A listener discussion about HP & torque

We got this email from listener Bryan Skinner, and thought the emails back and forth would make a good blog post. From Bryan: I stumbled upon your Podcast in search of finding an enjoyable conversation on motorcycling and I've really been enjoying listening to you both. Question: The issue I'm confused about is how can a Yamaha FJ-09 which is 847cc have so much more horsepower than my Honda VTX1300 cc ? My 1300cc has 57HP and 75 torque verse the FJ-09 847cc and 115HP and 65 torque. Doesn't cubic inches relate to Horsepower. Is it because the Yamaha is more modern than my 2005yr Honda VTX 1300 ? James: Bryan,
Thanks for writing. I think we’ll queue this up for an up coming show but I’ll respond here as well.
Displacement is only part of the equation. It’s really about squeezing quantities of gas and air and making it explode. I don’t know the numbers off the top of my head but I’d guess that the VTX tops out at around 6000 RPM. The FZ-09 probably doubles that number. It has less displacement but it can produce power more often. There are many other factors that can contribute such as compression ratio, power loss to friction in the motor, restrictions in the air box, other design decisions made by the engineers to produce the “feel” that they want out of the engine. RPM and compression are probably the biggest contributors.
On the upside, you’re probably getting better gas mileage AND buying cheaper gas than FZ-09 owners.
Chris: And if I may expand with some technical details to flesh that out...
Horsepower, while useful for bench racing and marketing, is a mathematically contrived measurement that's got a lot of factors going into it. In its basest form, calculating HP is simply a matter of taking the torque at an RPM, multiplying it by that RPM, then dividing that number by a fixed value of 5252. 
In the case of your VTX 1800, the I've seen docs suggesting that the torque maxes out at 120 foot pounds. To make the math easy, let's assume a good, flat torque all the way to redline. Your redline is 5750. So the resulting formula is:
T x R / 5252 = hp
120 * 5750 / 5252 = 131.4 , theoretical maximum horsepower.
In the real world, the VTX 1800 gets closer to about 105 hp with around 100 ft lbs of torque. This is because the overall breathing inefficiencies, the torque falling off at higher RPM, and mechanical drag in the engine, etc. 
According to this chart ( http://images.motorcycle-usa.com/PhotoGallerys/05PCTorque.jpg ), the VTX 1800 is good for 98 ft lbs maxed at 3700 RPM, and it starts falling off after that. So, 3700 RPM is where the engine makes its PEAK EFFICIENT POWER (which is different than maximum power) - the formula would then be:
98 * 3700 / 5252 = 69 max EFFICIENT horsepower. 
Using that chart, at max rpm of around 5500, the engine is putting out around 80 ft lbs.
80 * 5500 / 5252 = 83.8 horsepower.
No slouch by any means, especially in the "feel my arms stretch" department. 
So, as you can see, real-world numbers and theoretical, marketing numbers can vary GREATLY. 
You can modify those real world numbers a bit with better exhaust and airbox flow, tuning, etc.
But horsepower, as a thing, is fully contrived and 99.9% completely made up theoretical BS. 🙂
Me...? I'll take a nice big torque number a lower or mid-level RPM range over theoretical horsepower all day long. It's why I like twins and triples so much more than I4s. They develop their torque in lower RPM ranges, typically, and feel more spry around town.
The triple in question revs much, much higher and has a very different feel, and can produce higher contrived, theoretical (and very real) horsepower, but your VTX 1800 is going to FEEL so, so much more powerful in real-life RPM and driving speeds. Because.... it is. The Triple will have to rev much higher and feel more frenetic to develop its higher overall power.
Hope this helps. 🙂

And the winner is…

ThePaceFINAL-300x116 We asked riders to write up something that shows how a communications system could, or does, enhance their rides. We got lots of great feedback and have picked a winner. Out of 29 respondents, numbered 1 through 29 in order of their typed submission on the blog post, and using the online random number generator we use very often, the winning number is #5, Quentin Lewis! Congratulations, Quentin! We'll reach out shortly and get your your prize, a used-but-good-condition Scala Rider system, courtesy of listener and friend of the show, Ed Day! Thanks again, Ed! Stay tuned for March's give away. (for the sake of completeness, a list of the respondents is shown below, in the order of submission)
Stephane LaFrance
John Jones
Doug Kneissl
David Marzilli
Quentin Lewis
Jack Starcher
Mark Wingert
Peter Jowett
Alex Rode
Jeff Ditto
John Poe
John Prickett
Mike Jones
Nick Isherwood
Charlie Phelan
Paul Jones
Adam Forsberg
Tamas Toth
Dan Irwin
Justin Varner
Martyn Harris
Chad Bolling
John Jarocki
Jim long

Episode 197 – Router’s Ride Table, that’s the one.

Episode 197 - Router's Ride Table, that's the one. Recorded February 19, 2015 ThePaceFINAL-300x116
This week we're hosting February's Rider's Round Table, and we're joined by Michael Kaiser of KinderRider, Inc., Liza Miller from Motorcycles & Misfits, and Chuck Brewer of The Wheelnerds. Hilarity ensues upon pushing Play. Chuck Brewer, The Wheelnerds Michael Kaiser, KinderRider Inc. Liza Miller, Motorcycles & Misfits

Episode 196: It’s Winter

Episode 196: It's Winter

Recorded on Feb 14, 2015



Theme music composed and performed by Raoul Lowe

Episode 195: Kristin Casey Racing

Episode 195: Kristin Casey Racing

Recorded on January 14th, 2015

We're talking to Kristin (with an "i") Casey of Kristin Casey Racing. We cover what it's like to be injured far from home, what it takes to remodel a "bargain" RV and a whole bunch of other stuff. This one's a lot of fun.

Kristin Casey Racing

KCR on Facebook

KCR on YouTube

Theme music composed and performed by Raoul Lowe