Crank Case Pressure/Vacuum Theory

[RI Chevy]

Whst is the advantage of a 2 stroke diesel vs. a 4 stroke diesel?

 

[Marshy]

Whst is the advantage of a 2 stroke diesel vs. a 4 stroke diesel?

Same advantage as any 2 stroke vs 4 stroke. A 2 stroke completes all four phases of the combustion process in one complete revolution of the crank as opposed to two revolutions of the crank.

 

[Marshy]

 

[tree monkey]

a lot of 671's lost their blowers. mostly at night. had to do with light, space and time

 

[Al Smith]

Sounds like you have some experience with them also.

Not really ,I've just been around the installation of a few large high voltage generators .The GM 16 V 278's and FM 10 D 81/8 were WW2 submarine engines which I don't operate but part of my qualifications were I had to know how to start them in an emergency .That's a long time ago and I'd have to do some thinking now of days .I'd fumble through it some how .I will say this 4 big marine diesels running at flank speed is like music to my ears,the sound of a V twin Harley at 4500 rpm or a two cylinder John Deere tractor under a heavy load .

 

[fossil]

Not really ,I've just been around the installation of a few large high voltage generators .The GM 16 V 278's and FM 10 D 81/8 were WW2 submarine engines which I don't operate but part of my qualifications were I had to know how to start them in an emergency .That's a long time ago and I'd have to do some thinking now of days .I'd fumble through it some how .I will say this 4 big marine diesels running at flank speed is like music to my ears,the sound of a V twin Harley at 4500 rpm or a two cylinder John Deere tractor under a heavy load .

Or a Rolls Merlin driving a prop flat out 50 feet over the water. My favorite of all time.

 

[huskyboy]

a lot of 671's lost their blowers. mostly at night. had to do with light, space and time

I love the sound of a detroit. Sounds like it’s goung 100mph when it’s going 5mph. Lol

 

[Al Smith]

The 71 series GM were the Briggs and Stratton of large engines .From the 2-71 to the largest I've seen being the 12v 71 .If they needed more power they just hung another cylinder on it .Oddest I've seen was a low voltage generator between two 12v 71's ,one running clock wise the other counter clockwise .I think each engine was about 400 HP at the RPM they were running .That was a long time ago too .
A note on that ,might sound crude but the way those two big engines were sync tuned in was with an exhaust phyrometer ,measuring the exhaust heat .

 

[Marshy]

The 71 series GM were the Briggs and Stratton of large engines .From the 2-71 to the largest I've seen being the 12v 71 .If they needed more power they just hung another cylinder on it .Oddest I've seen was a low voltage generator between two 12v 71's ,one running clock wise the other counter clockwise .I think each engine was about 400 HP at the RPM they were running .That was a long time ago too .
A note on that ,might sound crude but the way those two big engines were sync tuned in was with an exhaust phyrometer ,measuring the exhaust heat .

That's still used today but they have also added the ability to measure the peak cylinder pressure relative to crank degrees so you can check fuel timing and overall health of the cylinder.

This video is actually kind of boring because the guy doesnt speak at all but here is a screen cut from it.

 

[Al Smith]

That high tech stuff is way beyond my pay grade so to speak .I'm so old school all I know is the now ancient "Edwards board" method of syncing single engine prime movers .three lights .if memory serves one bright two dim, syncro scope at 5 til 12 .Throw the transfer switch and one of them would roar like a lion as it synced in and picked up the load .Black smoke just rolled .

 

[Clemsonfor]

This is so crazy I don't hardly follow what you just said other than the part about load, syncing, the rest I'm lost.

That high tech stuff is way beyond my pay grade so to speak .I'm so old school all I know is the now ancient "Edwards board" method of syncing single engine prime movers .three lights .if memory serves one bright two dim, syncro scope at 5 til 12 .Throw the transfer switch and one of them would roar like a lion as it synced in and picked up the load .Black smoke just rolled .

Sent from my SM-G900V using Tapatalk

 

[Al Smith]

I think there is much confusion on designs .You could not take a large two cycle and run the induction through the crankcase .Why, because you would blow all the oil into the cylinder .The crankcase is full of oil .
The early oil field pump engines had open crankcases and only ran about 300 RPM .They used gravity fed McCoy type oilers .Literally the "real McCoy ".They worked crude as they were .

 

[Marshy]

That high tech stuff is way beyond my pay grade so to speak .I'm so old school all I know is the now ancient "Edwards board" method of syncing single engine prime movers .three lights .if memory serves one bright two dim, syncro scope at 5 til 12 .Throw the transfer switch and one of them would roar like a lion as it synced in and picked up the load .Black smoke just rolled .

Oh yeah, syncing we still use a good old sync scope. The engine analyzer is just to check the engine is running the way it should. Check for weak/strong cylinder(s). Otherwise, never heard of an Edward's board. Then again I'm not an operator either...

 

[CR888]

I always am intrigued & enjoy it when heading out offshore fishing on a boat with twin 2stroke outboards often Yankee Merc's & they seem to feed off each other resonating together kinda synchronizing there RPM. Just sounds sweet as your body soaks up the vibrating humm. My last half cabin setup was nice with a Saltwater Mercury 115, was as good the day I sold it after 150hrs. Could never buy a 4stroke outboard, it would be against my religion. This was meant to be about C/C-pressure but I gotz lost.

 

[Al Smith]

I probably used the wrong term with "Edwards board" it was something I picked up from a British engineer .This explains the use of sync lights . A lot of gobbly gook but it explains it better than I can https://circuitglobe.com/generator-synchronization.html