 V Twin vs Twin Engine
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After searching google for write ups on this and coming up empty - I will now ask as a noob -
What is the difference between a V Twin and a Twin Engine?
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Re: V Twin vs Twin Engine
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Joined: Jan 2005
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Learned Hand
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Learned Hand
Joined: Jan 2005
Posts: 1,500 |
A v-twin is a twin engine. A twin engine simply has two cylinders. A v-twin has it's two cylinders in a v shape.
Learning from my mistakes... again and again.
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Re: V Twin vs Twin Engine
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Joined: Jul 2007
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Now I really feel nooby. LOL. Thanks for the answer, nuthin.
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Re: V Twin vs Twin Engine
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Joined: Jan 2005
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Should be Riding
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Should be Riding
Joined: Jan 2005
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Just so you know we have Parallel Twins or P-Twin motors.
Soren
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Re: V Twin vs Twin Engine
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Loquacious
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Loquacious
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a v-twin has 2 cylinders & is shaped in a V. a twin engine has 2 engines.
we should do this every weekend!
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Re: V Twin vs Twin Engine
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So - is the P-Twin a bit quieter than the V-Twin?
How do the sounds compare? I'm just curious.
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Re: V Twin vs Twin Engine
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Joined: Jan 2005
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"Lighten up, Francis."
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"Lighten up, Francis."
Joined: Jan 2005
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I always thought it was V(ertical)-Twin.  
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Re: V Twin vs Twin Engine
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Joined: Mar 2007
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Check Pants
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Check Pants
Joined: Mar 2007
Posts: 5,616 |
Our P-twins fairly quiet  until you unleash them  
SOLD: 07 Black BA, 39mm FCRs, TPUSA stage 1 head, TPUSA 813 cams, TPUSA 10.8:1 pistons, TTP #3 igniter, Specialty Spares Long Cannons, Tsukayu Hard Bags. 82HP/55tq
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Re: V Twin vs Twin Engine
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Joined: Feb 2005
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Fe Butt
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Fe Butt
Joined: Feb 2005
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And to further "confuse" the topic here, Bonnies are not only parallel-twins, but because the two cylinder bores are 90 degrees from the horizontal, they are also known as vertical-twins, which are even rarer today, as most modern parallel-twins are canted or inclined forward(a la BWM and Kawasaki's latest P-twins) to some degree off the vertical plane.
Yep! Just like a good Single Malt Scotch, you might call me "an acquired taste" TOO.(among the many OTHER things you may care to call me, of course)
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Re: V Twin vs Twin Engine
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Joined: Jun 2007
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Adjunct
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Adjunct
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Quote:
a v-twin has 2 cylinders & is shaped in a V. a twin engine has 2 engines.
Leave it to Yota to see the obvious. 
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Re: V Twin vs Twin Engine
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Joined: Jan 2005
Posts: 18,825
"Lighten up, Francis."
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"Lighten up, Francis."
Joined: Jan 2005
Posts: 18,825 |
Quote:
Quote:
a v-twin has 2 cylinders & is shaped in a V. a twin engine has 2 engines.
Leave it to Yota to see the obvious.
He's nothing if not literal.
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Re: V Twin vs Twin Engine
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Joined: Sep 2006
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Adjunct
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Adjunct
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One long standing design flaw with the v-twin (imho) is that the rear cylinder always runs hotter, behind the other one out of the airflow. Our vertical twins have both cylinders in the wind, where they need to be G
I never wanted to lead, and I never wanted to follow.
I just wanted to ride.
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Re: V Twin vs Twin Engine
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Joined: Jan 2005
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Adjunct
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Adjunct
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Quote:
One long standing design flaw with the v-twin (imho) is that the rear cylinder always runs hotter, behind the other one out of the airflow. Our vertical twins have both cylinders in the wind, where they need to be
G
YES! It's why the HD 96 ci are having some issues to the point where the MOCO currrently has offered a map to cut spark to the rear cylinder at idleing speeds to help reduce the heat at the rear cylinder which is out of the airflow. Watercooling will probably be in their future (V-ROD already there) The faithful are going to hate the solution.
