Piston as seen using an endoscope
Discussion
poppopbangbang said:
The choice of rockers for valve actuation and small bore/long stroke was key to this.
Cheers, do you believe the rockers/cams were the cause of failures, what was the issue in particular?Can I ask where you are getting your information from and what involvement you have or had in F1, just curious?
Small bore certainly is a big disadvantage, the larger the bore the larger valves that can be fitted, the higher the breathing ability of the head and the more torque it can make especially at very high rpm's translating to more bhp
Pumaracing said:
Might I just ask a small technical question of Poppopfartfart. Do the pistons in your F1 engines generally run an offset pin or a central one? If offset, to which side and by how much?
Central pin in all of our stuff but I can't confirm if the Renault does or not. Haven't had cause to take that apart yet and rather hoping we never do 
Rwdfords said:
Cheers, do you believe the rockers/cams were the cause of failures, what was the issue in particular?
The piston was the main issue. Rockers were just an over complicated way of achieving the same thing which made the engine slightly taller and added another point for concern whilst chasing revs.Rwdfords said:
Can I ask where you are getting your information from and what involvement you have or had in F1, just curious?
Currently work with an ex BAR/Honda guy if you mean regards the Honda package? I'm ex engine engineer, engine support, engine package/installation, engine electronics guy who now works for a private company whos main role is ex F1 stuff. Rwdfords said:
Exactly! air pressure to control valves is the most light weight efficient design hence why it is so popular in F1 and will continue to be unless rules change which is unlikely to happen since it is a key component to making top end high rpm power from low cc
The pity is that the air system isn't road vehicle applicable (at least, without adding a lot of weight) and thus is another of those engineering dead ends formula cars -- and bikes -- charge down.Ducati never owned the patents -- Ing. Taglioni just simplified it, made it production ready on 1950s machine tools. But all the modern expertise is in Bologna.
Can Honda (say) put out a 4 stroke production bike with a red line of 12,000rpm and a 112 mm bore?
Did anyone produce a GP bike capable of revving to the same levels as the Ducatis, even with pneumatic valve gear?
TheRealFingers99 said:
The pity is that the air system isn't road vehicle applicable (at least, without adding a lot of weight) and thus is another of those engineering dead ends formula cars -- and bikes -- charge down.
That's not neccesarily the case. F1 use a total loss system with an air bottle presurrised to around 230bar to provide air to the system pressure regulator which drops it to between 16 bar and 25 bar depending on the required spec. The actual air consumption is tiny (the bottle is around 1 litre) and this could be easily served by an onboard compressor very similar to that use by LR in their air suspension system. Total all up weight would only be 5KG or so additional, maybe less depending on how much weight could be removed from the engine. There has been some technology transfer from F1 valvetrains to road car, specifically low friction coatings and engineering methods to reduce tolerances which have allowed some of the current crop of efficent engines to appear with very low valvetrain drive power requirements. These technologies wouldn't have neccesarily come about without F1 deciding 18K+ was a requirement first.
poppopbangbang said:
Total all up weight would only be 5KG or so additional, maybe less depending on how much weight could be removed from the engine.
In the world of LR, 5 kilos isn't a lot. Most sporting drivers would give an arm and a leg to loose 5 kilos. And no way is it in any functional sense superior to desmodromics. Can't see desmodromics adding 5kg to a car engine! poppopbangbang said:
There has been some technology transfer from F1 valvetrains to road car, specifically low friction coatings and engineering methods to reduce tolerances which have allowed some of the current crop of efficent engines to appear with very low valvetrain drive power requirements. These technologies wouldn't have neccesarily come about without F1 deciding 18K+ was a requirement first.
