Motorcycle Horsepower Question

On Dec 26, 9:15�pm, "Anonymous" <c....TakeThisOut@com.com> wrote:

> Conversely, the rockets are designed for high output, peaky operation.

That last statement is no longer entirely true. Advances in fuel/air
induction, exhaust systems, and improved connecting rod design have
led to small displacement engines that put out good torque over a 6K
to 7K wide power band, unlike certain engines of the mid-1980's that
had a power band only half as wide.
 >> Stay informed about: Motorcycle Horsepower Question 

David T. Ashley <dta.TakeThisOut@e3ft.com> wrote:

> From various places on the web, my Honda Shadow 600 (VT600C) appears to
> deliver about 40 HP, but a similar displacement sportbike from Honda seems
> to deliver about 100 HP.
>
> Why the huge difference in engine output for a similar displacement?
>
Because one engine is in a higher state of tune than the other. Next
question?


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On Thu, 27 Dec 2007 08:52:30 +0000, totallydeadmailbox.RemoveThis@yahoo.co.uk
(The Older Gentleman) wrote:

>David T. Ashley <dta.RemoveThis@e3ft.com> wrote:
>
>> From various places on the web, my Honda Shadow 600 (VT600C) appears to
>> deliver about 40 HP, but a similar displacement sportbike from Honda seems
>> to deliver about 100 HP.
>>
>> Why the huge difference in engine output for a similar displacement?
>>
>Because one engine is in a higher state of tune than the other. Next
>question?

Is that like a State of Yo ?


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 >> Stay informed about: Motorcycle Horsepower Question 

On Dec 27, 5:41�am, "Anonymous" <c... RemoveThis @com.com> wrote:

> Well, I'll certainly concede that engine design/refinement
> has contributed to a more flat operating range. But, with
> respect to the OP's Shadow, the 6-7K area could prob-
> ably still be described as peaky.

Back in the 1960's, Honda was exploring high RPM engine designs based
on ideas which had actually been used as early as 1910. Honda was able
to get their engines to survive at amazingly high RPM, but wasn't able
to fill the cylinders as well as later designs that the British
combustion engineers Costin and Duckworth.

Of course the famous Cosworth engine that revolutionized Indy car
racing was a combination of the two mens' names.

Before the turbulent combustion chamber was invented, Honda was
relying on transmissions with ever-increasing numbers of gears. The
Federation Internationale
Motorcycliste, which sanctioned grand prix events, set an upper limit
on the number of speeds a transmission could have, as did the American
Motorcycle Association.

As I recall, Honda had built a 3-cylinder, 50cc engine with a 12-speed
transmission, and Moto Guzzi had a 500cc V8.

With the numbers of cylinders and transmission gears limited, the
engineers had to make engines with wider power bands.

Motorcycle racers were excited when Suzuki announced they were going
to mass produce the GSXR750. Yoshimura's hot rod GSXR750 produced 135
horsepower at 13,000 RPM, but the production version didn't have the
trick Carillo connecting rods and had to be limited to only 11,500
RPM.

Riding an early model GSXR was like riding a 250cc 2-stroke, with an
upper power band starting at 8000 RPM and rev-limited to 11,500 to
avoid breaking the rods.

GSXR's didn't get improved connecting rods until about 1991, as I
recall, and the rev limiters were reset to 13.5K

And racers didn't understand the function of the carefully-designed
plastic airbox either. Conventional wisdom was to remove the airbox
and install separate air filters, hoping for more power.

The racers wound up with a flat spot in the midrange which was caused
by a reverse pressure wave from the 4-into-1 exhaust system while the
valves were still open during camshaft overlap.

Japanese engineers worked on that problem, and claimed that they had
it solved with a 4-into-2-into-1 exhaust pipe. But all the major
manufacturers have now gone to a computer-controlled exhaust
throttling valve, such as pioneered by Yamaha with their ExUP system.

The racers now leave their airboxes in place, the flat spot is gone,
and racers can concentrate on their riding.
>
> Although I've not ridden any recent rockets, I have to
> assume that any bike ridden around mostly in 2nd gear,
> probably has a torque curve that relies heavily on rpm.

While it is true that you need to use a lot of RPM to make big
horsepower numbers, racers also need to ride all the way a curve
without having to shift gears while leaned over.

A high RPM engine like Yamaha's YZF-R6 motor is capable of revving up
to 2000 or 3000 RPM past the power peak, so the racer can take a
corner in 2nd or 3rd gear without needing to shift.

