Vetter Fuel Economy Challenges; Hollister CA 7/2/16, Mid-Ohio 7/10/16

[sendler]

I did 105.6 on a stock CBR250R in the Ohio 2012 Vetter challenge with a 100 liter duffel bag on the back full of 50 pounds of camping gear. I was averaging 93 on my fast highway commute. The next year I took the 2009 Ninja250 with a similar luggage set up though most of it was unloaded, and got 87 mpg. Normally 73 on the highway. Last year at Ohio the CBR250R was back and with a truncated tail but still no nose. I got 117 mpg. The new Michelin Pilot street tires I took off of the R3 are way more fuel efficient the the Bridgstone S20evo that replaced them and seem to be about 10% better than the IRC that came off the CBR 31,000 miles front and 16,000 rear). so I hope to be closer to 130 this year if the weather is better. It was raining last year. My last 5 tanks on the commute have been around 115 real world.
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Keep in mind that there is alway some fill error and maybe some "wishfull filling" during competitions and the top guys are using only about 1 gallon so any error can make a difference. I would like to see the fills become "observed" as there was one competitor that was actually seen dumping in from a soda bottle at the museum stop.
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Though because of the fill plate in my bike and actually seeing the fuel I can get fills with .005 gallon acuracy when I want. Which is every time. Fuel logs for regular commuting are much more useful to see what any bike really gets. It seems most people don't use a log even though they talk about high competition results. My stock CBR250R with no mods other than a +15% gearing change got 135 mpgUS on the track at Watkins Glen for the Green Grand Prix fuel economy challenge. Twice.

[Grant-53]

Building a fairing need not be anymore challenging than making plywood furniture or a swing set. The big hurdle is the fiberglass but I have found that sheet metal or plastic formed like paper model shapes can be easier. See the HPV shell software at recombents.com.

[gregsfc]

Originally Posted by jkv357

I do think a bigger engine running at a lower RPM can do pretty well, but there are a few mechanical factors that will hold it back. The numbers are good, but the potential is much more limited. I have a SV 650, and I've seen over 60 mpg in normal back-road riding - which is pretty good IMO.

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For the competition, a streamlined 125-250cc single would most likely be the most efficient, but your CTX can do pretty well and still be a very useful all-around street bike.

I'm glad you brought up the SV650, and I agree that the potential is limited for larger displacement engines, including Honda's 670 cc for these competitions versus an engine that can just barely make the speed requirement before streamlining, because the smaller the engine, the less fuel it will consume generally speaking, but it is in the real world where a mid-size bike like mine has some advantages in safety and refinement w/o the fuel economy drop off that one would expect. I would expect that a streamlined CTX700 or NM4 would not reap the same level benefit than a minimum-displacement bike in the 125-300 setup exactly the same, because the 670 cc twin is already only mildly stressed with the weight and drag on the highway versus the smaller bikes, but my point is that if this 670 cc is already efficient enough to achieve 80mpg or so in this competition w/o tucking, that in streamline form, we'd see a bike with double the capable horsepower, and even more than double torque, at least 100 more pounds, and at least 125 mpg, versus--say--160 using the proclaimed minimalist approach.

The SV650 is a perfect example to illustrate my point. When one compares a typical, but well-engineered mc engine that was designed with fuel economy as at least one major factor in it's design, to Honda's bold, new choice that offers a similarly-sized engine extracted from the automobile industry; a few interesting things happen. There is a curb weight discrepancy of 30-40 pounds, but tires/wheels are exactly the same. The point you made about top-end performance is well taken, and this has been the problem for Honda with this entry. They have been raked over the coals for this power train by enthusiasts and mc media outlets due to the fact it hits the rev limit at 6500 RPM, it's not-so-impressive performance north of 70 mph, and the fact that for the first time in this size and style of bike, one has to short shift for best and most refined performance. The typical, high-revving mc, comparing near-equal displacement, in near-equal components to an automotive-style power train, will always produce more peak power, and therefore, will provide better performance at the top end and overall performance. And this is why most reviews regarding Honda's 670 versus other 650-700 bikes, gets a bad score.

