fly_tornado Posted November 24, 2014 Share Posted November 24, 2014 7 4 Link to comment Share on other sites More sharing options...
dazza 38 Posted November 24, 2014 Share Posted November 24, 2014 Other engine manufacturers may as well give up while they are behind. 3 Link to comment Share on other sites More sharing options...
Ultralights Posted November 24, 2014 Share Posted November 24, 2014 i dont think jabiru will get to this level, as they dont have the economics of scale like rotax has building other engines. Link to comment Share on other sites More sharing options...
Kyle Communications Posted November 24, 2014 Share Posted November 24, 2014 What a great video 2 Link to comment Share on other sites More sharing options...
Old Koreelah Posted November 24, 2014 Share Posted November 24, 2014 Stiffy and Ainsworth probably had a fair idea about the scale and quality control of the Rotax operation when they decided to build their own engine. How may of us would have had the balls to do what they did? Give them credit for their energy and enterprise- then lock the old bugger in a shed while younger heads negotiate a future for his company. 1 1 Link to comment Share on other sites More sharing options...
Ultralights Posted November 24, 2014 Share Posted November 24, 2014 yes, the Jabiru engine is still a good engine, and trying to compare it with rotax is a bit of a stretch, especially in light of recent events, Even the Rolls Royce engines fitted to the early B747-400s wernt as reliable as the GE options, for a while, so instead of just banning pax and others flying in roller powered aircraft, CASA suggested a slightly stricter maintenance regime until it was sorted. same has happened with the rolls Royce trents on the new A380's Jabiru, with a little refinement, and small changes, and an understanding of the causes behind their engine issues, can make their engine into a reliable machine, if only casa would allow them breathing space, just changing the maintenance requirements will help a lot, eg, head overhaul at 350hrs etc. removing jabiru from the industry, or killing their market will help no one..... except CASA, Empty skies are safe skies in their eyes... (wonder what they will do with so many staff and no industry left to regulate?) 3 Link to comment Share on other sites More sharing options...
ben87r Posted November 24, 2014 Share Posted November 24, 2014 Other engine manufacturers may as well give up while they are behind. I really don't think conti or lycoming have too much to be worried about to be honest. Link to comment Share on other sites More sharing options...
bexrbetter Posted November 24, 2014 Share Posted November 24, 2014 removing jabiru from the industry, or killing their market will help no one..... except CASA, We should start a thread about that ..... I really don't think conti or lycoming have too much to be worried about to be honest. Not yet. 1 Link to comment Share on other sites More sharing options...
Downunder Posted November 24, 2014 Share Posted November 24, 2014 Great vid...... any random comments about the engine Bex? Design/construction.....(nothing facetious please) Link to comment Share on other sites More sharing options...
bexrbetter Posted November 24, 2014 Share Posted November 24, 2014 I love Bombardier/Rotax engines, they have been doing it a long time and have been doing it very well indeed. I raced a 1974 Can Am 250 2 stroke motocross bike that had 36hp, so far ahead of the other engines of the day that the same engine was still used up until the 1980 model unchanged, and even then it was only changed due more to market trends rather than issues with the engine itself. Me and a few engine mate's drool at the roller big end/plain main bearing crank and wish we had the resources to achieve the same. Upon saying that, some improvements could be made in the area of crank windage, only minor in the bigger picture though. The only criticism is of the whole engine, it's aimed squarely at a culture stuck in the past that demands that this old design is what needs to be offered into the market. In comparison to other Rotax engine models, this is an absolute gutless, overweight antique - but buyer's money dictates the market of course. A market that saw the recent release of a side valve, still trying to get my head around that one. If I set out to build similar, I would likely use a 'dubble underhead cam' arrangement having each camshaft captive in each case half. The use of 2 camshafts would allow better counterbalancing, shorter pushrods/less valvetrain weight and less events on the crankcase split - all for the sake of a couple of kgs. Would look a little like this based on the above Rotax picture ... Link to comment Share on other sites More sharing options...
Downunder Posted November 24, 2014 Share Posted November 24, 2014 I see, but if going duel cams maybe keep moving it out a bit further into a "single overhead cam" (under rockers)? Link to comment Share on other sites More sharing options...
fly_tornado Posted November 24, 2014 Author Share Posted November 24, 2014 Or BMW style ? Link to comment Share on other sites More sharing options...
bexrbetter Posted November 24, 2014 Share Posted November 24, 2014 I see, but if going duel cams maybe keep moving it out a bit further into a "single overhead cam" (under rockers)? Then you have extra weight, extra width and extra cost considerations. Not an issue to me but an issue for marketing. FT, there's many "BMW styles"........... Link to comment Share on other sites More sharing options...
fly_tornado Posted November 24, 2014 Author Share Posted November 24, 2014 Link to comment Share on other sites More sharing options...
