Very interesting - I've never come across that before.
Presumably Fiat have given up trying to perfect their variable valve timing actuator and are trying a new tack.
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What are desmodronic valves then?
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What are desmodronic valves then?
When the valve are opened and closed by the camshaft, conventional valves are opened by the camshafts and closed by springs.
Pneumatics have been used instead of springs in motorsport.
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desmodromic valves - as used by Ducati are opened and closed by a cam.
One cam surface provides the open control, and another cam surface provides the close function. the mechanism incorporates a light spring, just to provide some initial load.
Ducati have used desmodromic valves for many years. Compare the Desmosedici MotoGP V4 against Honda and Yamaha's MotoGP machines, which have gone to pneumatic closure (or Hayden's bike has, I think Pedrosa's bike still uses springs).
Other companies - notably MB - have looked at desmodromic valves, but only Ducati are true believers !
I look forward to seeing more of this multiair.
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Desmodromic valve dispense with the valve-spring and the cam also operates another lever to shut the valve.
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Very interesting - I've never come across that before. Presumably Fiat have given up trying to perfect their variable valve timing actuator and are trying a new tack.
Umm.. do more research, the ALfa 75 had variable valve timing years ago, 100% reliable & long before Vanos or VTEC or any other johnny come lately!
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"highly advanced ?Multi-Air? petrol engines which dispense with a camshaft controlling the inlet valves. In its place will be individual actuators to operate the valves allowing almost infinite control over timing and lift.
Oh no; solenoid operated valves. It's been in the pipeline for a while - I just wouldn't have wanted the Italians to be the ones doing the development work. The Japanese maybe....
They can't be very reliable or Formula 1 would have used them years ago.
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I just wouldn't have wanted the Italians to be the ones doing the development work. The Japanese maybe....
My thoughts exactly. I remember something similar when I found out what the little "Selespeed" badge meant on the back of the Alfa 156....
Maybe the fact the Japanese are quiet on this tells a story in itself. Just like they're quiet on extended service intervals, and were quiet on the common-rail diesel until well into its development cycle. Generally if the Japanese are quiet on something, it's because they're nervous or in two minds, and want to let others cock up first.
I work for a Japanese electronic equipment manufacturer, and trust me, they're no different in this industry either. They might be innovators, but they're also very conservative under the skin.
Cheers
DP
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DP,
Don't have your 'inside' knowledge, but the Japanese have always been good at taking someone else's 95 per cent developed idea and putting the final touches to it.
One example is multi-cylinder motorcycles, first there was the Ariel Square Four and then there was an avalanche of multi-pots from the Land of the Rising Sun.
So I expect the camless Alfa to work in a sort of enthusiasts-only type of way and in two or three years' time there will be a bomb-proof version from Honda.
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I don't think anyone other than Ariel ever attempted a 'square' four. (Prepares to be shot down...) All the Japanese efforts have been in-line or Vs?
The Squariel did sound nice though.
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I don't think anyone other than Ariel ever attempted a 'square' four. (Prepares to be shot down...) All the Japanese efforts have been in-line or Vs?
The Suzuki RG500 was a square four two stroke where as the similar Yamaha RD500 was a V4.
Edited by cheddar on 12/08/2008 at 14:40
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indeed - many different engine combinations have been tried in bikes.
Matchless had a SOHC V4 in the 1930s, there were several inline fours in the 1920s (along the frame rather than across), and Moto Guzzi had a 500cc V8 for racing. There's still a V8 bike available - the 5.7litre Boss Hoss.
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Don't have your 'inside' knowledge but the Japanese have always been good at taking someone else's 95 per cent developed idea and putting the final touches to it.
Yes, they are very risk-averse (or rather very good at having others take the risk for them), but also unbelievably confident and determined when they decide to go for it. The delay is in taking the decision, which will often be signed off at the absolute highest level, and involve the collection of enormous amounts of research for what often seems to be relatively small things. Once that's done, they will throw absolutely every resource at their disposal at it to make it work. And make it work, they do.
