Member postings for paul Longley 1

The Kadenacy patent engines come to mind whenever two strokes without crankcase scavenging are mentioned. Petter reputedly came across the concept whilst testing the diesel version of their established two strokes with crankcase scavenging, the diesel was test running but with lower power output than previously when it was realised the crankcase inspection door was not fitted. This gave rise to their Harmonic engine range of two stroke diesel naturally aspirated engines. However General Motors threatened legal action as they already held patents for that system, so a settlement was reached where Petter took a license for supercharged two stroke ( linear) inlet in cylinder lower end and exhaust valves in head, as GMC Detroit Diesels were. All this was pre war. Wet case non scavenging two strokes are very long established. The surprise is being a side valve, compromising the combustion chamber shape normally reduces thermal efficiency, but perhaps an affordable penalty for the sake of installation. Certainly, using valves allows a degree of internal exhaust gas retention helping emissions. Perhaps the loss of controlled inlet valves ( allowing variable induction stroke or compression pressure) is made up for by combinations of hybrid transmission allowing the engine to operate at constant load, and the exhaust valves retaining measured quantities of exhaust gas to maintain compression rates with lower induction capacity when required. Certainly an interesting engine.

Just seen an update from an electrical channel I follow regarding electric cars charging, the insurance companies are now saying commercial ( non domestic) ve chargers must be 7.5 meters away from buildings. Yes, seven and a half meters, that makes in town business difficult if not impossible for employees and visitors to top up their electric vehicles 🤔🤔🤔🤔. If that’s the case for batteries in cars, how far away will they want hydrogen parked??

From a truly alternative perspective, just consider for a moment, where would we be now, if there never was public power generation??? What if the ‘country house’ lighting sets were as far as we ever got, the local garage having a DIY generator for wireless batteries. Quite a few technicians or home mechanics created their own sets pre-war. If each household and every business was responsible for their own power production, would the current problem (unintentional pun) be a more simple issue, or a lot worse? On one hand, there’s a few properties here in East Sussex not far from me that don’t have mains supply of any sort, electricity has to be generated by DIY wind turbine, and Lister CS startomatic. Some years ago I read about swimming pools using a gas engined generator for power and waste heat from exhaust and cooling to heat the pool. Also I believe there’s still a tomato producer in Kent running a gas engine from biomass fermentation, the exhaust is piped into the growing area , the engine drives the generator for lighting and supplementary heat and air management.

Wether we use LiFepo4 , hydrogen, or similar, these are just different types of energy storage. Batteries have to be charged, hydrogen has to be created. The principal point is we’re moving the bulk of pollution production to a controlled environment to lessen impacts on our own environment. Cummins engines company are investing billions into developing hydrogen production, storage and supply infrastructure, wether it’s used for IC or fuel cells is for the future. Either way, at the moment it looks like batteries for local and hydrogen for long distance. However we mustn’t forget that in about 1895, everyone was sure that cars for use around town would be electric, and long journeys would be steam cars ( albeit petrol or parrafin fired) but by 1900 IC petrol was dominant. So we shouldn’t assume there’s not another way. Shifting tack a little, on a radio interview a couple of years ago, on the subject of national energy use and emissions, a point was made that replacing all fossil fuel in housing, transportation and industry would require a doubling of our electricity generation, but if we used hydrogen in place of lpg ,natural gas and diesel, using electricity for only cars and light vehicles, then we would need to triple our electricity generation, at that time. Obviously new processes get developed when the demand is sufficient, but a contemporary report also suggested that processing hydrogen from lpg produced 9 tons of carbon for one ton of hydrogen 😖 it was better environmentally to burn the lpg in a vehicle. There’s a lot of work to be done, and what works in one country may not work in others, vehicle development is accelerating, we changed from horses to horseless carriages, I think the next change will be no less subtle 🤔🤔🤔

Certainly looks like there could be pockets in the bar for bearings. Fine if the rolling road is only for one particular model,,,,,as has been suggested, only a call away.

As an a​alternative, you could use eccentrics and con rods, like the early Bentley, or some NSUs. Still need a reduction gear though. Unless you're making an Atkinson type engine of course 😊

Another t​bought occours to me, the successful running of a two stroke engine on gas will depend on the type of gas. The free piston engines made at the end of the 19th century had little in the way of lubrication , they relied heavily upon the lubricating qualities of manmade town gas. Quite a bit of heavy vapour in it. I think there are quotes of having to strip and clean up some parts to return the engine to full power. The slide valves were a problem for some. So, a gas laden with lubricant may not be such an impossible option.

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The s​tepped piston two stroke engine goes back I think to the first war era in some of the submarine diesels. I think the recurring problem was reciprocating weight, most early sub diesels appear to have used dedicated compressor cylinders. I remember seeing on tv years ago, Norton were using their Wankel rotary engines in UAVs as well as their motorbikes to help justify production machine costs. Could be the same firm mentioned above. The company Jenbacher Werke of Tirroll, specialise in gas burning diesels, I found out by accident when researching my 1956 Jenbach diesel ( only a single cylinder type) but again I'm digressing 😵

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The ​Petter, and Kromhout two strokes I'm thinking of aren't diesels. They're hot bulb engines, sometimes called surface ignition, or true spark ignition, as in the Petter little pet, universal, m type, etc. The spark ignition types have a jet in the transfer port, the distance from jet to piston is fairly critical. They use a butterfly or shutter inside the transfer port to control airflow ( to a degree ) The hot bulb types have full airflow, but inject fuel into the bulb ( vaporiser ) at the moment induction starts. The fuel then has time to vaporise, ignition being started by the fresh air charge entering the bulb. As has already been stated, most of the diesels use scavenging pumps, a few such as the Petter Harmonic or the Field Marshall use crankcase scavenging with a virtually constant loss mechanical oiler. But, to return to the point, admitting gas through a jet in the transfer port should be successful. Possibly a shutter in the transfer port to help the mixture proportions. With the shutter at low flow, the air pressure in the crankcase wouldn't get to high, it acts as a rebound cushion for the piston. Minimal air is taken in through the reed valves when the transfer shutter is closed.

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Hi there,​ just read Graham Astburys reply on running a two stroke engine on gas, whilst he's right on the simple two stroke engine, re oil supply, I'd like to add that a large number of two stroke stationary engines ( Petter, Kromhout, etc ) added fuel to the air in the transfer port so avoiding fuel contamination of the crankcase. This is VERY handy, given the risk of crankcase explosion. Most of these engines have a mechanical oiler, as Graham mentioned. Hope this is useful info, regards Paul