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Hatz 1B20-6 Engine

The Hatz 1B20-6 is a compact, air-cooled, single-cylinder, four-stroke diesel engine designed by Motorenfabrik Hatz for high reliability in both mobile and stationary applications. It features a vertical (upright) cylinder configuration, a lightweight die-cast alloy crankcase, and a high-strength forged crankshaft. This industrial-grade engine is heavily utilized in small construction machinery, power generators, commercial vehicles, and agricultural pumps due to its robust architecture and certified compliance with modern emission profiles like EU Stage V and EPA/CARB.

The valve timing mechanisms are driven via a camshaft, mechanical finger followers, pushrods, and rocker arms. The engine houses a single inlet and single exhaust valve located in the cylinder head. The cylinder barrel has a nominal bore diameter of 69 mm matched with a piston stroke length of 65 mm. The total geometric engine displacement calculates to 243 cc (14.83 cubic inches) with an engine compression ratio engineered between 21:1 and 22:1.

Fuel System: Combustion operates using a high-pressure direct injection layout. The mechanical injection pump drive is completely enclosed inside the gear-train control cover. The system runs on a fuel-oriented mixture preparation setting to ensure high exhaust quality and robust cold-starting characteristics without extensive pre-heating. The integrated fuel tank maintains a capacity of 2.5 to 3.0 liters and operates exclusively on standard industrial diesel fuel matching EN 590, ASTM D 975, or EN 15940.

Lubrication is managed through a pressurized circulation spray system supplied by an internal gear-driven oil pump located inside the timing control cover. The system contains a replaceable main-flow fine filter mesh to protect bearings. The minimum operating oil pressure at a normal operating temperature of 100 C is 2.5 bar at 3000 rpm. Dual oil drain plugs are located on both narrow sides of the lower crankcase block for installation flexibility.

Thermal regulation relies on a forced-air cooling design. A high-efficiency cooling fan blower wheel is directly integrated into the engine flywheel configuration. The design draws in cool ambient air and distributes it across the external cooling fins of the light-alloy cylinder head and engine block, isolating the internal electrical components and the integral AC alternator from industrial dust contamination.

General Technical Data

Engine Specifications

Engine Model ............... Hatz 1B20-6
Engine Type ............... 4-stroke single-cylinder direct injection air-cooled diesel
Number of Cylinders ............... 1
Engine Bore, in (mm) ............... 2.716 (69.0)
Engine Stroke, in (mm) ............... 2.559 (65.0)
Displacement, cu.in (L) ............... 14.828 (0.243)
Rated Power at 3600 rpm, hp (kW) ............... 4.69 (3.5)
Continuous Power at 3600 rpm, hp (kW) ............... 4.56 (3.4)
Minimum Power at 1500 rpm, hp (kW) ............... 1.87 (1.4)
Rated Engine Speed, rpm ............... 3600
Maximum Torque, lb-ft (Nm) ............... 7.60 (10.3)
Torque Speed Peak, rpm ............... 2500-2800
Operating Speed Range, rpm ............... 1500-3600
Idle Speed, rpm ............... 850-950
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 21.5:1
Direction of Rotation from Flywheel End ............... Clockwise
Direction of Rotation from Power Take-Off End ............... Counter-clockwise
Cylinder Block Material ............... Die-cast light alloy
Cylinder Head Material ............... Light alloy aluminum
Lubrication System ............... Full pressure circulation
Oil Pump Design ............... Gear-driven trochoid pump
Oil Filter Configuration ............... Main flow screen filter mesh
Cooling System ............... Forced air cooling via flywheel blower fan
Combustion System ............... Direct injection with multi-hole nozzle
Air Filter Assembly ............... Dry type with paper element and integrated pre-cleaner
Starting Mechanism ............... Recoil starter or electric starter option
Electrical System, V ............... 12

Fuel System

Injection Pump Type ............... High pressure single plunger injection pump unit
Fuel Injection Nozzle ............... Multi-hole direct injection nozzle nozzle holder
Fuel Delivery Pressure, psi (bar) ............... 3625.94 (250.00)
Fuel Feed Method ............... Gravity feed from integrated tank top mounting
Fuel Filter Type ............... Disposable spin-on inline element cartridge filter
Standard Fuel Tank Capacity, gal (L) ............... 0.79 (3.00)
Optional Large Fuel Tank Capacity, gal (L) ............... 1.32 (5.00)
Approved Fuel Grades ............... EN 590, ASTM D 975 1D/2D, BS 2869 A1/A2
Fuel System Venting ............... Automatic venting via return line mechanism
Water Separator ............... Integrated fuel tank drain plug sediment bowl
Fuel Line Connection Diameter, in (mm) ............... 0.24 (6.00)
Injection Timing, degrees BTDC ............... 14.0-16.0 BTDC
Governing System ............... Mechanical centrifugal governor system spring-loaded
Stop Mechanism ............... Mechanical stop lever grounding circuit connection pin

