Engine Capacity

Bunyip · Mar 8, 2012

I read on David Emmetts (Krops) twitter, discussion between himself, Dennis Noyes and Matt Birt, discussion about the engine size for the Ducati, Honda and Yamaha motogp bikes. It started off with a photo of Rossi,s dash showing a tach going to 19000 rpm, and the concensus was that the engine would have a redline of over 18000rpm for this to be the case. Therefore an engine of just over 900cc would fit the piston speed to generate such an rpm ceiling. Suggestions of either 930 or 907 cc were made. There seemed also to be a concensus that both the Honda and Yamaha had max rpm of 16-17000rpm, leading to the conclusion that they were very close to the 1000cc maximum.

Surely this difference is significant, as the Ducati"s lower torque would reduce its acceleration out of the corners, but should theoretically increase its abilities at corner speed, corner entry and change of direction. Were these things seen at sepang? The ducati had slower lap times, but was it in sectors with straights or tight corners? And of course you generally overtake on the straights, not mid-corner. Now, if Dorna mandates spec ecus for 2013 with max rpm of say 16000rpm, then will Ducati need to completely redesign their engine, whereas Honda and Yamaha can keep the same stroke? Has Ducati just made a monumental error or can anybody see a subtle stroke of genius in there somewhere? I suspect that they have, in attempting to find an "advantage" over the others, may well have painted themselves into a corner. Again........

birdman · Mar 8, 2012

Maybe it suits the tire better? No use having any more power than can be put to the ground. But in the case of a friendly detuned 1000 grunter vs a more highly strung 900 I would take the 1000.

Nuts · Mar 8, 2012

I remember when the retun to 1,000cc was first discussed, there were people who suggested the optimum engine size would be around 930cc to achieve the right power at the righ rev ranges.

Nuts · Mar 8, 2012

And maybe related to optimum power for the fuel limits ??

Mental Anarchist · Mar 8, 2012

I would say that Ducati's list of successful engineering achievements is rather small so I wouldn't be surprised if they have failed to kick a winning goal with engine capacity specs.

povol · Mar 9, 2012

Nuts said:
And maybe related to optimum power for the fuel limits ??

If thats the reason than they are already ....... Yamaha has already done a full race simulation that was 17 seconds faster than Rossi's winning time in 2010 at Sepang. If Ducati gave up 70-100 cc to make it on fuel, they are way behind the technological curve of the competition.

cliche guevara · Mar 9, 2012

maybe theres a special lubricant in the engine that makes the higher revs not go hand in hand with more friction compared to the 1000cc engines, that way they'd get better maneuverabilty with the same fuel efficiency. theres enough power anyways and i have no doubt rossi/hayden are capable of keeping the revs up and marelli to keep a peaky engine under control.

i guess ducati have to think outside the box, who knows, maybe thats the way to stand up to the hondas and yamahas at some tracks at least

Geonerd · Mar 9, 2012

cliché guevara said:
maybe there's a special lubricant in the engine that makes the higher revs not go hand in hand with more friction compared to the 1000cc engines, that way they'd get better maneuverability with the same fuel efficiency.

I'm pretty sure the teams run thin, F1 style oil. How thin is unknown, but weights in the single digits seem likely. Oil film thickness is a function of surface speed and viscosity, divided by the load. Even with high loads, the engine's extreme RPM reduces the need for thick oils. That's one of the reasons the bikes idle at such high RPM; if they turned slower, the oil film would collapse, causing increased wear.

cliche guevara · Mar 9, 2012

Geonerd said:
I'm pretty sure the teams run thin, F1 style oil. How thin is unknown, but weights in the single digits seem likely. Oil film thickness is a function of surface speed and viscosity, divided by the load. Even with high loads, the engine's extreme RPM reduces the need for thick oils. That's one of the reasons the bikes idle at such high RPM; if they turned slower, the oil film would collapse, causing increased wear.

informative post ,thanks geo.never thought about the oil film actually ,i thought the high idle rpms were solely about thecompression.these 4 strokes are just too complicated

its just a wild guess that maybe they have something special that allows them to go that route

mylexicon · Mar 9, 2012

19,000rpm would correspond with 840cc-850cc, assuming mean piston velocity of 26m/s.

The old Ducati rev counter went all the way to 22,000rpm. Ducati actually displayed the rev counter for Dorna's onscreen graphics. Imo, the red line on the dash was about 3,000rpm over the actual rev ceiling of the GP11. The current rev counter is about 3,000rpm above the rev ceiling for an 81mm 1000cc engine.

They are all running 1000cc, imo. Running reduced capacity is a big risk for several reasons. First, if the advantages don't materialize, the manufacturer must build another new engine. Second, the rules are not set in stone. If the formula changes to rev limiting, for instance, a 900cc engine would be useless. Even if they use a rev limit as a safety valve to curb top speed, all participants need to be running on the 1000cc limit. Plus, Dorna want the manufacturers to run 1000cc engines for marketing. If I were Ezpeleta, I wouldn't pay unless they were on the 1000cc limit.

povol · Mar 9, 2012

I wonder if Honda and Yamaha are still using pneumatic valve trains, now that the revs have come down to where its safe to use springs again.Im guessing its still pretty expensive comparably speaking.

