The Pulley Center Invites You To The: Fill & Download for Free

I fell in a well..!I know it rhymes but was pretty scary.So, it was a 150 years old (that’s what the villagers say) above ground well but we use the water for everyday needs. It had pulley arrangement something like this expect that mouth of the well was quite wide and there is no such platform to place pots etc. I was 10 years old and the well would be half of my height from the ground and I can’t swim.My brother and I were back after school. Quickly had some snacks. My mother works as a Librarian and her shift timings are from 8am - 11 am and 4 pm- 7 pm. Before we reached home, she had left for her evening shift. My father was posted in a different place and used to visit us during weekends. For me to drag water out of well was a fun activity. And since we have less water stored inside the house that day, I though of having some fun by dragging the water out. My grand father was inside the house. My brother and I went near the well but the rope was out of pulley. So, I had this habit of climbing over the well on knees and bend forward to put the rope over pulley. I wore a full length nylon orange frock which my parents has bought me on my birthday. You’ll understand why I gave such description about my dress. So, when I climbed on knees over the well, it slipped and“BAM!!!”I fell into the well upside down. It was very deep and I could not understand what’s going on. The walls of the well were very rough and luckily I fell in the center of it and hence had no harm. Funny part was I carried the bucket and rope along with me into water and no spare was available outside to pull me out.My brother panicked and ran to my grand father shouting “ Thathayya..Akka nuyyi lo padipoyindi” (“Grand father.. Sister had fallen into well”). He froze!! He had no clue what to do. My brother ran house to house saying please save my sister..she fell into the well. No one knew how to climb down the well. They could not find a rope to just throw into well to save me from drowning.Now, let’s go inside the well and look at my condition. I can’t believe how lucky I’m to survive inside the well for good 20min. You know how? That long nylon frock I wore formed as a balloon around me and I was floating on surface of water !!! I was in complete shock, I saw up and can see the well surrounded by many people shouting but I could not relate anything.There was a small local hospital nearby (something like in the image) and patients visit in good number everyday. So, others started shouting that a girl fell into a well, only one patient there knew how to climb down the well and came running. He came for the checkup from a town far off which is around 60km away from our village. By that time, others managed to get some rope and this guy slowly climbed down the well. I started feeling uncomfortable as if I’m losing breath and drowning. I involuntary raised my hand and then within a minute he caught hold of it.That was a re-birth for me (date 25.06.2002). They sent a bucket into the well and pulled me out. Exactly like this.Later on my birthday, we invited his family for dinner and gave him gifts and clothes as a token of gratitude.I could not be more fortunate on that day for having my brother beside me, wearing that frock and being saved by a patient who visits once in 2 months. For me it was a real miracle and of course a scary experience.

I’ll supply this article from an expert TL / DRIf you’re really interested in knowing more about the basics of engineering an engine this should be your go to web site.EPI Inc. is a small corporation, started in 1994 by Jack Kane, for the purpose of designing, developing and manufacturing piston engines, power transmission systems and subsystems."LS” and "LT" based Crate Engines -LS-3, LS-7, LS-9, LT-4, LT-5NOTE: All our Products and Designs are ORGANIC, GLUTEN-FREE, CONTAIN NO GMO's, and will not upset anyone's precious FEELINGS or delicate SENSIBILITIES.LS and LT Crate Engine IntroductionThe GM LS engines discussed here (LS-3, LS-7, LS-9) are the later "Gen-4" engine versions of the LS series. The LS-7 and LS-9 engines were discontinued in 2017. The information remains here for general interest purposes.The LT series of engines (LT-1, LT-4, LT-5) are referred to as "Gen-5" engines, which differ in substantial ways from the Gen-4 engines, including the use of direct fuel injection (as opposed to port injection on the Gen-3 and Gen-4 engines), variable valve timing, cylinder deactivation, improved block structure, improved main bearing caps, improved oil system, and a host of other revisions / improvements.The LS and LT crate engines frequently come up for discussion as potential candidates for the basis of a lightweight liquid-cooled aircraft powerplant. The base LS engine weighs less than 390 pounds (less flywheel, alternator, exhaust manifolds, and accessory drives). Those interested in such a project believe these engines might provide reasonable reliability and power in the factory configuration.On the subject of reliability, it is worthy of note that in the GM Performance Parts Book, ALL of the LS and LT crate engines have the statement: "NOT INTENDED FOR MARINE USE". And "marine use" can certainly be considered similar to aircraft use, by virtue of long periods of operation at high or maximum power settings.CRANKSHAFTSThe LS-7, LS-9, LSA, LSX-454, LT-1, LT-4, LT-5, and LT-376 engines use forged steel crankshafts.ALL other LS engines use CAST IRON crankshafts.On the subject of forged steel production crankshafts, it is worthy of note that the material used in ALL EXCEPT THREE of the engines with forged cranks is an inexpensive low-alloy AISI-1053 "carbon" steel. The ONLY alloying elements it contains are carbon (0.48-0.55%) and manganese (0.70 - 1.00%), with low allowable amounts of contaminants like phosphorous and sulfur. It has low hardenability and a relatively low endurance limit, but it IS inexpensive.The three (known) exceptions to the lower-grade 1053 forged crankshafts are: (a) the 3.622" stroke LS-9 crankshaft, (b) the 4.000" stroke LS-7 (that initially was AISI-4140, a decent manganese-chrome-moly-silicon alloy, then was switched to the micro-alloyed compound 44MnSiVS) and (c) the 4.125" stroke LSX-454 crankshaft (P/N 19244018) that is advertised as "premium 4340" forged steel.For premium crankshafts, AISI-4340 nickel-chrome-moly steel has been used for decades (and still is). Although the LSX-454 is an iron-block engine, therefore suitable (weight-wise) only for some very special case applications such as the Stewart-S-51 (and similar) which NEED a heavy engine for empty CG purposes, it is noteworthy that the 4.125 inch stroke LSX crankshaft is somewhat alarming with regard to anything except occasional use.With its 4.125" stroke, 2.100" rod journals and 2.560" main journals, this crank has a crankpin overlap of only 0.268 inches and a CPO cross-sectional area of only 0.195 square inches, compared to 0.519 inches and 0.519 square inches respectively for the LS-9 crank. It is also noteworthy that this long-stroke, small journal crankshaft has no center counterweights.The LS-7 alloy 44MnSiVS is a precipitation-hardening steel 0.42-0.47% Carbon, 1.3-1.6% Manganese, 0.5-0.8% Silicon and 0.1-0.15% Vanadium) with good tensile and yield properties (159 / 87 ksi) and has the advantage of lower production costs because of precipitation-hardening instead of traditional quench-and-temper.I have not been able to specifically determine the material used in the LS-9 forged steel crankshaft. However, based on (a) a GM publication describing the engine and (b) on the huge power and torque that engine produces, I would guess that the material is the micro-alloyed precipitation-hardening steel used in the LS-7 (discussed above) or a better one.The GM specification document specifically mentions a "micro-alloyed drop-forged crankshaft". The "micro-alloyed" steels are precipitation-hardening products that were developed to provide a high-strength alternative to conventional quenched-and-tempered