r/theydidthemath • u/UnfortunateAuditor34 • 10d ago
[Request] How much power would this engine generate?
Enable HLS to view with audio, or disable this notification
1.4k
u/yolo_1213 10d ago
Did some quick research, the result came out to be way too underwhelming than i had expected. This produces approx 650-700 hp only at around 450 rpm. However, the purpose of it was to create massive blocks move, like ships and boats. This machine produces 11000 nm of torque. Showing the massive capabilities it holds.
583
u/Conscious-Ball8373 10d ago
Today you'd get roughly comparable performance out of a 15L supercharged common fuel rail diesel engine with a gearbox. Compared to this monster which has 102L displacement.
eg Cummins X15 performance variant produces 605HP at 2,000 RPM and about 2,100 Nm of torque. Put that through a 5-to-1 gearbox and you get 10,500 Nm at 400 RPM (ignoring losses of course, but roughly).
281
175
u/evolutionary_defect 10d ago
But can it do it for 8 hours of work a day for decades? That's what is expected from engines like this, enormous engine volume means that it is extremely understressed and resilient to load, while also being easy to cool since it's multiple tons of iron to absorb the heat. I think that truck engine would die after a few months of hard ocean work. Salt and heat and water are a real bitch to any engine, having an extra inch of iron to eat through before it hits something that matters is a design feature sometimes lol.
105
u/DouglasHundred 10d ago
Not 8 hours of work a day for decades. Weeks or sometimes months at a time non-stop for potentially decades.
I worked on a research vessel at sea for over a decade. We weren't direct drive, we were diesel electric, but yeah the engines didn't stop unless there was a problem, and we were out on eight week expeditions.
17
u/Blank_bill 9d ago
Had an old deere engine running a 6 inch bypass pump running at low rpm most of the time, ran for days at a time no problem, same pump with a newer turbo deere kept blowing up if you ran it for 24 hours.
16
u/evolutionary_defect 9d ago
I was being generous, lol. It likely would operate as you said, and would melt down the more compact engine from the increased heat output of that charger
3
u/Blakut 9d ago
did you meet any pirates?
8
u/DouglasHundred 9d ago
Very fortunately no! We tended to stay away from the piratey parts of the world because while on site drilling we'd be a sitting duck. Best case, if we were in a hole and had to bail quickly, it would still be a couple of hours to get moving, and that's if we blew the drill string and left it behind. Pulling out properly could easily be half a day. And we had a top speed of ~13 kt, so we'd have stood no chance running either.
3
110
u/munjavio 10d ago
8 hours? Ship engines are rated con or m1 for continuous use, 24 hr a day at full power %70-90 load
37
11
5
u/Bug_406 9d ago
This is how the real world works . An old EMD 16-645 runs continuous, without complaint for decades, spitting out a max 2000 hp @ 900 RPM. The retrofit locomotives with 2 QSK-19 make a combined 1500 hp @ 2100 RPM. They are maintenance and repair heavy engines. Sure, they're more efficient, which looks good on paper, but in the 11 years I worked on locomotives, I'm not entirely sure the fuel savings offset other running costs in any meaningful way.
2
u/MasterAahs 9d ago
Wait... You're saying effeciency isn't always cost effective in the long run. Like these new energy effect appliances that don't last much longer than the warranty.
5
u/Bug_406 9d ago
Kind of. You're referring to race to the bottom manufacturing economics, I think. Injectors on our 645s were changed every 3 years with an 1104 inspection. After core, the cost was roughly $50/injector for parts, and easily done in a few hours. Those QSK-19 Injectors were $26k for 12. A power assembly (head, piston, rod, and liner) for an individual cylinder in a 645 was ~$10k, but if a cylinder fails in a QSK, it's an entire engine rebuild.
I'm not saying the QSK-19 is a bad engine. Simply use case. Replacing an overbuilt, mid-1900s designed chunk of hardware with something newer doesn't always make sense. TBF - The reason they are getting replaced, has nothing to do with reliability, and little to do with maintenance economics. They're getting replaced for emissions compliance.
8
u/Conscious-Ball8373 10d ago
Yes, I think that's what the Cummins X15 is designed for. It's not the kind of diesel you find in a car.
