Comments by "Keit Hammleter" (@keithammleter3824) on "Repairman22" channel.

"Down 2 cylinders" most likely means the mechanic did a standard compression test. It is quite normal for air cooled VW engines to have little or no compression on test on one or more cylinders due to burnt exhaust valves from overheating. But during driving, the power output is nearly normal, as gas finds it hard to escape through a tiny gap. The main symptoms are not lack of power, they include a lot of popping and banging going down hill, being slightly hard to start, and rough idle.
7
It is the same as a normal engine.
6
The fact that it was not put into production by anybody after the patent expired should tell you something. The fact is - it is a dumb way to make an engine. It solves a problem that isn't a problem, and it can't be made on normal block boring and honing machinery. Any one who has completed the first year of an engineering degree can tell you why. In my first year, we had to do assignments on the losses in gasoline engines. Mechanical friction losses (not counting things like water pumps) account for less than 5% of the total. Most of it is in the bearings - the friction loss between pistons and cylinder walls is just a part of the 5%. So there is not much scope for making a noticeable improvement. There is a rule of thumb with modern car-type gasoline engines: 30% of the fuel energy is converted to mechanical energy available at the flywheel, 30% is lost to atmosphere via the exhaust, 30% is lost to atmosphere via the coolant and radiator (this includes bearing and piston friction loss), and the remaining 10% is lost in the oil pump, water pump, fan, and turning the alternator. The lube oil isn't just for eliminating mechanical rubbing - it is for cooling the pistons as well. Clearly, combustion gasses are in contact with the piston - the piston must get rid of considerable heat somehow. It does so by conducting it to the cylinder walls via the oil film between the piston skirt and the cylinder wall and thus into the coolant. In turbo diesels, that is insufficient, so oil is sprayed upwards onto the underside of the piston as well. So if this turkey thinks he can reduce oil supply to the piston he is deluding himself. Anyone who rebuilds worn engines for a living can tell you that cylinder bore wear is mostly not due to mechanical wear. It is due to sulphur in the fuel being converted to sulphuric acid in the combustion process. It occurs fairly evenly around the cylinder. Since the advent of low sulphur fuels some years ago, cylinder bore wear has been markedly reduced.
2
@keithpeterson6108 : This is not apparent in the simulation in this video. As others have posted, piston TDC inherently means the crank pin is positioned to make it so.
2
@keithpeterson6108 : My other post was in response to your post claiming the crank is past "TDC" when the piston is at TDC. Offsetting the cylinder from the crankshaft centre line is sometimes done as it changes the percentage of time the cylinder is in power stroke, but it makes almost negligible difference to engine performance or friction. You have a misconception about how the heat energy in the burnt gases is converted into mechanical energy. It is done by gas expansion as the piston goes down - the fact that the pressure cannot rotate the crankshaft at TDC is of no importance. You might like to look up the "standard air cycle" - a mathematical model taught to engineering students as it explains why raising the compression ratio improves performance. It assumes combustion occurs instantaneously at TDC and that no heat is lost during expansion. Neither is completely true of course, but are both approximately true. The short combustion time (mostly within a few degrees of TDC) is analogous to the "cut off" in a reciprocating steam engine. In a steam engine you get maximum efficiency when the steam valve opening time is kept within a few degrees of TDC, so that power is produced by expansion and not boiler pressure. This is a fact not often known except by engineers, but you can look up "cut-off" for yourself, and if you do, you will understand why arranging for crank leverage at TDC is not a good idea. (Actually, in steam railway engines, the cutoff (ie valve opening time) is made variable. On starting off, the driver lengthens the cutoff - this increases torque for starting due to the extension of time piston sees full boiler pressure, but it considerably reduces efficiency, so as the train builds up speed, the driver shortens the cutoff, reducing steam consumption and thus fuel.)
2
It seems a dumb way to design an engine. To minimise bearing loads you need to minimise conrod mass. This engine has greater conrod mass. Lubrication of all those rocking points would be interesting. For any given gasoline octane rating, there is an optimum cylinder displacement. For standard gasoline the optimum is about 500 cc. That's why we have 4 cyl 2 litre engines and 6 cyl 3 litre engines. And why 500 cc motorbike engines used to be single cylinder, however 2 cylinders gives a much smoother ride. The engine in this video is way too small to operate 4 cylinders efficiently - note the power output is only 75% of a standard engine.
