Identical Bike power and fuel efficiency

* Site Guru *

Captain Crash wrote:: If a bike with all the mods done (FI Processor / Power Exhaust / Hi-flo filter) was riding next to a bike with no mods done and they accelerated at exactly the same speed and changed gear at exactly the same point and both riders weighed exactly the same, there would be zero difference in fuel consumption. The difference in fuel consumption can only come into play when you use the additional available power increase.

Just to be controversial Identical Bike power and fuel efficiency 852880

Would the bike producing more power do it more efficiently? as it's using less of it's energy to reach the equivalent speed under the same load, Therefore using less fuel :what1:

Member

bugger - i wrote a reply to this on the other thread...then i deleted it as the original had gone..now its a new thread Wink

interesting question though - two part answer

(1) you aren't changing the efficiency of the engine, you're moving the inputs (air and fuel) to create different outputs - unless you change weight or inertia, you can't change the amount of effort you need to achieve the same results. So while a mapped bike may return greater performance, you're extending the engines output by (typically) messing with air and fuel, meaning that while 50mph might be 50% output instead of 55%, you've moved the top, not made the engine work better. The exceptions are full map outs of manufacturer restrictions or full map ins of improvements, but thats not how bottom end tuning works imho

(2) in the real world, bikes aren't driven by perfect computers at the same weight, time, speed, they are driven by people like you and I - we mess with them because we love to go faster! and when we have more oomph under our hand or foot - we use it! so while it could be true that you might use less fuel, in 25 years of tuning, riding and driving mapped, messed with cars and bikes, i've never increased MPG over a regular time period, with the exception of the smart diesel where the end goal was MPG.

just mho of course Wink

Suzuki800.com Founder ... & ... Senior Administrator

Identical Bike power and fuel efficiency 2516569736

Sorry rob, it was such an interesting and thought provoking question that decided it deserved its own space, by the way very well explained. Identical Bike power and fuel efficiency 3498837457

Identical Bike power and fuel efficiency 3498837457

As the two bikes in question are both Intruders, with the first one being a stock bike and the second being a correctly mapped bike, there would be a difference that is so small that it is almost a technicality. The Stock Intruder runs lean from the factory so in turn does not produce a perfect power ratio setup, so that would mean that it would use more fuel than a properly mapped bike as long as the additional power of the second bike was not used and the test was done under the conditions that Crash described.
Would you say that is right?

I love these questions that can draw on tiny differences, they get the brain ticking. Identical Bike power and fuel efficiency 852880

* Site Guru *

You've completely cooked my head there Rob Identical Bike power and fuel efficiency 2795157665

I'll come back to this one when I'm sober Identical Bike power and fuel efficiency 641964

Mentally Deficient lunatic ..... & ..... Site Moderator

With what has been written here already, it would explain loads to anyone that did not have an understanding of air and fuel ratios and there relationship to the effects of power and fuel efficiency.

Member

Mr Intruder wrote:: As the two bikes in question are both Intruders, with the first one being a stock bike and the second being a correctly mapped bike, there would be a difference that is so small that it is almost a technicality. The Stock Intruder runs lean from the factory so in turn does not produce a perfect power ratio setup, so that would mean that it would use more fuel than a properly mapped bike as long as the additional power of the second bike was not used and the test was done under the conditions that Crash described.
Would you say that is right?

hmmm as you say, this is what makes this kind of discussion great - its a fascinating topic...more fascinating for me, as my (tiny) knowledge is based on tuning and mapping in general rather than the intruder specifically, and thats what (having thought about it) makes my initial answer technically correct, but with the context you've given, not right Wink

I'd left out the fact that the stock bike runs lean (sorry guys) and thats what would give you the improvement in fuel economy. If you ran a power mods and left it lean, you wouldn't get the same gain, also, if you simply mapped the stock bike to correct the afr, and compared that to the modded bike, the mpg would be the same for the scenario described.

