Suzuki H25A

Suzuki H25AThe Suzuki H25A is a 2.5 L (2,495 cc, 152.25 cu·in) V6 4-stroke natural aspirated gasoline engine from the Suzuki H-family. The H25A engine was manufactured by Suzuki Motor Corporation from 1996.

The Suzuki H25A engine features an aluminum cylinder block and aluminum cylinder head with two overhead camshafts (DOHC) and four valves per cylinder (24 in total). The cylinder bore is 84.0 mm (3.31 in) and the piston stroke is 75.0 mm (2.95 in). Compression ratio rating is 9.5:1.

The H25A engine is equipped with Sequential Multiport Fuel Injection and electronic ignition system with individual ignition coil for each spark plug.

This engine produced 144 PS (106 kW; 142 HP) at 6,500 rpm of maximum horsepower and 203 N·m (20.7 kg·m, 149.6 ft·lb) at 3,500 rpm of maximum torque.

The breakdown of the engine code is as follows:

  • H – Engine family
  • 25 – 2.5 Liter Displacement

General information

Engine Specifications
Engine code H25A
Layout Four stroke, V6
Fuel type Gasoline (petrol)
Production 1996-
Displacement 2.5 L, 2,495 cm3 (152.25 cu in)
Fuel system Sequential Multiport Fuel Injection
Power adder None
Power output 144 PS (106 kW; 142 HP) at 6,500 rpm
Torque output 203 N·m (20.7 kg·m, 149.6 ft·lb) at 3,500 rpm
Firing order 1-6-5-4-3-2
Dimensions (L x W x H):

Cylinder block

The Suzuki J20 has an aluminum cylinder block with four bearing support system. It has an 84.0 mm (3.31 in) cylinder bore and 75.0 mm (2.95 in) piston stroke. The engine has two compression and single oil control ring. Compression ratio rating is 9.5:1.

Cylinder block (Suzuki Grang Vitara specs)
Cylinder block alloy Aluminum
Compression ratio: 9.5:1
Cylinder bore: 84.0 mm (3.31 in)
Piston stroke: 75.0 mm (2.95 in)
Number of piston rings (compression / oil): 2 / 1
Number of main bearings: 4
Cylinder inner diameter (standard): 84.000-84.050 mm (3.3071-3.309 in)
Piston skirt diameter (standard): 83.970-83.990 mm (3.3059-3.3067 in)
Piston pin outer diameter: 20.997-21.000 mm (0.8267-0.8268 in)
Piston ring side clearance: Top 0.030-0.070 mm (0.0012-0.0028 in)
Second 0.020-0.060 mm (0.0008-0.0024 in)
Piston ring end gap: Top 0.200-0.350 mm (0.0079-0.0138 in)
Second 0.350-0.500 mm (0.0138-0.0197 in)
Oil 0.200-0.700 mm (0.0079-0.0276 in)
Crankshaft journal diameter: 65.000 mm (2.5591 in)
Crankpin diameter: 50.000 mm (1.9685 in)

Cylinder head

The cylinder head is made of aluminum alloy which gives it good cooling efficiency. The engine has dual overhead camshaft design with four valves per cylinder. Intake valves are 30.0 mm (1.1811 in) in diameter, and the exhaust valves are 28.0 mm (1.1024 in). The H25A has self-adjusting hydraulic lifters.

Cylinder head
Valve Arrangement: DOHC, chain drive
Valves: 24 (4 valves per cylinder)
Valve head diameter: INTAKE 30.0 mm (1.1811 in)
EXHAUST 28.0 mm (1.1024 in)
Valve length: INTAKE
Valve stem diameter: INTAKE 5.965-5.980 mm (0.2348-0.2354 in)
EXHAUST 5.940-5.955 mm (0.2339-0.2344 in)
Valve spring free length: Inner: 36.08 mm (1.4205 in)
Outer: 40.44 mm (1.5921 in)
Camshaft cam height: INTAKE 39.445-39.605 mm (1.5529-1.5592 in)
EXHAUST 39.428-39.588 mm (1.5523-1.5586 in)
Camshaft journal diameter: 25.934-25.955 mm (1.021-1.0218 in)

Head tightening procedure and torque specs:

  • Step 1: 53 Nm; 5.3 kg·m; 38.5 ft·lb
  • Step 2: 84 Nm; 8.4 kg·m; 61.0 ft·lb
  • Step 3: Loosen all bolts to 0 Nm; 0 kg·m; 0 ft·lb
  • Step 4: 53 Nm; 5.3 kg·m; 38.5 ft·lb
  • Step 5: 105 Nm; 10.5 kg·m; 76.0 ft·lb

Maintenance data

Compression pressure
Standard 16.0-14.0 kg/cm2 / 250 rpm
Minimun 13.0 kg/cm2 / 250 rpm
Compression differential limit between cylinders 1.0 kg/cm2 / 250 rpm
Oil system
Recommended engine oil 5W-30, 10W-30
Oil type API SG, SH, SJ, SL or SM
Engine oil capacity (Refill capacity) ~ 5.5-6.2 L
Oil change interval, km (miles) 5,000-10,000 (3,000-6,000)
Oil pressure 3.9-4.7 kg/cm2 (390-470 kPa, 55.5-66.8 psi) at 4,000 rpm
Ignition system
Spark plug NGK: BKR6E-11; DENSO: K20PR-U11 or SK16PR11
Spark plug gap 1.0-1.1 mm (0.0394-0.0433 in)
Spark plug tightening torque 25 N·m (2.5 kg·m, 18.4 ft·lb)

Vehicle applications

Model Years Produced
Suzuki Escudo / Vitara Wagon / Estate 1996–
Suzuki Grand Vitara 1998–
Chevrolet Tracker 2001-2004
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