| Author | Message | ||
     Seanp |
I just read this letter and response in Road & Track:  I'm no engineer, but I presume it works the same for motorcycles as it does cars. Now I have a valid excuse! | ||
| Froggy |
It works for me. I even broke 70mpg once. | ||
| Herobluebuell |
damn im lucky to break 50. of course i don't think my bike has seen a slow day, Except in the winter when it sits for 4 or more months. | ||
| Paint_shaker |
Whether I hammer it or ride easy, I get basically the same results.. 44mpg | ||
| Just_ziptab |
You may have an excuse, but it's total crap.I've run many a test with MPG bottles and full throttle cuts the mileage by around 70% | ||
| Garyz28 |
"but officer, I was just doing my part to save energy" Good luck with that! | ||
| Seanp |
I think an important part of it is the short-shifting though. I have to say, I usually wind it right up when I take off so that probably negates the effect of the full-throttle benefits. I just like the fact that I have it in print from a reputable source that it's beneficial to crack it wide open!  | ||
| Brumbear |
Then Froggy sold his moped and bought ULYSeSS ps something going out to you tomorrow | ||
| Tramp |
I'd like to see some background on the expert who penned that Bullsiht. Too many morons are going to read that, take off with relatively cold engines, at WFO, and cause premature top-end failure, which they'll blame on the manufacturer, the dealer, the service guy, the kid next door, nostradamus, etc. Graduated, undemonstrative, low throttle opening takeoffs use less fuel. | ||
| Seanp |
Tramp - it was in the "Tech Correspondence" section of the December issue of Road & Track. The gentleman's name is Tom Wilson, and he can be reached at RTLetters@hfmus.com. I scanned the page, and it is undoctored up there in my original post. Like I said, I'm no engineer, so I can't personally vouch for the validity of Mr. Wilson's statement. However, seeing as he is the tech correspondent for one of the world's biggest car magazines, I'd be willing to bet he has a pretty strong background... | ||
| Sticks |
I thought it'd be shhhhh! your old mans home. | ||
| Tramp |
That being the case, maybe I could interest you in some prime real estate | ||
| Just_ziptab |
The dude is a tech correspondent??? The dude is a whack job nut case!I don't know who he is pandering to,but he is sadly WRONG and if you follow his advice......you loose. Google "full throttle saves gas" and you will find: You can save fuel immediately in whatever you drive by going easy on the accelerator. Jack rabbit starts and full-throttle acceleration boost fuel consumption dramatically. It's all a matter of degree: Light acceleration saves more than moderate acceleration. Test #1 Aggressive Driving vs. Moderate Driving Result: Major savings potential The Cold Hard Facts: Up to 37 percent savings, average savings of 31 percent Recommendation: Stop driving like a maniac. Don’t floor the gas. Not only do “jackrabbit” starts waste fuel, but one second of full-throttle driving can produce the same amount of carbon monoxide as a half-hour of normal cruising. That stated, my S-10 went from an average 20-21 mpg for the first 170,000 miles to 28.77 for this summers work drive by simply diving for momentum and very light acceleration. That equals 420 miles per tank instead of 300. That my friends is real savings.............let alone trickle down savings in consumables. | ||
| Sticks |
The title of the thread made me think of the game. Chick sits on your lap, they say "old mans home" you pull up your droors and go through a window, jump on your bike and haul ass. Fastest time wins, that's what I was havering about. | ||
| Bill0351 |
"Graduated, undemonstrative, low throttle opening takeoffs use less fuel." That may well be correct. However... Instantaneous, overtly demonstrative, WOT takeoffs are worth every drop of fuel they use, and they impress the kind of girls I like. Even if it is proven that instantaneous, overtly demonstrative, WOT takeoffs are more efficient, it won't ruin them for me. I would also prefer to believe that accelerating to two or three times the speed limit and then slowing back down saves even more gas. Sorry Tramp. I can't afford to look at your real estate since I blow all my extra cash on wheeled vehicles. Bill | ||
| Bigblock |
What Bill said... | ||
| Patrick2cents |
actually if you understand the post, he is correct. so long as you aren't winding everything out to high heaven and driving like an idiot, you will save gas. you will have far fewer pumping losses with your butterfly valves fully opened then with them partially cracked; as well, the less time you spend attempting to accelerate the less energy you will loose. sound strange? well, it works because energy can be defined as force multiplied by a distance, and acceleration is basically an unbalanced force, so the greater percentage of this force that is eaten up by friction (ie less torque you are producing) and the further distance this out of balance force has to go (ie slow acceleration) the more energy you waste per unit distance per velocity your are attempting to get to. to give you one example from my field (I am an Aerospace Engineer) you can often neglect air drag when doing basic calculations on a rocket launching into space, due to the MASSIVE amount of acceleration it undergoes. Now seeing real world results on a bike or car may not be easy to do, or sometimes conceptualize, but the theory behind what is said is actually sound. | ||
| Garyz28 |
If engine efficiency increases with the throttle more open then I should get really good mileage if I cruise at 130. Right? | ||
| Just_ziptab |
I give up......help me out here Tramp because the aerospace theory is way out of the box for automotive/motorcycle real world gas mileage...and yes, pinning the throttle is worth every cent of wasted fuel in a Buell.........until there is no more fuel. | ||
| Pkforbes87 |