Suzuki800.com Founder ... & ... Senior Administrator

We all live and learn Rob, us from you and you from us. Identical Bike power and fuel efficiency 3498837457

Member

indeed :)

I really like the idea of an auto-tuning system, but i've some experience of these on cars, and they work well when they work, but screw up royally when they don't. In fact what would be interesting to know from the guys that have them about the cobra is how its automation works, does it map to afr only? and if so what level? Do you have any control of the system at all?

ideal AFR is 14.7, maximum power is usually at 12.5-13.5, but its trial and error, if it had det sensors it would be able to do the trial and error (which is how i've always mapped, stick the det cans on, and map till it plinks, then knock it back a couple of notches) but i don't really understand how this works well unless it presets an AFR at certain points and adjusts to stick to it. maximum torque is too close to detonation for comfort, its probably got some safe zone mapped into it.

Maybe i'm just overcomplicating things here - should just stop worrying about it, no ones bike has blown up, and you guys all seem happy with it - so its obviously been designed and built by a smarter man than me (not difficult)

* Site Guru *

ghouluk wrote:: In fact what would be interesting to know from the guys that have them about the cobra is how its automation works, does it map to afr only? and if so what level? Do you have any control of the system at all?

No,we have no control at all, it's a sealed unit, but I supposed if you had the right technical ability? I'm sure it wouldn't be hard to get inside and see what's going on.
This is from the Cobra web site, If it explains any of your questions?

[b class="fi_knw_rgt_box" style="margin: 8px 0px 0px 25px; padding: 10px; background-color: rgb(240, 240, 240); width: 360px; font-size: 12px; overflow: hidden; height: auto; color: rgb(102, 102, 102); font-weight: bold; font-family: Arial, Helvetica, sans-serif; line-height: 18px; text-align: center;"][b class="fi_knw_rgt_box" style="margin: 8px 0px 0px 25px; padding: 10px; background-color: rgb(240, 240, 240); width: 360px; font-size: 12px; overflow: hidden; height: auto; color: rgb(102, 102, 102); font-weight: bold; font-family: Arial, Helvetica, sans-serif; line-height: 18px; text-align: center;"][b class="fi_knw_rgt_box" style="margin: 8px 0px 0px 25px; padding: 10px; background-color: rgb(240, 240, 240); width: 360px; font-size: 12px; overflow: hidden; height: auto; color: rgb(102, 102, 102); font-weight: bold; font-family: Arial, Helvetica, sans-serif; line-height: 18px; text-align: center;"][b class="fi_knw_rgt_box" style="margin: 8px 0px 0px 25px; padding: 10px; background-color: rgb(240, 240, 240); width: 360px; font-size: 12px; overflow: hidden; height: auto; color: rgb(102, 102, 102); font-weight: bold; font-family: Arial, Helvetica, sans-serif; line-height: 18px; text-align: center;"]Fi2000 PowrPro With CVT: An Intelligent System

When electronic fuel injection (EFI) first appeared on motorcycles, most riders embraced this technological advancement. However, they soon realized that this new technology brought up some new questions: How can these things be tuned? What if we want to switch air intakes or pipes or cams? Modifications change the amount of air entering the engine, which in turn alters the fuel mixture. And stock EFI systems cannot adapt to modifications.

Read What Customers Are Saying about the PowrPro Tuner
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Then came racing EFI systems that could be reprogrammed from a special hand-held box or laptop. That was a ray of hope, at least for people who had the right skills. Some motorcycle manufacturers, as well as other companies, began to offer specific modifications, a particular exhaust pipe and a particular cam, for example, with an EFI box factory-reprogrammed for their effects. This was great if you wanted those particular modifications, but there was no way to reprogram boxes for every combination of aftermarket parts. In other words, there was no intelligent system that could adapt itself to whatever modifications were chosen.

The next step was the creation of add-on tuning systems, which adjust mixture by manipulating existing sensors into reporting nonexistent changes in air temperature or pressure. By adding or subtracting from the value reported by the EFI's air-temperature sensor, the stock EFI computer leans out or enriches the fuel mixture. Imagine you have just installed an aftermarket exhaust system. Because it increases engine airflow, it makes the mixture leaner, so your engine makes less power and may even stutter.

These add-on systems adjust this information about where and by how much the pipe makes the engine run lean or rich. These systems gather this information from an oxygen sensor in the exhaust in combination with a few dyno runs that reveal power output. Then, it applies sensor corrections that cause the stock system to supply the altered fuel-mixture curve the modified engine needs to again deliver improved performance.