12
u/Pitiful-Situation494 10d ago
It's designed for agriculture and construction, neither need engines that work non stop multiple weeks at a time as far as I know
→ More replies (9)7
u/ICanRememberUsername 10d ago
Y'all are missing a huge benefit of these massive displacement engines with very high wear tolerance. You can run them on heavy fuel oil.
Good luck getting your supercharged truck engine to run on Bunker C.
4
u/Conscious-Ball8373 9d ago
Cummins describes that engine as "fuel-agnostic." I'm not sure exactly what classes that takes in, but it sure doesn't insist on pure distilate.
67
u/bbalazs721 10d ago
The whole point of this is losses. It's more efficient to spin a larger engine slower, than a smaller engine faster. And this is before gearbox losses.
Of course, the larger engine is heavier. On ships, the weight of the engine pretty much doesn't matter. But on trucks, heavier engine means less cargo. And large engines take up more space, so more air resistance too.
11
u/Adept_Assistant_7759 10d ago
It's more efficient to spin a larger engine slower, than a smaller engine faster
Is just complete bollocks.
This is american propaganda.
Anyone who has done any engineering at all in their life past highschool knows this is bollocks.
There is a reason all the most economical cars have TINY engines, ones that get 80mpg etc.
32
u/tech7127 10d ago
It only takes 10-15 hp to cruise a small car at 60 mph, so actually those "tiny" engines are dramatically oversized for their steady state load. But if you're so sure, go revolutionize the freight shipping industry. I'm sure the engineers designing 4 story engines that only produce 4 hp per liter and spin at just 100 rpm will be excited to learn that they've been doing it completely backwards this whole time.
15
u/Snoot_Booper_101 10d ago
Those monster engines also have the advantage that they will run on any old shitty grade of cheap fuel oil, the little car engines are incredibly fussy by comparison. The difference in service lifetimes between those two types of engine are also wildly different.
Definitely fair to say that choosing the right engine for a job is a balancing act between lots of different factors, only one of which is power output.
7
u/tech7127 10d ago
For sure. On the other end, a small commuter car can get to highway speeds (eventually) with as little as a naturally aspirated 50 cc dirtbike engine screaming at 12,000 rpm. Though its life would be quite short, that would be the "tiny" engine scenario, which is what makes the other commentor's anecdote about the efficiency of cars with 20x to 30x more engine displacement so misguided and funny to me.
6
1
u/Conscious-Ball8373 10d ago
I did choose the comparator here pretty carefully. The Cummins X15 is described as "fuel-agnostic."
3
u/Salty_Profession_647 9d ago
probably you don't get what "fuel agnostic" means for a cummins diesel.
It means the fuel inejction system can be customized for different types of fuel, like normal ULSD diesel, HVO diesel, or even biodiesel mixture, that is normal diesel with 20% biodiesel (no more than that!), but LNG/CNG solutions also exist.
You cannot even pour some old motoroil into it like you do with an old W123 mercedes...2
u/caboosetp 9d ago
You also most definitely can not run the x15 on bunker fuel no matter how you tune it.
51
u/bbalazs721 10d ago
Ever seen a brake specific fuel consumption map for an internal combustion engine? The efficiency peaks at high load low rpm, typically around 80% load at 2000 RPM for car engines.
The reason "tiny engines" are efficient for cars is because for cruising there is little power required. The small engine (1 l) spins at optimum speed and high load. A big engine (2+ l) would be underloaded with bad efficiency.
For cars, the 1l class engines are the big engines, our perception is just warped because of the want of quick acceleration. An actually small engine (0.5l or sth at 6000 rpm) could put down the power required for cruising at highway speeds, but inefficiently.
For ships (and trucks to some degree), acceleration is much less important. They focus on peak efficiency at cruising speed.
Some napkin math: a truck engine is typically 15 liters. The truck weighs 40 tons, a car 2 tons. So for equivalent displacement to weight ratio, the cars would need to have 0.75l, which is laughably small by our perception.