When you watch the AMA superbike racers on their GSXR1000's, you will
notice that they ride most American tracks in the lower three gears,
and only get into the upper gears on the longest straights.
 >> Stay informed about: Motorcycle Horsepower Question 

On Dec 27, 6:49�am, Wolfie <Wolfie@FrenchGirl'sBoy.org> wrote:

> Short stroke, many, many valves, high lifting
> overhead cams, better carburation and breathing and
> a power band that kicks in at 4k-6k rpm and only quits
> around 14k+. Sure you go fast, but in my experience
> most roads are not designed to support speeds above
> 120mph and on these light pocket rockets like the
> Kawasaki ZX10R, you are liable to get airborn if you
> don't watch it. Don't think I'd like that much at
> 145mph except on a track.

Well, that's what riders get when they fall in love with a high-
maintenance bitch like
a crotch rocket. It does its one thing well, especially when its one
thing is a fast smooth racetrack that doesn't make the suspension move
very much.

It's like living with a beautiful woman who doesn't cook or clean
house, but when you
get in bed with her...
 >> Stay informed about: Motorcycle Horsepower Question 

"*" <anoblewolf.TakeThisOut@gmail.com> wrote in message
news:69abda8c-18d5-47f3-a337-602d733c6073@s12g2000prg.googlegroups.com...
On Dec 26, 9:15?pm, "Anonymous" <c....TakeThisOut@com.com> wrote:

> Conversely, the rockets are designed for high output, peaky operation.

That last statement is no longer entirely true. Advances in fuel/air
induction, exhaust systems, and improved connecting rod design have
led to small displacement engines that put out good torque over a 6K
to 7K wide power band, unlike certain engines of the mid-1980's that
had a power band only half as wide.





Well, I'll certainly concede that engine design/refinement
has contributed to a more flat operating range. But, with
respect to the OP's Shadow, the 6-7K area could prob-
ably still be described as peaky.

Although I've not ridden any recent rockets, I have to
assume that any bike ridden around mostly in 2nd gear,
probably has a torque curve that relies heavily on rpm.
 >> Stay informed about: Motorcycle Horsepower Question 

On Thu, 27 Dec 2007 00:08:30 -0800 (PST), "*" <anoblewolf.DeleteThis@gmail.com> wrote:

>engines that put out good torque over a 6K
>to 7K wide power band, unlike certain engines of the mid-1980's that
>had a power band only half as wide.

The old Honda V4s had a power band from 7 to 9 and redlined at 10 to 11,
depending on displacement.

--
Jack
 >> Stay informed about: Motorcycle Horsepower Question 

Anonymous wrote:
> "*" <anoblewolf DeleteThis @gmail.com> wrote in message
> news:69abda8c-18d5-47f3-a337-602d733c6073@s12g2000prg.googlegroups.com...
> On Dec 26, 9:15?pm, "Anonymous" <c... DeleteThis @com.com> wrote:
>
>> Conversely, the rockets are designed for high output, peaky operation.
>
> That last statement is no longer entirely true. Advances in fuel/air
> induction, exhaust systems, and improved connecting rod design have
> led to small displacement engines that put out good torque over a 6K
> to 7K wide power band, unlike certain engines of the mid-1980's that
> had a power band only half as wide.
>
>
>
>
>
> Well, I'll certainly concede that engine design/refinement
> has contributed to a more flat operating range. But, with
> respect to the OP's Shadow, the 6-7K area could prob-
> ably still be described as peaky.
>
> Although I've not ridden any recent rockets, I have to
> assume that any bike ridden around mostly in 2nd gear,
> probably has a torque curve that relies heavily on rpm.

Short stroke, many, many valves, high lifting
overhead cams, better carburation and breathing and
a power band that kicks in at 4k-6k rpm and only quits
around 14k+. Sure you go fast, but in my experience
most roads are not designed to support speeds above
120mph and on these light pocket rockets like the
Kawasaki ZX10R, you are liable to get airborn if you
don't watch it. Don't think I'd like that much at
145mph except on a track.


--
Wolfie
 >> Stay informed about: Motorcycle Horsepower Question 

* wrote:
> On Dec 27, 6:49�am, Wolfie <Wolfie@FrenchGirl'sBoy.org> wrote:
>
>> Short stroke, many, many valves, high lifting
>> overhead cams, better carburation and breathing and
>> a power band that kicks in at 4k-6k rpm and only quits
>> around 14k+. Sure you go fast, but in my experience
>> most roads are not designed to support speeds above
>> 120mph and on these light pocket rockets like the
>> Kawasaki ZX10R, you are liable to get airborn if you
>> don't watch it. Don't think I'd like that much at
>> 145mph except on a track.
>
> Well, that's what riders get when they fall in love with a high-
> maintenance bitch like
> a crotch rocket. It does its one thing well, especially when its one
> thing is a fast smooth racetrack that doesn't make the suspension move
> very much.
>
> It's like living with a beautiful woman who doesn't cook or clean
> house, but when you
> get in bed with her...

