I would really only apply this to 4 cycle diesels but I was wondering, with all of the engines these days moving toward turbocharging, has there ever been an OEM that offered supercharging? It seems to me that there was but I couldn't find it so perhaps it didn't last long in production. Turbocharging has most of the advantages but what about supercharging? Must be something to be said about "super diesels"?
I understand gasoline engines are different but FORD can't seem to build enough turbos for the F150 since it's almost split down the center vs. non turbo.
The older Cummins offered super chargers in different models but I haven't seen any of the newer models with superchargers.Cummins offered the NH with supercharger or turbo.
They had the J series then too lol we would joke about the J series the JT we called it just trash the JS model we called it just sh**. Supercharged engines use power the turbo use waste that why everything is turbo now
Superchargers do create some parasitic loss. They are belt driven or gear driven so that's a thought to keep in mind. Turbos have much less parasitic loss, though there is some since it's creating resistance during the exhaust stroke of the piston. Some diesels are supercharged and in the case of our two strokes they are both :)
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Cat is bring back the supercharged engines in the marine engines I read a article last year they are getting 650 hp from the 8.7 with a supercharger
Thank you, Professor, but the blower on a 2-stroke Detroit acts as an air supply, whereas a supercharger acts as an increased air pump. The blower on a 2-stroke Detroit is not a supercharger.
--Geoff
Quote from: Scott & Heather on April 11, 2017, 05:25:13 PM
Superchargers do create some parasitic loss. They are belt driven or gear driven so that's a thought to keep in mind. Turbos have much less parasitic loss, though there is some since it's creating resistance during the exhaust stroke of the piston. Some diesels are supercharged and in the case of our two strokes they are both :)
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Lol. Geoff I'm not a professor, just throwing out thoughts. Here's some info I gleaned off the web. Kinda points to the fact that blowers and superchargers aren't all that different in their purpose of feeding air.
Superchargers and blowers also differ in size. Blowers stick out of the hood, while superchargers fit in. A supercharger is an air compressor that increases the pressure or density of air inside the combustion engine. It pushes air into the engine, increasing its density and allowing the engine to have more oxygen-intake cycles. Superchargers can be mechanically driven by use of a belt, shaft, gear or a chain connected to the engine's crankshaft. Conversely, blowers use centrifugal force to propel air forward. There is no major difference in how blowers and superchargers work, because they both use forced induction.
Superchargers can be compared to pumps because of the displacement that occurs with a stroke of pump. On the contrary, blowers act as fans, because they apply less displacement while functioning. A supercharger and a blower could appear as having no difference, given that both are air compressors. However, the functioning of the two is different.
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The terms "blower" and "supercharger" are generic, and in popular language, are used interchangeably.
Lets name the various ones we know of?
"Roots style" is what we 2 stroke Detroit owners have, and certain ones were swapped and bolted onto gasoline engines by the early hot rodders.
Anytime you found a 6-71 in a scrap yard, the blower was ALWAYS gone...
What else is out there?
happy coaching!
buswarrior
Quote from: buswarrior on April 12, 2017, 05:23:56 AM
The terms "blower" and "supercharger" are generic, and in popular language, are used interchangeably.
Lets name the various ones we know of?
"Roots style" is what we 2 stroke Detroit owners have, and certain ones were swapped and bolted onto gasoline engines by the early hot rodders.
Anytime you found a 6-71 in a scrap yard, the blower was ALWAYS gone...
What else is out there?
happy coaching!
Blowers come in 3 different configurations the roots are used on most Detroit's the centrifugal type which some 6L 110 Detroit's used so did some EMD made by GM then you have the screw type used on Cat and Cummins.