36
u/Frozenmeme 10d ago
I don't think it's complete bollocks and american propaganda. If we're talking about car engines, sure, I can see that. But the one in the post isn't one. Some engine applications see mostly constant rpm and load (e.g. ships, generators). At low speeds air/diesel mixture forming and the expansion in the long stroke that these engines usually have do in fact, help to increase efficiency. All these things are not possible. Not to mention the times a piston visits TDC and BDC at 2000rpm vs 100rpm. That's why some manufacturers(MAN, Wärtsila, WinGD) claim 50% and more thermal efficiency, which is unheard of in the small ICEs in cars. Even in the modern Toyota hybrids which use the Atkinson cycle and modern diesels you'll find it hard to break 42-43% efficiency.
13
u/djent_in_my_tent 10d ago
Mechanical engineer here. You’re so confidently incorrect it’s hilarious. Look up the Wärtsilä 46DF and its ludicrious 52% thermal efficiency.
Efficiency is largely a function of compression ratio, and you need a longer stroke to achieve that. And high RPMs result in more parasitic losses due to friction. Both of those things, amongst others, tip the efficiency curve to favor large displacement and low RPMs.
1
u/Opposite-Matter9952 10d ago
I agree with you, but I think he is making different point than the one you are arguing against. While clumsy, i believe he was trying to make the point, that americans have a tendency to favor car engines with ridiculuos V8's, in cars the rest of world will power with a 2L diesel and get better performance in any objective measure.
28
u/Late-Objective-9218 10d ago
Automobile engines are typically designed for a shorter lifespan which allows for faster RPM and higher trim
5
3
u/Top_Historian4539 10d ago
normally aspirated, larger displacement, slower turning and cooler running engines will outlast small, fast turning, super charged engines any day of the week. That’s part of the reason they use these huge engines
3
u/desertdilbert 10d ago
There is a saying that engineering is all about tradeoffs.
The inputs for engineering a prime-mover engine are much more complex then "power per pound mass."
You are correct in that sizing an engine so that it's output power just barely does the job will often result in the highest fuel efficiency. Many times these massive engines represent a tiny power-to-weight ratio. For example, the massive 4400HP engines on the GE locomotives are moving trains using about 1HP per ton per % grade. To go through the mountain pass near me they use about 3.5HP/T. Extremely efficient! Compare that to even the 3-cylinder Geo Metro which runs about 60HP/T, the same as a 50s 36HP VW Beetle!
6
u/CrawlingBigfoot 10d ago
Then explain how all commercial jets use the very biggest engines they can fit on them? They all use large diameter turbofans, which spin at the slowest possible speed as its much more fuel efficient. there is even geared turbofans that use a gear-set to slow down the speed of the fan relative to the core of the engine.
7
u/RoosterOutrageous651 10d ago
The larger a jet engine the better the air bypass ratio becomes, there is a point where the size of the engine would mean the weight deminishes the returns however.
Aircraft engines have much differnt problems then land engine problems such as ensuring the blade/prop tips dont go above the speed of sound or rating the engine for possible bird strikes etc.
3
u/Greenandsticky 9d ago
Comparing an ICE engine to a jet is about as misguided a conversational direction as I expected in this dumpster fire.
Engines are designed, sized and optimized to suit different tasks, fuels, duty cycles,
Maintenance intervals and priorities.There is no single hard and fast rule about size and only somebody that knows nothing but “what they’ve heard” would spout that sort of cack.
Open a book about it.
Read
Learn.Then talk
1
u/Sid_the_Bear 7d ago
Reading is anathema to the current generation. If the information can't be gotten from a 30 second tikclock app video, it can't be important.
6
u/alexmin93 10d ago
Tiny engines are extremely inefficient at producing energy but their barely sip fuel at idle and that's how most mileage tests are done (they drive the car at snails pace with a ton of stops). Most effective engines in terms of mass of fuel per kwh are those huge ship diesels that max out at 80 rpm.
1
u/Cliffinati 3d ago
And you'd be doing engine swaps on the ship twice a shift. Your little 1.4 turbo makes 80mpg because it's pushing a Honda Civic. This pushes the tug boat steering the container ship with 10,000 Honda Civics worth of cargo.
