My MPG Experiment

[dltang]

Ok, I was reading in another thread how the Rotax engine prefers higher rpms and should perform better and get better mpg if you run it the way it likes. So I tried a little unscientific experiment to test this theory. I usually get anywhere from 27-32 miles per gallon on my spyder for the everyday riding I do. This is a combination of stop and go, city, highway etc. On long drawn out trips on the highway, I usually get about 32-36 mpg.

Anyway, I decided to run a tank of gas and keep the rpms up as suggested. That meant I didn't hit 5th gear unless I was on the highway doing over 70. I very seldom hit 4th gear as most of the roads around home are no more than 45 miles per hour speed limit. So for the most part I was in 1st, 2nd & 3rd gear the majority of the time. Kept my RPM's between 5-6 on the gauge on average.

Today I filled up with 138 miles on my trip Odometer and I put in 5.1 gallons and I didn't even try to fill it all the way to the tip top like I often do. That is 27.05 mpg.

Conclusion, running at higher RPMs does nothing to increase mpg. Is it better for the engine? I can not answer that question.

Just thought I would pass on that little bit of info. Now, on a side note, I did just take my spyder in for running poorly. I do not know if this is a factor to take into consideration or not. I have noticed recently that my mpg has fallen in general not just for this experiment. So to be fair, when I get her back and all it well, I can try this again.

 

[bone crusher]

Ok, I was reading in another thread how the Rotax engine prefers higher rpms and should perform better and get better mpg if you run it the way it likes. So I tried a little unscientific experiment to test this theory. I usually get anywhere from 27-32 miles per gallon on my spyder for the everyday riding I do. This is a combination of stop and go, city, highway etc. On long drawn out trips on the highway, I usually get about 32-36 mpg.

Anyway, I decided to run a tank of gas and keep the rpms up as suggested. That meant I didn't hit 5th gear unless I was on the highway doing over 70. I very seldom hit 4th gear as most of the roads around home are no more than 45 miles per hour speed limit. So for the most part I was in 1st, 2nd & 3rd gear the majority of the time. Kept my RPM's between 5-6 on the gauge on average.

Today I filled up with 138 miles on my trip Odometer and I put in 5.1 gallons and I didn't even try to fill it all the way to the tip top like I often do. That is 27.05 mpg.

Conclusion, running at higher RPMs does nothing to increase mpg. Is it better for the engine? I can not answer that question.

Just thought I would pass on that little bit of info. Now, on a side note, I did just take my spyder in for running poorly. I do not know if this is a factor to take into consideration or not. I have noticed recently that my mpg has fallen in general not just for this experiment. So to be fair, when I get her back and all it well, I can try this again.

Very nice...I would figure that common sense would prevail but not many here agree with me...meaning, my common sense might be worth nothing!

Figure it this way....what drives RPM? Power...gas, O2, etc...to get the RPMs up, you have to deliver more power to the engine...this will require more O2 and more fuel...thus, it should lower your MPG.

As far as performance goes, there is no question that an engine rich in fuel will perform better...BRP says that max HP of 106 (110 with hindle) is achieved at 6-7k RPM...this makes sense.

I have not done an experiment such as yours but I'm excited to see you do it again when other variables can be eliminated...

Good luck with getting everything else with the bike cleaned up...

 

[Smylinacha]

I'll be interested in this once you get your :spyder:back to normal
opcorn:

 

[dltang]

The max rear wheel HP (about 90hp) is actually achieved around 9000rpm, max torque is around 6000rpm.....

Okay Mr. "Stirring the Pot" I have no idea what any of that means....:dontknow:

 

[Smylinacha]

Okay Mr. "Stirring the Pot" I have no idea what any of that means....:dontknow:

Me neither:shocked: He likes bar graphs, charts and stuff. I just wanna turn the key and go.:clap:

 

[Donk45]

I have a graph too...

 

[Smylinacha]

I have a graph too...

:2thumbs: So you got it up to 130 without the granny kicking in? Best I did was 104.

 

[Firefly]

It just means that if you want the maximum roll-on power, you want to start from about 5000rpm. 5000-7000rpm is where the Rotax creates the most energy to the rear wheel..... It doesn't always equate to the best MPG however.....Can't have your cake and eat it too....

:agree:

If it's the thread I was posting in - I didn't mean to imply that running at higher RPM's would result in better MPG - just that the Rotax likes to run at higher RPM's - where it will give you the most power without any lugging. You might see a decrease in MPG if you're running in 5th gear and actually lugging the engine - not sure - not something I would try!

Nice experiment. Also interesting to note the difference in how long people are getting out of their rear tires. Some are getting well over 10,000 - I can't imagine getting 10,000 out of the rear tire. I thought I rode pretty hard - but not THAT hard!

 

[zzneonzz]

I found riding at 5k rpms gave me best MPG results. Any higher or lower and the MPG drop atleast from the non scientific tests i have done. The 5k RPM range gives me 31-32 mpg most of the time around town and i get 38 mpg on highway trips

 

[BajaRon]

I'm not surprised that running high RPM cut mileage.

I'm hoping to do my own mileage test but in a different direction. There has been a good discussion about octane. I'm still pondering how you can run the compression ratio that we do on 87 octane and make the Rotax happy.

I'm convinced that electronics have much to do with it. Kind of a shell game approach.

Take the Aprilia ETV 1000, for example. Sounds like it uses a Carbon Copy of our Spyder engine. It has the same specs including compression ratio and calls for 95 RON (which translates to 90/91 Octane here in the US).