crankshaft alloys. One fatigue test I reviewed shows the "T4" micro-alloy having a 10^7 life at 66 ksi in a rotating beam test (fully-reversing stress cycles). Eliminating the Q&T and subsequent straightening processes, while at the same time achieving excellent material strength and fatigue life, could be a significant production cost saving.The flywheel bolt pattern on the LS-9 engine has 9 bolts to deal with the massive torque that engine produces; the LSA, LSX-454, LT1, LT4, LT-5, and LT-376 have 8 bolts; ALL others have a 6-bolt pattern.A more detailed discussion of crankshaft engineering and production can be found HERE.CONNECTING RODSThe LS-7 and LS-9 engines use forged straight I-beam titanium conrods that have very modest cross sections. There is a further discussion of these titanium pieces in the LS-7 section below.All other LS and LT engines use powdered metal straight I-beam conrods that have a fairly small cross-sectional area and polar moment of inertia (resistance to bending deflection).PISTONSThe LS-9, LSX-376, LSX-454, LT-4, and LT-5 engines use forged aluminum pistons; ALL other LS / LT engines (as far as I can determine) use cast hypereutectic aluminum pistons.The forged pistons used in those listed engines are forged 4032 aluminum alloy. Certainly these forged productions are superior to the castings used in the other LS engines. However, the premium piston alloy 2618, developed for aircraft engines by Rolls-Royce during WW-2, is a far stronger and more ductile alloy, and is the one I use in any of my designs.The drawback to 2618 is the fact that it has a substantially greater coefficient of expansion than does 4032, so it requires greater piston-to-wall assembly clearances. Because 4032 does not expand as much as 2618 during the rise to engine operating temperature, an engine using 4032 pistons can be built with much lower piston-to-wall clearances, thereby eliminating the (slightly) annoying piston slap noise during warmup. In an aircraft application, I think the substantially greater strength and ductility of 2618 far outweighs a little noise during warmup.FURTHER OBSERVATIONSBased on considerable experience in engine design, component analysis, engine building and engine testing, it is my considered opinion that cast crankshafts, forged crankshafts made from inferior material, and cast pistons DO NOT BELONG in an aircraft engine. That being said, a LIMITED case MIGHT be made for the LS-3, discussed below.FWIW, I have never built a V8 or V12 aircraft engine that did not have:a. A crankshaft made from either 4330-M (manganese-silicon-chrome-nickel-moly-vanadium) or from 4340 (manganese-chrome-nickel-moly) premium, VAR steels. (The chemistry of those premium steels, and other crankshaft materials, can be seen HERE.)b. Premium 4340 steel H-beam connecting rods, andc. forged or billet 2018 alloy ("Rolls-Royce aluminum") pistons.In fact, my new 125-HP O-200 Replacement uses those same premium materials.On the subject of engine power, look carefully at the factory dyno curves (reproduced below) and keep in mind that a reasonable MAXIMUM takeoff engine RPM for a 3.622" stroke engine is around 4900 (for for 2960 Ft/Min mean piston speed). If the stroke is 4.000", (LS-7) then the MAX takeoff RPM will be 4500 (3000 ft/min).So that "430 HP" LS-3 or that "505 HP" LS-7 engine that you are drooling over will, in reasonably-configured aircraft service, be limited to 390 / 400 takeoff HP respectively and 300 / 340 cruise HP (sea level standard values).Also keep in mind that at 10,000 ft MSL, the sea-level-standard power figures will drop to about 74% of their stated sea-level / standard values.CURRENTLY AVAILABLE ENGINES of POTENTIAL INTERESTLS-3The GM LS-3 crate engine (GM Part Number 19301326) frequently comes up for discussion as a candidate for a lightweight liquid-cooled aircraft powerplant. The LS-3 weighs less than 390 pounds complete (less flywheel, alternator, and accessory drives). Those in favor of its use believe it might provide reasonable reliability and power in the factory configuration.The graph below shows the power and torque curves for the stock LS-3, 6.2 L (376-CI) engine.Note that the power peak for the LS-3 is 430 HP, but that power level; occurs at 5900 RPM. Keep in mind that the engine is tailored for high-performance street vehicles (and for the ability to advertise 430 HP).At 5900 RPM, the mean piston speed (MPS) is 3561 fpm. It is interesting to note that every aircraft piston engine designed to operate at sustained mean piston speeds over about 3000 fpm have been short-lived. We have demonstrated with previous engines that mean piston speeds (MPS) of 2900 and 2600 FT/MIN for takeoff and cruise respectively are reasonable for extended life, all other things being correct.Because of the relatively flat torque curve (shown above), a stock LS-3 MIGHT make a reasonable aircraft powerplant IF IT IS LIMITED to operation at substantially below peak available power. I say that because, despite the automotive load model components in this engine, there are RUMORS that GM randomly pulls samples of these engines from the production line and runs endurance tests on them, subjecting them to 100 hours on a dyno at wide open throttle (WOT), cycling between max power and max torque. IF that is the case, then this engine MIGHT work if the suggested limitations are imposed on its operation. NOTE: that statement is pure speculation on my part --- I have NO DATA whatsoever to support it.And, keep in mind, the engine uses a cast iron crankshaft (instead of the high-grade Nickel-Chrome-Moly steel used in certified and high-performance engines), powdered-metal, straight, thin I-beam connecting rods (no comment necessary), cast aluminum pistons, and a plethora of other components designed for the automotive engine load scenario.If the takeoff and cruise RPM are constrained to 4900 and 3900 respectively, the engine provides a respectable takeoff power of about 390 sea-level, standard HP (4900 RPM = 2958 FT/MIN mean piston speed) and about 310 sea level, standard HP for max cruise (3900 RPM = 2354 Ft/Min MPS).However, it is important to match the maximum propeller speed and power absorption capacity to a takeoff engine RPM of 4900. For the 390 HP range, a propeller which can turn in the vicinity of 2600-2700 RPM MIGHT be suitable (see Selecting the Right Propeller).The ratio required for 4900 / 2700 is about 1.814. With that ratio, at 3900 engine RPM, the propeller would be at 2150 RPM. Using the selected ratio, examine your propeller performance curve to see how well it will operate with the available power at the propeller RPM provided by the selected cruise RPM and reduction ratio.And don't forget the effectiveness of the propeller governor at cruise RPM. Hydraulic prop governors have a LIMITED range of effective speeds.HOWEVER, before running off to buy an LS-3, take a close look at the Engine Conversions section of this site, especially the page titled Evaluating a Conversion.Bottom line: does 390 HP justify a powerplant package in excess of 750 pounds?LT-5 EngineThe LT-5 is listed in GM literature as: "OUR FASTEST CRATE ENGINE EVER", and "...THE MOST POWERFUL ENGINE EVER OFFERED IN A CHEVY PRODUCTION VEHICLE". And the baseline power output of 755 HP (at 6400 rpm) would seem to support those claims. The curve below shows the (impressive) power and torque curves for a box-stock LT-5.Examining the (reproduced) factory dyno curve above, it is noteworthy that the torque curve for this engine exceeds 650 LB-FT from 3000 RPM to 6000 RPM, and the peak power is 755 HP at 6500 RPM.This engine is an evolution from the LS-9 and LT-4 supercharged engines, with more evolutionary improvements. It retains the well-proven 4.060 bore and 3.622 stroke engine dimensions, for 376 cubic inched (6.2 liters).This engine uses a drop-forged crankshaft made from premium micro-alloyed steel, that incorporates the 8-bolt flywheel attachment flange. The pistons are forged 4032 aluminum (discussed above), but the conrods are an improved powder-metallurgy product (more on