast iron for excellent strength, rigidity, and wear
resistance. Cylinder walls are thick enough to allow multiple overbore
rebuilds, one reason these engines remain popular among restorers. The
engine’s construction emphasizes stability across the rpm range and
resistance to thermal deformation.
The crankshaft is a forged-steel, fully counterweighted six-throw design
supported by seven main bearings. This high bearing count provides
exceptional smoothness and long-term durability, especially at sustained
high engine speeds. Connecting rods are forged steel with ample bearing
area.
Pistons are aluminum alloy with lightweight construction and
conventional three-ring packs: two compression rings and one oil-control
ring. Oversquare geometry improves engine breathing, allowing higher rpm
capability without compromising reliability.
The L24 uses an aluminum overhead-camshaft (OHC) cylinder head with two
valves per cylinder (12 valves total). This design reduces valvetrain
mass, improves airflow compared to pushrod engines of the era, and
enhances thermal efficiency.
The camshaft is driven by a robust double-row steel timing chain. Chain
tension is maintained using a hydraulic tensioner and side-guide system.
Timing chains on L-series engines are renowned for long service
intervals but should be inspected periodically for guide wear.
Valve sizes vary slightly by year:
- Intake valve diameter: approx. 42 mm (1.65 in)
- Exhaust valve diameter: approx. 35 mm (1.38 in)
Valve lash is manually adjustable.
Clearances (cold) are:
- Intake: 0.25 mm (0.010 in)
- Exhaust: 0.30 mm (0.012 in)
Combustion chambers are of the wedge-type design, which supports
efficient flame travel, stable combustion, and strong torque
characteristics.
The L24 uses a carbureted fuel system. The most iconic configuration
uses dual Hitachi-SU (semi-downdraft) carburetors based on SU design.
These carburetors provide smooth throttle response and excellent mixture
atomization when properly tuned. Some markets used single or different
dual-carb arrangements depending on emissions requirements.
Fuel delivery system features include:
- Mechanical fuel pump driven by the engine
- Inline replaceable fuel filter
- Float bowl control system
- Manual or automatic choke (depending on carb model)
- Idle, main, and enrichment circuits
- Vacuum-controlled components on emission-era models
Carburetor tuning is essential for achieving correct drivability, idle
stability, and performance.
The L24 uses a full-pressure wet-sump lubrication system. A
trochoid-type pump driven by the crankshaft supplies oil to all major
bearings, camshaft journals, timing chain guides, and valvetrain
components. Oil jets and splash lubrication supplement piston cooling
and internal component lubrication.
Oil capacity with filter is 4.5 liters (4.8 US quarts). Recommended
viscosity for older engines ranges from SAE 10W-30 to 20W-50 depending
on climate and vehicle usage.
Normal oil pressure:
- At 3000 rpm: 350-450 kPa (50-65 psi)
- At idle: > 70 kPa (> 10 psi)
The L24 uses a water-cooled forced-circulation system. A belt-driven
centrifugal water pump circulates coolant through the block, cylinder
head, radiator, and heater core. Thermostat operation begins at around
82°C (180°F) and reaches full opening near 95°C (203°F).
Cooling system capacity is 8.0 to 8.5 liters (8.5 to 9.0 quarts).
Earlier models use mechanical radiator fans, while later variants may
include fan clutches for improved efficiency and noise reduction.
| Intake and Exhaust Systems |
Induction on dual-carb L24 engines uses a cast-aluminum intake manifold
designed to distribute airflow evenly to all six cylinders. Later models
incorporate emission-control components but retain the same basic
design.
The exhaust manifold is cast iron with a six-into-two design that routes
exhaust gases into paired ports before exiting into the downpipe. This
layout promotes efficient scavenging and durability. Performance
versions often use tubular headers to improve exhaust flow.
| Ignition and Electrical System |
Ignition on the L24 is distributor-based
and varies by year:
- Early models use breaker-point ignition
- Later variants incorporate electronic ignition modules
The distributor includes:
- Vacuum advance
- Centrifugal advance weights
- Condenser (breaker-point models)
Standard spark plug: NGK BP6ES or equivalent
Gap: approx. 0.8 mm (0.031 in)
Electrical system includes a belt-driven alternator rated between 35 and
50 amperes depending on model year.
Depending on market and emissions era, the
L24 may include:
- PCV (positive crankcase ventilation)
- EGR system (later models)
- Anti-dieseling solenoid
- Secondary air-injection pump
- Evaporative emissions canister
- Thermal vacuum switches
- Length: 720-750 mm (28.3-29.5 in)
- Width: 520-540 mm (20.5-21.3 in)
- Height: 650-720 mm (25.6-28.3 in)
Dry weight: approx. 190-210 kg (419-463 lbs), depending on accessories
and carburetor setup.
- Oil and filter: every 5000-8000 km (3000-5000 miles)
- Spark plugs: every 15,000-20,000 km (9,000-12,000 miles)
- Valve lash: every 20,000 km (12,000 miles)
- Fuel filter: every 20,000-30,000 km
- Air filter: every 20,000 km
- Coolant: every 40,000 km or 2 years
- Timing chain: inspect at high mileage
- Compression: 150-175 psi (1034-1206 kPa), variation <10%
- Cylinder head bolts: 100 Nm (74 lb-ft)
- Main bearing caps: 85 Nm (63 lb-ft)
- Connecting rod bolts: 54 Nm (40 lb-ft)
- Flywheel bolts: 110 Nm (81 lb-ft)
- Crankshaft pulley bolt: 155 Nm (114 lb-ft)
- Intake manifold bolts: 22 Nm (16 lb-ft)
- Exhaust manifold nuts: 28 Nm (21 lb-ft)
- Spark plugs: 18 Nm (13 lb-ft)
- Oil drain plug: 34 Nm (25 lb-ft)
The L24 powered several iconic Nissan
models, including:
- 1969-1973 Datsun 240Z (S30)
- Early Nissan Cedric and Gloria models
- Nissan 230/330 series sedans (regional)
- Nissan Laurel (C30/C130/C230)
- Nissan 810/Maxima (select early versions)
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