Detroit two cycles

[Speedo]

There's a lot of people who don't care much for the 2-stroke Detroits but there are still quite a few of them doing their job. Most of the disrespect comes from the fact that they don't have the grunt from the bottom end like a 4-stroke but wind them up and they get the job done. From a 3-53 up through 20V-149s they have done duty in gensets, boats, pumps, off road equipment, tanks, buses, trucks and a few other applications. I've worked on Cats, Cummins and Detroits as well as a few other diesels and I still have alot of respect for the old 2-strokes. I was even around when a KW with a Cummins 350 was repowered with a Silver 92 and he was very pleased with the change.



Gus

 

[MKoth]

My Uncle who was also a farmer put in feild tile for people w/a big ditcher

that had the dd in it you could hear thing thing beller for quite a ways. I always liked the sound,my cousins ran it wide open. The more they got done the more $$ they'd make.

Bob

My father has been doing farm drainage since the late 60's. Just sold the ditcher this last summer. It was a Kohering 700, repowered it sometime in the early 90's with a 4-71T



here is a picture of a similar machine: http://www.a-econstsupply.com/koehring700clickthru.htm

Dad's had a lot of modifications for better performance, including a large hydraulic oil cooler, custom made tile boot, and a enclosed cab made from Massey Harris combine parts.

 

[MKoth]

I worked for a construction outfit out of Spencer, IA that had 3 Michigan/Hancock scrapers that were powered by 12V-92T's. All straight piped.



We could only run from 8am-8pm every day, because the people in the town 2 miles away would complain about all the noise.

 

[Grey Wolf]

Here's a happy 4-53 owner. He isn't the original owner, but from the description of the rig it sounds very much like a conversion from a company in Sparks, Nevada. They did quite a few in the '70's, they're long gone now but I remember the name was Mentzer Detroit Diesel... .



http://www.gothelicopters.com/detroitrev.html

 

[Shelby Griggs]

For 3 summers after I got out of high school I worked for a couple of small outfits piling and disposing of logging and thinning slash in the Eastern Oregon forests. We had a couple of AC crawlers, a HD19 and a HD20 with 6-71's. I thought it was a lot of fun, however even with ear plugs, your ears were still ringing after a few hours on those. Quite the deluxe crawler compared to the D7 we had with the hand crank pony motor and manual transmission. The AC's had electric start and a two speed box with torque converter (circa 1956 models). We also had a 1956 GAMC snub nose with a 6-71 and a RR 10 speed, made a lot of noise but was gutless pulling the dozers on a lowboy, I stalled it once and the dang thing started rolling backwards along with the engine turing backwards, scared the **** out of me, of course I was about 19 and kind of green about such things then. Yep, alot of good memories those 3 years working that ancient iron. Also had a 1959 White with a Cummins 180 (I think that was the model) non turbo with a 5 speed main and a 3 speed brownie. Quite a feat for a young kid to be driving that around. A wonder I didn't kill myself! That old White would only make about 50-55 MPH empty and put one of the AC's on and whew was it slow, never could get into the top gears then. Stopping was a treat too, no engine brake just the service brakes, trucking was sure different then, it was a white knuckle workout just driving that old beast.



SHG

 

[Skydiver]

The Detroit's make good charter boat engines. It's funny (not) that I spent 80% of my time while in Panama city beach working on my uncle's 45 foot hateras. All I wanted to do was go fishing. No,no,no,I wound up pulling heads off of an 8v-71. The engine room was about 42 inches from floor to ceiling. Hot summer time. I felt like a fool when the babes walked by and all you could see of me was my teeth and the white's of my eyes. Rest was black. Oh did I mention the detroit's make good charter boat engines. That is when they run. They seem to love spinning a 2- foot propeller at 1600 rpm's for hours at a time.

Tim

 

[SGolden]

My brother has an old International with a 318 Detroit w/10spd. Never would go very fast but the darn thing was loud. You always knew when he was pulling into the shop. First you could hear him and then you saw the cloud of smoke. He used to pull his track loaders around with it but now he just uses it to pull a log trailer.

