Badfish740

I dunno if anyone remembers this part in the movie U571, but Matthew McCoune-whatever starts reminiscing about his father's fishing boat. He mentions that it had a noisy two stroke diesel. I've always wondered what in [Edit] it was, anyone want to give me the dime tour of how they work?

JKM

http://auto.howstuffworks.com/diesel-two-stroke.htm

that should explain it about as well as any of us can.

SjLingenfelter

Cylinder diameter - 9-1/16 inches
Piston stroke - 10 inches
DISPLACEMENT PER CYLINDER - 654 CUBIC INCHES
Number of cylinders - 16 or 20
Compression ratio - 14.5:1
Exhaust valves per cylinder - 4
Engine weight -
16 cylinders: 34,526 pounds / 15,661 kg
20 cylinders: 40,144 pounds / 18,209 kg (The oil pan alone weighs over a ton!)
Idle speed - 315 rotations per minute (rpm)
Full speed - 900 rpm



That right there boys and girls is a biggin

Haulin_in_Dixie

At one time most busses and half the truck were 2 stroke. The older Detroit engines were 2 stroke. The same rpm sounded like it was screaming. One power stroke for each time the piston comes up. Generally the piston comes up, the injector injects, the fuel is fired, the piston goes down till it uncovers ports that surround the piston liner for the air intake, the exhaust valves open, scaviging the cylinder, it goes up, the valves close and it all starts again. The Detroits had to have a Roots blower to run.

chaikwa

In terms of trucks and small to mid-sized commercial fishing boats, 'two-stroke' GENERALLY refers to diesel engines that are two cycle instead of four cycle like our Cummins', and were manufactured by Detroit Diesel.

Detroit Diesel means loud, leaky, oil driping hunks of iron that are also suitable for use as boat anchors.

Detroit used to use letters and numbers in their engine series to determine leakage amounts and actual gross horsepower, ie; the 6-71 series denoted 6 horse power and 71 leaks. The 8V-71 designated 8 horse power, a 'vee' configuration motor (as opposed to an in-line), and 71 leaks.

Other than that, what Haulin_in_Dixie said above is also true.

Hope this helps!



chaikwa.

SoTexRattler

I can't remember what member on which CTD website originally said:
"Detroit Diesel engines... The worlds most efficient diesel at converting #2diesel fuel into NOISE!"

They are Dirt Simple engines that have their place... Some say on the end of an anchor chain, others still would love to put one in an old pickup truck just for that unique 2 stroke sound...

K.

bulabula

In my book, not many diesel engines sound better than a screaming DD. Especially those twin 16 cylinder engines in the bigger landing craft.

laugh]

Badfish740

Hehe...noise is cool, I want one.

Thanks guys

Vulcan

Detriot has come a long way from the "screamin jimmy". Although the silver series 8V92 was a good engine, the inline sixes they use now in our big trucks run real good and are dependable. I have about 600K on the DD I drive.
V

SoTexRattler

Don't mistake 2cycle diesels with inefficiency and obsolescence..
Some of the truly most efficient modern diesels are HUGE 2 stroke slow RPM marine engines.

Even the WW-II Submarine engines were opposed piston, port scavenged, 2 stroke engines. Fairbanks-Morse and even GM made them, among others manufacturers.
http://www.maritime.org/fleetsub/diesel/chap1.htm
If you scroll down towards the bottom, you'll see some diagrams of the different types.

There's even a recently designed 2-stroke diesel light AIRCRAFT engine.. It uses a roots-type blower AND a turbocharger for performance at altitude. It'll get you back home if you lose one or the other but it won't start without the blower. The name escapes me right now, but it is a lot more efficient than the old flat 4 Lycomings and Continentals. 100LL avgas is still in the crosshairs of the enviro's for ultimate elimination... For a diesel aircraft engine, there's already high quality JET-A fuel available at most every decent FBO.

The EPA, treehuggers and high fuel costs have driven many of the 2cycle Detroits out of road service. MOst of the time when I see one now is in portable diesel powered oilfield equipment or hydroblasting pump rigs. LOUD!!
If you've ever heard one in an old semi pulling a load up a hill, you'll never forget the sound. Narrow torque band necessitated lots of gears to stay on the peak.

K.

upersleder

we had one in our diesel shop at the tech center when i was in HS, had a big air starter on it, man that thing SCREAMED when you wound her up. i miss the sounds of them pulling on the highway too, tattler is right, never forget that sound.

Nevada

I don't know if the specific engine you are referring to is the Thielert Turbo Diesel, but here is a very sexy airplane that is pending US certification that uses them. It is certified in Europe and is getting very good reviews.

http://www.diamond-air.at/Pressebild...T0085.jpg.html

183 Knots on 12.2 gallons per hour IN A TWIN???? Only with a diesel baby, ONLY with a diesel.

Haulin_in_Dixie

Nothing sounds like a 12v71 in a day cab with dual stacks. 535 horse pulling 55 yards of wet beach sand. You bulk haulers figure the weight, you would not believe me if I told you.

The post said or indicated no power, I had a 6v92tta that would take any Cummins or Mack 350 up a hill gross loaded. No was not stock. It was high torque rise, 9 speed.

Put over 1,000,000 on a 238, 671 hauling gross loads, 48 states. Shifted a lot.

edwinsmith

The only fault I found in the article is where it said a two stroke diesel must have a turbo or supercharger to run. There are two stroke model airplane engines which burn nitormethane and have glow plugs. They have no turbocharger. Instead they run the air/fuel mixture into the crankcase through a reed valve when the piston goes up. Then on the downstroke the mixture is compressed until the ports from the crankcase to the cylinder are uncovered then the fresh mixture is injected into the cylinder. At the same time the exhaust ports are uncovered to let out the burned exhaust. There is no reason why a regular diesel couldn't use the same mechanism but it probably wouldn't run nearly as well.

Those little glow plug engines really scream on nitro though.

Edwin

SoTexRattler

No, the one I was thinking of was the "DeltaHawk" diesel aircraft engine. I haven't kept up with its certification status. It is truly an original design of a 2 stroke liquid cooled, inverted V-4.
If I'm not mistaken, I think the Thielert is a very lightly modified Mercedes-Benz automotive 4stroke with a gear reduction prop drive unit added. Very good reports on that one!
The DeltaHawk has a smaller engine profile. Fewer parts count than a 4stroke engine...
Fits easier under Cessna's cowl than the original horiz opposed engines. The radiator mounting is what has to get creative.
Lots better fuel consumption than a comparable gasser.

Yeah! Diesel airplanes!!! Bring it ON!!

Just think, someone out there will figure out how to make their airplane SMOKE on takeoff! "Lets see, big injectors, slide this little plate forward, stuff this bigger turbo in here..."

K.