Peak RPM for Max Fuel Economy?

[GillaFunk]

I am making a semi-unplanned road trip from California to Kentucky. I was originaly planning on flying, but when I found out I have to stop in Dallas for a funeral I opted to ride. Dont get started on how BORING it will be buzzing down the interstate. :angry: Flying is just not an option this time.

So, I've done some searching and cant find answer.

What is the ideal RPM/speed on the interstate that will give me peak fuel economy on a Gen II bike? I'm guessing somewhere bettwen 60-70mph.

 

[HotRodZilla]

What is the ideal RPM/speed on the interstate that will give me peak fuel economy on a Gen II bike? I'm guessing somewhere bettwen 60-70mph.

Here's the deal...If you ride from California to Texas, and then wherever at 60-70 MPH, by the time you get to FlagStaff, you are gonna want to kill yourself.

This bike gets amazing mileage at amazing speeds. When I make my runs to Tennessee, I specifically go about 9 over whatever is posted...Around 84mph most of the trip, with stints into the 90 range. I stop for gas every 200 miles and average around 40mpg...

You're prolly gonna max out around 45mpg anyway, which is pretty insignificant...If it's money you're worried about; camp, and pack your food instead of buying fast-food. Finding optimal gas-mileage speed or RPM range is gonna be a ***** anyway...There is lots of elevation changes, wind direction traffic that is gonna screw with all of that; besides differences in bikes.

If you're gonna ride the bike, just ride the dammed bike.

 

[ionbeam]

Since your fancy Gen II has a mileage readout I would think that you should be able to sort this one out yourself. ???

 

[wheatonFJR]

Since your fancy Gen II has a mileage readout I would think that you should be able to sort this one out yourself. ???

:lol:

 

[Panman]

Since your fancy Gen II has a mileage readout I would think that you should be able to sort this one out yourself. ???

Long as you don't have a PCIII.

 

[Bounce]

Anything below the point where you get ticketed. The cost of 1 ticket (and the insurance hikes) will negate any effort to save on MPG.

 

[Ignacio]

What is the ideal RPM/speed on the interstate that will give me peak fuel economy on a Gen II bike? I'm guessing somewhere bettwen 60-70mph.

Is it NEPRT day? You want the long list of variables or the short list with assumptions and constraints?

Here are some:

Drag is probably one of the bigger ones and changes as a funciton of speed and is not linear.

Add-ons to you bike aerodynamically and weight

Windshield type and position

Headwind

Road surface

Fuel type

State of tune

Throttle position changes

Elevation

Regardless, I think your guess is probably high. I think you'll find peak fuel economy flirts with minimum speeds on some interstates (e.g. 25-55 mph). Then you get into adding the variable of "safety" as you're mowed down by trucks.

 

[GillaFunk]

Since your fancy Gen II.........

YA YA...I know. I just figured some extreme crazy LD Iron Butt FJR rider would know the special concoction for this crap.

PLUS my PCIII tells my display to lie to me....so I dont know the trooof!

 

[Ignacio]

YA YA...I know. I just figured some extreme crazy LD Iron Butt FJR rider would know the special concoction for this crap.

If my answers frighten you then you should cease asking scary questions.

 

[ionbeam]

Since your fancy Gen II.........

... my PCIII tells my display to lie to me....so I dont know the trooof!

Well, since science and technology has let you down I recommend an ages old method that always tells the trooof.

 

[ionbeam]

Seriously now :lol: For the cost of 17 gallons of gas buy and install a vacuum gauge like this type and you will have a real-time fuel economy indicator.

The higher the vacuum the better your fuel economy. Really, no BS. Tap into one of your TBS ports for vacuum, but you will need a vacuum restrictor to dampen the needle. Expect warm idle vacuum to be around 7-10 inches and fully loaded vacuum to be around 1-2 inches. I found that in general riding the vacuum hovers around 3-4 inches and it is very sensitive at detecting small changes in road slope, head wind and almost undetectable wrist movement.

 

[TomInPA]

Here is your answer..stick to 3500 RPM and you willl have great fuel economy. It may take an extra day to arrive, but you'll save a lot of fuel.