I have a screw type Stewart and Stevenson a Detroit dealer developed for use on the high hp 92 series to churn out 625 hp from the 6v92's.That is the only 3 types I know of.I am not real sure but I believe the auto manufactures used the screw type on their supercharged engines high performance engines, the roots type are the most common found
buswarrior
I think I'm right in saying that some modern city buses nowadays use switchable electric superchargers on the diesel engine part of their hybrid power systems. Because the diesel engine component of the system is quite small, and because the buses are constantly having to accelerate from stationary, they use the electric supercharger to boost the engine power in a clean-emissions kind-of way at times when the engine is at low revs and running inefficiently
Jeremy
Quote from: Jeremy on April 12, 2017, 06:03:45 AM
I think I'm right in saying that some modern city buses nowadays use switchable electric superchargers on the diesel engine part of their hybrid power systems. Because the diesel engine component of the system is quite small, and because the buses are constantly having to accelerate from stationary, they use the electric supercharger to boost the engine power in a clean-emissions kind-of way at times when the engine is at low revs and running inefficiently
Jeremy
I was reading a automotive magazine about 48 volt engine systems in hybrid engines and part of the function of the electrical system was to start spinning the turbo before the car moved to eliminate turbo lag. Once moving the exhaust would turn the turbo cutting off the electric booster.
--Geoff
P.S. I worked on an old Cummins (2-6 bits?) that used a supercharger and it had written on it ROOTS so a roots blower was an actual brand.
Roots was the name of the inventors according to Wikipedia (and presumably nothing to do with Rootes, which was once a major car manufacturer in the UK)
https://en.wikipedia.org/wiki/Roots-type_supercharger (https://en.wikipedia.org/wiki/Roots-type_supercharger)
Jeremy
Quote from: Geoff on April 11, 2017, 07:53:08 PM
Thank you, Professor, but the blower on a 2-stroke Detroit acts as an air supply, whereas a supercharger acts as an increased air pump. The blower on a 2-stroke Detroit is not a supercharger.
--Geoff
When all the drag race enthusiasts took the "blowers" off the 6-71's and put them on gas V-8's, they were called "superchargers". The real difference between all the types of chargers is the pressure boost and the thermodynamic efficiency of the drive method. To call the "blower" on a 2 cycle an "air supply" might be off the mark. There was a teeny bit of positive pressure involved so that all oil leaks could be revealed.
The main reason that a mechanical supercharger is not used on a 4 stroke Diesel is the supercharger is pumping 100% air all the time creating a constant 30-50hp draw on the engine. Compared to a gasoline engine with a supercharger-since the supercharger is down from the butterfly valve, when the engine is at idle or no power, the supercharger is not pumping-hence no power robbing. Superchargers are quite efficient on gasoline engines.
Virtually all on road Diesels are turbocharged and air to air intercooled. Most all marine Diesels are also turbocharged and aftercooled too. I can't think of a naturally aspirated Diesel made today (except small Diesels for generators). Good Luck, TomC
Just a question for my own interest: Why is it that a 2-stroke Detroit needs a blower if the net result is that the air going into the engine has either no positive pressure, or only a very small positive pressure? Is it that the inlet tract is somehow very restricted and if the engine was naturally aspirated it would struggle to suck sufficient air into the cylinders?
Jeremy
Quote from: Jeremy on April 13, 2017, 02:17:42 AMJust a question for my own interest: Why is it that a 2-stroke Detroit needs a blower if the net result is that the air going into the engine has either no positive pressure, or only a very small positive pressure? Is it that the inlet tract is somehow very restricted and if the engine was naturally aspirated it would struggle to suck sufficient air into the cylinders?
Jeremy
No, the DD two-stroke system is different from the configuration used on, say a two-stroke motorbike or a chain saw. In the other systems, the crankcase is used as a pump, air is drawn into crankcase and fuel metered along with the air (and usually oil is metered, too), then when the piston is traveling downward, the air/fuel mixture is pushed from the crankcase into the volume above the piston. This is the positive pump action for these systems and ports - at different levels on the cylinder to control timing - allow for transfer and exhaust.
