From http://6066gmctrucks.org/Diesel.htm as of 2004/10

GMC Diesel Engines

GMC's TORO-FLOW V-6 DIESEL ENGINE

The GMC TORO-FLOW Diesel Engine, was basically the gas V6 engines converted to a Diesel. I have not heard any good reports about these engines. Most ended up replaced by a Gas powered V-6 or V-8. They also built a 637 V-8 Toro-Flow Diesel Engine.

Toro-Flow Engine Specifications

Engine Model

Gross Horsepower

Net Horsepower

Gross Torque lbs. ft.

Net Torque lbs. ft.

Bore - Stroke

Displacement

Compression

Notes
D351 V6

130 @ 3200 rpm

~ @ 3200 rpm

~ @ 2000 rpm

~ @ 2000 rpm

4.56" - 3.58"

351.2 cu. in.

17.5 to 1

D478 V6

150 @ 3200 rpm

135 @ 3200 rpm

275 @ 2000 rpm

266 @ 2000 rpm

5.125" - 3.86"

477.7 cu. in.

17.5 to 1

DH478 V6

170 @ 3200 rpm

155 @ 3200 rpm

310 @ 2000 rpm

298 @ 2000 rpm

5.125" - 3.86"

477.7 cu. in.

17.5 to 1

D637 V8

195 @ 2600 rpm

185 @ 2600 rpm

450 @ 1800 rpm

440 @ 1800 rpm

5.125" - 3.86"

637.0 cu. in.

17.5 to 1

DH637 V8

220 @ 2800 rpm

200 @ 2800 rpm

458 @ 2000 rpm

444 @ 2000 rpm

5.125" - 3.86"

637.0 cu. in.

17.5 to 1

GM's 6V-71 DIESEL ENGINE

6V-71 DB-Model / 6V-71 DF-Model

The BEST DIESEL ENGINE ever built was the Detroit Diesel. Why GMC ever built the Toro-Flow when this engine was around is a mystery. [[A: Lower cost, lighter weight, better fuel efficiency.]] Chevy use the Smaller 53 series in their trucks, but GMC when [[sic]] with the 71 series. The series number is the cid of each cylinder, so a 6V71 would have a displacement of 426 inches. These engine could take the abuse and that is why you seen them in City Buses, Garbage trucks, and Firetrucks.

Detroit Diesel Engine Specifications

Engine Model

Gross Horsepower

Net Horsepower

Gross Torque lbs. ft.

Net Torque lbs. ft.

Bore - Stroke

Displacement

Compression

Injectors
6V-53N

195 @ 2600 rpm

185 @ 2600 rpm

447 @ 1400 rpm

439 @ 1400 rpm

3.875" - 4.50"

318.4 cu. in.

18.7 to 1

~~
6-71NE or 6V-71NE

195 @ 1950 rpm

187 @ 1950 rpm

570 @ 1200 rpm

557 @ 1200 rpm

4.25" - 5.00"

425.6 cu. in.

18.7 to 1

N55
6-71N or 6V-71N

218 @ 2100 rpm

209 @ 2100 rpm

604 @ 1200 rpm

591 @ 1200 rpm

4.25" - 5.00"

425.6 cu. in.

18.7 to 1

N60
6-71N

238 @ 2100 rpm

229 @ 2100 rpm

650 @ 1200 rpm

636 @ 1200 rpm

4.25" - 5.00"

425.6 cu. in.

18.7 to 1

N65
8V71NE

260 @ 1950 rpm

249 @ 1950 rpm

761 @ 1200 rpm

731 @ 1200 rpm

4.25" - 5.00"

567.5 cu. in.

17.5 to 1

N55
8V71N

290 @ 2100 rpm

275 @ 2100 rpm

805 @ 1200 rpm

774 @ 1200 rpm

4.25" - 5.00"

567.5 cu. in.

17.5 to 1

N60