Detroit Diesels

Tom in Mo. · Sep 10, 2013

These are not mine and if I could go I probably wouldn't mention it BUT,
That being said, there are two Detroit diesel power units being auctioned off in Emminence, MO on Saturday the 14th. One is a 318 and one is a 6-71. Supposedly both run well. Both from a sawmill selling out. Rick Dixon Auctions.

greygoat · Sep 10, 2013

318 is a 6V53

oliver fan · Sep 10, 2013

In truck applications the 6-71 and 6V-71's were rated at 238 horse power. The 8V-71's were rated at 318 horse power. When used in industrial applications with bigger injectors, etc. they had higher horse power ratings.

waltdavies · Sep 10, 2013

53 series have a bad habit of sucking valves. I have pulled the heads of hundreds of these engines while working for the army and most had at least one valve gone and the rest would be missing two to 3 valve heads.
Now the 6/71 is one of the best engines ever built great for a large water pump or small mill.
Walt

John T · Sep 10, 2013

I always thought the 318 HP was an 8 V 71 ??? Eight cylinders each with a 71 cubic inch displacement, you saying the 6 V 53 also produced 318 HP?????????

John T

Anonymous-0 · Sep 10, 2013

A 318 is a 8V71

Anonymous-0 · Sep 10, 2013

The 318 Detroit is most definately a 8V71T. Dad had 2. It, along with a MM G1000, a 1030 Case and later a M60A3 with a V 12 Contential, its 105 gun and 50 cal machine gun are the reasons I can't hear.

Mike (WA) · Sep 10, 2013

I learned something today- I thought the 318 referred to displacement, in which case a 6V53 would fit the bill.

John T · Sep 10, 2013

Im not so sure of that Mike, I still thought the 8 V 71 (568 total cubic inches) was 318 HP and truckers called them EITHER an 8 V 71 or the 318

John T

Scott 730 · Sep 10, 2013

(quoted from post at 16:37:07 09/10/13) The 318 Detroit is most definately a 8V71T.

No, it is not a 8V71T. T is for turbo. 8V71T would have 350 horse. 8V71N is a 318. Naturally aspirated.

Anonymous-0 · Sep 10, 2013

Thanks, I guess I am not to old to learn. Both of ours had turbos. Dad called them 318's. I am no expert, but the naturally aspirated thing has me curious. I though all of those 2 cycle 71 serious had gear driven roots type blowers. Maby I was I asleep in school that day ?

Dean · Sep 10, 2013

The roots blower is a scavange blower necessary for operation.

The turbo charger is a performance enhancement device.

Dean

roy prins · Sep 10, 2013

10-4 on the 8v71 is a 318HP when they added a turbo it became a 350HP then came the 8v92 with 400 HP the 6-71 had 238 hp with standard injectors --with bigger injectors it was up to 250 HP - a friend had a Peterbuilt big bunk cabover with a 12v71 with 500 HP - that was back in 1980 when fuel was cheap-- no hill to big-- ya had to wear ear plugs to drive the thing,but you got there in a hurry-LOL if you are interested I have a 3-53 for sale -- soup up a m farmall for sure--or anything in the 80HP range Have a good day

Rootsy · Sep 10, 2013

And of course the 8V92TA Silver @ 475... My dad owned a trucking company for many years, moved mostly steel around Detroit. Everything had 92's until the 60's became affordable in used trucks. Those you turn up with a computer... Lot of good memories as a child sleeping on the doghouse of the Transtar II with the 92 screaming beneath me. My favorite was his 1980 Pete with a Silver of course... That truck is still working in the D.

Anonymous-0 · Sep 10, 2013

Guess I am just dense and missing the point. I can't see the intake stroke on a 2 cycle Detroit Diesel. Seems to me it needs that blower to put air into the cylinder. What does naturally aspirated mean ?

waltdavies · Sep 10, 2013

Detroit engines are never advertised by horse power because you set them up with a large variety of parts that will determine the output of the engine. My 8V 71 is 220 HP BY CHANGING the injectors to 65 it increase to over 300 HP. Ad a turbo and make another jump use 90 injectors like the Navy did and WOW! There 3 sizes that I have worked on are the 92-71 and 53. The 8V92 with super, turbo charged can flat put out the power.
Walt

Dean · Sep 10, 2013

Correct.

