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Detroit Diesel 6-71 Power ratings
Naturally Aspirated Industrial engines at sea level
rpm	1200	1400	1600	1800	2000	2100
Horse Power SAE	136	160	186	205	220	230
Power kW	101	119	138	153	164	172
.	.	.	.	.	.	.
Torque Ft lbs	595	600	609	598	578	575
Torque Nm	807	814	826	811	783	780
.	.	.	.	.	.	.
Fuel Consumption	22	25	28	31	32	34
.	.	.	.	.	.	.
Max Toque Ft lbs	609 @ 1600 rpm
Max Torque Nm	826 @ 1600 rpm

Detroit Diesel 6-71 Power ratings

Naturally Aspirated Industrial engines at sea level

rpm

1200

1400

1600

1800

2000

2100

Horse Power SAE

136

160

186

205

220

230

Power kW

101

119

138

153

164

172

Torque Ft lbs

595

600

609

598

578

575

Torque Nm

807

814

826

811

783

780

Fuel Consumption

Max Toque Ft lbs

609 @ 1600 rpm

Max Torque Nm

826 @ 1600 rpm

Physical Characteristics Detroit Diesel 6-71N
Weight	2185 lbs	993 kgs
Length	54"	1372 mm
Width	29"	737 mm
Height	41"	1041 mm
Compression Ratio	18.7:1
Displacement	426 cu Inches	6981 ml
Bore	4.250 inches	107.95 mm
Stroke	5.00 inches	127.00 mm

Physical Characteristics Detroit Diesel 6-71N

Weight

2185 lbs

993 kgs

Length

54"

1372 mm

Width

29"

737 mm

Height

41"

1041 mm

Compression Ratio

18.7:1

Displacement

426 cu Inches

6981 ml

Bore

4.250 inches

107.95 mm

Stroke

5.00 inches

127.00 mm

Selected torque specifications Detroit Diesel 6-71N Engine
Torques (Non standard)	Bolt Size	Ft Lbs	Nm
Air box cover	3/8 NC	15	20
Con Rod bolts / Big Ends	7/16 UNF	67	90
Cam and Balance-shaft nuts	1 1/8 UNF	300	407
Cam follower guide bolts	¼NC	15	20
* Crank end bolt	1" UNF	290	393
* Cylinder head	5/8 NC	184	250
Flywheel Housing Bolts	1/2 NC	95	130
Fuel Connectors	7/16 UNF	35	45
Fuel Line Nuts	3/8 UNF	15	20
Idler gear hub bolts	3/8 NC	40	54
Injector clamp bolts	3/8 NC	25	34
* Mains	5/8 NC	184	250
Rocker shaft bolts	1/2 NC	96	130
Sump bolts	5/16 NC	10	14
* Flywheel bolts	9/16 UNF	184	250
.	.	.	.
*	Lubricate with 'International Compound No 2, or Copper-Slip' or equivalent.

Selected torque specifications Detroit Diesel 6-71N Engine

Torques (Non standard)

Bolt Size

Ft Lbs

Air box cover

3/8 NC

Con Rod bolts / Big Ends

7/16 UNF

Cam and Balance-shaft nuts

1 1/8 UNF

300

407

Cam follower guide bolts

¼NC

* Crank end bolt

1" UNF

290

393

* Cylinder head

5/8 NC

184

250

Flywheel Housing Bolts

1/2 NC

130

Fuel Connectors

7/16 UNF

Fuel Line Nuts

3/8 UNF

Idler gear hub bolts

3/8 NC

Injector clamp bolts

3/8 NC

* Mains

5/8 NC

184

250

Rocker shaft bolts

1/2 NC

130

Sump bolts

5/16 NC

* Flywheel bolts

9/16 UNF

184

250

Lubricate with 'International Compound No 2, or Copper-Slip' or equivalent.