that later).The lubrication system is dry-sump, and requires the addition of a suitable oil tank and oil system plumbing (which must be added to the installed weight calculation for the powerplant). The lubrication system includes oil jets that spray cooling oil onto the bottom of the pistons.This engine uses an improved, higher adiabatic efficiency Eaton 4-lobe helical supercharger that displaces 2.65 liters per revolution. The supercharger also has improved bypass valve technology and a 95mm throttle body for less restriction in the inlet side of the supercharger. The charge cooling system has enlarged heat exchangers with almost twice the capacity of that on the LT-4, in order to sustain a well-cooled intake charge at continuous high boost operation. Of course, suitable charge coolant pumps and air-to-coolant heat exchangers will be required on the vehicle to produce that desired effect.As part of the Gen-5 family, it uses direct fuel injection fed by a sophisticated 3-lobe pump run off the camshaft, with eight supplementary fuel injection nozzles in the intake ports to support the fuel flow required for the very high output, while at the same time keeping the main (direct) injectors sized so as to provide good low-flow response and accuracy. It also incorporates the well-proven variable valve timing and selective cylinder deactivation features (although I do not see much usefulness for cylinder deactivation in an aircraft application).The following picture shows a view of the LT-5, copied from one of the GM web pages.LT-5 Complete EngineIn a sensible aircraft application, the LT-5 MIGHT be successful with the imposition of a takeoff limit of 4500 RPM, which provides 600 HP, and a cruise of 3600 RPM that produces 500 HP (at WOT). Those are very impressive numbers, and are well below the max stress / power the engine is advertised for.Katech Engineering is a major development company that does a significant amount of high performance work for GM. In 2019, they did a torture test of the LT-5 to examine (a) how much power it could reliably produce, and (b) when it broke, what would give up first. That video can be seen HERE. The important takeaway is that, using the stock OEM bottom end components, they managed an amazing 1486 HP from the engine without breaking it. When they tore the engine down after that series of tests, they discovered it was just about to grenade, and the parts that were giving up were - - - the powdered-metal conrods.But that really says a lot for the OEM engine. It had well over 100 dyno pulls at 1200 HP and above. Again, dyno pulls are NOT THE SAME as extended operation at full throttle at one RPM.It is very interesting that, after making some baseline dyno test runs (to verify factory numbers), they did some MINOR modifications (replaced the OEM exhaust manifolds with a proper set of tube headers, used 104-octane racing fuel, and re-mapped the spark and torque curves to take advantage of the better fuel. The impressive results are shown in the following graph, compared to the box-stock engine.LS-9 Engine (discontinued)The LS-9, discontinued in 2017, is a remarkable supercharged 6.2 L (376 CI) engine with all manner of special componentry and some very clever engineering. The torque curve exceeds 550 LB-FT from 2700 RPM to 5600 RPM, and the peak power is 638 HP at 6500 RPM, as shown in this plot of factory power and torque figures for the LS-9.As mentioned above, this engine uses a forged steel crankshaft from a premium micro-alloyed material and forged aluminum pistons. The conrods are titanium, discussed further in the LS-7 section below.As with previous discussions, aircraft usage of this engine should be limited to about 4750 RPM (takeoff) for 529 HP, and 3750 (cruise) for 425 HP.GM has provided a fairly-complete summary of the engine features HERE, which also contains the following picture of an older version of this engine.LS-9 Complete EngineThe following chart shows a comparison between the LS-3, LS-7 and LS-9 power and torque curves.Note that for the high-power supercharged LS-9 engine (and for the current high-power supercharged LT-4 and LT-5 engines), GM abandoned the problematic 4.125" bore of the LS-7 block, opting for a 4.065" bore (stronger, straighter cylinder walls and a thicker cylinder liner).They also improved the crankshaft (over the LS-7) by using a forged steel 3.622" stroke crankshaft with a CPO of 0.519 inches and an overlap cross sectional area of 0.516 in², and provided a flywheel-attachment flange having nine 11-mm attach bolts in place of the standard six bolts(and 8 on a few).I have been unable to definitively establish the material used for this crank, but based on the power and torque numbers the engine produces, I am guessing it is the same or similar to the LS-7 crankshaft material discussed above under LS CRANKSHAFTS.As discussed in the introduction, the LS-9 uses forged pistons in 4032 alloy. As detailed above, I much prefer the superior strength and ductility of 2618 alloy forged pistons. Those superior properties far outweigh a little additional piston slap noise during warmup.The LS-9 also uses forged titanium conrods (discussed below in the LS-7 section), 6-bolt cross-bolted steel main bearing caps (instead of the cast iron in other engines) and a dry sump oiling system with oil squirt jets to cool the pistons. (The dry sump system means that the weight of an oil tank, de-aerator, and appropriate plumbing must be added to the powerplant weight tally.)The supercharger is an Eaton helical 4-lobe positive displacement unit which moves 2.3 liters of air (STP) per revolution, and can flow as much as 2844 kg/hour at a pressure ratio of 2.38. It provides reasonable compressor efficiency, with the map showing a peak island claiming 72% isentropic efficiency, and a very large island showing 65% or more, but at maximum performance, the efficiencies hover between 55 to 60%.This line of superchargers incorporates a clever bypass system that eliminates most of the supercharger drive power when boost is not required. At max boost, however, this blower (according to the manufacturer) can consume as much as 107 KW (144 HP).Keep in mind that the power to drive the blower is IN ADDITION to the power delivered to the flywheel, so that means (a) greater loads on the engine internals, (b) greater heat rejection requirements, and (c) substantially higher fuel specifics (BSFC).Eaton 2.3 Liter 4-Lobe Helical SuperchargerThis supercharger is driven by a micro-V belt from a pulley on the nose of LS-9 crankshaft. The belt is shared with the coolant pump and HX pump, and the pulley centerline is quite far forward on the crankshaft snout, thereby applying a large fully-reversing bending moment to the small snout at high power operation.That belt drive is perhaps a bit worrisome with respect to long term reliability under high power transmission (aircraft) usage. The upside is that if the belt fails, the engine will still operate naturally-aspirated but at substantially-reduced power. The downside is that the coolant pump will no longer operate, so the engine operation timeline is VERY limited.The LS-9 intake system includes a very clever liquid-to-air intercooler that is sandwiched between the blower outlet and the intake manifold inlet. It is very compact, and probably suitable for most automotive applications. In the automotive installations, the vehicle includes a separate nose-mounted air-to-liquid heat exchanger (HX) and a pump that circulates the coolant from the intercooler to the forward HX and back.That means that, in automotive usage, the entire charge of coolant is just above ambient air temperature most of the time. When a burst of full throttle usage occurs, the intercooler depends on the short-term heat absorption capacity of the coolant because the HX capacity is not capable of sustained removal of the heat of compression transferred by the intercooler. So for a sustained high-power application, the installation would need to provide a larger air-to-liquid HX and MAYBE a larger HX pump to handle the steady-state