Keshav · Mar 9, 2012

cliché guevara said:
maybe theres a special lubricant in the engine that makes the higher revs not go hand in hand with more friction compared to the 1000cc engines, that way they'd get better maneuverabilty with the same fuel efficiency. theres enough power anyways and i have no doubt rossi/hayden are capable of keeping the revs up and marelli to keep a peaky engine under control.

i guess ducati have to think outside the box, who knows, maybe thats the way to stand up to the hondas and yamahas at some tracks at least

Jumkie · Mar 9, 2012

mylexicon said:
19,000rpm would correspond with 840cc-850cc, assuming mean piston velocity of 26m/s. The old Ducati rev counter went all the way to 22,000rpm. Ducati actually displayed the rev counter for Dorna's onscreen graphics. Imo, the red line on the dash was about 3,000rpm over the actual rev ceiling of the GP11. The current rev counter is about 3,000rpm above the rev ceiling for an 81mm 1000cc engine.

They are all running 1000cc, imo.

Running reduced capacity is a big risk for several reasons. First, if the advantages don't materialize, the manufacturer must build another new engine. Second, the rules are not set in stone. If the formula changes to rev limiting, for instance, a 900cc engine would be useless. Even if they use a rev limit as a safety valve to curb top speed, all participants need to be running on the 1000cc limit. Plus, Dorna want the manufacturers to run 1000cc engines for marketing. If I were Ezpeleta, I wouldn't pay unless they were on the 1000cc limit.

Abraham's bike is suppose to be running a 999c. Well, if I remember, it was still unclear if the satellite bikes were going to run different displacements than the factory. However, you may also remember Yamaha tried something similar when the four strokes were introduced and they tried something below a 990cc. Do you remember? I think it was something to do with fuel. But I think since then the electronics have advanced so much so that fuel, though still an issue, is managed by the software. An engine under the 990cc (or in this a case a 1000cc) can make enough power, but in this case, I think the engine rule will make it even riskier to go with something less than the capacity limit. I mean, if Yamaha scrapped the lower displacement then (early 2000s) when this stupid engine rule didn't exist, how much more is it a risky proposition now?

If the factory did go with something much smaller, like a 930cc, it would def be a big risk if it turned out that the corner speed was not fully realized with the new tire vs the torque to compete with the 1000cc Japs since developing a new engine would violate this arbitrary engine rule. Again, Ducati must, as Clishe says, think our of the box. its how they were successful in 07, and with a new formula change, a big gamble might be in the cards.

mylexicon · Mar 9, 2012

Jumkie said:
Abraham's bike is suppose to be running a 999c. Well, if I remember, it was still unclear if the satellite bikes were going to run different displacements than the factory. However, you may also remember Yamaha tried something similar when the four strokes were introduced and they tried something below a 990cc. Do you remember? I think it was something to do with fuel. But I think since then the electronics have advanced so much so that fuel, though still an issue, is managed by the software. An engine under the 990cc (or in this a case a 1000cc) can make enough power, but in this case, I think the engine rule will make it even riskier to go with something less than the capacity limit. I mean, if Yamaha scrapped the lower displacement then (early 2000s) when this stupid engine rule didn't exist, how much more is it a risky proposition now?

If the factory did go with something much smaller, like a 930cc, it would def be a big risk if it turned out that the corner speed was not fully realized with the new tire vs the torque to compete with the 1000cc Japs since developing a new engine would violate this arbitrary engine rule. Again, Ducati must, as Clishe says, think our of the box. its how they were successful in 07, and with a new formula change, a big gamble might be in the cards.

IIRC, the Yamaha capacity was designed around the tires. In the KRJR Soupkast, he said that Suzuki were hopelessly outgunned in 2001 b/c Michelin created a new tire that helped Honda unlock their horsepower advantage. Back then the 500s had 190-200hp? Something like that.

Conventional wisdom at the beginning of the 990cc era was that the bikes could make over 300hp, but the tires could only handle about 200hp. Yamaha toyed with the idea of using less than 990c b/c they didn't think the bikes needed full capacity. The tires developed quickly, and horsepower figures began climbing.

Fuel was 26L until 2005. I don't think Yam were worried about fuel. However, I think the idea of using less than full capacity is as risky today as it was when Yamaha tried it.

Geonerd · Mar 11, 2012

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Well then, Ducati will be set to win the HP war. Uccio should have plenty to spare.

SuperShinya56 · Mar 11, 2012

All should be recuired to run 1,000 cc displacement and work with it as far as fuel is concern.

Bunyip · Mar 14, 2012

Come on Krop. What do you really think is the Duke,s capacity? I am surprised that you have avoided comment to date........

Kropotkin · Mar 14, 2012

Bunyip said:
Come on Krop. What do you really think is the Duke,s capacity? I am surprised that you have avoided comment to date........

My todo list for Jerez includes recording the Ducati to measure the revs. Then I'll tell you. Reports are that they are under the maximum capacity, at between 900 and 930cc, which sounds plausible. The 800s already made plenty of power, benefits of a smaller engine may outweigh added horsepower, without sacrificing torque. But we'll see.

Bunyip · Mar 14, 2012

So Ducati once again is risking a divergent strategy to gain an advantage, but the downside is that it could very well become a disadvantage. Good in theory , but will probably be as successful as the Greek treasury.

And that is not even factoring in all the re-engineering needed if/ when a spec ecu/ rev limit comes in.

David, what is the take on this form your paddock colleagues? Or are you all waiting for further confirmation, before offering opinions on the wisdom of this strategy.

BarryMachine · Mar 15, 2012

I wonder if the new Duc. engine layout has any bearing on the decision to go to a sub 1,000 capacity ?

I know its no much, but maybe they are pushing it so fine the physics of a 1,000 is too large.

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