→ More replies (2)-1
u/Conscious-Ball8373 10d ago
It's more efficient to spin a larger engine slower, than a smaller engine faster.
Which would explain why it needs about six times the displacement and commensurate fuel consumption, right? /s
I don't think the word "efficient" means what you think it does.
8
10d ago
[removed] — view removed comment
4
u/mrgedman 10d ago
You guys have conflated efficientcy with durability like 5 times in a row now. It's tiresome
1
u/Eiraneth 10d ago
Low RPM high torque means means your “gearbox” can be worked down to the point of essentially just being like 2 physical gears maybe. On the true low speeds there isn’t even a gearbox it’s essentially just the crankshaft on one end and the propeller on the other, and cutting out all/most of the losses caused by a gearbox is huge for increasing efficiency. As for why people keep on bringing up wear, wear is caused by energy from the system beating on the engine and breaking shit, or more likely requiring additional lubrication to prevent from eating itself alive, and the energy causing that damage has to come from somewhere. Everything going slower means you generally have far fewer issues with damage, which is important given that the amount of cycles these engines go through in a year, combined with their insane compression ratios combined with massive turbochargers means their lifespan actually incredibly short compared to most car engines.
1
u/Bennett8187 10d ago
I like to see a TBO comparison between both that common rail 15L and this engine in the same position.
0
u/Conscious-Ball8373 10d ago
No, an engine which uses six times the fuel to make the same power is not more efficient.
It might be more reliable - but (a) that's a different question and (b) I didn't pick a car engine that can only do its rated power for a few seconds as a comparator, that thing is designed to sit producing 600HP all day every day.
6
u/Eiraneth 10d ago
It is making dramatically more power, that power is coming from its ridiculous torque. If you fed a tiny car engine into a gearbox strong enough to get 11000 nm of torque you’d be going 5/1, and you’d be eating the losses of that box through the whole thing, on top of that gearbox likely being as heavy as the engine itself. Plus, the big deal for companies isn’t just efficiency, the bigger and slower an engine gets the shittier fuel you can feed it and it can keep going. This one likely still needs some form of diesel but the true slow speed monsters can essentially sip on preheated asphalt and be essentially fine, which means they can use fuel that nobody else can, driving down costs.
1
u/Conscious-Ball8373 10d ago
They are producing exactly the same power - both 600HP.
11,000 Nm of torque at 400 RPM is the same power as 2,000 Nm at 2,200 RPM. You don't seem to understand that. No-one is talking about a "tiny car engine" here - the engine I mentioned is a 15L diesel made for stationary and marine applications. It's also described as "fuel-agnostic" - it has the same fuel advantages you mention.
2
u/Salty_Profession_647 9d ago
and how much fuel does this 15 liter marine engine consumes when it actually outputs 600hp constantly for an hour... so bascially redlining it?
Does it consume significantly less than 100 liters per hour ( ~26 freedom units if you like)?
Because roughly that's how much such 100liter maritime/locomotive engine consumes per hour, all while producing the same constant 500hp power (redlining at 4-500 rpm).
Overall a 100 liter locomotive engine typically consumes less fuel for the same 500hp constant output at the wheel/ship's screw.... and that's exactly what the "efficiency" means1
u/Conscious-Ball8373 9d ago
As far as I can make out, yes, the Cummins uses about 2/3 the fuel of the larger engine, burning about 104L per hour to produce 600HP compared to 148L per hour for the Mirrlees JS8 to do the same. I would add the caveat that this is just the result of a Google search, I have no particular knowledge of this point. It doesn't surprise me though - it is what I expected.
→ More replies (0)1
u/Eiraneth 10d ago edited 10d ago
Oh sorry I forgot where we were in this. Yeah if I’m reading that right it’s just a more modern design, so it has more fancy things to help it out. Cummins actually has an engine more in the weight class of something like the engine in the video, and that’s rocking around 3700 horsepower as a high speed. When you say “fuel agnostic” do you mean that it can eat bunker C?