cooling requirements of the intercooler.I have not found a definitive weight for the LS-9, but starting with the known LS-7 figure of 390 pounds, then adding in (an estimated) 20 pounds for the alternator and accessory drive components, and (estimated) 80 pounds for the supercharger, intercooler, intercooler coolant pump, intercooler HX, dry sump oil tank and plumbing, the engine weight is nearly 500 pounds BEFORE accounting for the 110 additional pounds for a propeller gearbox and the flywheel portion of the torsional absorber.So again, you have to ask: Does 525 HP (max) justify a powerplant package in excess of 950 pounds?LS-7 Crate Engine (discontinued)The LS-7 engine became available in late 2006, and was discontinued in 2017. When it was introduced, it represented a new era in factory-crate engines. It is based on the GM Gen-4 LS series, with 427 cubic inches of displacement (4.125 x 4.000) and its own special block, crankshaft, rods, cylinder heads and valves.The block and heads are all-aluminum. The ports and combustion chambers are CNC-machined and provide very high flow numbers. The crankshaft is forged-steel instead of the currently-popular castings. The conrods are titanium (in an unspecified alloy).; The pistons are castings; The 1.8 ratio investment-cast rocker arms have roller trunnions. The engine has 2.20 inch titanium intake valves, 1.61-inch sodium-filled exhaust valves, and a dry-sump oil system.Techniques which were previously limited to custom engine shops are used in the production of this engine. For example, the final honing on the (special) block is done with deck plates torqued in place and with the main caps installed and torqued. Each engine is assembled by one technician, who signs the worksheets. Each engine is test-run at the GM engine factory before shipping.The following graph shows the factory power and torque curves for the LS-7 engine.Again, note that the impressive 505 HP occurs at 6300 RPM, and with the 4.000" stroke crankshaft (which has a rather low CPO value), 6300 RPM is a MPS of 4200 FT/MIN.Applying the sensible (long life) MPS numbers (4500 RPM - 3000 FPM for takeoff - - - 3800 RPM - 2533 FPM for cruise) for this engine (discussed in the introduction), the more realistic sea-level-standard power numbers are 400 / 317 HP for takeoff and cruise respectively.The blue lines in the graph below shows the stock LS-7 torque and power curves compared to those of the LS-3 (green) discussed above.The following details of the LS-7 engine are presented as a matter of general interest.As pictured below, the engine weighs about 390 pounds, but (as pictured) it has no flywheel, no accessories, and no accessory drive system. Further, this engine has a dry-sump oiling system, which requires the addition of an oil tank and appropriate plumbing, all of which increase the impressive-sounding 380 pounds and must be taken into consideration in the airframe weight analysis. (NOTE the lovely standard, hydroformed, double-wall stainless steel headers).LS-7 Engine (Nearly Complete)This picture shows the roller rockers and the special intake ports used in the LS-7 head. The LS-7 head design has been rolled over to 12 degrees (LS-2 and 6 are 15°), the intake ports have been raised and reshaped from the familiar "cathedral" shape of the earlier LS family engines. The LS-7 uses special, 1.8 ratio investment-cast roller-trunnion rocker arms. The exhaust rocker is in-line, but the center of the pushrod socket in the intake rockers is offset about 0.300" to the right, which tilts the intake pushrod enough to clear the wider intake port. The new intake ports flow in excess of 340 CFM. (For comparison purposes, the best of the Gen-1 small block heads we developed for our 500 HP engine flowed about 320 CFM while maintaining an excellent velocity profile).LS-7 Cylinder Head - Intake SideThe heads have 2.20-inch titanium intake valves and 1.61-inch, hollow-stem, sodium-filled exhaust valves (for substantially-reduced valvetrain effective mass), and beehive valve springs which avoid some of the problems associated with focused spring resonant frequencies.The LS-7 has a forged steel crankshaft. The early versions were AISI-4140, and the later versions are 44MnSiVS, a precipitation-hardening alloy. Note the absence of center counterweights.LS-7 Forged Steel CrankshaftThe LS-7 crankshaft design has issues with respect to sustained, High RPM, High-Load usage. First, as the crankshaft picture above shows, the center main bearing has no counterweights on either side. That causes a cyclic bending problem across the center main, since at TDC / BDC on both banks, the center two cylinders are applying loads to the crankshaft in opposite directions, which add together to produce a much larger bending load across that center main bearing.The problem is made worse by the low crankpin overlap (CPO) provided by a crank with a 4.000 inch stroke and the relatively small main and rod bearing journals (2.560 and 2.100) discussed earlier in this article.The next picture shows the LS-7 piston and connecting rod. The pistons are aluminum castings (by Mahle) in an allegedly hypereutectic alloy, and provide the engine with a static compression ratio of 11:1. The narrow, straight I-beam connecting rods are made from a titanium forging. I have been unable to determine the titanium alloy used. I asked several highly-placed GM sources, but none would reveal the alloy.LS-7 Titanium Rod and Cast Aluminum PistonRegarding these titanium rods, I have the following suspicions:a. Despite their being advertised as a "feature" I think they are required in order to get the engine to balance - - - in addition to lightweight (TI) rods, the production crankshaft needs tungsten slugs in the front and rear counterweights to balance as it is;b. A high quality set of 8 custom titanium 6al-4v conrods costs roughly 1/3 the total cost of the LS-7 engine, so the material used in the production engine is definitely questionable,c. The small I-beam (shown in the picture) is unsuitable for an aircraft application in a quality STEEL alloy (based on a lot of design and FEA work on conrods), so the use of a material in a small-beam conrod having 60% of the Young's Modulus and a much lower tensile and yield strength than quality steel is an eyebrow-raiser.When I mentioned to one very knowledgeable GM Racing Tech that the reason for my deep interest in the LS-7 was the potential use in an aircraft, he said he would DEFINITELY recommend replacing the OEM TI rods with a stout set of aftermarket steel H-beam rods (although he would not reveal the TI alloy in subsequent pointed questioning).The LS-7 has a dry-sump oiling system with an internal two-stage oil pump (pressure and scavenge) driven off the nose of the crankshaft (same location as the single-stage LS-1 / 2 / 3 / 6 pump). The scavenge pump has approximately 1.5 times the capacity of the pressure pump. The oiling system also includes eight oil-squirt jets, that spray oil onto the underside of each piston and onto the cylinder walls as well. That carries away a substantial quantity of heat from the pistons under high load.An additional issue with this engine (in aircraft service) is the fact that with the 4.125 inch bore in an aluminum block with 4.400 inch bore spacing, the minimum spacing between adjacent cylinders is 0.275" (just a bit over 1/4"). That spacing determines the thickness of the two adjacent press-fit cylinder liners AND the available aluminum structure needed to support those liners.GM discovered early in their production process on this engine that maintaining an acceptable bore straightness and roundness was problematic. They spent a lot of money to solve the problem in production, but there is a strong suspicion that in severe service (aircraft) the cylinder shape would again become a problem.It is interesting to note, in that regard, that the current generation of high-performance production LS / LT engines is limited to a 4.065" bore.For all the exotic equipment and specifications this engine has, I am somewhat disappointed by the