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Old 08-01-2012, 12:18 PM   #2536
turbodieseli4i6
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Originally Posted by VAridinguy View Post
I'm running 89 octane Ethanol-free and getting 72 mpg like clockwork. Got 65 before switch to ethanol-free, so I am really suprised your not getting better....I ride mine responsibally, but I do have fun.
That 47 mpg was a magazine article, they said at 85 mph returned 47 mpg. I haven't ran a tank through mine yet, but it is beating 47 mpg pretty bad I would bet.

85 mph around my neck of the woods would get your license and cash removed from your wallet.
Luckily I live near Oklahoma and get ethanol-free gas there.
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Old 08-01-2012, 12:24 PM   #2537
Bugz
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Hello lads,

I'm just a lurker on this forum pretty much. Really like the website but somehow I don't post very often here though I do like to get involved in this ungoing fuel consumption discussion! (I'm dutch. my dutchized english isn't THAT good).

I'd like to start with efficiency of engines and specific fuel consumption.

Most people do know that the thermal efficiency of a normal petrol engine is about 30% whereas the thermal efficiency of a diesel engine is about 40%. We're talking about car / motorcycle engines here. Industrial diesels found in ships and energy plants can go up to 50% currently.

What most people do not know is that the efficiency of a combustion engine is far from constant. It is about as variable as it gets (variable as in running conditions, not because the stars don't allign that well on mondays). The easiest way of 'seeing' the different thermal efficiencies of an engine is by using a SPF diagram (Specific Fuel Consumption Diagram). Let's use one I found on wikipedia from a VW 3 cylinder 1.5. diesel engine found below;


On the x-axle there is RPM and on the Y-axle there is the effective pressure of the engine. For the sake of simplicity the Y-axle can be read as a form of power output. The red lines are the working borders of the engine. It will nut run above those conditions.

SPC (Specific Fuel Consumption) is how much fuel you need to get a certain power output. SFC is defined as SFC = r / Pe where r = gramms of fuel (weight) en Pe is effective power of the crankshaft. In other words; The higher the SFC the higher the efficiency of anengine is. In the above diagram we see that the ultimate sweet spot of 206 kilogram / kilowatthour with regards fuel consumption of this engine is at about 15 Pe and 2300 RPM. For maximum fuel efficiency one would have to create driving conditions to get this.

The reality with modern cars and motorcycles is that it is near impossible to achieve these running conditions. Running on a 80% load with modern cars will end you up flying way above the speed limit! Our engines in cars and motorcycles are incredibly overpowered with regards what they have to do; My estimate is that most cars / motorcycles will be running on an engine load of around 25% (and that's for european cars, not the american supermarktet V6 / V8 / V12 SUV's. They will do much worse). You can see in the SFC diagram that an engine load is way below the optimum SFC. If we take an estimated 250% load of an engine at 2500 RPM (highway conditions) we can see that the SFC is 260ish. You need 260 - 206 = 54 gramms of fuel extra just because of how we design our cars / motorcycles. You don't need 150 BHP to get a car in motion. 40 HP is more that sufficient to get you op to 85 mph.

I think the main reason for manufactures is that people don't really want these cars yet. People want a car / motorcycle that's responsive to their foot / wrist which means we want pretty low end gearings (I think most motorcycles go above 6000 RPM on the highway @ 85 mph) and want power.

Now back to Honda's claim. I'm very willingly to believe it will achieve 60ish mpg figures under highway conditions. It's build in a way it will obtain a high engine load since it has such long gears / low maximum RPM, and I think even the NC is still quite a bit away from maximum efficiency! It's not that a Honda fireblade doesn't have a sweet spot, it's just nowhere near normal driving conditions.

Don't get me wrong. do not know anything about building or constructing engines. I'm a maritime student so I have a good understanding of operating principles of combustion engines. If anyone sees major flaws in what I've written feel free to correct me.

I do not know exactly what causes the sweetspot (apart from that it obvious has to to with pressure ) and I do know that engineers can build engines to suit their operating conditions (a racecar will have a sfc sweetspot around it's maximum RPM under full load, since that's the place it will be running during a race) but engineers cannot peform miracles. You cannot build a sportbike to suit maximum economy if the engine has 180 bhp on tap.

Regarding torque; all the fancy diagrams showing diagrams of hp and torque could be shown just without the torque as well. The torque of an engine shows nothing. It's just a sort of derivative of the power output of an engine. It's quite simple if you think about it as well; AN ENGINE WITH AMAZING TORQUE DOWN LOW....just produces a lot of horsepower down under.....