So, since I'm doing East Tennesse - California and back next month I'm going to have time to run all 3 grades of fuel. I'll do several hundred miles with 87, then 89 then 91 and see if there is any appreciable difference.

I need something other than looking at the back of Lamont's trailer to keep me occupied!

 

[bone crusher]

:agree:

If it's the thread I was posting in - I didn't mean to imply that running at higher RPM's would result in better MPG - just that the Rotax likes to run at higher RPM's - where it will give you the most power without any lugging. You might see a decrease in MPG if you're running in 5th gear and actually lugging the engine - not sure - not something I would try!

Nice experiment. Also interesting to note the difference in how long people are getting out of their rear tires. Some are getting well over 10,000 - I can't imagine getting 10,000 out of the rear tire. I thought I rode pretty hard - but not THAT hard!

I couldn't remember the specific number BRP was discussing for peak HP...I saw it on a video once...if it's near 9000 RPM, then that's high, but reasonable...still below red-line.

The hp is 106-110...how many tests verified it at 90? More than one?

As far as mileage goes, obviously pounding your bike at 9000 RPM isn't going to be very efficient!

 

[bone crusher]

I found riding at 5k rpms gave me best MPG results. Any higher or lower and the MPG drop atleast from the non scientific tests i have done. The 5k RPM range gives me 31-32 mpg most of the time around town and i get 38 mpg on highway trips

Have no idea how you get 38 mpg on the highway unless you have a cruise control or never pass anyone.

As far as the 31-32 range goes, that's about where I am...although on Sunday I got under 30 for some reason...perhaps all the start and go and engine revving at Rolling Thunder!

 

[fastfraser]

I have a graph too...

Come on DONK45 you havent hit 10 yet ?:roflblack::roflblack::roflblack:

 

[Lamonster]

Been playing with the Juicebox I got from No Magic and he sent me some settings that really woke up the Spyder and I was getting 32mpg towing the trailer. :thumbup:

 

[Roaddog2]

It just means that if you want the maximum roll-on power, you want to start from about 5000rpm. 5000-7000rpm is where the Rotax creates the most energy to the rear wheel..... It doesn't always equate to the best MPG however.....Can't have your cake and eat it too....

I like Donuts:ani29::chat:

 

[bone crusher]

The 106 hp is what the engine (only) is capable of. Known as Brake Horsepower. Measured with the engine out of the vehicle......Rear wheel horsepower is what you really have available, measured on a dyno with the engine actually in the vehicle. RWHP takes into account all of the drivetrain losses suffered. Drivetrain losses are commonly around 20%. The Spyder really only has about 90hp available....Manufacturers typically publish brake hp numbers-it sounds more impressive........:doorag:

Yes...makes sense...this is why Porsche makes a mid-engine...less reduction in hp...do they even have a drivetrain??

I've heard the figure of 15-20% loss...

If it was tested at 90, then obviously that's what it was...I'm wondering how much that number would change with a hindle, NMN's performance filter, etc...probably up a couple more...with the juice box, even more?

 

[sabunim5]

Like Deb, I have read several posts in the past about people getting better gas mileage at higher RPM. I had seen the horsepower and torque curves before and so I did my own one tankful experiment. I normally get 30 +/- 1 mpg regardless of what kind of ryding I am doing or how heavy I am loaded. The only thing that seems to pull my mileage down is fighting a headwind. I thought perhaps if the engine is running nearer that sweet spot maybe ?????
My results were abysmal; my mileage went down to about 25 mpg. Oh well, Live and Learn. I keep my RPM's appropriate for the load and have gotten 32 mpg on a couple of tanks recently, so maybe my mpg is improving slightly with more miles. It could happen.

 

[irish2themax]

What seems to be the consensus on 5th gear RPM at "cruise speed"?

 

[Star Cruiser]

The max rear wheel HP (about 90hp) is actually achieved around 9000rpm, max torque is around 6000rpm.....

Thanks HDX. I was looking for this graph to see if the power "levelled off" at a particular rpm. Apparantly not. Just more power as you increase the rpm. A little steeper at 6,000 rpm I see, but not dramatic. I get more pickup shifting at 5,500 to 6,500 so I guess my experience compares to the graph. Nice verification - much appreciated.
Judging from the graph, less than 4,200 rpm would be lugging the engine and probably getting less mpg if there were any load at all (uphill or accelerating)

 

[FANG]

Like Deb, I have read several posts in the past about people getting better gas mileage at higher RPM. I had seen the horsepower and torque curves before and so I did my own one tankful experiment. I normally get 30 +/- 1 mpg regardless of what kind of ryding I am doing or how heavy I am loaded. The only thing that seems to pull my mileage down is fighting a headwind. I thought perhaps if the engine is running nearer that sweet spot maybe ?????
My results were abysmal; my mileage went down to about 25 mpg. Oh well, Live and Learn. I keep my RPM's appropriate for the load and have gotten 32 mpg on a couple of tanks recently, so maybe my mpg is improving slightly with more miles. It could happen.

I agree Sabunim5 - I average about 30-32 mph under normal conditions and daily driving - I have gotten 38 mpg but it was all highway driving on an extended ryde and no head wind. A head wind seems to kill the mileage for me also. Last week with the wind as bad as it was on the Gulf Coast I got 27 mpg in my normal driving. I usually run my rpms 4500 to 5500. That seems to give me the optimal mpg. Shift are at 5000 usually but I have been know to get on it from time to time .