LOL yes, we did two things well together, one of which was fight...

--
Wolfie
 >> Stay informed about: Motorcycle Horsepower Question 

On Dec 27, 12:46�pm, matt weber <matthew... RemoveThis @verizon.net> wrote:

> �Try pushing the compression ratio of a 600cc twin to 12.5:1 with 92
> Octane fuel and see how long it lasts before it knocks itself to
> bits....

Do not fear the numbers, just because you don't know what they mean.

Geometric compression ratios are just numbers. If you retard to cam
timing to give you larger lobe center numbers, you need more cranking
compression to get your machine rolling.

On the dyno, you see the first hump in the torque curve. That's
cranking compression.

The second hump in the torque curve is the exhaust system working to
increase dynamic compression. You get maybe three to five psi dynamic
compression from the exhaust pipe.

If the valley between the humps is low, your air box is working with
your cam timing.
 >> Stay informed about: Motorcycle Horsepower Question 

On Dec 27, 12:15 am, "Anonymous" <c... RemoveThis @com.com> wrote:
> "David T. Ashley" <d... RemoveThis @e3ft.com> wrote in messagenews:duSdnQQj0cWlt-7anZ2dnUVZ_gOdnZ2d@giganews.com...
>
> > From various places on the web, my Honda Shadow 600 (VT600C) appears to
> > deliver about 40 HP, but a similar displacement sportbike from Honda seems
> > to deliver about 100 HP.
>
> > Why the huge difference in engine output for a similar displacement?
>
> > Thanks.
>
> > --
> > David T. Ashley              (d...@e3ft.com)
> >http://www.e3ft.com         (Consulting Home Page)
> >http://www.dtashley.com     (Personal Home Page)
> >http://gpl.e3ft.com         (GPL Publications and Projects)
>
> Without the exact details on either bike, it all comes
> down to torque and rpm. Horsepower is merely a
> product of torque * rpm.
>
> No doubt, your Shadow probably redlines somewhere
> in the area of 6-7K. The other bikes of which you speak,
> will redline in the 10, 11, and 12K range(s).
>
> Although even if you could spin you Shadow at those
> speeds, you would still not get those elevated perform-
> ance numbers, you would certainly gain substantially.
>
> Your Shadow is designed for a smooth, linear operation,
> with regard to power output. Conversely, the rockets
> are designed for high output, peaky operation.

If you want maximum power out of the rocket you need to keep it in the
upper part of its rev range, but as someone else pointed out, modern
rockets aren't as peaky as older ones. And if you are not in need of
maximum power, which is most often the case when riding on the street,
then it will be quite happy puttering along at lower rpm in a higher
gear. Nothing says you *have* to wring its neck all the time. The
main down side for using a crotch rocket as a commuter or tourer is
that the riding position can get uncomfortable.

Bruce
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On Wed, 26 Dec 2007 23:29:45 -0500, "David T. Ashley" <dta RemoveThis @e3ft.com>
wrote:

>From various places on the web, my Honda Shadow 600 (VT600C) appears to
>deliver about 40 HP, but a similar displacement sportbike from Honda seems
>to deliver about 100 HP.
Smaller displacement cylinders mean they can achieve much higher
RPM's, and smaller parts have less momentum.. Most of the 600cc super
bikes redline in the 12,000+ RPM range, and have 4 valves per
cylinders. The smaller displacement means higher compression is
possible with relatively low risk of knock, so they can run of
relatively ordinary gasoline. Fast burning fuel isn't a major problem
with very small combustion chambers.


Try pushing the compression ratio of a 600cc twin to 12.5:1 with 92
Octane fuel and see how long it lasts before it knocks itself to
bits....

So a combination of a higher compression ratio, and higher redline are
the major contributors.
>
>Why the huge difference in engine output for a similar displacement?
>
>Thanks.
 >> Stay informed about: Motorcycle Horsepower Question 

On Wed, 26 Dec 2007 23:29:45 -0500, "David T. Ashley" <dta.DeleteThis@e3ft.com> wrote:

>From various places on the web, my Honda Shadow 600 (VT600C) appears to
>deliver about 40 HP, but a similar displacement sportbike from Honda seems
>to deliver about 100 HP.
>
>Why the huge difference in engine output for a similar displacement?
>
>Thanks.

This is all a bit of an over simplification but Horsepower is mainly a
function of how much fuel mixture you can combust through the engine per unit
time. So bigger carbs, bigger valves/timings, less restrictive exhaust would
allow your bike to consume more fuel per unit time. That combined with the
greater efficiency of a high compression ratio pistons might raise your HP to
about 50+.
So how do you get it to burn more fuel per unit time,? Make it run faster with
adequate fuel mixture delivery.
In an ideal world, an engine running 2x the rpm produces 2x the HP.


Ben
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