Dimensions and Weight

Overall Length, in (mm) ............... 13.1 (330)
Overall Width, in (mm) ............... 15.6 (395)
Overall Height, in (mm) ............... 16.2 (410)
Dry Weight (Recoil Starter), lbs (kg) ............... 62 (28)
Dry Weight (Electric Starter), lbs (kg) ............... 75 (34)

Maintenance Data

Service Information

Oil Pressure at 3000 rpm, psi (bar) ............... 36.26 (2.50)
Oil Pressure at Idle Speed, psi (bar) ............... 8.70 (0.60)
Maximum Cylinder Head Temp, F (C) ............... 482.0 (250.0)
Maximum Oil Temperature, F (C) ............... 284.0 (140.0)
Inlet Valve Clearance (Cold), in (mm) ............... 0.008 (0.20)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.008 (0.20)

Engine Oil

Engine Oil Type .................. SAE 10W-40, SAE 10W-30, or 15W-40
API Service Classifications ......................... CF or CH-4
Engine Oil Capacity (Max Mark), qt (L) ............... 0.95 (0.90)
Engine Oil Capacity (Min Mark), qt (L) ............... 0.53 (0.50)

Service Intervals

Change engine oil ............... Every 250 hours
Clean oil filter ............... Every 1000 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 500 hours
Valve clearance adjustment ............... Every 250 hours
Fuel system inspection ............... Every 250 hours
Check battery ............... Every 250 hours
Inspect breather valve ............... Every 1000 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 2.7165-2.7171 (69.000-69.015)
Cylinder Bore Wear Limit, in (mm) ............... 2.7205 (69.100)
Cylinder Out of Roundness, in (mm) ............... 0.0012 (0.030)
Cylinder Taper Maximum, in (mm) ............... 0.0016 (0.040)
Connecting Rod Big End Bore I.D, in (mm) ............... 1.6535-1.6541 (42.000-42.015)
Crankshaft Main Journal Diameter, in (mm) ............... 1.6531-1.6535 (41.980-41.990)
Crankpin Journal Diameter, in (mm) ............... 1.4957-1.4961 (37.990-38.000)
Crankshaft Main Bearing Clearance, in (mm) ............... 0.0012-0.0028 (0.030-0.070)
Crankshaft Big End Bearing Clearance, in (mm) ............... 0.0011-0.0026 (0.028-0.066)
Crankshaft Axial End Play, in (mm) ............... 0.0039-0.0118 (0.100-0.300)
Piston Skirt Outer Diameter, in (mm) ............... 2.7142-2.7148 (68.940-68.955)
Piston to Cylinder Bore Clearance, in (mm) ............... 0.0018-0.0029 (0.045-0.075)
Piston Pin Outer Diameter, in (mm) ............... 0.8266-0.8268 (21.000-21.006)
Piston Pin Bore Inside Diameter, in (mm) ............... 0.8272-0.8276 (21.012-21.022)
Piston Pin to Small End Bushing Clearance, in (mm) ............... 0.0002-0.0010 (0.006-0.026)
Top Ring Groove Height, in (mm) ............... 0.0787-0.0795 (2.000-2.020)
Second Ring Groove Height, in (mm) ............... 0.0787-0.0795 (2.000-2.020)
Oil Ring Groove Height, in (mm) ............... 0.1181-0.1189 (3.000-3.020)
Top Ring Side Clearance, in (mm) ............... 0.0016-0.0031 (0.040-0.080)
Second Ring Side Clearance, in (mm) ............... 0.0012-0.0028 (0.030-0.070)
Top Ring End Gap, in (mm) ............... 0.0079-0.0138 (0.200-0.350)
Second Ring End Gap, in (mm) ............... 0.0079-0.0138 (0.200-0.350)
Oil Ring End Gap, in (mm) ............... 0.0079-0.0138 (0.200-0.350)
Cylinder Head Flatness Distortion Max, in (mm) ............... 0.0020 (0.050)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.2354-0.2358 (5.980-5.990)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.2343-0.2346 (5.950-5.960)
Valve Guide Inside Diameter, in (mm) ............... 0.2362-0.2368 (6.000-6.015)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0004-0.0014 (0.010-0.035)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0016-0.0026 (0.040-0.065)
Valve Seat Angle, degrees ............... 45.0
Valve Face Angle, degrees ............... 45.0
Intake Valve Recess Depth, in (mm) ............... 0.0236-0.0354 (0.600-0.900)
Exhaust Valve Recess Depth, in (mm) ............... 0.0236-0.0354 (0.600-0.900)
Valve Spring Free Length, in (mm) ............... 1.4961 (38.000)
Camshaft Journal Diameter (Timing Side), in (mm) ............... 0.9445-0.9449 (24.000-24.010)
Camshaft Journal Diameter (Flywheel Side), in (mm) ............... 0.7874-0.7878 (20.000-20.010)
Camshaft Bearing Clearance, in (mm) ............... 0.0012-0.0028 (0.030-0.070)
Camshaft Axial End Play, in (mm) ............... 0.0020-0.0059 (0.050-0.150)
Tappet Bore Inside Diameter, in (mm) ............... 0.3937-0.3945 (10.000-10.022)
Tappet Stem Outer Diameter, in (mm) ............... 0.3921-0.3929 (9.960-9.980)

