MPG

[Desert Spyder]

Here's a question I've never seen asked here yet. It may seem like a stupid question but with this wonderful high-tech bike, who knows.

We all average about 150 miles to the tank, a round number to the next fill up. Now, would you use more gas going at high speeds than slow. In otherwords, if you were going 150 MPH (remember, the speedometer say 200), would you use the same amount of gas, more or less, than if you were travelling 25 MPH?

I remember the carberator (sp) days in a car, anything over 55 MPH and the secondarys open up. But my car didn't have a TPS, whatever that does, or a nanny, etc.

 

[3wheeldemon]

Here's a question I've never seen asked here yet. It may seem like a stupid question but with this wonderful high-tech bike, who knows.

We all average about 150 miles to the tank, a round number to the next fill up. Now, would you use more gas going at high speeds than slow. In otherwords, if you were going 150 MPH (remember, the speedometer say 200), would you use the same amount of gas, more or less, than if you were travelling 25 MPH?

I remember the carberator (sp) days in a car, anything over 55 MPH and the secondarys open up. But my car didn't have a TPS, whatever that does, or a nanny, etc.

Is not a stupid question in the sense that you need a mechanical engineering degree to answer it. The optimum MPG of a vehicle depends of many variables. Ever if you simplify a lot of them you will still need to find the multivariable optimum point of cross of the air drag vs. speed curve, the efficiency vs. RPM curve of the engine and the power vs. speed curve on the optimum gear (probably 5th). Most street vehicles are optimized for a maximum efficiency at 55-75 MPH.

Sorry if this leaves you worse that where you started.:dontknow:

3WD

 

[COOLMACHINE]

I'm not touching that one.....:sour:
Face piles of trials with smiles. It riles them to believe that you perceive the web they weave. And keep on thinking freely. Back at ya.

 

[3wheeldemon]

I'm not touching that one.....:sour:

What I did not think that answer? beats the hell out of mine:roflblack:

3WD

 

[QuadManiac]

There is an optimum speed, as mentioned above, that is a mix of the most efficient RPM of the engine and the least amount of drag (both rolling friction and air resistance).

As speed goes up, air resistance becomes the dominating force. Power required to overcome air drag goes up as the CUBE of velocity... so you can be sure that as you reach high speeds, the mileage is going to go way down - example - 120mph, twice the speed of 60 mph, requires 8 times the power (2 cubed or 2 x 2 x 2) from the engine to overcome air resistance compared to 60mph. This equates to something close to 8x the fuel also. (BTW, I always see a large dip in my mileage when I've spent any significant amount of time above 100mph during that tank - check 8/20 on my FUELLY link)

The place where air resistance becomes dominant is a function of the aeronamic design of the bike, how big the rider is, windshield, accessories on the bike, etc. But, typically, the dominance starts somewhere at or below 70 mph.

 

[Tom in NM]

I spent too much time around engineers . . . .

Why I did not think that answer? beats the hell out of mine:roflblack:

3WD

. . . . I "understood" your first answer, but "who knows" works too.

Since I bought my Spyder I have wondered were the sweet spot was of RPM, Gear, and speed that would deliver the best MPG. My riding style is all over the map (both figuratively and literally) and I can never quite close in on it.

On my other motorcycles, I could tell. But with the Rotax and how the gears are set, I don't get that feeling. My guess is around 65mph.

It would be great to get 10 Spyders on the bricks at Indy and have each ride to different speeds, gears, and RPM and see who went farther on the same amount of gas.

3WheelDemon, maybe you guys in Houston could do that on 610 and report back?

Tom

That would not exactly translate to real world driving, but it would be close enough for me.

 

[QuadManiac]

. . . . My riding style is all over the map (both figuratively and literally) and I can never quite close in on it.

Yes, if those twisty roads didn't call to me, and the occasional long straight without any cars (or LEO's) in sight wasn't so inviting, I'd like to figure it out too... but, alas, I have so little willpower when it comes to riding fun.

 

[bone crusher]

I would say that to maximize MPG, keep your tach low...so, if you could perpetually go down hill, you'd use little engine power yet you'd be traveling a far distance...this would give you good mpg.

