360 vs 180. Why, and says who?

Lay it out, brothers. Why did Honda change from a 360° crank in their early 80s road and track V4s to a 180° crank in their road engines with the VFR?

How different would a 360° crank VFR be? Better, worse, just different?

Lay it out

 

Cut and pasted:

"Insurance companies noticed the sportbike wars, and when the 1986 VFR750/700F was released, it was no longer called the Interceptor. The new bike was heavily redesigned, and it had lost 49 pounds, as Belinda Carlyle of the Go-Go's was to also do shortly thereafter. A 50% stiffer aluminum frame made of large rectangular tubing peeked out from beneath a sweet new full fairing. (Belinda started wearing bikinis) Graphics were simple and tasteful. But the big news was the engine updates, based on lessons learned at the track. Higher revs were needed for racing, and the streetbike got the cam gear drive of the Superbikes. Precise cam control and reduced internal friction resulted, as well as the signature engine sound that still signals the arrival of a VFR. Each valve got its own rocker arm, as opposed to the forked rockers of old. This drastically reduced the load on the lobe facings. Intakes grew a millimeter, but the valves grew lighter and flowed better with undercut stems. The reciprocating valvetrain mass was further lightened with 33 percent lighter valve springs. Honda went the extra effort to make this assembly durable and routed individual oiling to each lobe.

Intakes were straightened, pistons and con rods lightened, and a 360 degree crankshaft was fitted in place of the 180 degree unit. . This made for improved scavenging in a lighter exhaust system which no longer required a huge plenum chamber and coincidentally yielded a less droning exhaust note. Flywheels were 20 percent lighter. Peak power went up to a claimed 105 hp, torque was up 22 percent, and the whole thing revved 500 rpm faster. The transmission was updated to 6 speeds, and the cases were lightened and cast into a smaller shape. The legendary torqueing motor with such linear response had gotten better."

VFR Article Link

 

Thanks for the post but I believe this is the other way round.

The VF series, along with the NC30, RC30 and kR all had 360 degree cranks (AKA 'big bang') engines.

 

So technically the 500 had a big bang firing order???

 

Yes, the 500 has a 360 degree crankshaft.

 

What you guys will notice if you test ride other gens of the VFR in terms of power delivery the older bikes have toms of mid range power, I wish bonds would take a step back and listen to some of there owners and built a new VFR that doesn't cost a arm & leg and bring us back the gear driven cams a 1000 with a 360° crank that's my soap box and my two cents.

 

What is the difference between a 180 and a 360 degree motor? I grasp that is has to the angular difference between the pistons as they rise and fall. And why use an uneven firing sequence? If you used an even sequence like a V8, the power delivery to the crankshaft would be smoother. I had assumed ( yes I know what happens when we ass/u/me) that it was like half a V8. I was so happy in my ignorance.
I can't quite wrap my head around the firing order /timing /piston motion. Anybody got a "Visible V4 model" I can work it out on?

 

A bit more intel to help visualize the 360 degree crank:


(source for table above: Big-bang Firing Order, Wikipedia)


[video=youtube;gxWj-2MHxUQ]http://www.youtube.com/watch?v=gxWj-2MHxUQ&feature=player_detailpage[/video]
(source for video above: stjepantisljar, YouTube)


(source for post below:Classic VFRs)


MarkJHarris
27-06-2007, 12:39
Time to simplify things folks....

A 180 degree crank is just like a bicycle crank and pedals. One goes up while the other is down. When you apply that to a 90 degree V4, it does get more complicated. But suffice it to say that when the front bank are both half way up their strokes, the rear bank at at TDC and BDC. With a 360, you'd have to take the left crank off and re-fit it so it matches the right side. Try riding it without clips or SDs would be a bit difficult and your tummy would feel it in no time too.

The actual firing order for the 180 engines, i.e. VFR750 and 800 is BangBang...bang........bang you can hear it if you listen. The VFR400R and RC30/45 engines are far more regular in beat, more suited to high revs.

On an RC45 it goes rear left, front right, rear right, front left. BangBang.....BangBang.....BangBang......BangBang.. ...lovely.


(source for post below: BusyLittleShop, VFRD)


Mick Doohan and the Big Bang connection from the pages of MCI
magazine:

Developments of the 91 NSR 500 focused around Doohan testing a number
of designs as HRC shifted their main push behind the new up and
comer... For some while Doohan had been asking engineers to replicate
the wide power band characteristic of the RVF750 4 stroke endurance
bike, which he and Gardner had used to lead the previous summer's
Suzuka 8 Hours... HRC answer was the 2 stroke equivalent of the the 4
stroke Big Bang... technically speaking all four cylinders fried
within 70 degrees to afford the tire more time to hook up...

Consider and instant success by Gardner "Jesus, this is amazing" but
Doohan was a doubter... the 92 NSR droning big bang had a very flat
exhaust note which made it sound slow to riders... It was only during
HRC's final preseason phase that Doohan began to believe in the Big
Bang... He found little difference in lap times but the close firing
order was easier on tires and set up...

Rainey and company were in for the shock as the season kicked off...
Utilizing the Big Bangs ability to find traction where others could
not... Doohan ran away with the first four races... winning by
anything up to 28 seconds wet or dry... The Big Bang proved such a
giant leap forward that rival factories Cagiva, Suzuki, Yamaha rushed
to build copies... having learned the NRS's secret by playing track
side audio recording against an oscilloscope...