71 Series Pistons

On Cross-Head pistons - Torquing con rod to piston/gudgeon pin

Caution - Failure of piston pin retainer bolts is always catastrophic, often a hole in the block - it happened on two occasions to me while dyna-testing engines
Suggestion - Apply "Locktite" (or equivalent thread lock compound) to the 7/16 UNF bolts
torque to 60 lb-ft, 80 Nm; do not exceed torque

Installing piston/gudgeon pin retainer plates

Caution - Leaking retainer plates are only remedied by extensive rework, i.e. head and sump at least must be removed again.
Suggestion - Apply shellac (or equivalent compound) to rim of retainer plates
Rap retainer plate into place with a domed/rounded object of similar size to the plate. (small machined nylon rod is ideal)
Allow shellac to dry (overnight)
Test piston plate seal by pouring power-paraffin or diesel into the inverted piston, the outside of the plate must remain completely dry, let it stand for a few minutes before using it to make sure.

Selected Settings Detroit Diesel 6-71N
Set	Inches	mm
Injectors (N60)	1.460	37.10
Injectors (N65 brown tag)	1.484	37.69
Valves (4v head -cold)	0.016	0.41
Valves (2v head -cold)	0.012	0.30

Selected Settings Detroit Diesel 6-71N

Set

Inches

Injectors (N60)

1.460

37.10

Injectors (N65 brown tag)

1.484

37.69

Valves (4v head -cold)

0.016

0.41

Valves (2v head -cold)

0.012

0.30

Selected Standard Sizes and useful clearances Detroit Diesel 6-71N
Part	Min inches	Max inches	Limits ins	Min mm	Max mm	Limits mm
Con Rod - ID Small End Bush	1.5025	1.5030	1.5080	38.1635	38.1762	38.3032
Con Rod - Length center to center	10.1240	10.1260	.	257.1496	257.2004	.
Crankshaft end float	0.0040	0.0160	.	0.10	0.41	.
Crankshaft Big end Std Diameter	2.7490	2.7500	.	69.8246	69.8500	.
Crankshaft Mains Std Diameter	3.4990	3.5000	.	88.8746	88.9000	.
Cyl liner - flange below block	0.0450	0.0500	0.0500	1.1430	1.2700	.
Cyl Liner - flange below block variation	0.0000	0.0020	.	0.00	0.05	.
Cyl Liner - ID	4.2495	4.2511	.	107.9373	107.9779	.
Cyl Liner - OD Std	4.6250	4.6260	.	117.4750	117.5004	.
Piston skirt diameter	4.2428	4.2450	.	107.7671	107.8230	.
Ring gap - compression rings	0.0180	0.0430	0.0600	0.4572	1.0922	1.5200
Ring gap - oil rings	0.0050	0.0140	0.0340	0.1270	0.3556	0.8636

Selected Standard Sizes and useful clearances Detroit Diesel 6-71N

Part

Min inches

Max inches

Limits ins

Min mm

Max mm

Limits mm

Con Rod - ID Small End Bush

1.5025

1.5030

1.5080

38.1635

38.1762

38.3032

Con Rod - Length center to center

10.1240

10.1260

257.1496

257.2004

Crankshaft end float

0.0040

0.0160

0.10

0.41

Crankshaft Big end Std Diameter

2.7490

2.7500

69.8246

69.8500

Crankshaft Mains Std Diameter

3.4990

3.5000

88.8746

88.9000

Cyl liner - flange below block

0.0450

0.0500

1.1430

1.2700

Cyl Liner - flange below block variation

0.0000

0.0020

0.00

0.05

Cyl Liner - ID

4.2495

4.2511

107.9373

107.9779

Cyl Liner - OD Std

4.6250

4.6260

117.4750

117.5004

Piston skirt diameter

4.2428

4.2450

107.7671

107.8230

Ring gap - compression rings

0.0180

0.0430

0.0600

0.4572

1.0922

1.5200

Ring gap - oil rings

0.0050

0.0140

0.0340

0.1270

0.3556

0.8636

Selected Tune up & useful information 6-71N Detroit Diesel engines
Item	Condition
Altitude deration	2.5% for every 300 m or 1000 ft
Cooling System - engine capacity	6.90 litres
Cooling System - radiator capacity	13.90 litres
Firing Order	1-5-3-6-2-4
Oil consumption	normal 100 to 200 ml per hour
Oil pan capacity	average 26 litres, full mark 50 mm below sump top
Speed full load max	Most common at 2100 rpm
Speed no load max	Most common at 2275 rpm
Speed at idle	commonly at 680 rpm