1
@magnusatheos7301 : What compressor manufacturers? Name just one that has it in volume production.
1
@PatricioGarcia1973 Parlà di chì?
1
@jackmcslay : That will work for boring but not honing, and honing requires both rotation and up & down motion of the hone. The hone will have to be a continuous shape-shifter. There's bound to be a way of honing satisfactorily enough by some slow hand process, but not a high volume production process.
1
@Unkl_Bob You watch it again. And do a bit of googling and check your facts. This view goes on about compressors from 4:43 onwards, but no manufacturer is named until Tausem at 5:06. No other manufacturer is named - only manufacturers who looked at it (and rejected it). Tausem is a small volume Argentine compressor manufacturer, pretty much unknown outside Argentina and represented but not very well known throughout South America. Low oil and oil less compressors are made in volume by major manufacturers such as Atlas Copco, using the diaphram type and other methods depending on requirements. It is not in production as an engine. In an engine, oil is needed for piston cooling. Using oil means the cylinder must be honed. In an oil-less or low oil compressor, especially if multi-stage, there is no need for honing.
1
Whoever wrote the script thinks 2-strokes all work the same way as lawnmower engines. Not so. Large 2-strokes used in railway locomotives, truck & bus engines, and ship main engines all use forced induction by an external blower and don't cycle air or fuel/air mix though the crankcase. The design presented in this video seems a daft way to make an engine to me. Principal defects are the difficulty in accelerating the upper piston down fast enough, considerable cam stress, and, given that a conventional engine has less than ideal volumetric efficiency, due to the increased piston speed, the volumetric efficiency in this engine is going to be exceptionally low. If the upper piston seats just right at the right time on the bottom piston so that the bottom piston's rods take the power stroke load, during warmup that won't be the case, due to thermal expansion/contraction. Depending on various factors, that means full power transmitted via the cam, or the pistons destructively hitting each other, or both. However, some of the stated disadvantages given in the voice over aren't true. Eg it is claimed that oil spray cooling of pistons is mandatory, but truck and large engines all use spray cooling anyway. It isn't needed in car engines because a car engine is never run at full power for more than a few minutes.
1
You would need an immense amount of air pressure. The inertia in the upper piston and its conrod is the major issue with this engine. In normal engines the con rod length is kept as short as possible to minimise bearing loads for this reason.
1
@Twiggieh : Yep. Piston is at TDC when the crank throw (ie a line joining the centre of the main bearing to the centre of the big end) and the conrod are in line - this is the point where the distance between crankshaft centreline and the piston is maximum - always.
1
This video is amusing. It mentioned the use of centrifugal and vacuum advance as though they were special features of VW. By the time VW production started, centrif and vacuum advance had been standard in almost all makes for years. I recall the Porsche engine had only centrif advance. The VW engine was a shocking thing, absolute rubbish. It may have been alright in 985 cc form in a little Beetle in relatively cold Germany. Here in Australia, made in 1200 cc form and larger, hot climate, they all overheated. Due to burnt valves, when Beetles were common you would hear them running rough, and when going down hills, continually popping and banging due to unburnt fuel/air mix being pumped into the exhaust. A large company I worked for bought a fleet of 1600 cc Kombis. We typically loaded them to approaching the certified weight limit, as any business would. The result of this commercial service at Australian speed limits was engines ruined in as short as one year. I remember visiting the service garage we had a contract with. Down one side of the shop they had a row of about 20 partly dissassembled VW engines - all showing clear signs of overheating. Because of the boxer layout, the engines when new were very smooth. Drivers used to think they were ok at low revs, and use too high a gear, causing bearing damage. If you kept the revs up high, it would be very noisy, but the engines would last longer. Until about 5-10 years ago you still saw Kombis occaisonally. Survival of the fittest - they all had large external forward-facing air scoops the owners fitted to get more air flow over the engine, to try and keep it a bit cooler. VW scrimped on wiring. It was quite normal to see Beetles at night with one headlight much dimmer than the other. Other 6 volt cars did not show this trouble.
1
@sancharino4672 What makes you think it was running at half the normal RPM? If it was, there could not be ANY power output increase, only a decrease because of reduced volumetric efficiency, and more loads on more bearing surfaces.
1