Kawasaki Motorcycle Forums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
2,159 Posts
Discussion Starter #1
Okay...when I'm looking for the maximum Mile per gallon just with a chart, it it maximum Torque, Maximum Horsepower, or where the lines intersect? Curt, will probably be the one to ask about grades, tailwinds, drag, rolling resistance, gearing...actually just basically where would the MPG efficiency be found on just a chart of hp/torque?
 

·
Registered
Joined
·
2,159 Posts
Discussion Starter #2
AERODYNAMICS aside

This is on a bare/naked bike...lets not get concerned about setting directly in the aerodynamic airflow and cruising at sealevel...no wind at 29.92" mercury...all the variables...
 

·
Registered
Joined
·
456 Posts
ZX-2R said:
Okay...when I'm looking for the maximum Mile per gallon just with a chart, it it maximum Torque, Maximum Horsepower, or where the lines intersect? Curt, will probably be the one to ask about grades, tailwinds, drag, rolling resistance, gearing...actually just basically where would the MPG efficiency be found on just a chart of hp/torque?
I have no idea. Actually I have some idea, but I'm sure it's different for every bike. And I think that the factors that you want to ignore make a huge difference.

Generally speaking, the fuel consumption of the engine is fairly linearly related to the horsepower output of the engine. What that means is that the fuel efficiency (which is the ability of the engine to transform chemical energy into kinetic energy), which is not the same thing as the MPG's, is fairly (not exactly) flat through a lot of the RPM range. But as the RPM's get higher, the pistons have to reverse direction more often, and that consumes a lot of the energy of the engine. You can overcome that by adding more fuel, but then efficiency of the engine drops. So your maximum horsepower comes at a point when the engine is not very efficient.

But when the RPM's are very low, the fuel economy drops off, too. For many cars, the sweet spot is around 45mph. You can go a lot faster, but your engine efficiency drops and wind resistance increases, so your fuel economy goes right into the toilet.

If I were to guess, I would guess that the sweet spot for our Ninja 250's is also around 45mph. I have heard of people who get better mileage in the city than on the highway, because this little engine is fairly inefficient at highway speed. And lower than 45mph, you're probably risking lugging the engine, which is not so good either.

So to sum it up, that's my guess. Maybe it's not a great guess, but it's the best I can give you right now.

Now for a related subject ...

Some cars have an MPG readout on the dashboard. Some of the people who own those cars become MPG fanatics, and they drastically adjust their driving styles and meticulously keep up with maintenance to maximize their MPG's, and they have very impressive results. Wouldn't it be fabulous to do that with the Ninja 250? I'm looking into it, but I have so many mods on the "to do" list that it's getting ridiculous.
Curt
 

·
NO---I ain't dead--yet
Joined
·
266 Posts
In a car---wind resistance really becomes a factor over 70 mph---no idea
what this point would be on a bike---as a car is generally more aerodynamic.

Also on the hiway---you get better gas mileage by leaving the windows up and running the A/C----than by rolling the windows down and not using the A/C----simply because of wind resistance.

See----I actually remembered something from shop class.-----lol
 

·
Registered
Joined
·
2,159 Posts
Discussion Starter #5
CURT

Curt, I'm still playing around with various muffin fan values...for attaching to a new airbox lid...14Vdc not exactly a supercharger, just a mild Booster and airflow assistance to help get the cooler air to the airfilter, therough the airfilter, and carb, without them having to do all the SUCKING that helps rob power and even allows ambient heat to interfere because the airflow hasn't been moving at a constant rate...ZX-2R
 
1 - 5 of 5 Posts
Top