There could be no doubt now... Honda now had the best 500 on the grid
by quite some margin... the big bang NRS proved to be a winner in a
variety of hands... Since the 80 when engine HP dramatically
outstripped tire and chassis performance... GP teams had been hiring
tail sliding dirt trackers form America and Australia because no one
else could wrestle these monsters into submission...

Honda only raced the big bang 360º crank... and every V4 they produced
was big bang... but that all changed in 86 with the 180º V4 crank...
Honda was loosing marketing shares to the inline and they split the
crank throws 180 apart to change the pitch from a drone to a scream...
this move sold more V4s but it also muted the drive out of the
corners... you'd have to compare a your 180 5th Gen VFR with an 360
RC45 to get my point... they are basically the same engine except with
regard to crank throws...

Technically speaking 360 means all 4 crank throws rotate together in
one 360º circle whereas the 180 means the 4 crank throws are split
180º apart... it's independent with regard to the 90º cylinder
angle...

I think Honda should design the next Gen VFR without the silly Vtec
and adopt the visceral 360º big bang crank of their race bred V4s.

 

The 360 makes a better racing engine with smooth power pulses and superior high rev capability but sounds like absolute shite!
180's sound much better and multiple references are made to their pleasing tone on this forum and elsewhere. :ear:

I owned the original 360 V45 nearly 30 years ago. They were warp-speed fast and F1 nimble compared to virtually everything else out there at that time, real dragon slayers.
The ultra smooth power delivery gave no hint to the 'seat-of-the-pants-dyno' just how fast you were traveling or how quickly you were catapulting out of corners.

The 1st time it really dawned on me what a missile my arse was planted on was during a spirited ride along a challenging route with my brother (who is a better rider than I) he on his Suzuki GS1100, the Holy Grail of two wheeled power at that time.
The ease with which I left him behind even before attempting to was amazing!

This nudged the devil in me to start pouring it on with enthusiasm, the result leaving me giggling to myself inside my helmet with evil delight while tipping the machine to and fro and wrenching at the throttle, "Tee-Hee!"
Fun exercise... :whoo:

But subjectively those Interceptors were not all that enjoyable to ride overall:
The seamless power delivery offered no adrenaline stimulating acceleration rush and that droning exhaust note imparted no aesthetic inspiration to the pilot, quite blah... bland and appliance like unless ridden Hell fast.

Another very maddening glitch they also displayed was the inability to be shifted adroitly unless riding WFO or nearly so.
No matter how hard I tried each gear change under moderate load was like those made by a rank amateur... aggressive use was quite flawless though.

The V45 was my first bike with hydraulically actuated clutch and I erroneously attributed this flaw to that feature at the time.
Have since seen references made to the actual source of this awkwardness, maybe here at VFRW...?
Although unrelated to this thread topic perhaps a knowing someone could be good enough to chime in on this. :yo:

 

I'm on the other end of the spectrum. I love the sound of the 360 degree. Specially if you get two together. The deep Ducati type lower sound but more of it.

I thought the 360 crank was for great torque at lower rpms coming out of corners, which it does have. With the double bang bang, the second bang really enforces the first. I don't know how many times I've started out in 2nd gear and just pulled away. It's the old tq vs rpm argument.

Hammerspur the reason your tranny wouldn't shift smooth is because you didn't have your carbs tuned right. Mine will do the same if all cylinders are not firing in sync with each other. Throws to many osculations from the crank on to the input shaft. It doesn't take much to be out of sync. You just have to know what your doing when setting carbs cold and hot.

Mine shifts smooth as any other bike out there. It will also get the Honda false neutral at times if I'm not coordinated with shifts. But that's even rare. The hydraulic clutch is a godsend over cable.

 

"The 360 makes a better racing engine with smooth power pulses and superior high rev capability but sounds like absolute shite!
180's sound much better and multiple references are made to their pleasing tone on this forum and elsewhere."

Amen. I bought a new VF700R in "84 or '85 (have CRS syndrome) and I thought the exhaust note on it was awful. No excitement to it IMO. Very smoooooth, but just a blatty drone.

 

"HA-HA!" :lol:

Beats having that other, terminal condition... SFB. :wacko:

 

An interesting topic and perhaps part of a larger philosophical question.

Performance on one side, including how the bike feels and responds to the rider and on the other side a more desirable engine sound (which as noted is somewhat subjective).

What should be the deciding factor?

I wish we could ask Soichiro Honda his opinion on this...

 

How the bike feels and responds to rider input has a large subjective component as well.
When ridden near the edge the 360 configuration is accepted as superior in ultimate performance...
BUT how much of any given rider's saddle time is in that mode?

Considering populated zones, dawdling traffic, etc. encountered while getting to prime areas and the ever present need to beware for LEOs... maybe 50% at most for the aggressive rider...?

During those lazy stretches my 360 V45 felt vague, like it was not really immediately at hand. IMO it's a matter of that intangible quality sometimes called 'soul'.
It had little to none except when flogging it. Otherwise it was as dull as a slice of squishy white bread.

My '96 VFR750F telegraphs a good deal more feedback than I remember getting from my '83.
Even if it is ultimately less responsive than it might be were its crank degree-ed otherwise no such disappointment presents itself in terms of feel... subjectively in other words.