The mechanically driven roots blower charges the cylinder when the piston opens the ports. The pressureized charge air also scavanges the cylinder of exhaust gasses when the exhaust valves open. The engine would not run without the blower.

Unlike small two cycle engines, out board motors, etc., that use premixed fuel (lubricating oil in fuel), the Detroits have a crankcase and pressure lubrication so it is not possible to charge the cylinder through transfer ports from pressureized fuel/air mixture in the crankcase.

As with other engines, adding a turbo increases boost at higher RPM, which, in conjunction with increased fuel, increases power at higher RPM.

Dean

guido · Sep 10, 2013

Hello John T,

You were thought right. 8v 71 with C65 injectors was rated @318 H.P. at 2100 R.P.M.'s

Guido.

guido · Sep 10, 2013

Hello Scott in SF,

Two cycle Detroit diesel all used a roots type blower. That is how air was delivered to the cylinders, no intake valves. They were also ones with both a turbo on top of the blower. It provided more air, and more power was derived from the same engine with the turbo.
Here is a picture of one 8v71 318 H.P. @ 2100 R.P.M.'s
Guido.

Anonymous-0 · Sep 11, 2013

Then there's the 8V71TA (turbo/aftercooler if I
recall) with 370 or 375 H.P. Can't remember which
but know a guy with one in an 82 IH 4200. The 4200
was shorter than the 4300 and was built for the 8V71
series engines. The 4300 had a few different engine
options.

sdc eastern ia · Sep 11, 2013

318"s, 238"s, Turboed, not, all I know is at the end of the day my right arm was pretty tired.

buickanddeere · Sep 11, 2013

Look for the roots blower on the 110 Detroit series of two strokes.

guido · Sep 11, 2013

Hello Walterdavis,

You are right! also when you change to higher CC injectors, you will also need to change the engine timing. Lower H.P 8V71 engines would have standard timing. So higher CC injectors would require advanced timing, Blower speed would be the same ratio as the smaller injectors. Unless you went way more on the injectors,

Guido

Rootsy · Sep 11, 2013

(quoted from post at 14:33:44 09/11/13) Hello Walterdavis,

You are right! also when you change to higher CC injectors, you will also need to change the engine timing. Lower H.P 8V71 engines would have standard timing. So higher CC injectors would require advanced timing, Blower speed would be the same ratio as the smaller injectors. Unless you went way more on the injectors,

Guido

Specific injectors are set at a specific height by adjusting the push rod and using a gauge. This adjusts their timing. Then of course you need to time the rack so that all of the injectors are giving the same fuel volume at a specific throttle position.

Cam to crank timing was only ever modified for specific liner / piston combinations.

Rootsy · Sep 11, 2013

(quoted from post at 14:33:44 09/11/13) Hello Walterdavis,

You are right! also when you change to higher CC injectors, you will also need to change the engine timing. Lower H.P 8V71 engines would have standard timing. So higher CC injectors would require advanced timing, Blower speed would be the same ratio as the smaller injectors. Unless you went way more on the injectors,

Guido

Specific injectors are set at a specific height by adjusting the push rod and using a gauge. This adjusts their timing. Then of course you need to time the rack so that all of the injectors are giving the same fuel volume at a specific throttle position.

Cam to crank timing was only ever modified for specific liner / piston combinations.

guido · Sep 11, 2013

Hello Rootsy,

I had the opportunity, before DD school helping a DD dealer mechanic to convert a 8V71 290 HP to a full 318 H.P. What we had to do is remove the flywheel housing and set the timing to the advanced settings. New injectors as well as the usual tune up. What sticks in my mind the most, the flywheel housing was cast! It was an highway vehicles, the usually have an aluminum one.
Standard timing injectors are as follows: S55, 71n5, s60, n55, n60 and n65.
Advanced timing injectors all four valve model are as follows: N65, and N70
Specifications out of the 1975 DD 8V71 manual

Guido.

Anonymous-0 · Sep 12, 2013

Yep, that is what they look like, except yours needs paint. They were called green grenades for a reason. The problem I have, is it proper to call a engine that has a roots blower (a superchager ?) naturally aspirated ? And would everybody please talk louder, I spent my youth around 2 cycle Detroits. Let me know when you are going to start that thing up so I can put in my ear plugs.

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