Definition of Insanity: "Doing things the same way over and over and expecting different results."
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Re: V Twin vs Twin Engine
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Joined: Feb 2005
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Fe Butt
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Fe Butt
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The newer Buell XBs use an electric fan which is ducted to the rear cylinder in order to cool it, however I get the feeling that all air-cooled(even air/oil cooled) M/Cs will, unfortunately, eventually go the way of the Dodo due to future environmental/noise regs.
Yep! Just like a good Single Malt Scotch, you might call me "an acquired taste" TOO.(among the many OTHER things you may care to call me, of course)
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Re: V Twin vs Twin Engine
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Another thing to note, although I am not a mechanic or anywhere near one, but one explained to me.
Fundamentally......
V-Twins great at making torque (peaked at lower rpm's) but not so great at creating hp.
P-Twins great at creating hp (peaked at higher rpm's) but not so great at making torque.
Correct me if I am wrong....
Ceuls
'07 SM - Ellipse Mirrors, Progressive 412's, Freak, Bub Exhaust, AI Removed, Summer Screen, Low-Pro Saddle
Happy Trails!
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Re: V Twin vs Twin Engine
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Joined: Feb 2005
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Fe Butt
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Fe Butt
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Not so sure that's true, Ceuls. The way I figure it, the reason Harley V-Twins in particular make more torque is because they are an "undersquare" design(the stoke dimensions is larger, or longer actually, than the bore dimensions)
A long stroke motor will make more torque, but is limited by that longer stroke to lesser RPM figures, where the horsepower lives.
The modern Hinckley Bonnies are all oversquare in design(bore dimension larger than the stroke dims), which is why their redline is two thousand RPMs higher than most air-cooled Harleys, and why their powerband peaks higher. Not to mention that an OHC design(ours are DOHC, BTW) will also allow for a higher redline, in most cases.
And one more thing, because a parallel-twin's width plays a part in deciding how big it can be, not to mention the more inherent primary imbalance that(especially) a 360 degree crank parallel twin has(without a counter-balancer installed), that too has an effect upon how large of a displacement a P-Twin can be.
Older Meriden Triumph 650s were all slightly undersquare, which for their size made them quite "torquey" motors.
Last edited by Dwight; 08/09/2007 7:59 PM.
Yep! Just like a good Single Malt Scotch, you might call me "an acquired taste" TOO.(among the many OTHER things you may care to call me, of course)
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Re: V Twin vs Twin Engine
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Joined: Aug 2005
Posts: 15
Complete Newb
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Complete Newb
Joined: Aug 2005
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Quote:
One long standing design flaw with the v-twin (imho) is that the rear cylinder always runs hotter, behind the other one out of the airflow. Our vertical twins have both cylinders in the wind, where they need to be
G
I wonder if anyone has any thoughts or comments on the Moto Guzzi "V" twin engine which has the "V" facing the wind?
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 Re: V Twin vs Twin Engine
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Joined: Jun 2006
Posts: 2,626
Loquacious
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Loquacious
Joined: Jun 2006
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Quote:
Another thing to note, although I am not a mechanic or anywhere near one, but one explained to me.
Fundamentally......
V-Twins great at making torque (peaked at lower rpm's) but not so great at creating hp.
P-Twins great at creating hp (peaked at higher rpm's) but not so great at making torque.
Correct me if I am wrong....
Ceuls
You're wrong. 
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Re: V Twin vs Twin Engine
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Joined: Apr 2006
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Loquacious
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Loquacious
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Dwight, interesting!
It'll be curious to see how Triumph makes a big cc P-Twin.