Tightening Torques

Cylinder Head Nut (1-Step), lb-ft (Nm) ............... 7.3 (10.0)
Cylinder Head Nut (2-Step), lb-ft (Nm) ............... 14.7 (20.0)
Cylinder Head Nut (3-Step), lb-ft (Nm) ............... 16.2 (22.0)
Connecting Rod Cap Bolt, lb-ft (Nm) ............... 23.6-25.8 (32.0-35.0)
Flywheel Mounting Center Hex Nut, lb-ft (Nm) ............... 59.0-66.3 (80.0-90.0)
Crankcase Cover Screws (M6), lb-ft (Nm) ............... 7.3-8.1 (10.0-11.0)
Crankcase Cover Screws (M8), lb-ft (Nm) ............... 16.9-18.4 (23.0-25.0)
Main Bearing Flange Cap Screws, lb-ft (Nm) ............... 16.9-18.4 (23.0-25.0)
Camshaft Thrust Washers Plate Screws, lb-ft (Nm) ............... 7.3-8.1 (10.0-11.0)
Rocker Arm Shaft Bracket Nut, lb-ft (Nm) ............... 16.9-18.4 (23.0-25.0)
Cylinder Head Cover Screw Cap, lb-ft (Nm) ............... 6.6-7.3 (9.0-10.0)
Fuel Pump Mounting Flange Hex Nuts, lb-ft (Nm) ............... 16.9-18.4 (23.0-25.0)
Fuel Valve Clamp Bracket Tension Nut, lb-ft (Nm) ............... 11.0-12.5 (15.0-17.0)
High Pressure Fuel Delivery Line Nuts, lb-ft (Nm) ............... 18.4-22.1 (25.0-30.0)
Fuel Injection Nozzle Holder Cap, lb-ft (Nm) ............... 29.5-33.2 (40.0-45.0)
Oil Drain Hex Plug, lb-ft (Nm) ............... 36.9 (50.0)
Oil Pressure Switch, lb-ft (Nm) ............... 11.1-14.7 (15.0-20.0)
Oil Pump Assembly Plate Screws, lb-ft (Nm) ............... 5.2-6.6 (7.0-9.0)
Governor Weight Carrier Assembly Nut, lb-ft (Nm) ............... 25.8-29.5 (35.0-40.0)
Speed Control Lever Pivot Nut, lb-ft (Nm) ............... 8.8-11.1 (12.0-15.0)
Recoil Starter Assembly Housing Screws, lb-ft (Nm) ............... 5.1-6.6 (7.0-9.0)
Electric Starter Flange Mounting Nuts, lb-ft (Nm) ............... 33.2-36.9 (45.0-50.0)
Alternator Mounting Screws Internal Block, lb-ft (Nm) ............... 5.1-6.6 (7.0-9.0)
Exhaust Silencer Muffler Flange Nuts, lb-ft (Nm) ............... 16.9-18.4 (23.0-25.0)
Exhaust Heat Shield Mounting Bolts, lb-ft (Nm) ............... 5.1-6.6 (7.0-9.0)
Dry Air Filter Housing Mount Bracket Nut, lb-ft (Nm) ............... 7.4-8.1 (10.0-11.0)
Air Filter Element Center Fastener, lb-ft (Nm) ............... 1.4-2.2 (2.0-3.0)
Fuel Tank Base Cradle Mounting Nuts, lb-ft (Nm) ............... 11.1-13.3 (15.0-18.0)
Fuel Tank Bottom Drain Plug, lb-ft (Nm) ............... 14.7-18.4 (20.0-25.0)
Decompression Engagement Pivot Pin, lb-ft (Nm) ............... 11.1-13.3 (15.0-18.0)
Breather Valve Cover Plate Screws, lb-ft (Nm) ............... 2.9-3.7 (4.0-5.0)
Crankcase Breather Assembly Screw, lb-ft (Nm) ............... 3.7-4.4 (5.0-6.0)
Crankshaft PTO Side Oil Seal Carrier Screws, lb-ft (Nm) ............... 7.4-8.1 (10.0-11.0)
Timing Gear Cover Hole Cap Plug, lb-ft (Nm) ............... 18.4-22.1 (25.0-30.0)
Governor Speed Stop Adjustment Screw, lb-ft (Nm) ............... 5.2-5.9 (7.0-8.0)

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• Hatz Engines Specs
  
• Hatz 1B20 Specs
  
• Hatz 1B30 Specs
  
• Hatz 1B30E Specs
  
• Hatz 1B40 Specs
  
• Hatz 1B50 Specs
  
• Hatz 1B50E Specs
  

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