relatively low 11.6 bar BMEP (168 psi) which the stock engine produces. That modest BMEP is probably the by-product of the optimizations required for modern automotive applications, including (a) NVH requirements, (b) emissions requirements, (c) fuel economy standards, and (d) the extremely wide-range of operating response and flexibility which modern engines must provide.In order to provide a naturally-aspirated version of an LS-based aircraft engine producing 500-hp at a mean piston speed less than 3000 fpm, we determined that several of the internal parts of the LS-7 engine would need to be replaced in order to achieve both the required performance and in pursuit of adequate reliability.It is my current opinion that a stock LS-7, in normally-aspirated form, limited to 4500 RPM for takeoff (400 HP at sea level) and 3900 RPM for cruise (330 HP at sea-level), and operated exclusively on a diet of 100-LL avgas MIGHT POSSIBLY be used as a reliable aircraft powerplant. That is only an opinion, and I have no (ZERO) test data to back it up.The reason I think the stock engine should be limited to avgas is that the high 11:1 static compression ratio and sustained full-throttle operation near peak torque will produce very high cylinder pressures which will invite detonation on mogas.The ECU strategy for dealing with detonation is based on the occurrence of transient events, and is handled by removing spark advance until the incipient detonation subsides. That is fine for an automotive application during a transient, but that strategy causes EGT to rise dramatically, which is not terribly good for exhaust valve life.Although the LS-7 is a remarkable production engine, the crate engine is quite expensive (GM factory list price in 2017 was around $14,000). The base cost of the engine, coupled with the limited availability and the extensive modifications needed to transform it into an aircraft powerplant with the performance and reliability we require, make it less interesting as the basis for a 427 CI engine. The same effect can be achieved at a lower cost by purchasing the required components at the beginning, rather than spending a huge sum for a crate engine and then subsequently replacing many of the expensive parts.And again, does 420 HP justify a powerplant package in excess of 750 pounds?One More ComparisonFor the sake of completeness, I am including the following quick comparison of performance between the three LS engines presented here and the EPI Gen-1 Aircraft V8. This EPI engine (no longer available) was tailored to aircraft operation - - sustained high output at a max mean piston speed of 3000 fpm (15.2 m/s) with the use of extremely high quality components and carefully designed camshaft, valvetrain, combustion chamber, intake and exhaust system properties.As shown in the following graph, the EPI engine was designed to have a "peaky" torque curve, especially suited to aircraft usage. It produced peak torque (593 lb. ft) at 4250 RPM, and then fell off quickly as RPM increased. That produced a naturally-aspirated peak power of 501 HP at 4500 RPM (3000 ft/min MPS). Note that the power also falls off rapidly above peak.Compare that to the LS-7 for example. In order to get 505 HP, the engine has to turn 6300 RPM at a mean piston speed of 4200 fpm (21.3 m/s). That, like most high-performance automotive engines, is too high for sustained aircraft operation.Engine Performance ComparisonThe Bigger IssueA major issue with these engines is the fact that all the LS engines are electronically controlled by a dedicated computer system (aka Engine Control Unit, or ECU). That system (computer, sensors, injector solenoids, spark coils, and wiring) completely controls the engine's fuel delivery and the spark timing, and a host of other variables as well. Many of the newer engines have "fly-by-wire" throttles (no direct connection between the gas pedal and the butterfly). Although the level of control provided by these systems is remarkable, there remains the problem of reliability, fail-safe operation, and the question of "What do I do when the engine fails (or even hiccups) at when the engine fails (or even hiccups) at when I am 300 feet off the ground on takeoff at Vx ?"For a more detailed look at converting engines for aircraft usage check this link.Aircraft Engine Conversions by EPI Inc.

Sweet Home (Korean: 스위트 홈; RR: Seuwiteu Hom) is a South Korean webtoon written by Kim Carnby and illustrated by Hwang Young-chan.[1] First published in Naver Webtoon, the webtoon ran for a total of 140 chapters plus one prologue from October 12, 2017 to July 2, 2020.[4][5] It centers on a suicidal high school boy who, along with a group of fellow apartment residents, tries to survive a "monsterization" apocalypse (goemulhwa)[a] where people turn into monsters that reflect their innermost, most desperate desires.[6]The webtoon is the second collaborative work by Kim and Hwang, the first being Bastard (2014-2016).[6] As of January 2021, its official English version garnered 2.4 million subscribers and 15.2 million likes.[7][8] A print version of Sweet Home was released since February 28, 2020 by Wisdom House.[2][9][10][1][3] It has also been adapted into a Netflix series of the same name which was released on December 18, 2020.PlotPrologue, Chapters 1-38After his family died in a vehicular accident, suicidal high-school boy Cha Hyun-soo[b] moves into Room 1410 of an apartment called Green Home. Strange things soon begin happening to him and to the people around him. He starts hearing a voice talking to him despite being alone in his room. A week into his loner life, he learns of people having nosebleeds, such as the security guard and his girl neighbor from Room 1411, and people hearing voices, such as an anonymous person in a game chatroom claiming the "voice" is goading him to murder his own parents. One night, he witnesses through his video door-phone the Room 1411 girl transform into a human-eating monster.Two days later, Hyun-soo realizes the world around him has fell into chaos as people turn into monsters in what the Internet calls a "monsterization" apocalypse (goemulhwa).[a] Downstairs, the residents, led by Lee Eun-hyuk,[c] fend off the first monster from outside to attack the apartment, a blood-sucking monster[d] with a long proboscis-like tongue, but not before it claims its first victim. Despite hearing voices inside his head once again, Hyun-soo fights against an eyeball monster[e] after it caused a man rappelling down the building from Room 1210 to fall to his death. Room 1408's Han Du-shik manages to subdue the monster with his makeshift gun, and he pushes Hyun-soo into rescuing the Room 1210 man's children, 9-year-old Kim Soo-young[f] and 6-year-old Kim Young-soo.[g] Du-shik tells Hyun-soo to come to his room and to use his phone as a monster tracker: if he makes a phone call and hears a beeping noise, it is a sign of a nearby monster.Hyun-soo and his electrified spear in a scene from Chapter 17After escaping from a blind half-headed monster,[h] Hyun-soo heads out to Room 1408 along with his weapon, a makeshift spear with a knife as a spearhead. Du-shik modifies the spear so that an electric charge passes through the knife and Hyun-soo can both stab and shock a monster. Hyun-soo encounters the half-headed monster, a huge muscular monster[i] and an liquid monster[j] before he manages to reach Room 1210 and extract Soo-young and Young-soo. While heading back to Room 1408, Hyun-soo manages to resist an attempt by his inner monster to monsterize him but their trip is interrupted by the muscular monster. The battle against the monster separates Hyun-soo from the kids and ends as Room 1510's Yoon Ji-soo (armed with a baseball bat) and Room 1506's Jung Jae-heon[k] (brandishing a long sword) intervene and rescue him.Ji-soo becomes wary when she learns that Hyun-soo is already suffering from the monsterization process but she dispels of her distrust upon Jae-heon's encouragement. Soo-young and Young-soo become trapped in the midst of a fight between the muscular monster and the