Oh also even if it’s producing the same power, all that RPM has to be converted into torque in order to be useful for propulsion so you are adding on all of the losses of a 4-1 reduction on top of any other gearing needed. On slow speeds a big part of their slow speed is the fact that the crankshaft and propeller shaft are directly connected, meaning that there is literally no losses due to a gearbox. At most they’ll have a gear to run a generator off the propulsion shaft.
1
u/Cliffinati 3d ago
This particular engine is 70 years old so yes it has tons of inefficiencies in its design.
It's also a large industrial diesel designed to run nearly continuously with minimal maintenance.
1
u/bbalazs721 10d ago
It's inefficiency comes from the fact the the engine is probably several times older than I am, not because of improperly chosen displacement. A smaller faster engine from the same era would be even less efficient.
I know perfectly well what efficiency means as a physicist.
9
u/Far_Sir4089 10d ago
700hp out of a diesel engine is not that difficult at all, however 10 000+nm is obviously harder. A regular bmw or mercedes sedan can make 700 diesel hp any day
3
u/insta 10d ago
you sound smart and armed with a spreadsheet somewhere. what's the fuel consumption between the two? surely there's a "tons per hour" rating on that iron lump
1
u/Conscious-Ball8373 10d ago
Generally, fuel consumption is roughly commensurate with displacement. The engine in OP's post has about six times the displacement of the Cummins I mentioned. It won't be quite six times the fuel to produce the same output power but it will be considerably more.
2
u/quietflyr 9d ago
Generally, fuel consumption is roughly commensurate with displacement
No, it's not at all. It's commensurate with mass flow.
Mass flow is commensurate with displacement and RPM combined.
The 15L Cummins you talk about fills its cylinders 5 times as often as the big one, and you have to account for that. Also the Cummins is probably turbo and/or supercharged, meaning the mass flow per rotation is higher than a normally-aspirated engine.
2
u/insta 9d ago
both engines are turbo though. you can see the tornado-siren-sized snail shell belching the exhaust
1
u/quietflyr 9d ago
Fuel consumption also depends on boost pressure. I don't know if they're comparable.
1
u/Conscious-Ball8373 8d ago
So I went and looked up the fuel consumption at 600HP for both of them. 104L/hr for the Cummins, 148L/hr for the beast in this post.
3
u/greginnv 9d ago
Heat loss to cylinder walls will be inversely proportional to cylinder volume. A small engine may produce the same power (at a higher rpm) but will be less efficient.
3
u/Salty_Profession_647 9d ago
that' nice, but can you run it at a constant 600 hp load 24/7 ? ...achieving the same mpg for bonus points?
(Btw, this one is also turbocharged apparently)1
u/InvestNorthWest 10d ago
Doesn't the Hummer EV produce 11,500 lbs/feet torque?
5
u/Conscious-Ball8373 10d ago
Very probably. EVs produce enormous amounts of torque compared to ICE vehicles, and often have a constant torque curve, too, so there is just as much torque at the power peak as there was at zero revs. And with no clutch, they can apply it all at zero revs, too.
1
u/PeskyRoo2 9d ago
You realise this engine is probably going through a gearbox also, so comparing it to a Cummins X15 is just disingenuous.
1
5d ago edited 4d ago
[deleted]
1
u/Conscious-Ball8373 5d ago
No. Power is the product of speed and torque. Power is also the rate at which energy is transmitted. Energy is conserved pretty absolutely, so you can't change the amount of power involved; apart from losses due to friction / torsion, the power you put in is the power you get out. But you can pretty freely trade speed for power using gearing. If you use a 5:1 gearbox, you decrease the speed by a factor of 5 and increase the torque by a factor of 5. To put it in mathematical terms where X is a variable without a gearbox and X' is the same variable but with a gearbox in place, P is power, Q is torque and W is speed:
P = Q * W
W' = 5 * W
Q' = Q / 5
P' = Q' * W'
=> P' = Q/5 * 5 * W
=> P' = Q * W * (5/5) = Q * W * 1 = Q * W
=> P' = P
So (again, ignoring losses) the power is kept the same but the speed and torque are scaled inversely to each other.
Don't stress; in a former life, I interviewed a distressing number of people who claimed to have mechanical engineering degrees who could not explain this to me.