Selected Tune up & useful information 6-71N Detroit Diesel engines

Item

Condition

Altitude deration

2.5% for every 300 m or 1000 ft

Cooling System - engine capacity

6.90 litres

Cooling System - radiator capacity

13.90 litres

Firing Order

1-5-3-6-2-4

Oil consumption

normal 100 to 200 ml per hour

Oil pan capacity

average 26 litres, full mark 50 mm below sump top

Speed full load max

Most common at 2100 rpm

Speed no load max

Most common at 2275 rpm

Speed at idle

commonly at 680 rpm

Operating Conditions 6-71N series engines
Item	Condition
Compression (sea level)	New parts - average 39 bar
Compression (sea level)	New parts - min 35 bar @ 600 rpm
Fuel Pressure @ 1500 rpm	3 bar
Oil Pressure - normal operation	3.5 bar
Oil Pressure - idle	0.8 bar
Oil Temperature - sump	90-113°C
Water Temperature	77-91°C

Operating Conditions 6-71N series engines

Item

Condition

Compression (sea level)

New parts - average 39 bar

Compression (sea level)

New parts - min 35 bar @ 600 rpm

Fuel Pressure @ 1500 rpm

3 bar

Oil Pressure - normal operation

3.5 bar

Oil Pressure - idle

0.8 bar

Oil Temperature - sump

90-113°C

Water Temperature

77-91°C

Full Load expected Air Box Pressures for Detroit Diesel engines
Indicated in inches and mm of mercury
rpm	1800	2000	2100
Naturally aspirated N engines	1", 25 mm	4", 100 mm	5", 125 mm
Turbo engines	22", 594 mm	28", 756 mm	30", 810 mm
TI engines	27", 686 mm	32", 864 mm	35", 945 mm
Notes: Measuring Air Box Pressure Connect a manometer to one air box drain. Measure pressure at fixed RPM's The above table gives an indication of what to expect, but air box pressures vary with altitude and from engine to engine, injector to injector, turbo to turbo; so take nothing as definitive. If your air box pressures are close to the values listed in the table there is normally no problem in this area. If you're at all concerned, contact the local agents with your model and serial number for further advice.

Full Load expected Air Box Pressures for Detroit Diesel engines

Indicated in inches and mm of mercury

rpm

1800

2000

2100

Naturally aspirated N engines

1", 25 mm

4", 100 mm

5", 125 mm

Turbo engines

22", 594 mm

28", 756 mm

30", 810 mm

TI engines

27", 686 mm

32", 864 mm

35", 945 mm

Notes: Measuring Air Box Pressure

Connect a manometer to one air box drain. Measure pressure at fixed RPM's
The above table gives an indication of what to expect, but air box pressures vary with altitude and from engine to engine, injector to injector, turbo to turbo; so take nothing as definitive.
If your air box pressures are close to the values listed in the table there is normally no problem in this area.
If you're at all concerned, contact the local agents with your model and serial number for further advice.

Detroit Diesel 6-71 engine specs at Barrington Diesel Club

Barrington Diesel club provides Detroit Diesel engine specs and technical Data

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Specs for diesel engines and technical data provided courtesy of Barrington Diesel Club's Advertisers and Members

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71 Series Pistons

On Cross-Head pistons - Torquing con rod to piston/gudgeon pin

Installing piston/gudgeon pin retainer plates