This was a big step but one still heavy into hardware: What if the nearest dyno is 200 miles away? What if my bike's EFI system doesn't have an oxygen sensor? A truly intelligent system should be able to gather and analyze the information it needs as you ride with no extra equipment, no extra hassles. This was the goal of the Fi2000Â® PowrPro with CVT: Continuously Variable Tuning.

You already own a highly accurate dyno: your engine's crankshaft. We think of crankshafts as turning smoothly, but in fact, when a cylinder fires, it accelerates the crankshaft slightly. Every engine has some kind of torsional shock absorber between crank and gearbox, which is there to accommodate this slight variation in crank speed. With the application of modern high-speed electronics, we can access this information and time the rotation of the crank from one firing to the next, and analyze whether the next firing is slightly stronger or weaker than the previous one.

Now comes the clever part: using the measurement of how hard a cylinder accelerates the crankshaft as a way to correct fuel mixture. If the mixture is a bit lean and our system adjusts it to be a bit richer at the next firing, more power will be produced and the piston will give the crank a slightly stronger kick. We can use this as a tool to move from whatever fuel mixture the engine is actually receiving, toward a more efficient mixture.

The next step is a way to time the rotations of the crank, so crank speed at one firing can be compared with crank speed at the next firing. Fortunately, bike manufacturers give us this info for free as the time from the beginning of one fuel-injection squirt to the beginning of the next one, 720 crank degrees later. Yes, the engine's other cylinder may be slowing the crank by being on its compression stroke, but all we need is comparative information. We also need to experiment with fuel mixture, just as race tuners or EFI programmers do. If we make the mixture a little leaner and the next crank cycle takes a little bit longer than before, we know we are going the wrong way. This is just like what old-time race tuners did by changing carburetor jets and then looking at the bike's quartermile ET or lap time. However, in the case of the Fi2000 PowrPro, this process now occurs up to 80 times per second--it is literally Continuously Variable Tuning.

The Fi2000 PowrPro conducts its fuel-mixture tuning by varying the mixture slightly. If the crank moves a tiny bit faster when the mixture leans out slightly, the PowrPro knows that's the right direction and the system leans the mixture again, or vice-versa. With a big twin-cylinder engine turning 5000 rpm, one cylinder is giving us 42 of these opportunities to tune the fuel mixture every second.

The result is that the Fi2000 PowrPro continuously and quickly drives fuel mixture to the value that gives best power. This process allows the system to adapt to any engine modifications you make. It's like going to the drag strip with a stopwatch and boxes of carburetor jets more than 80 times every second.

When this system was still in its initial planning stages, one option under consideration was to use this data to create a new conventional fuel map similar to the one programmed into the engine's stock EFI, and then to periodically update it. That turned out to be unnecessary because Continuously Variable Tuning does the same job without the expense and complication of storing, updating and retrieving data to or from a fuel map. CVT is a continuous mixture-correcting process, not a fixed set of values in a can, like that of the stock EFI system or older EFI tuning systems.

Instead, CVT operates continuously, detecting throttle movement that indicates significant acceleration, and there is a threshold below which it switches to one of two other modes. If the bike has an exhaust oxygen sensor, this data typically controls the mixture in steady cruise or during slow roll-ons, and the PowrPro system adjusts this to 14.2-to-1 air/fuel ratio, giving maximum-power operation. If the bike has no oxygen sensor, the system observes the range of variation of mixture over several cycles and sets the mixture to the rich end of that variation.

Given the intelligence and speed of modern electronics, it seems that engines should be self-tuning; they should be able to adapt automatically to modifications and compensate for engine changes that result from component wear.

- See more at: http://www.fi2000r.com/html/knowledge_center.php#sthash.8EU9SmEc.dpuf

Member

I was right - it is designed by someone way cleverer than me Wink

so it keeps adding/subtracting fuel until its right - or more probably right with a nice margin of safety error Wink

fascinating bit of tech though, i love solutions that appear complex, but are beautifully simple.

problem is now i want one again! :)

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