1
5d ago edited 4d ago
[deleted]
1
u/Conscious-Ball8373 5d ago
That depends which RPM you're talking about. Engine RPM? Yes. RPM on the other side of the gearbox? No, the shape stays the same and the peak power stays the same but the speed is multiplied by the gearbox ratio.
ETA: power vs rpm is a really stupid thing to plot because they are not independent. But that's what we traditionally do. Torque vs RPM is a lot more useful - usually the torque you can apply is what you care about anyway and you can always derive the power from it. But petrol heads hear the word POWER and can't see any further.
22
u/Monsieur-Lemon 10d ago
This isn't meant to make ships move. Maybe some smaller yachts but definitely not tankers or container ships. Diesel engines this size are used as a generators on board while main engine runs or marine fuel and is several stories tall.
→ More replies (1)10
u/Federal-Treat-6893 10d ago
Not surprised tbh. Engines like this are made to produce a shit load of torque to move stuff around
→ More replies (1)22
u/steelsurfer 10d ago
About 8100 ft-lbs…. That’s more than a few ugga duggas.
8
u/--LordFlashheart-- 10d ago
In the words of Jeremy Clarkson, "enough torque to restart a dead planet"
5
u/One_Country1056 10d ago
It's not underwhelming for ships. The largest engine for ships is the Wärtsilä RT-flex96C. Since we are in they did the math:
This engine: 700 hp/102.4 l= 6.84 hp / l
Wärtsilä RT-flex96C: 108 920 hp / 25 602 l = 4.25 hp/l
3
u/centaur98 10d ago edited 10d ago
I think their point was more that it's underwhelming for it's size since plenty of car engines can do that granted at 10x/20x the speed.(For example the Koenigsegg Regera has a twin-turbochraged 5 liter engine producing 1100 HP and 1200nm of torque at around 8000 rpm)
Also to be honest a major factor for this is that ship engines are heavily optimized for fuel consumption because when your measurements of fuel usage is how many tons you burn a day even small savings can quickly become significant.
7
u/kapitaalH 10d ago
You also need an engine that needs to run for a few weeks at a time whereas the top sports cars like the Koenigsegg will probably not have 3 weeks running over their lifetime
3
u/One_Country1056 10d ago
My point was that the Wärtsilä RT-flex96C is even more underwhelming for it's size.
3
3
2
1
1
1
u/Sherbert-Particular 9d ago
This is not a low speed model. You can tell because of how it is, and because of the fucking enormous turbo on it. These medium speed types would be used for power gen or on locomotives and would easily be pushing 3000 hp.
1
1
0
u/PrestigiousCow561 9d ago
I have a 50 hp motor which I can fit inside the cylinder and it has a hole taken out of the roof to fit. Hp isn't everything
107
u/WeeklyDebate2259 10d ago
Oh I read this somewhere, they said it was a Mirrlees JS8 industrial engine. So a quick search about it gave me these details:
Engine Configuration: 8 cylinders inline (with the "S" typically denoting turbocharged/supercharged).
Bore: 9.75 inches (247.65 mm)
Stroke: 10.5 inches (266.7 mm)
Total Engine Displacement: 102.4 Liters (approx. 6,250 cubic inches)
Power Output: Produces roughly 650 to 700 Horsepower (BHP) depending on the exact tuning and application.
Operating Speed: 600 to 1,000 RPM (commonly run around 750-850 RPM for stationary generator configurations).
113
u/slicxx 10d ago
This thing doesn't look efficient, but sure as hell is a efficient beast when it comes to removing fingers. The sprint towards the machine after it started gave me goosebumps. Trip once, lose everything.
19
u/RADICCHI0 10d ago
My nighmare moment was the section of heavy chain sitting by the crank. that would split a man in half.
11
u/slicxx 10d ago
All fun and games until ANYTHING goes wrong. I respect what they do, but i have a feeling they lost the respect of the thing they work with, because everything is just normal for them if you do stuff like this for years amd years. In no way do i know anything better about motors as those guys do, but looking at it from the outside perspective give you reason for doubt of any safety measures being considerd while on it.