But this limited high-end performance aspect from this unprecedented entry from Honda, is why it is so efficient. You're experience in the SV650 can return at or about 62 mpg along backroads. My experience, with my CTX700 with the manual shift can return, in normal riding (not lugging or tucking, but revving to 3500 or so between gears, which is pretty quick on this bike due to its torque curve), in warm weather, is at or about 78.

Most motorcycle enthusiasts in this range have an expectation of performance, but the Honda 670 provides a performance style more akin to a mid-size or compact sedan, a large scooter, or a big, torquey cruiser; and so it has been mostly scooter enthusiasts, downsizers from big bikes, and beginners who have sought out this bike, and most of them choose the DCT automatic, which gives up at least 3 mpg and a touch of performance to the straight shift. And this is a shame that this concept has been rejected by and large by the media and the consumer base, because this efficiency advantage of a lower-revving engine can be applied up and down the displacement range until we reach a point at which the auto-style engine cannot provide an acceptable peak horsepower for highway transportation, which is likely at or about the 400 cc range, compared to a similar set up with a 250 cc.

[Grant-53]

Multiply displacement by rpm to get volume flow of A/F. This gives a rough comparison.

[gregsfc]

I can't find results of the Vetter Fuel Economy Challenge (2016 AMA Vintage Days) anywhere; not even through a search on here. Has it gotten so low interest that one can't find any news, or have I just gotten that bad at researching on the web?

[sendler]

There is no official result yet since the winning numbers are close to a tie and one bike is electric. It is coming down to what value to use for the cost of electricity to determine the winner.

[gregsfc]

Thanks for the reply. I didn't know what was going on.

I know that Craig has argued this point in the past, stating it's only the cost of fuel or energy that matters, but I wish someone helping with posting results would calculate and post the mpg-e values for the electrics just so we can compare them from an energy standpoint. Energy density comparisons will always be the same unless a fuel itself changes, but cost comparisons are fleeting from one region to another and over time, and he never had any qualms showing us diesel and biodiesel mpg along with the cost comparisons; and I've never heard or read anyone arguing that the way KW/hrs are converted to a gasoline base equivalent was flawed in any way, so I'm not sure of the objection of including that information.

I think maybe the e-bikes may get more attention if people saw how they equated on a gallon of gas equivalent. I know I can figure it myself, but I can't show it to all that may be interested like the officials of the event can.

[Grant-53]

Right now the key issue with electrics is range. Cost wise they are still roughly double in price of a comparable gas unit but efficiency is so much greater. The recharge time is at least 45 minutes versus 10 minutes at a gas pump. They really shine in stop-and-go traffic.

[sendler]

Originally Posted by gregsfc

Energy density comparisons will always be the same unless a fuel itself changes, but cost comparisons are fleeting from one region to another and over time, and he never had any qualms showing us diesel and biodiesel mpg along with the cost comparisons;

Wh/mile are being shown in the results.

[gregsfc]

Originally Posted by Grant-53

Right now the key issue with electrics is range. Cost wise they are still roughly double in price of a comparable gas unit but efficiency is so much greater. The recharge time is at least 45 minutes versus 10 minutes at a gas pump. They really shine in stop-and-go traffic.

I agree. I follow the technology somewhat and root for it, but I'm not going for cordless electric on anything larger than a weedeater at this point, and even a $100 weedeater is frustrating, mainly because the e-industries that compete against gas power won't get together and offer us a single set of charging systems and battery compatibility. When I buy a stinky, loud, unreliable, and overpowered gas weedeater, at least the fuel dispensers from gas stations and from cans work for adding fuel to my machine no matter the brand or product type; at least I can expect that my range will not start dropping every year until I replace my fuel tank; and at least, if I do need a new fuel tank, it won't be the most expensive component on my gas weedeater, or be obsolete wherein I cannot even replace it.

So while I hail the fuel efficiency of electric motors via battery power, I'm not yet a fan. If the e-industry worked more closely together to make their versions of power more competitive, I would be more of a fan.