Why does HD make their engines like this?
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Tourer
Joined: Feb 2011
Posts: 410
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From: Portland, ME
So if the V-Rod is high performance and hi revving, what is the advantage of that? Am I correct to think that the lower revving traditional engine is higher torque, meaning more power in lower gears, but less speed at the high end?
Seasoned HDF Member
Joined: Sep 2009
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From: SE Michigan
All the advantages and disadvantages of pushrod vs ohc are layed out here: http://wiki.3400z24.com/Pushrod_engine
Grand HDF Member
Joined: Nov 2007
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From: Chesterfield, VA
No, that is why I am going with the Fat Boy. But I am trying to learn about how the bike works and why some are done one way and others another way.
So if the V-Rod is high performance and hi revving, what is the advantage of that? Am I correct to think that the lower revving traditional engine is higher torque, meaning more power in lower gears, but less speed at the high end?
So if the V-Rod is high performance and hi revving, what is the advantage of that? Am I correct to think that the lower revving traditional engine is higher torque, meaning more power in lower gears, but less speed at the high end?
Grand HDF Member
Joined: May 2006
Posts: 3,636
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From: Ohio
Harley has always been about the motor throughout their history...that is why they named themselves the Harley Davidson Motor Co. very early. The 45 degree v-twin is the perfect design for a motorcycle frame. Look it it visually...it fits perfect. By comparision other engine configurations just look clunky and misplaced. You will also notice Harley's are designed to expose and enhance the look of the motor and it draws your eye directly to it where the competition tends to hide their ugly motors.
The twin cam lineage goes all the way back to the knucklehead and can be traced through the panhead, shovel, EVO and the 88 Twinkie. They all share some common design constraints:
- AIR COOLED
- 45 degree narrow angle v-twin
- Same firing sequence and timing
- Single pin crank
- Longer stroke than bore
- Push rod overhead valve design
- Low RPMs and high torque
These design constraints are largely what makes a Harley a Harley. It's also why none of the wannbe copy cats can ever get it right IMHO. The Harley motor is a masterpiece IMHO. It is utterly simple but amazingly reliable. Harley motors are d@mn near bulletproof. But it's more than that...it provides a riding experience unlike any other. The sound...the torque...the vibration...the heat...the rawness...it's all part of that Harley experience we love. I know some of the newbies want water cooled and more modern improvements but I consider that blasphemy. Those 7 bullets above are the discriminators that seperate Harley from the pack. I hope they never abandon those.
The twin cam lineage goes all the way back to the knucklehead and can be traced through the panhead, shovel, EVO and the 88 Twinkie. They all share some common design constraints:
- AIR COOLED
- 45 degree narrow angle v-twin
- Same firing sequence and timing
- Single pin crank
- Longer stroke than bore
- Push rod overhead valve design
- Low RPMs and high torque
These design constraints are largely what makes a Harley a Harley. It's also why none of the wannbe copy cats can ever get it right IMHO. The Harley motor is a masterpiece IMHO. It is utterly simple but amazingly reliable. Harley motors are d@mn near bulletproof. But it's more than that...it provides a riding experience unlike any other. The sound...the torque...the vibration...the heat...the rawness...it's all part of that Harley experience we love. I know some of the newbies want water cooled and more modern improvements but I consider that blasphemy. Those 7 bullets above are the discriminators that seperate Harley from the pack. I hope they never abandon those.
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Tourer
Joined: Feb 2011
Posts: 410
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From: Portland, ME
Just trying to learn more about how they work. I know how high performance bikes work, now moving to an HD, I'm trying to understand the difference. I understand that it's probably 95% tradition that keeps the HD engine the way it is and different from newer designs.
Thanks for the link, Keithhu. So the advantages appear to be smaller size, less complex and more torque. When they say torque, they mean that strong pull when you gas it in lower gears, right?
Thanks for the link, Keithhu. So the advantages appear to be smaller size, less complex and more torque. When they say torque, they mean that strong pull when you gas it in lower gears, right?
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Joined: Sep 2009
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From: SE Michigan
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Thread Starter
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Tourer
Joined: Feb 2011
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From: Portland, ME
Thanks!
Elite HDF Member
Joined: Jun 2008
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From: Connecticut
High rpm does take a toll on parts. Low rpm torque is the same way a diesel makes power, vors have OHC and 60 deg to allow it to make more HP and rev higher and smoother. It is also a more complex engine than a twincam. Give me an old style Harley anyday. The v-rods have their place, they are fast. All it is the 45 deg is a modern addaptation of an old design and the 60 deg is a modern design engine