Kevin - Luceo Non Uro
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Re: V Twin vs Twin Engine
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Joined: Jun 2006
Posts: 2,626
Loquacious
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Loquacious
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Quote:
Not so sure that's true, Ceuls. The way I figure it, the reason Harley V-Twins in particular make more torque is because they are an "undersquare" design(the stoke dimensions is larger, or longer actually, than the bore dimensions)
A long stroke motor will make more torque, but is limited by that longer stroke to lesser RPM figures, where the horsepower lives.
The modern Hinckley Bonnies are all oversquare in design(bore dimension larger than the stroke dims), which is why their redline is two thousand RPMs higher than most air-cooled Harleys, and why their powerband peaks higher. Not to mention that an OHC design(ours are DOHC, BTW) will also allow for a higher redline, in most cases.
And one more thing, because a parallel-twin's width plays a part in deciding how big it can be, not to mention the more inherent primary imbalance that(especially) a 360 degree crank parallel twin has(without a counter-balancer installed), that too has an effect upon how large of a displacement a P-Twin can be.
Older Meriden Triumph 650s were all slightly undersquare, which for their size made them quite "torquey" motors.
Sorry Dwight, you're wrong too.
Small valves make better torque, larger valves make better hp.
Undersquare engine's smaller bores don't have room for large valves. If an oversquare engine is given small valves, it too makes higher torque.
Cam duration plays a big part, too. Short duration makes good torque at low rpm, long duration makes good hp at high rpm.
It's not the stroke, and I'm not pulling this out of my butt. It's from an old TDC article.
Steelheart- '03 Speedmaster Black/Yellow
The Hayabusa Killa
16" Shorties/140 mains/Airbox drilled
Procom CDI
"There is no cure for Celibacy. But we can treat the symptoms."
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Re: V Twin vs Twin Engine
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Joined: Jan 2005
Posts: 6,821
Bar Shake
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Bar Shake
Joined: Jan 2005
Posts: 6,821 |
Quote:
The way I figure it, the reason Harley V-Twins in particular make more torque is because they are an "undersquare" design(the stoke dimensions is larger, or longer actually, than the bore dimensions)
I think that the hundred pound (hyperbole here folks) flywheel has something to do with it too. 
Contra todo mal, mezcal; contra todo bien, también
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Re: V Twin vs Twin Engine
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Joined: Jan 2005
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Bar Shake
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Bar Shake
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Quote:
Just so you know we have Parallel Twins or P-Twin motors.
Quote:
I always thought it was V(ertical)-Twin.
The correct term is actually in-line twin. The mounting, longitudinally or laterally has nothing to do with it.
Contra todo mal, mezcal; contra todo bien, también
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Re: V Twin vs Twin Engine
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Joined: Mar 2006
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Adjunct
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Adjunct
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[quote Small valves make better torque, larger valves make better hp. Undersquare engine's smaller bores don't have room for large valves. If an oversquare engine is given small valves, it too makes higher torque. Cam duration plays a big part, too. Short duration makes good torque at low rpm, long duration makes good hp at high rpm. It's not the stroke, and I'm not pulling this out of my butt. It's from an old TDC article.
Well your both right. There is more to it. Putting smaller valves, or less valves in a short stroke will increase torque, but the peak will be at a higher rpm than a similar displacement long stroke motor. Putting larger or more valves on a long stroke will increase hp and rpms but again less so then a similar displacement short stroke. In the end the short stroke is capable of higher rpms and peak hp simply because the pistons have a shorter distance to travel and there is room for more aggressive valving. But it is not capable of attaining the very low rpm peak torque numbers of a long stroke.
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Re: V Twin vs Twin Engine
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Joined: May 2007
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Worn Saddle
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Worn Saddle
Joined: May 2007
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Quote:
In the end the short stroke is capable of higher rpms and peak hp simply because the pistons have a shorter distance to travel and there is room for more aggressive valving. But it is not capable of attaining the very low rpm peak torque numbers of a long stroke.
Starting make Wiseco's stroker kit look very appealing...
A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)
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