Girlie question approaching

A 'screamer' and a 'big bang' engine?



No there isn't a punch line coming, I just wanted to know what the difference was. I've recently read about the different bikes Rossi has been on and they too have mentioned this and just wondered.



To you guys it maybe a dumb question, but, I put to you, isn't it even more dumb to wonder what it is and not ask the people who knows what it is about such a thing?

I know its to do with the firing order of the engine. But that's about as far as my knowledge goes without resorting to Google.

No doubt there will be some members with a more technical understanding that can enlighten us.

Its about the intervals between the power strokes of each of the cylinders. A screamer has its power strokes evenly distributed, which means the rotating parts balance naturally and the engine will produce more power overall and be more reliable. A big bang has its power strokes distributed un-eavenly (is that a word?) which means power and reliability (to some extent) its sacrificed but the engine gives a clearer connection to the rider with the throttle, so is omre driveable.

oooooo, interesting - learn something new everyday. Thank you

So here's another two questions then.



screamer and big bang engine - i surprisngly get it! So the teams have two seperate types of engines to chose from. Now at the start of the year do they have to choose which one and stick with them 6 styled engines for the rest of the year or can they mix it up if a rider thinks some tracks are more suited to a big bang rather than a screamer?



The replica bikes that we all buy (we i mean you guys i aint got one) ie zx10r or r1 what kind of an engine is in that then? A screamer or big bang or a different style?

/\ WHS.



The main benefit of the big bang though is the way it delivers the traction through the rear tyre. Its basically designed to give a number of power pulses before a gap, then repleats that cycle. This way the delay in the power pulses aids traction and how well you get the power down.



Both engines have a different feel though from what I understand.

halfpint said:

oooooo, interesting - learn something new everyday. Thank you

So here's another two questions then.



screamer and big bang engine - i surprisngly get it! So the teams have two seperate types of engines to chose from. Now at the start of the year do they have to choose which one and stick with them 6 styled engines for the rest of the year or can they mix it up if a rider thinks some tracks are more suited to a big bang rather than a screamer?



The replica bikes that we all buy (we i mean you guys i aint got one) ie zx10r or r1 what kind of an engine is in that then? A screamer or big bang or a different style?

Click to expand...

The 6 engines don't have to be the same specification at all. They could all be completely different if the team wanted them to be. However developing multiple engine configurations at once would be incredibly expensive, especially when the software has to be programmed to suit. Additionally the way the engine delivers the power will have an effect on the chassis behaviour and required setup because of the way it induces weight and load transfer, along with the vibrations transmitted through the chassis.



As for the road bikes people buy, i'm not too sure. The newest model of the R1 was a 'big bang' (actually Yamaha's own long bang but i'll group them all together for now) and was the first of it's kind. The new ZX-10 i don't know about, but Lex has been following it as close as anyone around here as far as i know

There's an explanation of Yamaha's Cross Plane (long bang) crankshaft in a promotional video by Yamaha. If you watch this, you get the general idea. Then all you need to know is that firing configurations (the point at which the mixture in each cylinder is sparked) can be rearranged at will, though they all have advantages and disadvantages. And by changing the firing order, you change the noise the bike makes. The screamer makes a much higher pitched noise, the big bang a much lower boom. Think Honda vs Yamaha MotoGP bikes.



[media]http://www.youtube.com/watch?v=UvTXMtTTKQw[/media]

halfpint said:

The replica bikes that we all buy (we i mean you guys i aint got one) ie zx10r or r1 what kind of an engine is in that then? A screamer or big bang or a different style?

Click to expand...

generally all bikes are screamer because they are cheaper to built and have clear advantages in road use where feel for the limit of grip isnt as important as reliability,hp figures for advertising and fuel economy





the only exception is the mentioned new r1 that has received the new big bang

ducatis are the exceptions,a v twin has always irregular firing order!don't sure whether you'd call that big bang but they have the same advantage as a result compared to normal inline 4 screamers because of better grip and feel.



maybe a question for the americans here: I've read somewhere that harley v twins were intentionally changed that both cylinders fired at the same time,like a gigantic single cylinder engine.



how do you do that?that thing would vibrate as hell, my bmw does and it has something on tis crankshaft to counter the extrem vibrations and it still goes like a playstation controler

halfpint said:

A 'screamer' and a 'big bang'

Click to expand...

ooooh, i love it when you talk dirty

I think big bangs are considered only when the engine makes so much power as a screamer that it cannot be used effectively by the tire. At which stage, the the engine is detuned into a "big bang" for better traction control. Since Ducati's electronics appear to be advanced enough to manage the traction for the screamer effectively they are offering both configurations. Yamaha, gave up on the screamer and went the big bang. the father of big bang, Honda, started using big bangs during the 500cc days. Although, I am not quite sure sure what the configuration of the RCV212 is.