 

[Greenleaf]

The two-strokes certainly have their place... . they are a VERY unique engine.



They are desigend unlike anything else.



Blocks are made to be bolted together, crank to crank. Designed to operate CW or CCW



They rev-up quite quickly which is needed in some instances like oil field work when pulling pipe.



The engine internals can be inspected by mearly removing an inspection plate on air box.



They have to have a blower because they do not breath on their own, hense they have low power/torque due to poor volumetric efficiency. They may have twice the power strokes but they have a very short power stoke and poor cylinder scavenging. A turbo mounted in conjuction with the blower helps with this to some degree.



They leak because they have all the holes in the block drilled clean through, everything, all. I believe the head is the same way.



The engine is very light when compared to a four stroke unit. Thats why it's used in certain applications.



The engine is desgigned to be used in EVERY application imaginable. That is why all the holes are drilled clean through. There isn't anything that cannot be bolted onto the engine. They are used for everything from powering a washing machine to a locomotive.



I worked as a welder/mechanic in the Ohio oil/gas fields for five years. The Detroit is used nearly exclusively to power just about everything. I wrenched on 53,71,92 and 149 series engines.



And I'm happy I don't have to do it NO MORE!!



Scott

 

[David Oxland]

While I never liked the small two strokes in engine rooms I have always wanted to see or even own a 1-71 with generator mainly for a toy or standby duty. I'enever seen one in the flesh.

 

[Greenleaf]

I forgot to mention the Two-Stroke engine piston.



It is a two-piece designe. The top half contains the fire ring and is cast from iron. The skirt is aluminum w/coating of tin alloys etc. etc.



The two halves are joined by way of a pin and a slipper bushing. This allows the top half to "cock" side to side under the loading foce of the power stroke, thus readucing the piston/liner wear ... ... ... ...



as well as contain the fire ring which is always the piston ring taking the brunt of the force thus wearing out the piston.



The slipper bushing is designed to have a very large surface area at the top where it takes the pounding forces of the power stroke.



Pretty darn smart if you are to ask me.





Cylinder liners are dry with a series of holes around the middle portion to allow the pressureized air to enter the cylinder from the blower.



GL

 

[nickleinonen]

t is a two-piece designe. The top half contains the fire ring and is cast from iron. The skirt is aluminum w/coating of tin alloys etc. etc.



The two halves are joined by way of a pin and a slipper bushing. This allows the top half to "cock" side to side under the loading foce of the power stroke, thus readucing the piston/liner wear ... ... ... ...

that's the articulated piston... almost every larger bore diesel engine [10-16 liter size] use that now... lets you run the top compression ring closer to the top of the piston, making the dead space smaller... makes for better emissions...



heck, i believe the marine version of the ISBe engine has articulating pistons in the 380hp version... ? [so i have heard, i can't confirm it though]



different 2 cycle engine fyi info...

EMD 2 cycle pistons are sorta like articulating pistons, but they are not... ? they have cast iron piston that goes from the crown down to the bottom [4 compresson rings, 2 oil rings] and inside the piston is a cast iron carrier with a brass/copper thrust washer that goes between it and the piston. the carrier is held in the piston with a snapring [max clearence between carrier and snapring is 0. 050"] the piston pin to conrod is crosshead type [rod bolted to piston pin]. the piston pin is bearing supported on the top 1/3'rd of the surface... and either tabbed in place, or a small bolt [1/4"] and washer hold it centered... conrod and carrier weighs a little under 100lbs...



here you can see 2 conrod/carrier's [one cleaner, one beat to heck] and most of a piston and the liner ports

 

[David Oxland]

Boy Nick, You guys run'em to destruction

 

[nickleinonen]

Boy Nick, You guys run'em to destruction

well, i was fishing parts out of a sump this morning... yep. . we run them till they blow, fix them up and keep running them... we've got one GE unit in the shop that had major failure... it needs 5-6 power assemblies & pistons/rods, new turbo, 2 new aftercoolers, new pushrods on all 16 cylinders, new crankshaft split gear [2 piece gear clamped/keyed to crank to drive cams] 3 new camshaft sections, many new cam followers, 2 new camshaft drive gears [±20" across]. . probably some more stuff too...



them EMD power assemblies end up costing just about $10,000usd a piece when you count man hours, parts & downtime... [assuming it is a simple failure when it is back running in ±12 hours]

 

[tgee]

I forgot to mention the Two-Stroke engine piston.