half-headed monster. When the muscular monster wins the melee, it turns against the children. Just in time, half-monsterized woman Im Myung-sook[l] defends the children against the monster. Hyun-soo, Ji-soo and Jae-heon comes to her aid and manages to send the monster away.After staying for a day at Room 1408, Hyun-soo, Ji-soo and Jae-heon decide to join the survivors in the ground floor; the trio entrusts Myung-sook, Soo-young and Young-soo to Du-shik. In a battle against a tentacled monster,[m] Hyun-soo is struck by a tentacle and is knocked out. While unconscious, his inner monster gives him a taste of a parallel world where Hyun-soo's desire—watching his best-loved film Maria From the Sky[n]—is fully met. Sensing that he is just inside a hallucination, Hyun-soo rejects his inner monster's temptations and finally wakes up. By his side are Eun-hyuk and his younger sister Lee Eun-yoo:[o] he has survived the battle against the tentacle monster and reached the ground floor.Chapters 39-85[edit]A meeting is convened in order to discuss whether or not they must expel Hyun-soo for being in the process of monsterization. Eun-hyuk suggests resolving the issue through voting, telling the group that indiscriminately expelling Hyun-soo would be tantamount to murdering him. The voting results in a tie; when an imperious elderly man Kim Seok-hyun[p] expresses objection, his nose bleeds, a sign of the monsterization process.Later, Eun-hyuk asks Hyun-soo and a gangster-like man Pyeon Sang-wook[q] to extract the survivors in Room 1408 so that they can take advantage of Du-shik's technical skills, especially for converting a car into an armored vehicle that the survivors can use in gathering supplies from outside the apartment. Hyun-soo becomes angered at Eun-hyuk who secretly tells him to leave the children behind when the situation worsens. While Hyun-soo and Sang-wook leave the ground floor for the mission, Eun-hyuk tells the indignant Ji-soo that Hyun-soo's half-monsterization can be the survivors' weapon against the monsters. In Room 1408, Myung-sook finally succumbs to her inner monster but her strong desire to be reunited with his lost baby turns her into a harmless, giant fetus monster inside the bathroom.(From left) Yoo-ri, Gil-seop, Hyun-soo and Sang-wook in a scene from Chapter 58Hyun-soo and Sang-wook encounters a long-armed monster[r] which grabs Hyun-soo, breaking his wrist. To Sang-wook's surprise, Hyun-soo electrocutes the monster despite also getting the shock himself and his wrist heals within minutes. The duo run into the tentacle monster and inadvertently cause it to evolve into a stronger spider monster.[s] An elderly man Ahn Gil-seop[t] (armed with Molotov cocktails) and his caretaker Park Yoo-ri (armed with a crossbow) come to their rescue and fend the monster off. A speedy track-and-field monster[u] interrupts their journey to Room 1408 and knocks Yoo-ri and Sang-wook out; Hyun-soo faces the monster alone while Gil-seop proceeds to Room 1408. Hyun-soo sets a trap and successfully burns the monster alive while his half-monsterization causes his injuries to heal by themselves within minutes.Hyun-soo and Sang-wook return to the ground floor with Du-shik while Gil-seop, Yoo-ri and the children remain in Room 1408. Du-shik fixes one of the apartment's elevators which will be used instead of the stairs in going through different levels of the building. But restoring the elevator inadvertently leads to the monsterized security guard, which gets stronger after every murder, reaching the ground floor and killing a few survivors, including Jae-heon. The shock of seeing Jae-heon's dead body makes Hyun-soo's inner monster to temporarily manifest. Upon regaining control, Hyun-soo stabs the blood-sucking monster's tongue, which breached the barriers, at the security guard monster which loses all of its fluids and dies. Gil-seop, Yoo-ri, Soo-young and Young-soo use the elevator and reunite with Hyun-soo and the survivors in the ground floor.A team consisting of Hyun-soo, Sang-wook, Ji-soo, Gil-seop and Yoo-ri successfully reclaims the underground parking lot from the monsters. While Du-shik finishes creating the armored car, another team consisting of Hyun-soo, Sang-wook, Gil-seop and another survivor Byung-il is commissioned to gather food from a nearby convenience store and medical supplies, particularly inhalers for the asthmatic Yoo-ri, from a nearby hospital. The party's mission fails as the muscular monster, which has evolved into a stronger form, attacks the armored car and kills Gil-seop; Byung-il escapes from the scene. Eun-hyuk and the other survivors prepare to step out of the apartment to help Hyun-soo and Sang-wook when a prison bus suddenly arrives and drives into the muscle monster, killing it. Byung-il emerges from the bus accompanied by a group of outsiders, the first four recognized by Sang-wook to be criminals—group leader Shin Joong-seop,[v] con-man Im Hyun-shik, rapist Seo Kap-soo, gangster Baek Ho-yeon, and a young man Jo Yi-hyun.Chapters 86-111The Green Home survivors are forced to take in the outsiders; tensions rise as the outsiders implement their secret plan to take over the apartment. As Hyun-shik attempts at spreading fear and discord among the Green Home survivors, Joong-seop tries to invite Hyun-soo to join their group and reveals Yi-hyun to be a strong half-monster capable of arm extension. Joong-seop also shows to the survivors his hostility against monsters and monsterizing humans by killing Seok-hyun's battered wife Ahn Seon-young[w] and commanding his group to burn the harmless liquid monster. Yi-hyun defeats the spider monster, while Hyun-soo is forced to kill the aspiring celebrity Ryu Jae-hwan[x] who turned into an attention-seeking monster.As the criminals assumed superiority, Green Home survivors Son Hye-in, Sang-soo and Ji-eun joins their side. The pain of killing Jae-hwan drives Hyun-soo to join the criminal's side much to Ji-soo's frustration. After not sharing any plans to the criminals, Eun-hyuk is locked up with Sang-wook, with Sang-soo guarding at the door. Eun-hyuk reveals to Sang-wook that he actually has a plan that only he and Du-shik knows; his nose starts to bleed and he faints. Du-shik is forced to reveal to Joong-seop a large box containing what appears to be a rope made of a chain of clothes; when Joong-seop dismisses it, Du-shik is relieved. He reveals to Byung-il that the rope is over 100 meters long and has a grappling hook attached in the end.Hyun-soo battling against fellow half-monster Yi-hyun (in the foreground) in a scene from Chapter 101On Joong-seop's orders, Hyun-soo and Yi-hyun search the upper levels of Green Home for other monsters. By letting his inner monster communicate with Hyun-soo's, Yi-hyun discovers the giant fetus monster in the Room 1408 bathroom and, controlled by his inner monster, intends to kill it. Hyun-soo battles against Yi-hyun to defend the fetus monster and manages to knock Yi-hyun back to his normal self. Hyun-soo and Yi-hyun goes to Room 1408 to check on the monster and, to Hyun-soo's shock, discovers in its place a human-sized cocoon-like structure. Hyun-soo deduces that the thing is alive when he hears its heartbeat. Fearing it could be a threat, Yi-hyun tries to destroy the cocoon but his lengthened arm strangely fights back by punching him hard, knocking him out.Ji-soo goes to Room 1408 and finds Hyun-soo who is hesitant to destroy the monster-turned-cocoon. Though she also perceives it as a possible threat, Ji-soo is just as hesitant to destroy the cocoon, and reveals to Hyun-soo about Eun-hyuk and Sang-wook being locked up. Yi-hyun wakes up in his inner monster's personality and tosses a lighter to the cocoon, setting it on fire. All monsters in the vicinity sense the destruction of the cocoon and angrily swarm to the apartment. Yi-hyun leaves the room first to fight against the monsters, while Hyun-soo electrocutes a bat-like flying monster[y] which broke through the window and attempted to snatch Ji-soo.Yi-hyun goes to the rooftop where he apparently sees a naked woman