@ Sendler; I love your efforts @ cbr250.net mate! I got a CBR 250 R as well though I'm running the stock gearing still. Im also achieving nowhere near your fuel economy (im at around 70) which is what I get when I run about 120 km/h indicated (110 km/h GPS speed) and spirited backroad riding. Iam thinking about changing up to a 15T up front though; not because for the extra saving in fuel consumption since I read they are just about 3-5% but just so I can run a bit higher speeds while still achieving good fuel consumption. My findings are that the CBR starts to eat fuel above 7000 rpm on the highway... (which is 120 km/h indicated on the stock gearing). Any thoughts on this? Thanks!

~Bugz

Some reading stuff;

SPC on wiki; http://en.wikipedia.org/wiki/File:Br...onsumption.svg

http://autospeed.com/cms/title_Brake...6/article.html

http://www.heat2power.net/en__wasteheat_in_ices.php
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Old 08-01-2012, 01:54 PM   #2538
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Quote:
Originally Posted by Cortez View Post
Here's something new for the NC series, announced 2 days ago.




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Old 08-01-2012, 02:43 PM   #2539
Mike Cash
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Originally Posted by larryboy View Post
I intend to get the 700x in the fall and will use it as intended and dream of 64 mpg, but a current test of the bike has returned 47 mpg.
I've had mine for about a month, have put about 1800km on it so far, am large enough that it is like always riding double, and my attention to economical riding has been on a par with the "ride it like you stole it" guys.....and I average 63mpg (US).

Maybe someday I'll see what I could get out of it if I tried.
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Old 08-01-2012, 02:53 PM   #2540
RxZ
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I do not own one of these bikes, but I do find them very interesting for their purpose. About mileage, I am seeing a lot of 60's so far, and that is very good in my book. My ex500 has similar HP and torque specs (I think, close anyway) and I get right at 50MPG. An extra 10-15 MPG on average would be very nice.
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Old 08-01-2012, 03:34 PM   #2541
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I will probably be thinking very seriously about one of these in a couple years. I am getting ~45mpg pretty regularly with a 08 CBR1000RR on my commute so I think I could do well with the NC. I don't really have the cash to add another street bike to the stable or I would be thinking seriously about it now (when did college get so expensive and how did my baby girl get so grown up that I have to worry about it?).
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Old 08-01-2012, 04:17 PM   #2542
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dropped the the local dealer for a look see. I immediately liked the bike, I couldn't believe how light it felt. My xxl flip up fit into the Xbox, with room for summer gloves maybe. If I had the coin, I would have picked it up right then, just for fun. It's very upright, but not dorky, squishy, soft suspension. This pretty girl who was helping me wouldn't sit on the bike for a picture, imagine that. I told her, well being turned down is a story too, and she laughed.

The tag read $7960 with set up and freight, tax here would be $719 plus 120 for tags = $8796. That's about $3500 more than I paid for the cbr250r. Pretty good deal if you compare it to the smaller bike, but still a good chunk of change.

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Old 08-01-2012, 04:40 PM   #2543
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Originally Posted by larryboy View Post
That's the thing, I am backing it up with facts. There has been a good real world test of the 700x and the tester rode it hard like it will be ridden and returned 47 mpg and that sounds about right to me for a low hp naked bike.

I know sendler wants to discount what I'm saying about these "new" Honda's as he puts it, but the facts are that I'm filling up twice a day on the new CBR250R and riding 175 miles per day and after one month my average mpg is 58, no way around it and I'm being sensitive by NOT mentioning my worst tank. I intend to get the 700x in the fall and will use it as intended and dream of 64 mpg, but a current test of the bike has returned 47 mpg.

I have had one bike that I averaged better than anybody else in that "group", 2007 TE610 with a carb, 60 mpg. It's too bad the engine wears out so quick as it'd be a great commuter.

Fact.






