12v-71 detroit diesel

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New member
nw nj

the 12v71 is not only a mostly marine engine did make it into semi tractor trailer rigs back in the early 70's . they were common around the time cat was building the 1693 ta 425 hp monster. i know this as we had them in several trucks in the company i worked as oo for. i know so as i ran a long nose gmc rig from coast to coast for many years with a 425 hp v12, while the motor served me very well. it's main problem was i never got more then 200k out of a build and every thing was times 2. 4 turbos,2 blowers. 12 piston,cylinder sleave kits.

gm to make a v12 took 2 v6's and bolted them nose to tail to make the v12's, forms made were in 53,71 and 92 series. they were used in industrail,marine,generateration and onhighway rigs.

as to why they died off, first was emissions,being a 2 stroke they were dirty running, even when dd came out with the electronic 92 series. 2nd detroit got brought out by MB who almost right away dropped the 2 stroker for their own design long running 4 stroke ohc motors.


New member
Ramona, CA
Exactly correct.

I acted as two bolted V-6, but was a true single cast block.

If it were two bolted sixes, I'd have saved a lot of work trying to pull engines from PD4901 chassis!


Active member
Phelan, CA
Sorry mate, the 12V71's were there own block...all 12 holes not two V6's like the later V12's.
The 71 series was the only one to have a solid cast v12 block.... The 92 series was two v6 blocks. I don't know if they ever made a 12v-53, I've never seen one but it would have been two v6 blocks if they did.

The largest 92 series was a 16v-92 (two 8v blocks) and the largest 71 series was the 24v-71 (two 12v blocks)



New member
nw nj
man i can say the bare block,ouch! they weigh a ton and half,i have both v12's out of my boat in my shop right now,
i stand corrected as i thought i was going to have to deal today with a double v6-92 as i was used to working on when i worked for pensky detroit diesel.

break down of the DD's seems to be

51 in 2 and 4 cylinder a smaller 53 with out any valves a true ported 2 stroke,
53 made in 1,2,3 4,6,v6 a marine A 12V53 is a V12 that used two 6V53 based blocks directly bolted together, two blowers. 2 to 4 turbos
71,available in both inline and V configurations, the inline models included one, two, three, four and six cylinders, and
the V-types including 6,8,12, 16 and 24 cylinders. The three largest V units used multiple cylinder heads per bank to keep the head size and weight to manageable
proportions, the V-12 and V-24 using two and four heads from the inline six cylinder model and the V-16 using four heads from the four cylinder
inline model
92,produced with versions ranging from four to 16 cylinders. Among these, the most popular were the 6V92 and 8V92, which were V6 and V8
configurations of the same engine respectively.
110 made only in a inline 6,
149 made in v12 and v16,
from there you get the gm based EMD motors of
567,645.710 inchs per hole

The PIG Smith

Fort Wayne, Indiana
Here is a custom built Freightliner that is powered by a 12V92.
NOte how large the engine is and how much the nose of this truck was streached to cover that 2 stroke 12 cylinder monster.
IMHO, kewl, but not practical.

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