If you are going up hill and you have to throttle the whole way, you are telling the engine to pump more fuel in, thus decreasing your mpg.

I know many here say that maximum HP is at the 6500 rpm range...that's nice for power, but you are going to have to release a lot of fuel to get this power.

Less RPM means less engine movement (think about it...rpm...revolutions per minute)...the less the engine works, the less fuel you are going to consume.

So, for me, I try to get the most speed I can with the least amount of engine use...this is how you have to look at it to maximize mpg...

I think the more efficient I have become with riding, the better the gas mileage has gotten. It also took over 600 miles on the bike for it to settle down and get 'broken in.' It's likely that the bike continues to get broken in for some time after this too.

If you average around 30 mpg, you're doing fine...after the update, many are saying this gets better...I haven't been out enough to confirm this...

 

[bjt]

There is an optimum speed, as mentioned above, that is a mix of the most efficient RPM of the engine and the least amount of drag (both rolling friction and air resistance).

As speed goes up, air resistance becomes the dominating force. Power required to overcome air drag goes up as the CUBE of velocity... so you can be sure that as you reach high speeds, the mileage is going to go way down - example - 120mph, twice the speed of 60 mph, requires 8 times the power (2 cubed or 2 x 2 x 2) from the engine to overcome air resistance compared to 60mph. This equates to something close to 8x the fuel also. (BTW, I always see a large dip in my mileage when I've spent any significant amount of time above 100mph during that tank - check 8/20 on my FUELLY link)

The place where air resistance becomes dominant is a function of the aeronamic design of the bike, how big the rider is, windshield, accessories on the bike, etc. But, typically, the dominance starts somewhere at or below 70 mph.

Glad you put the "science" in your answer. All I can say is that from firsthand experience, riding the Spyder at a sustained (over an hour) 90 + MPH resulted in much worse fuel economy than riding at 80 MPH or less.

 

[SE5spyder]

All I know is that I'm still getting HORRIBLE mpg...21-23:gaah:. No hills here in Fl. and not even driving it hard !!! se5,stock,city driving:dontknow:

 

[Desert Spyder]

So as I understand it, because I'm 6-1 & 245 with a "touring" windshield, using supreme gas and a heavy throttle in hot air, I would be using more gas because I represent a drag. Now because I'm bald, and I took my helmet off, there would be less of a drag.

However, if I was of small stature there would be less drag. Right?

Now, how about mechanically?

I'm not clear on the fuel delivery system. City driving, less drag because of less speed however more stop and go. In a car the mileage is worse than on the highway.

What about the Spyder? Better mileage city or highway? Regular or Supreme?

Although I prefer Supreme now because of better response my mileage is worse than with regular, especially since the recall.

Would the "canisterectomy" I hear about improve the overall performance and MPG and would this cause warranty problems?

 

[QuadManiac]

Stop and go throws the air drag issues out the window. Now you have to move ALL that inertia - the bike and rider - from a stop to road speed over and over. This takes a lot of energy and is why highway MPG is usually better than city MPG (except for Prius's). In stop and go, the 'gentility' in which you accelerate to speed becomes the dominant factor in MPG. I have problems with mild acceleration. My city mileage sucks!

As to regular vs. supreme - most will say there SHOULD be no difference. However, with current engine designs - computer controlled fuel injection with 02 and knock sensors - manufacturers depend on running just a bit lean to meet smog standards and depend on ping/knock sensors to retard timing when necessary to prevent engine damage (AND it appears as if the software update has leaned the fuel map even more).

So, IF, and only if, your knock sensors are detecting pre-ignition regularly, as they may in warmer coniditions of summer with a lean mixture, then premium (whose sole purpose is to help prevent pre-ignition) can prevent these knocks, which will keep the ignition timing from being retarded, which will ultimately show better performance.

 

[Tom in NM]

one thing to check . . . .

All I know is that I'm still getting HORRIBLE mpg...21-23:gaah:. No hills here in Fl. and not even driving it hard !!! se5,stock,city driving:dontknow:

. . . . a couple people have found that their gas caps were not seating properly and they lost gas through evaporation. Check that.

Tom

 

[COOLMACHINE]

Hopefully I did not come off being disrespectful.

