ptwizz Posted December 26, 2014 Author Share Posted December 26, 2014 Temporary assembly to verify correct balance. The counterweights match the sum of the oscillating parts (rods, gudgeon pins and pistons, I balanced the rings on the pistons for the check). Also a photo opportunity. Quote Link to comment Share on other sites More sharing options...
Guest Posted December 27, 2014 Share Posted December 27, 2014 That is genuinely amazing. I would not have had the patience to make one of those pistons I am sure I have asked before, but what's the CC when built mate.? SW Quote Link to comment Share on other sites More sharing options...
ptwizz Posted December 27, 2014 Author Share Posted December 27, 2014 2300cc. I'm aiming for about 100BHP at 3500rpm. The heads are from a motorcycle engine which develops 18bhp per cylinder, so I think that 100 total (approx. 14 per cylinder) is not unrealistic. What happens when the supercharger is engaged is anyones' guess. I've had a swipe at the boost pressure calculation, but there are so many assumptions that I can't have any faith in the results. There may be some fettling of supercharger gear ratios when it's up and running. Quote Link to comment Share on other sites More sharing options...
Guest Posted December 27, 2014 Share Posted December 27, 2014 You just HAVE to run that down the strip when its breathing nicely!!! Can you run a Nitrous Oxide kit through one of those? SW Quote Link to comment Share on other sites More sharing options...
ptwizz Posted January 1, 2015 Author Share Posted January 1, 2015 Performance is not really my goal here. The supercharger exists primarily as a means of improving mixture disribution between the cylinders. The ability to add some modest boost is a bonus. This week, I have mostly been marking out and machining heptagons. I have also learnt to post the pictures in reverse order so they show up in the intended order. Quote Link to comment Share on other sites More sharing options...
Neilzy Posted January 1, 2015 Share Posted January 1, 2015 Pete are you gonna hold a first run up party I'd love to hear this bad boy start up Quote Link to comment Share on other sites More sharing options...
Guest Posted January 1, 2015 Share Posted January 1, 2015 That can only be a good idea :-) SW Quote Link to comment Share on other sites More sharing options...
ptwizz Posted January 5, 2015 Author Share Posted January 5, 2015 I will let you all know when the first 'public' run will be. I will be making a test stand so that I can take the engine to events (such as the fly-in). Don't expect to see it running this year. Don't get your hopes up for next year either. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted March 17, 2015 Author Share Posted March 17, 2015 Between a new job, starting NPPL training and life in general, I have made some progress with the engine: The first picture shows one of the barrel base plates. 7 of these make up the outside of the crankcase, with a cylinder barrel mounted to each one. In this pic, the plate is bored and drilled but has yet to be machined at the angled ends. The second pic shows the setup for machining the angled ends. These are individually matched so that when everything is bolted together, there is equal compression in all the joints. The third pic shows the crankcase partly assembled with 3 of the barrel base plates machined and one part machined. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted June 22, 2015 Author Share Posted June 22, 2015 More swarf has been created, as I have pocketed the inside faces of the crankcase front and rear plates. Switching into production mode, I made 28 Aluminium Bronze inserts for the locations where the cylinder studs screw into the crankcase. By the Fly-In, I should have it assembled into something that looks like a radial engine. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted June 29, 2015 Author Share Posted June 29, 2015 The crankcase assembly is now fitted with 28 dowels to ensure alignment after dismantling and reassembly. The first picture shows the assembly set up on the mill to finish the main bearing bores. The second picture shows the crankshaft, rods and pistons assembled into the crankcase. This week: Trial fit barrels and heads, fabricate a test stand. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted July 6, 2015 Author Share Posted July 6, 2015 Trial assembly giving an overall impression of the engine. Quote Link to comment Share on other sites More sharing options...
daneellard Posted July 6, 2015 Share Posted July 6, 2015 Engineering porn! Quote Link to comment Share on other sites More sharing options...
Guest Posted July 6, 2015 Share Posted July 6, 2015 Again... WOW!! That is actually amazing dude!! SW Quote Link to comment Share on other sites More sharing options...
