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Discussion Starter #1
On the 2-stroke Detroit Diesels, 6V-53, 6V-71, 8V-71, 12V-71 what are the cylinder bank angles? Are they all 90 degree? Are they all 60 degree? Are the 6V's and 12V's 60 degree and the 8V 90 as you would expect in a 4-stroke?
I can't find anywhere that it actually says what the cylinder bank angle is on any of the Vee engines.

It's obvious I have absolutely zero practical or hands on experience with these engines otherwise I wouldn't ask such a dumb question.
 

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Discussion Starter #2 (Edited by Moderator)
Really? No one knows the answer to this? Or am I to assume this is such common knowledge that it's too dumb a question to answer? I swear, I've been scouring the Interwebs and can not find it anywhere...It's now driving me nuts.
 

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2-Stroke Detroit Diesel questions come up rarely and I think LMJD responds because he used to work on them.

You might PM him.
 

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This YouTube video does not answer your question but highlights the amazing sound of 2-Stroke.

 

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From eyeballing the figures on this document, it looks to me like the V53 and V71 series Detroits have 60 degree bank angles.
Wondering why you need to know, or are you just curious?
 

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Discussion Starter #6
From eyeballing the figures on this document, it looks to me like the V53 and V71 series Detroits have 60 degree bank angles.
Wondering why you need to know, or are you just curious?

I'm a scale model builder and getting this most basic building block correct is an imperative.
Thank you so much for taking the time to answer me. I really appreciate it. I need to make sure this is correct.
 

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I think its possible that different models had different V-angles.

Is there a specific motor and application you are building?
 

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My neighbor has an old Ladder Truck with a Model 92 DD.

Do you want me to go measure its V-angle?

Can you imagine being in the cab with one of those screaming just feet away?
 

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Discussion Starter #10
My neighbor has an old Ladder Truck with a Model 92 DD.

Do you want me to go measure its V-angle?

Can you imagine being in the cab with one of those screaming just feet away?
Oh my gosh, I can't even imagine what it would take to get to it to see the beast!
 

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Oh my gosh, I can't even imagine what it would take to get to it to see the beast!
I can maybe get over there later today. Check here tonight and I will try and snap some photos and see if I can get to the front of it😀
 

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I've been around plenty Jimmies on boats, skidders, graders, forklifts and buses. I would have guessed that an 8V-92 was 90 degrees but I found this image of the 8-92 in my bus getting an in-frame in Vineland, NJ. I don't think there's any way that's 90 degrees so I'd have to go with 60. BICBW

158571
 

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Discussion Starter #14
I've been around plenty Jimmies on boats, skidders, graders, forklifts and buses. I would have guessed that an 8V-92 was 90 degrees but I found this image of the 8-92 in my bus getting an in-frame in Vineland, NJ. I don't think there's any way that's 90 degrees so I'd have to go with 60. BICBW

View attachment 158571
That would make sense since it came out after the 12V71. Two strokes just don't shake like 4-strokes so the V-angles just may not make the huge difference like they do in a 4-stroke.

I can't that you enough for humoring me. This so important to my project. Again, thanks!
 

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I can't tell where you are but if you like 2-strokes go to an ocean marina anywhere except California. The working boats - tug and fishing in particular - are still primarily powered by 2-strokes and there's plenty of pleasure boats with a couple of big 8-92s in their engine room too. The amazing feature of a 2-stroke in marine service is how much power they can squeeze out of them. With unlimited cooling they can set an 8-92 north of 700 HP.
 

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Well its much less accessible to access the front than I would have thought for a photo but I can go back over with some tools to get sone measurements on the block off of plumb.
 

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Discussion Starter #17
I was emailed by a former Detroit Diesel engineer, long retired who told me that all Detroit Diesel 2-strokes Vee engines are 60 degrees, no matter if they are 6-cylinder, 8-cylinder or 12-cylinder. Since the 12V71 was the first Vee engine they went with the 60 degrees as that is the best angle for V-12's and based all subsequent Vee engine bank angles off of that. I can't imagine a more incredible powerplant than a 2-stroke V-12.
I wish they could/would update the 2-stroke V-12. With the advanced machining, electronics and computer design we have today, Perhaps using a Lysholm twin screw supercharger in place of the roots blower, like I saw in a YouTube video. I can only imagine what such an engine would be like.

Unfortunately, it will never happen. Only zero emission systems have a future, electric, hydrogen, fuel cells...maybe gaseous fuels for a bit.

Such a shame...
 

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Unfortunately, it will never happen. Only zero emission systems have a future, electric, hydrogen, fuel cells...maybe gaseous fuels for a bit.
Its not impossible but I agree its unlikely. Don Bradner was involved with a company called Clean Cam Technology. A quick Google now turns up some patents and industry references but the company appears to be defunct. ICBW about that - it was a very quick search. Regardless, at one time Don had California CARB certification for - I believe - Tier 3 emissions compliance. His technology modified the duration of the cam lobes so that the engines ran cleaner. His explanations were way above my pay grade but it was a thing. As with a lot of good ideas, money, timing and technology have to all collide in exactly the right fashion to create a big bang and unfortunately this time it didn't happen.
 

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I can't tell where you are but if you like 2-strokes go to an ocean marina anywhere except California. The working boats - tug and fishing in particular - are still primarily powered by 2-strokes and there's plenty of pleasure boats with a couple of big 8-92s in their engine room too. The amazing feature of a 2-stroke in marine service is how much power they can squeeze out of them. With unlimited cooling they can set an 8-92 north of 700 HP.
Bob,
You got me thinking so I contacted a retired 80-year old AK Skipper friend and this was his response:

“Fishermen liked these General Motors based engines because they could most readily get parts and repair for them in remote Alaska areas. Canneries ran Jimmy power plants and would have Jimmy powered boats and would have parts , both new and from old salvaged jimmies. Old ones. Because engine hadn't changed since 1940s.”

Ofcourse, he has been near deaf for half his life!
 

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We spent 7 or 8 winters living aboard a trawler on the BC coast. We had twin Lehman power but we moored in a working marina and there was Jimmies all around us. We didn't spend a lot of time in the marina when we were onboard because we liked exploring but there were 3 old tugs that moored across the fairway behind us. So late at night when the tugs left or returned I could lie in bed and listen to them. Our bed was pretty much on the waterline so I'd hear their prop long before I heard the Detroit. The previous owner of our boat bought a Knight Carver - roughly 65 feet - with twin 8-92s. I loved being in his engine room. He had twin Perkins gensets and each of those engines was roughly the size of my propulsion engines. We also spent several years living in a converted highway bus and once you get back past the mid 80's all those old buses have 2 stroke power. I used to open the ticket window on the bus when we were going through tunnels or across a bridge with railings just to hear the Detroit echo off the walls.
 
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