standing on the parapet and battles against the flying monster. Sang-wook escapes from imprisonment, carrying Eun-hyuk with him. Eun-hyuk wakes up and suggests going to the outsiders' prison bus, where they find coolers containing chopped up human cadaver. Sang-wook tries to lure the monsters away from the apartment using the human cadaver as bait and ends up in a grove where four cocoons stand. While in hiding, he witnesses to his shock a naked human being emerge from one of the cocoons.Chapters 112-139As the monsters start to breach the front door barricade, Eun-hyuk returns from the prison bus and calls on the Green Home survivors to evacuate to the second floor. Eun-hyuk goes to the underground parking lot and confirms to Du-shik and Byung-il that they have to implement Plan B: the survivors shall escape from the apartment by launching the grappling hook from the rooftop and using the rope to zipline to a hill 80 meters behind the apartment. Hyun-soo, Ji-soo and Eun-yoo extracts the children, with Eun-yoo using Ji-soo's phone as a distraction for the monsters. Joong-seop and Hyun-sik escape to the prison bus; Sang-wook returns and steals the keys so that he can use the bus to block the front door. He throws Joong-seop to the monsters, one of them disfiguring his face with corrosive fluid and another dragging him into the adjacent woods.Du-shik decides to stay behind due to his impending monsterization and starts a fire, burning the monsters that breached the underground parking lot. Eun-hyuk and Byung-il carry the escape equipment and reunite with the other survivors. Hyun-soo insists on rescuing Du-shik; as Eun-hyuk and the other survivors climb the stairs to the rooftop with the escape equipment, Hyun-soo goes to the underground parking lot, only to find Du-shik dying. A naked man, one of the emergent humans, appears to Hyun-soo, declares "[their] time has finally come," and puts his hands on Hyun-soo's shoulders, instantly triggering another hallucination with Hyun-soo's inner monster.The inner monster reveals the nature of the monsterization phenomena, which he calls a "revolution" and a "new beginning." An inner monster—revealed to be a malevolent form of the host's soul—takes advantage of its host's innermost, most desperate desires. When the host succumbs to the inner monster's calling, the inner monster transforms the host into a monster reflecting that desire while the host's subconscious is held in a parallel world where those desires are fully met ("a paradise of desires"). After the host exhausts his or her desires, they transform into a new human being (i.e. the emergent humans) void of desires and emotions and thriving on a "sense of futility."Near-monsterized Hyun-soo emerges victorious in a fierce battle against monsters in a scene from Chapter 135Hyun-soo firmly decides to stay as himself and continue the fight against the monsters. Du-shik's dead body is resurrected into its fully monsterized form; Sang-wook arrive from the bus with Hyun-sik and kills the monsterized Du-shik. As Hyun-soo, Sang-wook and Hyun-sik rush to reunite with the other survivors, Eun-hyuk's party reaches the rooftop. Ji-soo leaves the group, goes to Room 1510 and uses her bass guitar and amplifier to lure the monsters away from the rooftop, leaving a manageable number that Yi-hyun and the survivors can fight against. Hearing the bass guitar, Hyun-soo lets his inner monster control him and goes to Room 1510 near-monsterized to rescue Ji-soo.After Eun-hyuk and Byung-il successfully install the escape equipment, Eun-hyuk decides to stay in the building due to his ongoing monsterization. The women and children zipline to the hill first using all available pulleys; Hye-in is unfortunately killed by the flying monster. As Byung-il traverses the rope without a pulley, Eun-hyuk, Sang-wook and Yi-hyun join Hyun-soo and Ji-soo's battle against the monsters in the building. They all go to the roof afterwards but their escape from the building is thwarted by the fully monsterized Joong-seop which, in its pre-monsterized state, ironically asked an emergent human to let him be transformed into a monster. The overwhelmingly powerful monster, which kills Hyun-sik and Yi-hyun, reflects Joong-seop's desire to be feared and to take revenge against Sang-wook.Left with no other choice, Hyun-soo makes the ultimate sacrifice by fully succumbing to his monsterization, which turns him into a powerful monster in the form of his favorite character from Maria From the Sky. The monsterized Hyun-soo defeats the monsterized Joong-seop with one blow. Ji-soo tries to communicate with it, but the true Hyun-soo inside the "paradise of desires" responds only faintly to her voice and the physical monster reacts to her with utmost hostility. Eun-hyuk decides also to let himself be fully monsterized in order to subdue the monsterized Hyun-soo. As the remaining survivors brokenheartedly escape the building, Eun-hyuk's monsterization turns him into a large tangled mass that completely covers the monsterized Hyun-soo, killing them both.Soon after, rain falls over the dead remains of the monsterized Hyun-soo and Eun-hyuk. Most of the tangled mass disintegrates and two cocoons materialize; one of them hatches and a new Hyun-soo emerges from the cocoon. He descends the building and, upon reaching the ground floor, he notices Ji-soo's phone which Eun-yoo had used earlier to distract the monsters and is already opened to display a music player app. He picks up the phone and plays an audio file: it is the musical piece that Ji-soo composed and was supposed to have lyrics written by the old Hyun-soo. Strangely, the new Hyun-soo listens to the music and sheds tears.Chapter 140 (Epilogue)Winter, in the post-apocalyptic[z] world—the Green Home survivors live in a military camp. Byung-il, who guards the perimeter, suddenly sees something. Ji-soo is fetched from one of the tents; she rushes to the perimeter and sees the new Hyun-soo clad in thin clothing and walking towards the camp, barefooted on the snow. Upon seeing Ji-soo, the new Hyun-soo smiles teary-eyed. Ji-soo steps out of the camp in tears and hugs Hyun-soo tightly as the other Green House survivors rush out to meet him.CharactersMainThe main characters of Sweet Home. Clockwise from upper left: Cha Hyun-soo, Yoon Ji-soo, Lee Eun-hyuk and Pyeon Sang-wook.Cha Hyun-soo[b]an 18-year-old human turned half-monster who is the sole occupant of Room 1410 in Green Home; the protagonist of the webtoon. Being ignored and treated unkindly by his family, Hyun-soo is a suicidal high-school boy who hates his family and has set a date for his death. After his family died in a vehicular accident, he moves into Green Home apartment and finds himself caught in the middle of a "monsterization"[a] apocalypse. In fighting against the monsters, he uses a makeshift spear with an electrified knife for its spearhead. His strong resistance against his inner monster leads to the inner monster failing to monsterize him completely, turning him into a "half-monster." His half-monsterization endows him with abilities (such as self-heal, resistance to electricity, and superhuman strength, agility and durability) which he uses in battling against monsters. He later harbors feelings for Ji-soo.Yoon Ji-sooa 20-year-old bass guitarist, composer and sole occupant of Room 1510 in Green Home; Hyun-soo's love interest. Ji-soo moved into Green Home after her boyfriend's suicide. Since her room is directly above Hyun-soo's, she disturbs Hyun-soo when she plays the bass loudly. She frequently accompanies Hyun-soo in fighting against monsters, brandishing a baseball bat as weapon. She later harbors feelings for Hyun-soo.Pyeon Sang-wook[q]a 32-year-old ex-policeman and occupant of Green Home. Sang-wook is often mistaken as a gangster, owing to his tall, muscular and intimidating appearance. He uses his brute strength in fighting against the monsters alongside Hyun-soo. He is also in charge of guarding the food and monitoring the rations. It is revealed in latter chapters that he is a former police officer