For bike engine configurations, Honda's CBX1000 was quite interesting. A litres worth of 24v DOHC straight six slung across the frame. Apparently it's still eerily smooth even by today's standards.
Cheers
DP
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I doubt that the Ariel 4 had any influence at all on the first Honda 4 road bike. A double crankshaft, push rod engine, chain driven separate gearbox, compared to an inline, ohc, in-unit pressure die cast alloy engine/gearbox. There is no common lineage, other than the number 4:) More likely, the MV or other racing fours, or even the 1960's Honda 250's, and the 500 wielded by Hailwood were the inspiration. Incorrect to imply the Japanese needed to copy in the era of the 750 Honda. In earlier days they were certainly influenced. NSU, DKW and Adler were copied. Respectively, the Honda Dream, the Yamaha 125 piston-port two-stroke (may have been based on the Bantam but that was a DKW design!) and the early Yamaha YD1 twin 2 stroke. None of the sub-standard dinosaurs still made by the British figured.
Edited by nortones2 on 12/08/2008 at 17:42
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Early Japanese two strokes were influenced by MZ, MZ works rider Ernst Degner defected from East Germany with a box of bits and sold them to Suzuki, around 1961 I think.
Agree that the production 750/4 etc was not influenced by Ariel, rather it was basically two CB45 (or whatever) engines, more cyls offered more power and more refinement though the CBX1000, Z1300 and Benelli 750/900 took it too far.
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Did the square-four Suzuki racer have two linked crankshafts like the Ariel? Can't have been easy to organise linked pressurised crankcases for a two-stroke?
IIRC the Ariel started out as a 500cc before WW2, grew to 600cc and ended as 1,000cc, but was never a sports bike - best at sidecar lugging.
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Did the square-four Suzuki racer have two linked crankshafts like the Ariel? Can't have been easy to organise linked pressurised crankcases for a two-stroke?>>
Actually easier on the Suzuki square four, which was in effect two twins, than on the Yamaha V4. The Yamaha was the better engine and is considered more of a classic though the slightly later Suzuki had a more advanced chassis with an alloy beam frame.
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You're right Cheddar. The racing Suzuki two-strokes were, certainly. MZ adapted a rotary disc inlet valve on their 125 (same engine derived from DKW again) plus better understanding of the need to use resonance in the exhaust system, to maximise power. Poor Walter Kaaden of MZ: rug pulled out from under his feet! Perhaps not so much the bread and butter machines, except for a few Yamaha (YG1 of 80 cc, and a 125) and Kawasaki engines. Bridgestone had a tasty 350 rotary inlet valve bike, IIRC.
Edited by nortones2 on 12/08/2008 at 20:27
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The square four 250 had two cranks: presumably liked by gear or chain. "Whispering death" was its nickname, due to tendency to seize:) Nasty!
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Bit of a tangent but same subject. Years ago I read about a camshaft drive fitted by NSU (I think), that didn't use belts, chains or gears. I've searched the internet for more info. with no luck !
All I can think of is a sort of connecting rod from crankshaft to camshaft. I get the feeling that the engineering might be steam engine sort off stuff - anybody know ?
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Bevel drive: as used by Kawasaki on their W650:) And by Norton in 1920's. www.supershowevents.com/magazine/articles/04nsu.ht...l
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There is some blurb about Mulit-air on the UK FIAT website:
www.fiat.co.uk/content/?id=10857
This is worth a read too:
www.greencarcongress.com/2007/09/fiat-panda-aria.h...l
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This engine technology will be used in all Fiat Group models sooner or later. In an interview Marchionne has stated that because Fiat now have money they won't be licensing this technology, and have a patent on it, unlike the invention of the common rail diesel, which came at a time when Fiat finances were in a poor state and they had to license the idea out.
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