3wheeldemon,
Please accept my apologies if I what I wrote came off as being disrespectful towards your post. I certainly didn't mean to. It's all good. I got a kick out of your answer because what you wrote in your post was so far beyond what my brain was willing to take in at the moment, it's not even funny. So what I was really meaning to do was make a joke about myself and the way your answer flew right over my head. Rock on Dude. :thumbup: Keep it on 2-wheels... or 3.
Jerry

 

[3wheeldemon]

3wheeldemon,
Please accept my apologies if I what I wrote came off as being disrespectful towards your post. I certainly didn't mean to. It's all good. I got a kick out of your answer because what you wrote in your post was so far beyond what my brain was willing to take in at the moment, it's not even funny. So what I was really meaning to do was make a joke about myself and the way your answer flew right over my head. Rock on Dude. :thumbup: Keep it on 2-wheels... or 3.
Jerry

No problem, bro Actually I had a good laugh with your answer. I could not believe myself that I let my normally repressed inner geek escape like that:roflblack:

3WD

 

[SSG Bean]

Less RPM means less engine movement (think about it...rpm...revolutions per minute)...the less the engine works, the less fuel you are going to consume.

I'm not an engineer, but I thought there were more variables than just engine speed. It is my understanding that different engines are optimized for different power bands. That is why my VW can turn roughly 4K rpm and still get better mileage than a similar sedan with a larger v-6 turning 3k. If the engine is lugging at a lower rpm, it is not working as efficiently as a motor steadily humming along in its optimal powerband. If some of you scholarly engineering types can shed some light on this for me, it would be greatly appreciated!:thumbup:

 

[NancysToy]

I'm not an engineer, but I thought there were more variables than just engine speed. It is my understanding that different engines are optimized for different power bands. That is why my VW can turn roughly 4K rpm and still get better mileage than a similar sedan with a larger v-6 turning 3k. If the engine is lugging at a lower rpm, it is not working as efficiently as a motor steadily humming along in its optimal powerband. If some of you scholarly engineering types can shed some light on this for me, it would be greatly appreciated!:thumbup:

You are absolutely right! There are a bunch of variables, including several outside the engine.

 

[QuadManiac]

You are absolutely right! There are a bunch of variables, including several outside the engine.

In my case, my right hand!

 

[bone crusher]

I'm not an engineer, but I thought there were more variables than just engine speed. It is my understanding that different engines are optimized for different power bands. That is why my VW can turn roughly 4K rpm and still get better mileage than a similar sedan with a larger v-6 turning 3k. If the engine is lugging at a lower rpm, it is not working as efficiently as a motor steadily humming along in its optimal powerband. If some of you scholarly engineering types can shed some light on this for me, it would be greatly appreciated!:thumbup:

You answered your own question...two differerent vehicles will perform differently...no question about that...

As far as the Spyder goes, since we are all comparing the same vehicle, it can be said that less RPM does mean that the engine is working less...of course, we have to assume that we're not at an RPM where the vehicle is 'lugging'. Beyond that, with everything else being equal (forget weight and air resistance, etc...), higher RPMs do equate to more work...

 

[Tom in NM]

Have I got a solution for you . . . .

In my case, my right hand!

:roflblack:

. . . . . put the throttle on the LEFT side.

SSG Bean, you are right, but I wish it were that easy. While the physics can be calculated, the number of variables just gets out of hand - otherwise, everybody would be agreeing on "the" answer.

I am with you, I am looking for a nice general sweet spot of operation for my general conditions of driving. I have the same issue as QuadManiac, of inconsistency tending towards being a rocket jockey. Higher speeds, as far as MPG goes, like Brian said, it can just suck all the gas out of your tank.

I have noticed ( for me, stock SE5, small guy, 5,000' altitude ) 55 mph in 5th, right around 5K RPM is smooth and easy. But I have the "feeling" when I go over 75, I am dropping of the MPG cliff. There seems to be a very sharp decline in MPG. On trips where I stay at/under 75, I get around 37-40mpg. My guess is, going 95 mph is around 10 - 15 mpg or less.

When I get my right hand under control, I will post my results.

Tom