Far too many people in this thread are confusing WOT with redlining the tach. The two don't necessarily happen at the same time. Either way I'm gonna keep riding mine like I stole it, even if gas goes back to $4.00/gal | ||
| Tramp |
Gonna hafta disagree witcha, Pkforbes87, while recognizing your very salient point. Most here (Me included) are responding to the sentence in the OP response that suggests exactly this disparate combination: "...best mileage gained by...rapid acceleration...large throttle opoen9ings...low rpm" Not only does this concept fail to stand up to many long decades of collected performance data, but it can, indeed, lead to shortened engine life. That being said, I only responded to the OP, as , when I ride with some extremely notorious 'packs', WFO takeoff is often the norm....although only AFTER a significant static warm-up period, at rest, outside of a given establishment/function. | ||
| Seanp |
Hey, just so y'all know, as the OP - this was not my article. I just found it amusing that it was printed in a major automotive magazine. I am a historian by education, and an army computer guru by trade. I can speak with no valid foundation on the merits or lack thereof in full-throttle take-offs. I had no idea this was going to cause such a ruckus! That being said, I ride my bike like I want, and when it needs gas I fill it up. I don't really care about the mileage it gets, because it's just a damn good time riding, and if it gets me where I'm going, and puts a smile on my face, it's a win-win situation. | ||
| Bcordb3 |
Theory is theory, and because it is written doesn't make it fact. | ||
| Reepicheep |
I'm not an expert, but I spent a bit of time digging into a topic like this, and testing it with the Saab (2.0 liter turbo charged motor with instantaneous MPG monitor)... My theory is that a motor makes its best fuel economy around the point it is at it's torque peak (not HP peak). So the perfect motor for fuel economy is one that is sitting at it's torque peak and can just hold the car at 55 MPH. Obviously, you can't change the size of your motor while driving, and that would be a way lame motor for anything but maximum fuel economy at 55mph. So applying that, I figured that next best thing might be to attempt to maximize the amount of time during acceleration that the motor is around its torque peak. Which means that you do apply more then a little throttle, but not WFO. Especially not on a cold motor. I tried this, and tried really gentle acceleration, and both seem to do about the same. WFO will *trash* my economy in an amazingly short period of time. One 0-70 WFO sprint will take maybe 50 miles of crawling and coasting to get back to a good MPG trend. Cold starts are even worse. At 65 MPH steady on a hot motor holding speed, my Saab can pull 30 MPG easy. Throw in a couple cold starts, and maybe 20% stop and go driving around town, and I am closer to 24 mpg. | ||
| Pkforbes87 |
Come to think of it, I experienced this whole idea a couple weeks ago driving a 17 ft uhaul. Wot acceleration from 2 stop signs burned more gas than the 30 mile 60 mph drive to return it. But the truck was an automatic, so nearly impossible to cause lower rpm shifts while accelerating "briskly". | ||
| Tramp |
actually, "lugging" offers more opportunity for engine damage (unladen torque), and less for economy. | ||
| Hughlysses |
Wow- never thought that posting would result in so much controversy. I guess the subject line incited most of the comments because the quote does NOT say to drive at WOT. Historically we were advised to minimize throttle openings at all times for best fuel mileage. Vacuum gages (sometimes called "economy meters") used to be available and it was stated that best fuel economy could be obtained by driving such that the vacuum was highest at all times. Remember that some of the historical info you guys refer to on driving technique comes from when cars had carburetors with accelerator pumps. A rapid throttle opening automatically resulted in a shot of raw gas getting pumped down the throttle bores. AFAIK fuel injection doesn't require the "burst" of fuel to compensate for a rapid throttle opening. I'm pretty sure the technique advocated by this author is completely proven, at least on modern cars. Some of you may remember BMW specifically designed an auto engine back in the 80's that was intended to optimize fuel mileage when driven in the manner described above, the 325e (e for "Eta"). Article on the car here: http://www.e30eta.com/hotrod.htm | ||
| Mr_grumpy |
My 2c worth, I've been driving 40 ton rigs for over 20 years, & yes Reep you're right an engine is most efficient at peak torque. A few years ago I did the economic driving course on our works Volvos, By short shifting & keeping the motor around peak torque til reaching cruising speed, rather than my old style of caning the **** out of it, my fuel consumption improved by over 20%. This of course is on 12 litre diesel engines but the principal is the same as the original article, it's standard doctrine in the transport industry. Just to add some clarity, this assumes that you're accelerating to cruising speed, which is 56 mph governed here. Most any truck these days is in the top of the green at this speed. (Message edited by Mr_grumpy on November 25, 2008) | ||
| Hughlysses |
More appropriate article on the BMW 325e: http://www.e30eta.com/popmech.htm "High-efficiency engineering The reason for the dramatic jump in low-speed power stems from the fact that this engine belongs to the high-torque, low-rpm "eta" engine family, named for the Greek letter engineers use to denote efficiency. BMW's thinking goes like this: By using a relatively large displacement engine at a lower crankshaft speed with a wider throttle opening, fuel efficiency is improved. " | ||
| Tramp |
Huglysses- My Buell has a carb with an accelerator pump. Bear in mind that the ETA (and it's 2-wheeled counterpart, the R65) were two of the worst hand-grenades ever to leave Bavaria. Efficiency at peak torque does NOT equate highest possible MPG. |
