Quote:
Originally Posted by Tim in Belgium
Well PB have done a scientific test:
1. Test a standard GSXR.... in January on a cold track.
2. Do a BB conversion & BORE IT OUT at the same time.
3. Test the bike produced in step 2 in summer, and if it blows up test again in later summer.
4. Surprise surprise the bigger displacement bike in warmer conditions laps quicker, which proves naff all. It might sound good, it may have extra traction but they proved naff all. Where is the control? Bike journalists doing science? No, never, luckily my bag of salt split all over the magazine on the way home from the supermarket (getting extra traction from my 4wd system which being a boxer is semi big bang) before I could shower it with a pinch...
5. I quite like PB normally until they spout sh1te! Just read 80% of the mag.
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Aye they do compair the two but they never say look the big bang is more powerful... as you said it should be with the tuning. It was the mad tuning (comp ration of 14:1) and a valve being too slow that caused the blow up.
Quote:
Originally Posted by Berlin
If we look at the Dyno graphs of a Curvy 650 versus a K1 GSXR 600 K1 (helpfully overlayed on page 148 of May's Bike mag) we see that they have a fairly similar curves until the SV runs out of puff. The Gixer then goes on to rev through to 107 bhp maintaining the same torque as the SV has. The SV runs out at 68 bhp. So the Gixer is producing about 40% more power for the same torque. I belive it is this that is causing the difference and not a relaxation of power between pulses allowing for grip.
If you rode the Gixer round at no more than 8000 RPM (where the power graphs diverge) what do you think would be the chances of spinning out the rear?The SV and Gixer are developing similar torque and power at 8000 rpm (surprisingly)(~70bhp and ~40 lb.ft. torque. Also surprising is that from 5,500 they are producing about the same. It's only below 4000 where there's a significant advantage to the SV.)
Cheers,
Carl
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I dont think most people would be able to tell the difference in grip...
Quote:
Originally Posted by Berlin
If we increase the torque for the Gixer by making it a big bang engine so it produces the same power and torque graph as that of a 1000 V twin, We'd have a higher ratio or torque to power and most probably better traction. Or the same traction as a 1000 V twin.
I'd be happy to be proved wrong though.
Cheers,
Carl
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You couldnt make a 600 have the same torque/power characteristics as a 1000cc V-twin. Power = torque x revs /5252... basically its the big torque that is the reason a V2 revs less but produces more power than a 600. A 600 revs more as it needs to chase the revs to get the power (as shown with the sum). If you could (simplistic this is) make the SV650 rev like a IL4 600 you'd have the same/more power with the SV.
*Edit* Forgot to mention that making a big bang engine doesnt increase torque by its self.
Also a gixxer 1000 vs a V2 1000cc is like compairing a Sv650 to a IL4 600. A 1000cc V2 has a little more power u until 8K rpm then the IL4 1000 takes off... this is again because the IL4 can rev more easily and so takes off with the power. V2's have more issues with reving... big pistons = more wight to keep stopping and also valve area vs piston area is worse. Very complicated. But thats going off topic.
Quote:
Originally Posted by Pedrosa
Big Bang is a way of extracting more useable power from an IL4 donk. The real alternative to what is sought is the V4.
Rumour has it that the 2008 Fireblade will be the last of the iconic machine, it will be replaced in 2009 by a V4....bring it on!  |
I hope so!!!
Quote:
Originally Posted by yorkie_chris
Lowering the gearing would, for an instantaneos part of it, increase torque, but you still have a narrower powerband which is going to be harder to use well.
And just to throw another factor in, using one gear and getting drive all the way through is going to get more power down than having 'breaks' in the power delivery to shift gears.
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Doesnt increase torque, the engine still produces the same goods, its the drive force that is felt. That is explained well
here.
Quote:
Originally Posted by Berlin
Sooooo! It turns out that Yamaha have different ideas on What the Big bang engine configuration gives in the way of traction.
It turns out that they don't think it's the time that the firing order gives the rear tyre to "regrip" between power pulses.
Its actually due to the mismatch between combustion torque and inertial torque and nothing to do with the tyre regaining grip between pulses!
That (for me) is a lot more believable and based on actual science instead of vague gesswork. After all, they won the world championship using it.
a Big bang engine minimises inertial torque and actually spreads the power *more* smoothly, not less.
Thank you Yamaha.  |
Indeed... Basically they made it fire like a VFR 750/800 to get rid of the inertial torque.
Quote:
Originally Posted by muffles
And the new R1 isn't technically big bang, is it? Thought it had to fire all cylinders at the same time for that. Mr Greek will be along some time to comment on that  |
Indeed your right. It isnt. A true big bang has TINY times seperating pairs of the firing of the cylinders.
Here is a question for you. Ducati went from a screamer to a big bang V4, why is that? V4's dont suffer from the same problems that a IL4 does with inertial torque, so why change it if it doesnt make a difference?
Ive also noticed that the Yams dont have the best drive out of corners, the Honda and the Ducati have it beat on that. Maybe that is the big bang thing vs the inertial torque theory?
All I know is that a M1 Yamaha sounds Ace so does a VFR 750/800 and so will the new R1.