jetjr Posted November 24, 2014 Share Posted November 24, 2014 Cool video, I was surprised how small and hands on production was actually, kind of assumed they would make the years production in 2 days on main assembly line. Link to comment Share on other sites More sharing options...
facthunter Posted November 25, 2014 Share Posted November 25, 2014 The BMW engine is very wide because of the head height as the short skirt pistons and rods arrangement is as compact as you can get. A lot of this is not quite "right" for an aircooled aero engine. This particular motor relies a fair bit on oil taking the heat away, but is unlikely to get the type of loads in a bike that it does in an aircraft. Build an aero motor from the ground up to get it right. Nev. Link to comment Share on other sites More sharing options...
bexrbetter Posted November 25, 2014 Share Posted November 25, 2014 Ok FT, that one. That's a surprisingly Japanese way to go about things for the Germans, kind of answering a problem that no one asked then expecting brownie points. They would have been better off with hi-cam in block (double underhead cams as I explained) but the marketing department would have turned their nose up at retaining a pushrod design, but in the BMW's case they really do have a practical width and high CoG issues to overcome. Link to comment Share on other sites More sharing options...
Downunder Posted November 25, 2014 Share Posted November 25, 2014 Can't say I've liked chain driven cams ever since my Vf750FD.............That and the 16inch front....... This is the go...... Link to comment Share on other sites More sharing options...
facthunter Posted November 25, 2014 Share Posted November 25, 2014 IF you are going to aircool a cylinder head you can't close the rockers in a great big cover that allows no air through . You don't see many done better that the Wright J-5 Whirlwind of about 1930 for fin design and even cooling. They went to lot of development using paints that changed colour on reaching certain temps. Like a "G" meter they read the highest figure reached. Sorry I don't have a thing to attach but Lindberg used a similar engine in the Ryan he did the record cross Atlantic run to Paris. Wikky would have a reference to the motor. Nev Link to comment Share on other sites More sharing options...
bexrbetter Posted November 25, 2014 Share Posted November 25, 2014 Can't say I've liked chain driven cams ever since my Vf750FD............. Oh come on DU, the VF750D and the 1000 to a lesser extent, would put anyone off camshafts and chains for life! What a dog. And also a period of time that Honda should have been taken to task with all their camshaft failures throughout their whole range, cars also, as well as the XR250D that some idiot in Honda decided could have teenagers thrashing it all day long in the bush using just 1.2 liters of oil for the entire engine/gearbox lubrication and cooling system .... that worked out well ..... not. IF you are going to aircool a cylinder head you can't close the rockers in a great big cover that allows no air through . Your post is hard to accept when there's been a couple of billion highly successful SOHC aircooled motorcycle engines made since the 1960's and still being made to this day. Single cylinder through to 6 cylinder with high specific power outputs. Couple of billion, with a 'b', is not a typo. Link to comment Share on other sites More sharing options...
facthunter Posted November 25, 2014 Share Posted November 25, 2014 Sure but I did mention the suitability of using this type of head in an AIRCRAFT aircooled in a related post.. Billions of motorcycles have nothing to do with it. Motorcycles rarely hold high outputs for more than seconds, unless you are on a salt lake.. People see a pushrod operated motor as Passe They are still the lightest and most compact and for engines that don't rev above 4,000 rpm,adequate . Nev Link to comment Share on other sites More sharing options...
bexrbetter Posted November 25, 2014 Share Posted November 25, 2014 Motorcycles rarely hold high outputs for more than seconds, . Name a Japanese motorcycle since the 70's that couldn't be held full throttle indefinately. Excepting a VF750D Maybe you have spent too much time in the land of old British crap. People see a pushrod operated motor as Passe They are still the lightest and most compact and for engines that don't rev above 4,000 rpm,adequate . Nev Not the lightest, sidevalve and SOHC are lighter. Sidevalve, also more compact, is a dog and SOHC is wider. 1 Link to comment Share on other sites More sharing options...
fly_tornado Posted November 25, 2014 Author Share Posted November 25, 2014 BMW injects oil onto the pistons and into the exhaust valves. the BMW heads are a serious bit of kit Link to comment Share on other sites More sharing options...
bexrbetter Posted November 25, 2014 Share Posted November 25, 2014 BMW injects oil onto the pistons and into the exhaust valves. the BMW heads are a serious bit of kit The first models of Suzuki GSX-R750 and 1000s were the first serious oil cooled engines although plenty of engines thru history have used oil for cooling underneath pistons and other critical areas. But the Suzuki was a specific and complete packaging of it. http://en.wikipedia.org/wiki/Suzuki_Advanced_Cooling_System They only went to water cooling to combat 'drive by' noise regulations. 1 1 Link to comment Share on other sites More sharing options...
fly_tornado Posted November 25, 2014 Author Share Posted November 25, 2014 the casting BMW use is impressive you can see between the head of the combustion chamber and the valve gear Link to comment Share on other sites More sharing options...
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