On the DD two-stroke, there is little timing effected by the intake ports - when the piston is low, they're open. The exhaust is controlled by valves in the head (like ordinary 4-stroke poppet valves). To fill the cylinder with air (fuel comes later), there has to be positive pressure blowing fresh air in near the lower part of the cylinder. The timing comes from the exhaust valves. Once enough air has been injected to scavenge the cylinder of exhaust gases, the rising of the piston closes the intake ports and begins the compression phase of the cycle.
So it's this "flow-through" aspect of the DD two-stroke system that requires positive pressure to help blow out burnt gases through the exhaust and fill the cylinder with fresh air; it's the "blower" that does this.
(Somewhat simplified for brevity, but that's about right.)
HTH and FWIW, BH etc.
On locomotive EMD (Electro Motive Diesel) on series 567, 645 and 710, they are just like giant engines to our bus engines. What makes them unique is the mechanically driven turbocharger with over ride clutch. When the engine is at idle, the clutch engages and the engine spins the turbocharger to maintain proper boost. When the engine accelerates and the boost starts, the turbocharger rises in RPM faster then the engine is driving it and it turns into a normal turbocharger (think of a bicycle). Hence EMD's are very fuel efficient-so much so most all railroads outside of California prefer the 710 series (not smog approved in California anymore). Good Luck, TomC
Even amongst supercharging there are different types.
The ones I've had most development experience of- have been the Roots type positive displacement types.
The luxury sports/coupe/saloon I helped design/develop in the UK used an Eaton M112. The beauty of this device on a petrol engine- is that it does no internal compression work. This means it can be bypassed at part load and the losses incurred are minimal- like the parasitics of an alternator. At WOT full load- on a 4 litre engine it will consume about 70 bhp. It consists of 3 lobes that are twisted through 60-90 degrees ( I don't rememeber how much exactly).
The Gen 5 of this device used an abladable composite coating to get the tolerances tight and the seal to further increase the efficiency.
But the best improvement was the latest iteration of this- the TVS blower- which uses quad lobes that twist through 160 degrees. This unit similarly can be bypassed but its peak efficiency is up at 60-70% compared to the M112s 55% ish. This ensures the tank temps have lower temperatures and parasitics are better.
I do intend to get one of these TVS on my Jaguar one day and continue the work I did as a young man!
The other type of supercharging often consists of something akin to a small compressor like that found on a turbo charger (rotrex for example) - this DOES internal compression work. Similar to this is a Lysholm compressor- again- consisting of a male and female rotor- it DOES internal compression work and therefore bypassing wont reduce parasitics. In the past these units were always more efficient than the old M112 Super chargers, but now with the advent of the TVS units, the difference is small and there's the added disadvantage of bypassing giving nothing.
The other advantage of a positive displacement device like the Eaton Roots style blower- is that their air charge/boosting response to the throttle is pretty much linear- which feels like a big big engine- this isn't the case with the turbo style Rotrex for example.
As has already been covered- a diesel engine is a different animal to a petrol- it is effectively pretty much running at full airflow (like a petrols WOT) always- but the load is moderated by the injected fuel amount. Therefore a Super charger on a diesel will always incur a parasitic loss.
Out two strokes NEED a positive displacement pump of some form of boost- as the piston doesn't suck to bring in fresh charge. You will notice that going from the 8v71 to the 8v92 Detroit actually did what they could to drive the super charger less hard and rely on the turbo more- again to bring down parasitics.
Tom C I have a friend who works for EMD- he swears by the two stroke.
He's a young chap, from Germany, very data driven and has no bias either way, but believes the 2 stroke EMD is here to stay....
I had assumed originally with the acquisition of EMD by CAT, that they would force one of their 4 stroke leviathons on EMD but it may not pan out that way afterall...
Looks to me like the older technology is finding it way back into engines the Cat C8.7 uses the supercharger and turbo inline like some models of the old NH and Kta Cummins engines of the 70's.