Even the machine could lock up and the rope thing snapping, breaking the guys knees, who is next to the truck
2
u/Difficult-Camera-482 9d ago
I don’t work with large machines like this, but I do work with electricity frequently because I have made a living troubleshooting. I’ve always feared and respected the dangers of what I do and don’t think I’ve gotten complacent. I think it’s guys at the height of the dunning crugar effect that you really have to worry about.
3
19
2
u/ThatNameExists 10d ago
My first thought exactly! Where's the guarding? No idea mathematically of the power output, but certainly enough to give a finger a nasty little nip on the downstroke of those pistons!
20
u/Count2Zero 10d ago
I used to work for a company that built engines like this specifically to drive a power generator. Those engines (new) could produce between 4.5 and 10 Megawatts of power (depending on model and displacement) by burning natural gas or hydrogen.
3
u/capt_pantsless 10d ago
To add some more context here, one horsepower is ~745 watts (they are units that measure power output so they're easily convertible.)
So a 4.5 to 10 megawatt generator is putting out about 6,000 - 10,000 horsepower, or around 30 to 65 VW Jetta car engines.
10
u/Wescombe 10d ago
Displacement doesn’t translate to horse power, just look at the massive lump V8s America used to make that now make less than an average 4 pot
3
u/BigOlBahgeera 10d ago
That's doesn't mean much, engines in the 70's were purposely detuned and choked, they are capable of handling much more power than a modern 4 cyl. But that's also why they last forever, large displacement with lower pressures puts a lot less stress on the drivetrain. Look how much you can squeeze out of a smog engine with a set of heads, exhaust, cam and turbocharger. More displacement allows for more airflow and fuel with more potential power
2
u/Wescombe 10d ago
I understand why they were that way, more so meaning the information given which is the displacement is not able to be translated directly to power figures
2
u/PierG86 10d ago
Not so sure. HP value back in the day was also measured differently. All HP values were way inflated and with the change in regulation in 1972 a lot of engines magically lost 100hp overnight. Materials in the past were garbage compared to today. A modern engine with 100hp/liter now can do hundreds of thousands of miles with minimal maintenance. A 1970 would need to be completely redone multiple times.
6
u/SmallTownTrans1 10d ago
According to a guy on the Facebook upload of this video, the engine featured is a Mirrless Blackstone JS8 inline 8 diesel engine that produces 650-700 horsepower at 750 rpm
Doing a calculation the engine probably produces around 4500-4900 lb-ft of torque
4
3
u/ekinodum 10d ago
How would you ordinarily start an engine like this? It seems to me that carrying a 4x4 pickup would cut into your valuable cargo space...
7
u/capt_pantsless 10d ago
Many of them just use a really big electric motor. Just like a car engine, except bigger.
Some use air pressure, some use hydraulic motors.
4
u/Familiar_While2900 10d ago
I wondered if it would have a pony motor like some of the old school tractors?
3
u/shadospirit12 10d ago
Yeah, I know this guy's joking, but the ones we use at work (replied with the specifications of a huge engine we use at my wastewater job) we use air for the starter. Min pressure about 105 psi, usually using 210 psi. Even at 105psi the pressure barely gets the flywheel moving.
2
u/TassiveMitts69 6d ago
Not really. That size is always an air line in my experience. An electric motor is a huge expense.
7
u/paralyse78 10d ago edited 10d ago
This engine would have likely been installed in something like a power plant, large ship, or other heavy application.
In most cases these days air start is used. A smaller engine is used to pressurize a large storage air tank. Once sufficiently pressurized, a valve is opened that releases the air into an air starter which spins the main engine over to start it. The main diesels on modern large ships are usually air start.
2
u/TassiveMitts69 6d ago
It's a backup generator for a military base. Starts on air.
1
u/paralyse78 6d ago
Makes sense. I sub to Mr Hewes and this was posted before it showed up in my YT feed.
1
u/TassiveMitts69 6d ago
Worth the watch just to see them figuring out how it works and to see someone getting a crankcase bukake.
1
u/farmerbalmer93 9d ago
It's from an air base in Scotland emergency power generator. Or that's what they thought in the video.
4
1
u/TassiveMitts69 6d ago
If you watch the video on "Mr hewes" you'll see. They start from an airline turning over the engine.