OK, here's the pedantic technical answer.



It's all about a characteristic called inertia torque. This torque is caused when the con rods and pistons come to a halt at top and bottom dead center. Each time a piston slow to a stop, it transfers its momentum (inertia energy) to the crank, causing it to spin slightly faster. Then the crank then has to pull on the piston to start it moving again. This causes the crank to slow down a little. On a classic straight 4, all the pistons are coming to a halt at the same time, producing notable pulses of positive and negative energy (rotational speed) in the drive system. This irregularity rises rapidly with RPM to the point that it can travel down the drivetrain into the tire, producing irregular traction and sketchy feedback. On a crossplane I4 (or properly timed V engine), one bank of pistons is coming to a halt as an other is accelerating, This allows the inertial energy to be exchanger between piston pairs, so very little of it escapes the engine.



The old theory, that irregularly spaced power pulses give the tire time to grip, is wrong. At high revs, the inertia torque pulses are actually stronger than the combustion pulses! Firing order is far less important than achieving minimal IT transfer (to the tires).

chopperman said:

ooooh, i love it when you talk dirty

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Right on schedule!

So after watching that video - which was good thanks i'm now trying to marry up the techincal term with the slang. Have I got this right???



Flat plane crankshaft is a 'big bang'

Cross plane crackshaft is a 'screamer' - becuase the video said it was smoother



Am i right. I get both bits but wanna check the technical term with the video - god knows why i aint got a bike and I'm not about to take one to peices and replace and race. Just interested.

halfpint said:

So after watching that video - which was good thanks i'm now trying to marry up the techincal term with the slang. Have I got this right???



Flat plane crankshaft is a 'big bang'

Cross plane crackshaft is a 'screamer' - becuase the video said it was smoother



Am i right. I get both bits but wanna check the technical term with the video - god knows why i aint got a bike and I'm not about to take one to peices and replace and race. Just interested.

Click to expand...

You have it exactly the wrong way round. The cross plane crankshaft (each cylinder firing at 90 degrees) is the big bang engine (though Yamaha call it a long bang engine). The flat plane crankshaft (cylinders firing every 180 degrees) is a screamer.



To put it in terms of the Ducati: The Desmosedici is a 90 degree V4, which has two banks of cylinders at 90 degrees to each other. If the two cylinders next to each other fire together, that would make it a big bang. If they fired 360 degrees apart (a four-stroke fires once every 720 degrees), that would make it a screamer.



In reality, the firing order is a little more complex, as they stagger the firing of a big bang to avoid loading the crankshaft, so the cylinders fire a few degrees apart.

halfpint said:

So after watching that video - which was good thanks i'm now trying to marry up the techincal term with the slang. Have I got this right???



Flat plane crankshaft is a 'big bang'

Cross plane crackshaft is a 'screamer' - becuase the video said it was smoother



Am i right. I get both bits but wanna check the technical term with the video - god knows why i aint got a bike and I'm not about to take one to peices and replace and race. Just interested.

Click to expand...

Other way around.

halfpint said:

So after watching that video - which was good thanks i'm now trying to marry up the techincal term with the slang. Have I got this right???



Flat plane crankshaft is a 'big bang'

Cross plane crackshaft is a 'screamer' - becuase the video said it was smoother



Am i right. I get both bits but wanna check the technical term with the video - god knows why i aint got a bike and I'm not about to take one to peices and replace and race. Just interested.

Click to expand...

think of it this way : big bang fires all cylinders within only a few degrees of crank rotation where as in screamer it always takes 180°.those milliseconds the big bang doesnt fire are used by the tyre to grip again.thats the theory

I dont really care but if you go on Youtube & listen to Stoner's 07/08 bike oh baby thats music to this fan's ears



Scream baby Scream!!

Two Ducati engines.



Screamer

[media]http://www.youtube.com/watch?v=cp6flKZ4z1U[/media]



Big Bang

[media]http://www.youtube.com/watch?v=-LU8LOHSqak[/media]

Screamer oh i know thats the one that sounds like its got a can of marbles rattling around init And scary but when that film was shot you weren't by chance sat next to me thats my laugh even though i've never been to that track



And thanks for clearing it up guys, as soon as i typed it i thought it was the wrong way around. Now be honest who on reckons they know it all about bikes but had a sneek look to cause they didn't know the answer either