For sure, there's been some drip down. But had they gone for a "real" engineering solution (or even gone wankel!) it would still have happened. It's fairly widely believed that the Ducati GP engines were safe to 20k, but some caution was necessary in order to avoid a rev limit being imposed. TheRealFingers99 said:
For sure, there's been some drip down. But had they gone for a "real" engineering solution (or even gone wankel!) it would still have happened. It's fairly widely believed that the Ducati GP engines were safe to 20k, but some caution was necessary in order to avoid a rev limit being imposed.
http://youtu.be/qLVp3SOKGJACA06 was reliably doing 20K RPM on 1150KM engine lifes (at 18K in CA10 spec it was over tripple that), I think thats nearly three times what Ducatis 20K GP bike engine was lifed at? Desmo is really an overly complex solution to a problem that doesn't exist. Modern road car engine design relies on emissions compliance and good economy something very high reving engines are not suitable for. Desmo has no more place in a production road car than air valves do for the same reason - no one needs the revs.
I think many people are blind to just how much technology "drips down" from F1 and other very high end motorsports to every day stuff, not just road car but aerospace, medical, communications etc.
This TED talk explains one very interesting link that many will not be aware of:
http://www.ted.com/talks/peter_van_manen_how_can_f...
poppopbangbang said:
http://youtu.be/qLVp3SOKGJA
CA06 was reliably doing 20K RPM on 1150KM engine lifes (at 18K in CA10 spec it was over tripple that), I think thats nearly three times what Ducatis 20K GP bike engine was lifed at? Desmo is really an overly complex solution to a problem that doesn't exist. Modern road car engine design relies on emissions compliance and good economy something very high reving engines are not suitable for.
You're probably right about the life. But generally bike engines are shorter lifed than cars. CA06 was reliably doing 20K RPM on 1150KM engine lifes (at 18K in CA10 spec it was over tripple that), I think thats nearly three times what Ducatis 20K GP bike engine was lifed at? Desmo is really an overly complex solution to a problem that doesn't exist. Modern road car engine design relies on emissions compliance and good economy something very high reving engines are not suitable for.
poppopbangbang said:
Desmo has no more place in a production road car than air valves do for the same reason - no one needs the revs.
I hope no one needs them. Honda may disagree, but......Still, on road bikes, they -- controlled valves -- make some sort of sense if you need (or want) to avoid multi-cylinder engines. Compare the piston speeds of, say, a Panigale with those of Honda's S2000 car.
You'd know: what ever happened to those experiments ( I think it was Hart with hillclimb cars) with carbon fibre blocks?
poppopbangbang said:
This is a TJ engine, you can see the piston design etc. very clearly.
This engine was producing inexcess of 300bhp/litre in qualifying spec, the only coatings used was Xylan on the skirts for friction reduction.
Many interesting things to comment on here. I've already mentioned the obvious high valve lift of circa 0.5 valve diameter.This engine was producing inexcess of 300bhp/litre in qualifying spec, the only coatings used was Xylan on the skirts for friction reduction.
Excellent conrod shape with much wider beam sections than lower revving engines would normally use. Note weight reduction in the area just above the big end pin.
Top ring is well down from the piston crown to avoid the worst of the peak piston crown temperature and any harmful effects of trace detonation.
Conrod little end appears to be laterally supported in the precisely machined piston bosses to complement the big end being laterally supported by the crank flange. This helps prevent rod flutter at high rpm.
Pistons run directly in the aluminium block with presumably a Nikasil or similar hard bore coating. With the block and piston having similar coefficients of thermal expansion this will probably mean very low skirt/bore clearances can be achieved which helps avoid piston slap at high rpm with short skirt pistons. Aluminium pistons in a cast iron block or liners is the norm for road engines but is really a worst case scenario for thermal expansion considerations.
Valve shape is interesting. Even in very downdraft ports I've found that flatter backed valves achieve flow numbers just as good as tulip valves and weigh much less. I wonder if this is an area where even F1 engine designers are missing a trick.
Valve seats appear to be 45 degrees or close to which is very conventional.
Port diameter appears to be circa 0.85 valve diameter which gives an area ratio of 0.72 - sufficient to achieve the maximum discharge coefficients that Annand and Roe achieved on dummy ports.
Note the very thin conrods and consequently thin big end bearings. These will be maybe only 60% to 70% of the width of a conventional 20mm wide road engine bearing to reduce frictional losses.
Edited by Pumaracing on Tuesday 15th April 14:24
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