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post #11 of 21 (permalink) Old 10-31-2012, 11:46 PM
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from the info we received the heavy crank was to help with the drive out of corners to make the engine response less nervous, this year they are using a lighter crank with the better electronics, this is all based on the info we received, as i dont work in wsbk i cant say that we are 100% sure of the info we get, but it makes sense to me after working with this engine
i personally belive that there would be a benefit in a lighter crank and we are looking at about 10% i will post reults when we have tested it early next year
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post #12 of 21 (permalink) Old 11-01-2012, 07:05 PM
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Quote:
Originally Posted by antonn View Post
from the info we received the heavy crank was to help with the drive out of corners to make the engine response less nervous, this year they are using a lighter crank with the better electronics, this is all based on the info we received, as i dont work in wsbk i cant say that we are 100% sure of the info we get, but it makes sense to me after working with this engine
i personally belive that there would be a benefit in a lighter crank and we are looking at about 10% i will post reults when we have tested it early next year
With my limited experience,I tend to agree with your comments.
I have a 2010 light crank bike,I've just sold a 2011 heavy crank bike and have just got a 2012 bike.All bikes similar spec

2010 bike made 203rwhp din
2011 bike made 191rwhp din
2012 bike made 202rwhp din(with only 550 miles on the clock!)and knocks spots off the '11 with 6nm more torque right through the range and certainly revs free-er than the '11.
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post #13 of 21 (permalink) Old 11-02-2012, 02:29 AM
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Originally Posted by antonn View Post
from the info we received the heavy crank was to help with the drive out of corners to make the engine response less nervous, this year they are using a lighter crank with the better electronics, this is all based on the info we received, as i dont work in wsbk i cant say that we are 100% sure of the info we get, but it makes sense to me after working with this engine
i personally belive that there would be a benefit in a lighter crank and we are looking at about 10% i will post reults when we have tested it early next year
I can say with 100% certainty, save your money.

The heavier crank is absolutely critical to stabilize power delivery off the corner and get some rear grip and a little less wheelie. If anything, I'd go heavier. And it has zero to do with reliability.

You can go to a lighter crankshaft with electronics, but not the kind you'll ever get. There's a MotoGP Marelli system ( I have a picture of it somewhere...) that uses an accelerometer to build a 3D model of the bike in real time and perfectly blend power delivery with the beginning of the wheelie. On TV it looks like a mildly floating wheelie that lasts a really long time.

Last I checked, Marelli wanted something like 50K Euro per rider, per year, in licensing fee's and then 250K euro for the equipment and basically you're on your own to tune it.

If you're going to build a crankshaft, do something bad-ass like destroking it 5mm.


EDIT: Also, unless I'm mistaken FIM WSBK rule 2.4.8.10 requires homologated crankshafts with the only weight reduction coming from balancing.

Last edited by dagor6; 11-02-2012 at 02:34 AM.
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post #14 of 21 (permalink) Old 11-02-2012, 07:29 AM Thread Starter
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Quote:
Originally Posted by antonn View Post
this year they are using a lighter crank with the better electronics, this is all based on the info we received,
That's interesting. I'm curious though, was the lighter crank homologated that you know of?

Quote:
Originally Posted by gixerconvert View Post
2010 bike made 203rwhp din
2011 bike made 191rwhp din
2012 bike made 202rwhp din(with only 550 miles on the clock!)and knocks spots off the '11 with 6nm more torque right through the range and certainly revs free-er than the '11.
That's a pretty significant difference. Was that with all other variables equal? Your numbers certainly support antonn's sources if that's the case. HP/torque is a great argument for an upgrade unless the drivability tradeoff is too high as mentioned below.

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Originally Posted by dagor6 View Post
I can say with 100% certainty, save your money.
The heavier crank is absolutely critical to stabilize power delivery off the corner and get some rear grip and a little less wheelie. If anything, I'd go heavier. And it has zero to do with reliability.

EDIT: Also, unless I'm mistaken FIM WSBK rule 2.4.8.10 requires homologated crankshafts with the only weight reduction coming from balancing
According to these guys it was changed for reliability's sake as well, but of course they could be wrong like anybody else. If I recall, there were one or two reported early crankshaft failures, but by no means was it a trend.

If that rule is correct and current, then it conflicts with antonn's sources, and gixxerconvert's results, unless maybe BMW slipped a lighter crank in there and didn't bother to introduce it to the serial production bikes

Last edited by d40; 11-03-2012 at 02:39 AM.
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post #15 of 21 (permalink) Old 11-02-2012, 08:00 AM
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[QUOTE=dagor6;166988


EDIT: Also, unless I'm mistaken FIM WSBK rule 2.4.8.10 requires homologated crankshafts with the only weight reduction coming from balancing.[/QUOTE]

you are correct, balancing is only allowed but you can add or deduct 15% weight in order to reach a racing balance, so you can lighten the crank by up to 15%, and that is the number we were given.
there are a lot of changes we are testing with our spare engines, a light crank is just one of them we are also trying to get a c/r of 15:1 without skimming the head, will post results as soon as we test early next year.
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post #16 of 21 (permalink) Old 11-02-2012, 09:20 AM
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Originally Posted by d40 View Post


That's a pretty significant difference. Was that with all other variables equal? Your numbers certainly support antonn's sources if that's the case. HP/torque is a great argument for an upgrade unless the drivability tradeoff is too high as mentioned below.
2010-full akrapovic/mapped pcv
2011-full arrow/mapped pcv
All on same dyno,same operator,2010 and 2011were back to backed
2012 using the '11 arrow system and re-mapped pcv.

What was interesting was the fuelling needing considerable changes from the '11 map which just shows that installing somebody else,s map(or even dynojets own)is not necessarily the ideal solution.

Of course,it is possible the 2011 bike was a Friday afternoon special!!
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post #17 of 21 (permalink) Old 11-02-2012, 02:43 PM
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Originally Posted by d40 View Post
That's interesting. I'm curious though, was the lighter crank homologated that you know of?
It was present in the 2010 model until june or july. Have to check the EPC, but its in there.
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post #18 of 21 (permalink) Old 11-02-2012, 09:47 PM
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15% could be removed, but it'd really have to look like it was done to balance the crank. You could try removing 20% and say, weighting it back to 15%. But, there's a lot of work done to make sure a crankshaft is designed correctly in the first place. So, I think the rule is probably pretty effective at keeping them weighted normally.

Anyway, this bike definitely does not need a lighter crankshaft. The power is always going to be peaky because it's a large bore.

C/R of 15:1 is no problem without skimming, 16:1's also pretty doable.
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post #19 of 21 (permalink) Old 11-03-2012, 02:31 AM Thread Starter
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Originally Posted by MasterTommy NL View Post
It was present in the 2010 model until june or july. Have to check the EPC, but its in there.
The issue was whether or not BMW went with a lighter crank in WSBK this year, and if so, was it put BACK into production as another member's HP/torque numbers from successive years indicated. Apparently, the answer is no because there is a +/- 15% weight allowance to achieve racing balance per the rulebook, and the member with the wide variance in numbers probably has Friday afternoon bike...
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post #20 of 21 (permalink) Old 11-03-2012, 06:17 AM
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Originally Posted by dagor6 View Post

C/R of 15:1 is no problem without skimming, 16:1's also pretty doable.
other than custom pistons i dont see ant way to reach 15:1, i know cp do custom pistons, the only other way is to skim the block and re-machine the 14:1 cp pistons but i dont really want to do that, what did you have in mind to reach 16:1 without skimming the head?
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