SteveH

I've been reading a few old bike magazine articles and there was something about 'big bang' on a yamaha? Think its where 2 cylinders fire at once (central pair) then the other 2 (outer pair). There wasnt much info on it, and I was wondering if anyone knows anything about it? Are there advantages/disadvantages?

Mark Shead

The firing was stagard close together to change the pulses through the rear tyre which helped traction.

Mark

glancy2081

as mark has stated above

philram

iTrader: (3)

might find this interesting.. http://blogger.xs4all.nl/daisy/archi...24/355605.aspx

SteveH

cheers!!

westus1

iTrader: (6)

remember something about this from a while back, i'm sure it tried to shake itself to bits, wasn't very smooth at all

markk

iTrader: (2)

it was alot more complexed than it sounded, but would love to try one in a turboed car engine to see what torque it could have on a peak basis

AlexF

I still can't see how bigger bangs - which will create more torque - can possibly IMPROVE traction.

Alex

SteveH

Alex, that article explains it very well, its about loading and unloading the tyre with spaced out 'pulses' of power, rather than a smooth band.
Its very good, check me out educating people. I wish

AlexF

No I can't see the scientific logic behind that articles argument.

Bigger less frequent pulses are more likly to overwhelm the limited grip avaivble surely?

SteveH

I'm not sure. Totally see your point, I was thinking the same, but it was on about how the newer tyres let go in a very sudden manner and it gives the tyre time to recover between pulses, and the rider can feel more of the action. The bit at the end about radios made it click for me

Mike Rainbird

iTrader: (3)

Mountune tried this some years ago and the engine suffered too much from excessive vibrations.

SteveH

Mike, say I wanted to try this (i'm not going to, just fascinated really) would it be a case of having cams made up to pair up the cylinders, and altering the firing order?

Mike Rainbird

iTrader: (3)

Yep. That's how they did it on the bikes .

AlexF

At say 12,000 RPM you are getting 200 Revs/sec.

Every revoultion of the engine 2 cylinders will fire together.

Thats 200 BIG bangs per second - or 1 bang every 0.005 secs = 5mS intervals.

How the does he think a rider can feel that?

Alex

AlexF

You would do - its inherantly imbalanced which will kill power and reliability.

On a motorbike engine your dealing with much lighter components so there are much reduced forces - but the same disadvantages remain.

Alex

SteveH

Fair comment, but would it not be 100 bangs per second as its a 4 stroke? Either way, you would have twice the frequency if it were a screamer would you not?

Chip

iTrader: (3)

You dont gain torque on average through the cycle, so would see no change on any dyno graph (as it is a smooth curve, it doesnt show your torque rising and falling during individual strokes of the engine anyway.

very bad idea IMHO, especially as you will need a massive exhaust housing to allow the gasses out all at once from 2 cylinders.

philram

iTrader: (3)

no problem.. the new 2009 r1 road bike is fitted with a big bang engine. i know yamaha tried it in the bsb a few years ago aswell, but the engine wasnt designed to be a bang engine like the new one..

Chip

iTrader: (3)

Ps

would be good for early spooling of a turbo though of course!

SteveH

Very interesting... i know a lad with an 08 model, might have to ride his then hop on a 2009 one for myself...

Garage19

Honda went big bang with their 500cc two stroke moto GP engines ages ago. Their lap times came down and the other teams employed sound engineers to analyse the exhaust note and find out what they had done.

Rossi's yamaha moto GP bike has run big bang for the last 4 years.

Its something to do with being able to feel/find the limit between grip and spin better.

So yes, moto GP riders can feel the difference.

AlexF

One stroke = 180 degrees

one rev = 360 degrees

Alex

SteveH

Yep, sorry, my bad

Wasnt trying to be picky or anything, i Just wasnt quick enough.

AlexF

Nah thats ok mate - I double checked it before I wrote it down thats all...

Had discussions on other forums about the subject before and came to the conclusion that most of the articles written are bollox BUT there must be somthing else that I'm not considereing as it makes the bikes faster.

Alex

SteveH

As I understood it the bike make less power, but they get the rideability out of them somehow. Still dont quite get the traction thing since you pointed it out though.

One thing it may explain is why we have seen a rise in bike powersliding in recent years. If they do have more control and feel, they are able to approach limits more easily.

pa_sjo

I think one of the older Renault F1 cars was a 'banger'.. maybe 2000 or so.. can't remember now, but sounded raucus!

Mike Rainbird

iTrader: (3)

Steve,
Buy the November issue of Performance Bikes, as Yamaha have just productionised a "big bang" engine (well a "long bang" one, with a staggered crank and a 270, 180, 90 then 180 firing order ) in the form of the latest R1 . There are details in there on how this works .

For those that are interested they are saying that the reason for the increased grip is that at 100-120mph and with just a 180° firing order, there is a power pulse every 10cm of travel, whereas a big bang has 20cm. This means there is more time for the tyre to recover grip in between power pulses .

joffy

iTrader: (1)

with regards to traction is it better to have one big hit on the rear tyre or lots of little ones?? either way would you gain more traction by running a 12 cylinder engine rather than a four if the tourque/hp was the same, as there would be 3 times the pushes??

Chip

iTrader: (3)

Id say yes, for the reasons you are thinking, but yahama would say no due to the fact the tyre could never settle, and im sure they are right not me

Alps Pacino

the new r1is big bang apparently

joffy

iTrader: (1)

i was thinkin it would be better to do lloads of little taps rather than one big hit (for want of a better way of explaining it) as there would be less force on the tyre at anyone time but the same force on it over one stroke, yamaha must no something we dont lol

Chip

iTrader: (3)

Exactly my opinion too!

Maybe they could spring load the rear sprocket on a really strong spring, so that it takes some of the shockload during the hits too to further smooth the pulse?

Must be some reason that does work though, or they would have done it, lol

I guess ultimately they want as much time as possible with NO load on the tyre, and everything me and you are suggesting actually makes that worse not better, we're focussing too much on what happens during the load, and not in between them.

Chip

iTrader: (3)

So essentially it goes

Small bang, big bang, small bang, no bang

if looking at the engine in 90 degree segments.

interesting!

joffy

iTrader: (1)

Does Anyone On Here Work For Yamaha!!!!!!

Kevin_Mc

i understand what the big bang engine is but fail to see how it can be better but anyway, what is an ever-firing screamer engine?

how does that work?