It is a two-piece designe. The top half contains the fire ring and is cast from iron. The skirt is aluminum w/coating of tin alloys etc. etc.



The two halves are joined by way of a pin and a slipper bushing. This allows the top half to "cock" side to side under the loading foce of the power stroke, thus readucing the piston/liner wear ... ... ... ...



as well as contain the fire ring which is always the piston ring taking the brunt of the force thus wearing out the piston.



The slipper bushing is designed to have a very large surface area at the top where it takes the pounding forces of the power stroke.



Pretty darn smart if you are to ask me.





Cylinder liners are dry with a series of holes around the middle portion to allow the pressureized air to enter the cylinder from the blower.



GL

71 liners are dry, 53s and 92s are wet liners. Interesting thing, in the diesel industry, alot to be said about maintaining cooling system to prevent cavitation of liners and blocks. Have seen this on many DDC 4-strokes, as well as Cummins and Cat motors, but never on a wet liner DDC 2-stroke. Wonder why?

 

[JKlopp]

Only good memories from my experience with the DD 71's. Had them in the river boats in Vietnam. We filed the flyball governor weights to allow us to run way over max RPM from sunrise to sunset. At nite the boat would be nosed into a river bank and left running to stop any swimmers from putting explosives under the boat. These engines were more than flogged, but they survived and so did we, while being maintained by 19 year old kids wearing a flack jacket with a beer in one hand and a "cigaret" :-laf in the other.

 

[Joe G.]

A friend of mine who is long gone now was an engineer on landing craft in WWII. He ran the engines in his boat for landings in the Pacific. They also "fixed" the governors on the 6/71s in those boats. Firewalled the throttles and left them that way from the ship to the beach and back. Even shifted from forward to reverse to get back off the beach with the throttles that way. He said the only engines they lost had holes shot in them.

 

[SGibson]

A few questions for those knowledgeable about detroits, first mine was completly rebuilt about 80k miles ago, a friend of mine who worked on detroits as a fleet mechanic says it's probably due for another as they wear out quickly, the paperwork for the rebuild has a 10k$ receipt stapled to it and it was done in 94 seems awfully high for such a supposed simple engine, lastly is there a way short of a cummins swap to get more power out of it (6-71n) with out radically shortening it's lifespan? thanks, Steve.

 

[tgee]

$10,000 in '94 was pretty high, even for an out of frame major overhaul. If properly overhauled, it should last alot longer than 80,000 miles. Biggest deal on these is not fitting liners in the block properly, too loose, they wont last long. Excessive idle time on any diesel is bad, but especially with a two stroke. What size injectors are in it? Probably N65s, you could put N70s in, but it will smoke more. You could turbocharge it, but compression ratio is different, different pistons and liner port size.

 

[RThompson]

You know these old detroits are a motor out of the 30's without much in the way of changes. They were used for all sorts of service in WW2 most notably

in landing craft and gen sets. There wasn't much in the way off 'cummins power' in those days.

Times move on, and I am glad I don't have to work on that type of power plant anymore. Remember that the design is very old. If it wasn't for EPA they probably would have stuck around for a few more years.

One of the most novel 71 series was a 1-71 used in military for a gen set. :--)

 

[Grey Wolf]

Although they don't mention it in this history, I have a friend that worked on them during WW11. He was told that the goverment wanted something that may only be used a few times, basically a throw away engine and the 2 cycle DD was what they gave them. It had a pretty good run for a throw away engine



http://www.detroitdiesel.com/Corporate/History/index.asp