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  1. lohring

    Bugatti straight 8 cylinder with blower, design, 3D printed molds, castings , machining, assembly

    It's been done in 1/4 scale. See Bugatti Typ 50 1/4 Scale model Lohring Miller
  2. lohring

    COVID-19 Coronavirus Disease

    It's a good time to work on projects. I've been 3D printing face shields for my office where they're still seeing emergency patients with a few of my younger employees. I started to print masks for my wife's adult foster home workers to protect the patients as well. However, the bed...
  3. lohring

    COVID-19 Coronavirus Disease

    As a dentist in an age range where the fatality rate is between 9 and 10%, I have stopped seeing patients as of now. My office, staffed by younger people, will remain open. We will be screening the forehead temperature of everyone, staff and patients, at the door. It's a crude and inaccurate...
  4. lohring

    which engine to buy/make to run generator for rc ?

    Like I said, these engines are for 1 to 2 meter boats. You can consider the 20 cc Zenoah, but that's still a little big. Our race boats in the 1/2 meter sizes run 7.5 cc engines. Again, what performance are you looking for? Electric drives are much more suitable for this size low speed...
  5. lohring

    which engine to buy/make to run generator for rc ?

    You can get a lot more than 1 or 2 hp from a marine Zenoah, especially if you run a tuned pipe. The Chung Yang is a less expensive alternative. See https://www.gizmomotors.com/online-store/zenoah-g260pum-watercooled-marine-engine The standard belt start attachment...
  6. lohring

    which engine to buy/make to run generator for rc ?

    What size boat are you thinking about? How fast do you want to go? I would pick an industrial weedeater type engine for a 1 to 2 meter long boat. There are lots of commercial hulls and engines available. Lohring Miller
  7. lohring

    Piston ring rotation

    Two strokes use pinned rings to keep the ends from catching in the ports. A long time ago the 23 cc engines we used for racing had two rings. One standard modification was to remove the lower ring for more power. The current engines come with one ring pistons. Lohring Miller
  8. lohring

    Fusion 360 for a beginner

    Since when? I just downloaded the latest version onto a new computer. Autodesk disabled Fusion on my old computer, but it runs really well with a high end graphics card and fast processor on my new computer. It was getting seriously bogged down when handling big projects and especially large...
  9. lohring

    Barr & stroud engine ?

    See http://www.strictlyic.com/ser01.htm for plans. It's at the bottom of the page and was published in their final issue. Lohring Miller
  10. lohring

    Test run on air

    Welcome back. I would be very interested in the details of your new engine. What improvements have you made? Lohring Miller
  11. lohring

    Feasibility of small 4-cycles in practical usage?

    I forgot about pulse jet engines where the reeds are actually in the combustion chamber, but that is still a relatively low pressure and temperature application. Reeds have also been used in four strokes to back up intake valves with a lot of overlap to prevent blow back at low rpm. I still...
  12. lohring

    Feasibility of small 4-cycles in practical usage?

    I don't believe there are any cases of reed valves being used to seal combustion chambers. The crankcase of a two stroke is a cold, low stress area by comparison. Lohring Miller
  13. lohring

    Feasibility of small 4-cycles in practical usage?

    Intake reed valves in two strokes run in the crankcase while in a four stroke they would run in the combustion chamber. They would be totally unsuitable. There a lot of rotary valves that, while leaky, would be simple and suitable. Lohring Miller
  14. lohring

    Help regarding internal gear

    Fusion 360 has alot of gear generation programs available. My free version came with a spur gear generator, but lots of others are available in the app store. Lohring Miller
  15. lohring

    Feasibility of small 4-cycles in practical usage?

    Model aircraft rarely run high performance engines. In that case all the above is true, but these days arguments for electric power make it increasingly rare to run any internal combustion engines except on very large models. Even jets run electric ducted fans in modest sized planes...
  16. lohring

    2 cycle rotary valve engine

    The last words describe the article's content. Be sure you don't include them in the url. Lohring Miller
  17. lohring

    2 cycle rotary valve engine

    This is a little off topic, but I'm in the middle of writing a series on high performance, glow ignition engines. They cover the history as well as the issues that are important for performance. The first parts are below: namba.com/content/library/propwash/2018/october/14/ History...
  18. lohring

    270 Offy

    Thanks for the credit, but my solution was cruder. I believe you will still need to accurately line bore both the seats in the crankcase halves and the bronze bearings. My plan was to make each of the bronze bearings separately and then face mount them to webs in the crankcase. That way there...
  19. lohring

    270 Offy

    Not to be critical, but did you consider using the original Offy crankshaft bearing design with the split crankcase? If you allow a little float it should be easy to align the bearings before firmly bolting them to the crankcase. You could then dowel them in place. Lohring Miller
  20. lohring

    Cylinder bore surface help

    In experiments with a 26 cc racing engine, it was found that the hone pattern made a small power difference. The bore was 34 mm diameter. The cylinder at that time was nitrided steel with a single commercial steel ring. The best power was with a course hone with the peaks smoothed off leaving...
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