Where do I sign up for one of those?
If I can get 50mpg tucked doing 75-80 on I-5 (superslab) on my 1989 ZX-10, I REAAAALLY doubt that this bike gets 47mpg

just sayin..
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Old 08-01-2012, 05:29 PM   #2544
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Quote:
Originally Posted by Bugz View Post
Hello lads,
Great post. I was getting around to all of that about Base specific fuel consumption charts and the sweet spot on my new thread over here.
.
http://www.advrider.com/forums/showthread.php?t=813587
.
Would you care to copy your post over onto that thread so we can continue the general conversation of fuel efficiency over there without being so far off topic as we are here?
.
Your bsfc map shows how narrow the sweet spot of efficiency is which is why Pulse and Glide makes such a big difference to fuel economy and why Honda put "just enough" power into the NC700 engine even though they would have known that sporty riders would whine against the bike as being low revving and under powered.
.
Your 70 mpgUS on your CBR250R is right in line with the average. I hope you have joined us in promoting the best all around value in motorcycling on Fuelly as it seems to be the best and still growing English speaking resource for comparing real world fuel mileage. Spirit Monitor is also quite active. There is an Indian site that shows very impressive numbers for their air cooled 110cc bikes many of which are in the 120 mpg range due to their limited top speed of 100 kph. Those bikes sell for $1700 brand new!
.
.
You would like changing to the +1 tooth 15T on the front of the CBR. It is only 7% longer but makes high rpms in the ultra low first gear hand off to second more smoothly. Your rest of world speedo error will be almost completely corrected though your odo will be then be long by 7%. And top speed will go up a 1 % to 94 mph as will your FE.
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Old 08-01-2012, 07:37 PM   #2545
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Well, I did it. I brought a NC700x home today. I generally like it, but the seat is from hell. I tried an Alaska Leather sheepskin to see if it helped. It does, but the seat is shaped wrong. It pushes you forward. How is it they get the difficult stuff right and miss something so obvious and seemingly simple? Oh well, I have not owned many bikes where I kept the stock seat. This one will be a challenge to "custom" because of the way the front and back are split, but SOMETHING is going to happen.

It is a well done package, but it is entry level (read budget) in terms of suspension, brakes, and power. Mine happily came with Metzeler tires instead of the normal Dunlop or Bridgestone "rim protectors" so I am happy with that. Tomorrow I call Revzilla and order a set of Givi V35 side cases with mounts.



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beemerphile screwed with this post 08-01-2012 at 08:18 PM
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Old 08-01-2012, 07:54 PM   #2546
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Originally Posted by beemerphile View Post
Well, I did it. I brought a NC700x home today. I generally like it, but the seat is from hell.
Ping Seat Concepts, they might be looking to develop a seat for your bike.

http://advrider.com/forums/showthread.php?t=621311
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Old 08-01-2012, 08:43 PM   #2547
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congrats on the new bike beemerphile
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Old 08-01-2012, 08:54 PM   #2548
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Congratulations!

I said the same thing about the seat but that was only the first 50 miles or so. I've had mine a week now. After four rides totaling 450 miles I don't notice the seat at all anymore. I wore jeans that first ride and some Tourmaster mesh pants the other rides. The jeans seemed to bunch up in the front but the riding pants don't. I plan on doing a 400 or 500 mile ride on it Saturday and that will tell me more. I'll take a sheepskin I have with me just in case! I could do 500 or 600 miles on the stock ST1300 seat and had to go to a Sargent to get a 1000 mile in a day seat. Mine came with Metzelers too but the Bridgestone 023 on other 700's are very good tires. I ran a set on my ST1300 and really liked them. I kind of looked forward to 023's again but oh well.
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Old 08-01-2012, 09:09 PM   #2549
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Congratulations!

I said the same thing about the seat but that was only the first 50 miles or so. I've had mine a week now. After four rides totaling 450 miles I don't notice the seat at all anymore. I wore jeans that first ride and some Tourmaster mesh pants the other rides. The jeans seemed to bunch up in the front but the riding pants don't. I plan on doing a 400 or 500 mile ride on it Saturday and that will tell me more. I'll take a sheepskin I have with me just in case! I could do 500 or 600 miles on the stock ST1300 seat and had to go to a Sargent to get a 1000 mile in a day seat. Mine came with Metzelers too but the Bridgestone 023 on other 700's are very good tires. I ran a set on my ST1300 and really liked them. I kind of looked forward to 023's again but oh well.
I will probably transition to Michelin Pilot Roads after the Metzelers wear out. We'll see. I run both Metzelers and Pilot Roads on my BMW with good results. I hope I get as lucky as you adapting to the seat, but I am a 600-1000 mile per day rider on long trips so I expect a custom is in order. I am sure the nut can be cracked but they sure would have made it easier with a side gas fill and a one piece seat. Dang 'em!
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Old 08-01-2012, 09:24 PM   #2550
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Here is a link to the Honda worldwide site with some details on the engine design. Another important aspect of Honda's current philosophy is evident in the large catalysts that the NC700 and the CBR250R have. Take a look.
. http://world.honda.com/Global-700cc-engine/index.html
.
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