Answer two is, don't use a top case or side-cases. Carry a duffle bag over the pillon seat right behind you. That is much lower in wind resistance than the bags or a trunk. Just look how these things stick out and catch wind:

I bet you can't hold to that going across the southwest. :lol: Improve the aerodynamics and speed will have much less effect.

 

[HotRodZilla]

Holy flying horse ****...Did I not provide a serious helpful answer? See if I do that **** again!

 

[Fred W]

Wow. I only saw one question and yet there are all sorts of answers about all kinds of crazy stuff

To recap, here was the (spelling adjusted) question:

What is the ideal RPM/speed on the interstate that will give me peak fuel economy on a Gen II bike? I'm guessing somewhere between 60-70mph.

Your guess would be wrong! That would be much too fast to give the peak fuel economy. The correct answer is that (with all other things being equal, which must be assumed from the limited scope of the question) the lowest possible rpm, resulting in the lowest possible ground speed, that you can achieve while in top gear will give you the peak possible fuel economy on any bike.

Whys:

Lower speed = less aerodynamic drag.

Lower rpm in highest gear = open throttle plates for lower pumping losses in engine.

Highest gear = maximum distance per engine rotation.

Now, don't get run over, ya hear?

 

[Bounce]

Holy flying horse ****...Did I not provide a serious helpful answer? See if I do that **** again!

i thought so. i figured yours and mine combined would cover all the bases.

 

[GillaFunk]

Well **** ballz. I thought for SURE one of you guys would have an answer based on factual riding experience.. TominCA stated the obvious, Ionbeam approached an answer, and Ignacio posted the most honest.

Thanks gents. I'll see what turns up. I'll have 5,339 miles to test my hypothesis. :angry:

 

[wfooshee]

OK, suppose your minimum MPG is 40 'cause you got all in a hurry or sumthin', and your maximum achievable is 45. Just guessing, and playing with numbers.

To go 5339 miles at 40mpg is gonna take a bit over 20 tanks. To go at 45mpg is gonna take a little less than 18.

So 40 bucks over how many days is worth this kind of worry????

The only reason you'd really need to worry about mileage is if there's no gas for 300 miles, and that won't happen on the slab.

BTW, doing that distance at 80 is 22 HOURS quicker than doing it at 60. Yer hotel and food for the entire extra day in the saddle (spread over however many actual calendar days) will cost way more than the gas.

This is why driving to save gas makes no sense at all on a long trip. Takes too damn long!!

Ride, and ride fast, and get there on time.

Even if your maximum achievable mileage was 50mpg, you'd only save 80 bucks over that distance, but you'd spend more than that being on the road longer at 20 mph slower. Gotta eat, gotta sleep.

Now, if 5mph saved you that much money, drop your speed. It doesn't, though.

 

[Bungie]

Kay, serious answer time. If your revs go over 5G's you'll take a pretty significant mpg hit. So you good up to about 75mph. After that, you'll be able to hear the sucking noises. It must be the default map for the ECU, if your above 5G it richens the mixture up a lot for performance.

That being said, the best I ever got was a little Sunday afternoon jaunt up the arctic watershed north of here. 65mpg running at a steady 50mph.

... but I sure wouldn't want to ride across the country like that.

 

[UHOH]

I am making a semi-unplanned road trip from California to Kentucky.

What is the ideal RPM/speed on the interstate that will give me peak fuel economy on a Gen II bike?

my $.02 says after 90 minutes of fuel efficient cruising I'd up the speed to whatever the fastest cars are doing for two reasons:

* safety, I am uncomfy with being an obstacle on the road that others have to pass

* trip cost, the difference in fuel costs / trip mileage are small relative to having to spend an extra night in a motel along the interstates.

figure $60 - 80/ night plus $30 food. That is $100/day = 25 gallons of fuel. Once you think like this, you'll wrap up the throttle to stay with the faster crowd.

If you want to minimize travel time, the 'only real way' is to get on the road very early each day...

enjoy the trip, if you can set aside a bit of time for diversions, sometimes you can't though. that's life.