Neilzy Posted July 6, 2015 Share Posted July 6, 2015 Not just any old engine porn "Serious Engine Porn" Quote Link to comment Share on other sites More sharing options...
ptwizz Posted July 31, 2015 Author Share Posted July 31, 2015 A view of the engine internals in place with the crankcase front plate and crankshaft timing end removed. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted August 27, 2015 Author Share Posted August 27, 2015 One of the more challenging parts to manufacture is the cam ring. The first picture shows the blank being turned. This a an 8kg billet of EN8 steel which will be a 1.5kg part when finished. The second picture shows the first stage of machining the cam profiles. In this operation, the base circle is being created. I have left the inside diameter of the blank smaller than finished size so that I could drill some small holes at the centres of the various radii which form the cam profile. The cam profile is based on the timings of the Dnepr cam (from the same engine as the heads). I have modified the profile to take advantage of the large radius cam ring and generate near constant acceleration valve motion. This reduces stress on the valve train components and permits the use of softer valve springs. The followers will be roller type, eliminating the need to harden the cam ring beyond the properties of the EN8 material. Quote Link to comment Share on other sites More sharing options...
Guest Posted August 27, 2015 Share Posted August 27, 2015 It all looks sooooo much smaller in the pictures that it actually is !!! I feel a little silly being one of the people who asked in the early days if it was for a Paramotor LOLOLOL fkin thing could power a spitfire!! lolol SW Quote Link to comment Share on other sites More sharing options...
ptwizz Posted August 27, 2015 Author Share Posted August 27, 2015 Unfortunately the power / weight ratio won't be adequate for flying anything modern. At a projected 100BHP output and 120Kg dry weight, it would just about drag a small WW1 biplane into the air. I wouldn't be confident that it wouldn't shit out at 50ft. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted September 9, 2015 Author Share Posted September 9, 2015 Machining the crest radii on the cam profiles and finally boring out the surplus material left in for fixturing. On the wall next to my mill is a sheet of paper with a long list of angles and offsets required to generate the relatively simple cam profiles. I am amazed that I managed to do all of it without a single phuquup! I had planned in some detail how I could recover the part in the almost inevitable event of a major machining error. Next: timing gears. A relatively simple compound planetary arrangement. For complex timing gears, look up the Bristol Centaurus - described as a 2500 horsepower Swiss watch! Quote Link to comment Share on other sites More sharing options...
ptwizz Posted September 16, 2015 Author Share Posted September 16, 2015 Timing gears. The gears were purchased as blanks (i.e. chunk of steel bar with gear teeth) then turned, drilled and bored. Lots of visual result for relatively little work. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted November 4, 2015 Author Share Posted November 4, 2015 I've had a short break from carving large lumps of aluminium and steel. I've spent a while carving small lumps of balsa wood, resulting in this. Thanks to Nielzy. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted November 4, 2015 Author Share Posted November 4, 2015 Back to metal hacking. The largest chunk of aluminium so far at 10-1/4" diameter and 2" thick will become a ring which is located around the cam and supports the tappets. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted February 3, 2016 Author Share Posted February 3, 2016 14 billets of 2014 Aluminium, followed by a series of operations in decidedly Heath Robinson set-ups on the mill. Result: 14 swinging tappets. Each will a needle roller cam follower fitted. Quote Link to comment Share on other sites More sharing options...
ptwizz Posted February 3, 2016 Author Share Posted February 3, 2016 At the limit of the machines capacity, the holes for the pushrod tubes are bored into the tappet ring. Each hole is counterbored to house an O ring seal at the base of the pushrod tube and similar features will be machined into the cylinder heads. Anyone with experience of Meriden Triumph engines will understand! Each of the 7 lugs on the inside of the ring supports a pair of the swinging tappets, whose forked ends overlap. Inlet and exhaust tappets are identical, it is the design of the tappet and the offset created by the overlapped ends which places each tappet in line with the appropriate cam. Quote Link to comment Share on other sites More sharing options...
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