FWIW EMD was building the 4 stroke EMD engines 5 years before it was sold to Cat,they even had a CNG version .EMD engines run a DC generator it is nothing like a automotive type engine, they are not cast each piece is welded together .You see lots of CNG fueled CAT and EMD engines pass through Needles along with the diesel fueled engines
Quote from: Oonrahnjay on April 13, 2017, 04:19:17 AM
No, the DD two-stroke system is different from the configuration used on, say a two-stroke motorbike or a chain saw. In the other systems, the crankcase is used as a pump, air is drawn into crankcase and fuel metered along with the air (and usually oil is metered, too), then when the piston is traveling downward, the air/fuel mixture is pushed from the crankcase into the volume above the piston. This is the positive pump action for these systems and ports - at different levels on the cylinder to control timing - allow for transfer and exhaust.
On the DD two-stroke, there is little timing effected by the intake ports - when the piston is low, they're open. The exhaust is controlled by valves in the head (like ordinary 4-stroke poppet valves). To fill the cylinder with air (fuel comes later), there has to be positive pressure blowing fresh air in near the lower part of the cylinder. The timing comes from the exhaust valves. Once enough air has been injected to scavenge the cylinder of exhaust gases, the rising of the piston closes the intake ports and begins the compression phase of the cycle.
So it's this "flow-through" aspect of the DD two-stroke system that requires positive pressure to help blow out burnt gases through the exhaust and fill the cylinder with fresh air; it's the "blower" that does this.
(Somewhat simplified for brevity, but that's about right.)
HTH and FWIW, BH etc.
Thanks for that; I was vaguely aware that the ports and valving arrangements were entirely different but I've never sat down studied how the cycle works on a DD 2 stroke - and I'm one of those people that is always slightly surprised when reminded that the Otto cycle isn't the only game in town. Just the other day I was watching a video on Youtube of a (petrol) IC engine configuration that had extra 'low pressure' cylinders working off the exhaust gas, just like a compound steam engine - which I suppose in many ways is an alternative to a turbo as a way of increasing output by extracting energy that would otherwise be wasted down the tailpipe
Jeremy
2 stroke engines.
I have a single cylinder engine from a motorcycle that has 2 pistons on a y shaped rod.
It is referred to as a twingle.
The front piston sets on the exhaust port.
the back piston sets on the intake port.
Years before exhaust chambers to control the back pressure.
uncle ned
Didn't Detroit make a short-lived 51-series engine that was valveless? it used intake and exhaust ports in the cylinders? I assume it still needed a scavenge blower.
Yes, other engine designs are fascinating. I was reading about a 5-stroke engine - is that the compound style that was mentioned? There was a significant increase in efficiency when steam locomotives adopted compound cylinder arrangements.
(Talking of steam locos, did you send the recent video of Tornado achieving 100 MPH? Tornado is a modern replica of a LNER Pacific loco, built just a few years ago using modern techniques such as a fully-welded boiler, and it's being tested for its suitability to run mainline trains at 90 MPH in Britain. Sometimes the distinction between old and new blurs.)
John
Yes, the 'compound' petrol engine is described as a 5-stroke - as I say there are videos of the configuration on Youtube, although the one I saw was only of a cutaway to show the operation - I'm not entirely sure whether it's still just a concept at this stage or if running examples exist.
And Tornado is certainly cool, although it's a Peppercorn class rather than a Pacific class incidentally. There's another steam loco already in regularly-scheduled mainline operations here now as well, and the heritage steam scene in the UK generally is absolutely huge (I sell the magazines that cover it!). It's especially big in Germany too I believe, and they've been developing and building 'modern' steam locos there for years which are just worlds-away from the coal-fired heavy-metal dinosaurs that everyone thinks of when you say 'steam'
Jeremy
Quote from: uncle ned on April 13, 2017, 07:36:29 AM2 stroke engines.
I have a single cylinder engine from a motorcycle that has 2 pistons on a y shaped rod. It is referred to as a twingle. ...
uncle ned
Sachs (F&S), Ned??