who was dismissed from his job due to excessive use of force. He later harbors feelings for Yoo-ri.Lee Eun-hyuk[c]an 18-year-old occupant of Green Home; Eun-yoo's elder brother and leader of the Green Home survivors. Despite his age, Eun-hyuk became the leader among the apartment's survivors because of his cleverness and competence to lead.SupportingGreen HomeHan Du-shikthe sole occupant of Room 1408 in Green Home. Du-shik lost his left leg after rescuing a child and is bound to a wheelchair. A former engineer and a skilled craftsman, he makes his own weapons in fending the monsters off, makes upgrades to the Green Home survivors' weapons (notably Hyun-soo's spear) and collaborates with Eun-hyuk in planning the survivors' ultimate building escape plan.Jung Jae-heon[k]a Korean language teacher and occupant of Room 1506 in Green Home. A devout Christian, Jae-heon wields a long sword and usually whispers a prayer while battling against the monsters.Lee Eun-yoo[o]an occupant of Green Home; Eun-hyuk's younger sister. Eun-yoo carries with her a lighter and an aerosol spray which she uses in setting monsters on fire.Park Yoo-ria 28-year-old occupant of Green Home; Gil-seop's caretaker. Yoo-ri uses a crossbow in battling against the monsters. She becomes romantically involved with Sang-wook in the latter part of the webtoon.Ahn Gil-seop[t]a 50-year-old occupant of Green Home. Gil-seop is being taken care of by Yoo-ri. He uses Molotov cocktails in fighting against the monsters.Kim Soo-young[f]the 9-year-old daughter of the man from Room 1210 in Green Home; Young-soo's elder sister.Kim Young-soo[g]the 6-year-old son of the man from Room 1210 in Green Home; Soo-young's younger brother.Im Myung-sook[l]an half-monster occupant of Green Home. Myung-sook believes her infant is still alive despite her infant being dead already due to an accident. Her desperate desire to see her infant once again made her resist her inner monster's malevolent power and she turns into a harmless giant fetus monster.Byung-ilan occupant of Green Home. Byung-il brings a group of outsiders to Green Home, unknowing of their identities and their ulterior motives.Ahn Seon-young[w]an occupant of Green Home; Seok-hyun's battered wife.Kim Seok-hyun[p]an occupant of Green Home; Seon-young's abusive husband. Seok-hyun is a typical old-school person who thinks adults are superior over younger people.Son Hye-inan occupant of Green Home. Hye-in is a fearful girl who tends to make rash decisions for her survival; one of the survivors who sided with the outsiders.The security guardthe unnamed security guard of Green Home. He turned into a monster that reflects his hatred towards the Green Home occupants, most of whom have treated him harshly and disrespectfully. As a monster, he gains more weight and strength after every kill.The girl from Room 1411the unnamed sole occupant of Room 1411 in Green Home; Hyun-soo's next-door neighbor. She is a celebrity wannabe who goes to multiple auditions and frequently starves herself. Her monsterization into a starving, flesh-eating monster was the first one that Hyun-soo witnessed during the apocalypse.Ryu Jae-hwan[x]an occupant of Green Home. Jae-hwan is an aspiring celebrity who later turns into an tall attention-seeking monster which causes a very painful headache to a victim who does not give it a positive feedback (e.g. "You're handsome.").Sang-sooan occupant of Green Home; one of the survivors who sided with the outsiders.Ji-eunan occupant of Green Home; one of the survivors who sided with the outsiders.OutsidersShin Joong-seop[v]an outsider who is the leader of the group of criminals. Joong-seop is hell-bent into killing monsters after his entire family died because of them. He is acquainted with Sang-wook.Im Hyun-shikan outsider and criminal who is part of Joong-seop's group; a con-man.Jo Yi-hyunan outsider and half-monster who is part of Joong-seop's group. Yi-hyun has multiple personalities, which leads to his inner monster controlling only one personality and not being able to monsterize him fully. He has the ability of arm extension, in which he can lengthen or swell his arm or transform it into a deadly branching form that he can use to stab multiple monsters at once.Seo Kap-sooan outsider and criminal who is part of Joong-seop's group; a rapist.Baek Ho-yeonan outsider and criminal who is part of Joong-seop's group; a gangster.Notable monstersNote: The monsters contained in this list are those which are already in monster form in their first appearance in the webtoon (the former human forms of some are revealed only through flashbacks or hints given in the story).Blood-sucking monster[d]the first monster to attack Green Home from outside. It is a hematophagous, humanoid monster with a gaping mouth that extends to its chest and has a long proboscis-like tongue which it uses to suck the fluids of its victim.Half-headed monster[h]a blind humanoid monster which became half-headed after Jae-heon sliced its head transversely. It is very sensitive to sound and is capable of arm branching similar to Yi-hyun's which makes it capable of puncturing objects and stabbing humans and fellow monsters at great speed. The monster was once a disgruntled office worker who lost his job.Eyeball monster[e]it has the body of a man with a long, extendible neck and a giant round mass with multiple eyes for its head.Muscular monster[i]appears to be a tall, muscular humanoid monster. It usually mutters the words "protein," "strength" and "muscle"; it is angered when it is teased of being weak.Liquid monster[j]a relatively harmless, non-hostile monster that appears as a mass of transparent slime shaped like a human being with two floating eyeballs in its "head." It is revealed that the monster was once a young boy named Min-cheol who was hiding in a closet when his mother was killed by the half-headed monster. Min-cheol's desire not be seen is reflected by the sentence the monster mutters, "Can you see me?"Tentacle monster[m] / Spider monster[s]a monster that appears to be a human corpse in supine positionwith multiple tentacles shooting out from its back and acting like legs. When Hyun-soo and Sang-wook set it in fire, it douses itself with water through a fire sprinkler and evolves into a spider monster capable of spitting a corrosive fluid.Long-armed monster[r]a humanoid, gibbon-like monster capable of arm extension. It is revealed that the monster was once a man who lived in immense guilt after failing to rescue his son from the monsters, which is reflected in the phrase it mutters, "hold my hand."Track-and-field monster[u]a fast-moving humanoid three-eyed monster which mutters "too slow." It is revealed that the monster was once a track-and-field athlete who murdered his roommate and rival before his monsterization.Flying monster[y]a bat-like monster; the only monster known to be capable of flight.Other characters involved in the monsterization apocalypseThe inner monstersthe malevolent personas that awaken in people and transform them into monsters; the prime movers of the monsterization apocalypse. It is revealed in latter chapters that the inner monsters are the fiendish forms of the souls of humans beings born through the repression of human desires; seeking for the satiating of those desires, they incite a "revolution" through the monsterization apocalypse. An inner monster takes advantage of its host's innermost, most desperate desires and transforms the host into a monster that reflect those desires, while the host's subconscious is imprisoned in a "paradise of desires," a parallel world where those desires are fully met (letting the host turn into an emotionless, desireless human being later on when the desires are finally exhausted).The emergent humansa new race of humans that emerge from cocoons that form from the remains of dead monsters. When a monster dies or after a monster's true persona exhausts his or her desires while being in the "paradise of desires," the monster transforms into a new human being void of desires and emotions and thriving on a "sense of futility."