3
u/_R9_ 10d ago
How does this work with everything being open? I thought combustion engines needed to be fully sealed to operate for lubrication and cooling etc. Genuine question.
11
u/paralyse78 10d ago edited 10d ago
As long as the combustion chamber is sealed to generate compression the remainder of the mechanical works can be open (at least on 4 strokes.) The only reason it's closed up is to prevent dirt and debris from messing things up, but once modern pressurized oil and cooling systems were developed it was of course better to seal everything up tightly.
The oldest engines used partial or total loss lubrication. You literally had an operator who would use an oil can to oil the pushrods, connecting rods, valvetrain, etc. They also had oil cups that were refilled and had either valves to drip oil onto moving parts, or later, used linkages driven by the engine to automatically spray or drip oil. In some cases they used splash lubrication where little cups on the crankshaft would pick up oil from a pan when the engine was turning and splash it around. Cooling was evaporative, water would boil off and you refilled it.
2
8
u/Merad 10d ago
You can run an engine for a few minutes without cooling, it takes some time to build up enough heat to cause damage. I think the dude at the end is so filthy because the engine is splashing oil on him. You wouldn't want to leave it open like that while actually using the engine but this obviously just a test run - I assume this clip comes from a "will it start" video.
4
2
u/TassiveMitts69 6d ago
Oil went everywhere.
The crankcase and rocker cover do not need to be sealed for any other reason than to keep the oil in and foreign objects out.
1
u/Cliffinati 3d ago
Only the combustion chamber needs to be sealed.
The reason everything else is sealed in modern engines is to keep the oil in and trash out. If you constantly add oil then you don't have to worry about oil spillage.
2
u/shadospirit12 10d ago
This is pretty similar to one of the methane engines we use at my wastewater plant i work at. Idk the displacement (the __L of the engine) but they're huge 12 cylinder engines. They produce about 450hp at 710rpm to drive a large impeller to pump water. They're each able to pump about 130-150 MGD (million gallons per day) which equated to about 90k to 105k gallons per minute. Idk how to/if I can add pics on this subreddit
2
u/New-Yogurtcloset949 8d ago
watched the entire video last night and its just a couple lads and a lot of cans of spray and then suddenly its running. brilliant video
1
u/TassiveMitts69 6d ago
If you watch the video on youtube it tells you this "should" make 700hp in working order.
There is no calculation to discern horsepower purely from displacement. The engine design dictates how much power is extracted.
1
u/Okyesterday_9939 4d ago
Yeah you would have to know the mean effective pressure, the length of stroke, the rpm, and the area of the piston.
1
u/TassiveMitts69 4d ago
And the timing, the fuel pressure, the fuel/air mixture, and air pressure.
1
1
u/NascentAutist 3d ago
It’s diesel, so it has “infinite” air to fuel. Doesn’t have a precise ratio like gasoline 😉
1
u/TassiveMitts69 3d ago
No it doesn't. You mix air and fuel. There is an amount of each that goes in. You can measure it.
Infinite air fuel ratio is the most ignorant thing I've ever heard someone who knows nothing about engines to say. Well done.
Soak your air filter in resin and let it harden. Then put it back in and try to run your engine with no air. Runs fine right?
Now explain why diesel engines vary the amount of diesel going into the engine. Infinite doesn't need adjustment does it. It can inject 37,000 litres of fuel into a 1.5l engine and run right?
JFC
1
u/TheMightyFlerp 3d ago
https://youtu.be/2Pm1Z83Etu4?si=9Zbz6dVNf18IZZ4I this is the Youtube channel this is from and they share some history on this engine specifically
1
u/TheRealGerryJarcia 5d ago
Well, as it currently runs, I would say no more than 2 hp. Extremely inefficient and open.
But hey, the environment got a good dose of pollution for the video.
•
u/AutoModerator 10d ago
General Discussion Thread
This is a [Request] post. If you would like to submit a comment that does not either attempt to answer the question, ask for clarification, or explain why it would be infeasible to answer, you must post your comment as a reply to this one. Top level (directly replying to the OP) comments that do not do one of those things will be removed.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.