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Big Bang vs Screamer?
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Posted: 11/12/10 06:18 AM
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I have been following the press on the MotoGP bike tests.
The articles refer to the riders choosing between a screamer and big bang engine.
I know that the difference has to do with firing order of the pistons, but what are the advantages and disadvantages of each type of motor?
How does one type fit a particular rider better in terms of riding style?
What production bikes are more like screamers and which ones are more like big bangers?
Ride Proud, Ride Safe, Have Fun.
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kento1
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Posted: 11/12/10 10:20 AM
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The "screamer" firing order is able to put out more outright horsepower on top end, because the "big bang" firing order spaces the power pulses farther apart, which allows internal friction and other issues to rob power (also, a counterbalancer is often required to keep the vibration levels in check, robbing more power). However, the big bang's firing order has better traction feel as you near the limit because its clustering of the power pulses closer together in relation to a revolution of the crankshaft allows the tire time to regain some grip.
The question wouldn't be so much fitting a particular rider's riding style, but more of the engine type suited for a particular track (a rider can adapt to suit, an engine much less so). The screamer would probably be better suited for faster, flowing tracks such as Mugello or Brno, while the big bang would help more at tighter tracks such as Valencia or Laguna Seca.
Nearly all the inline-four sportbikes are the screamer configuration. The latest generation Yamaha R1 is similar to a big bang firing order, but not exactly. Its crankshaft spaces the crankpins at staggered 45 degree intervals instead of evenly 180 degrees apart. The best production example of a big bang firing order would be the old Honda RC30/45 V-4 engine, which clustered a pair of cylinders' firing order close together with each revolution of the crankshaft.
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Beeyouel
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| Posts: 83
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Posted: 11/12/10 01:24 PM
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Why did Yamaha stagger the crankshaft spaces and crankpins at s 45 degree intervals instead of evenly 180 degrees apart? What did they gain, and what did they lose compared to the 180 degrees? Also, isn't the R1 engine a bit heavier because of this Big Bang configuration?
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kento1
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Posted: 11/12/10 01:47 PM
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By staggering the firing order at 45 degree intervals, they accomplished the same improved traction feel at the limit without the massive counterbalancing that would've been required with a closer-firing-order big bang configuration on an inline-four engine. The gains and losses were explained in the previous post, with the exception that yes, the new engine is indeed heavier than the previous generation.
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Trevitt
Administrator
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Posted: 11/12/10 06:09 PM
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The Yamaha's crankpins are staggered at 90 degrees, which gives it firing intervals of 270/180/90/180 as opposed to all 180 degrees. Here is some more info about the Yamaha in particular: http://www.sportrider.com/bikes/146_0812_2009_yamaha_yzf_r1_fz6r/index.html
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kento1
Administrator
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Posted: 11/13/10 10:16 AM
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D'oh! That's correct, not sure what I was thinking with 45 degrees...or if I was even thinking at all.
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Posted: 12/02/10 08:17 PM
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Interesting points related to MotoGP and Yam R1 on the screamer versus big bang firing order. With the MotoGP test at the end of this season we saw Rossi switching over to Ducati and from reports on Motogp.com it appears he mainly tested the Big Bang version of the Duc. Unfortunately due to his injuries and short test period he didn't get to test it too long but it appears he liked the BB version of the engine.
However, based on Kento's points, it doesn't look like there is one best engine version. While the BB version may give a little in the upper rev range it gives up a little in overall power however the control or rideability of that configuration provides may be why it's preferred by some riders.
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shamarone
New User
| Posts: 3
| Joined: 08/11
Posted: 08/12/11 08:31 AM
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i've coined a new term for the R1 engine. i call it "fast bang". technically it's not big bang (although that's a common reference). in some ways it's more "screamer" than even screamers are...? they (yamaha) have a cylinder lighting off every 90 degrees (much like a 180 degree VFR's staccato hence the similiar sound) very "fast and furious" if you ask me. twice as often as a traditional I4. it actually rails against the theory behind big bang and tire recovery. all credit to yamaha for actually making it work. there's something else that mimics this rapid power delivery... it's called the 2-stroke...! i think it's interesting to observe lorenzo's massive crash (sans TC) recently at laguna and his early crashes when he first got on the M1. highside city...! if you think about it, when was the last we saw "hang time" of this degree...? you guessed it, the 500cc 2-stroke era.
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