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Originally Posted by alvaro84
The question is, what is lugging?
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Good question. It is a term that we all use but can mean many things. On a single cylinder engine the most obvious sign is when the bike is at such a low rpm that it is chugging and bucking. This is the only time when it is extreme enough from a mechanical standpoint that it can do any damage from shaking and loading the parts. Even at these low rpms, you will notice that there is still some useable output from the engine at very slight openings but it quickly changes to bucking if you try to add more throttle. At which point you have to switch to an easier gear to accelerate.
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To a hypermiler, lugging can also mean running too much throttle at too low of an rpm even when you don't feel any chugging. You are using a less efficient part of the engine's power map. Not really gaining any more power with increasing throttle angles. Just wasting gas because you would be more efficient by changing gears to a slightly higher rpm. Engine vacuum can give a rough idea of load vs throttle opening. At low rpm it may only take 20% throttle to go all the way down to 0 inches of vacuum. At the power peak, it might take 90% throttle.
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I have just put a vacuum gauge on my CBR250R but it isn't working right for some reason as it never goes higher than 7 inches and goes right to 0 with any throttle at all. I must have it on a restricted vacuum port that is connected down stream to a slight consumer. A scan gauge such as the MPGuino would be better to find the most efficient throttle and rpm.
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Here is a BSFC map of a four cylinder car engine for example. They read like a topo map. The most efficient range is in the circular peak. Which will be 90-95% load (load not throttle) at an rpm just below the first torque peak.
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There are also different fuel maps involved with fuel injected motorcycles that may be more efficient when using lesser load ranges of 50% because the designers have chosen to help prevent burning the piston at high rpm and load by richening the mixture. I don't know how accurate it is, or have any charts of lesser throttle openings, but I have seen a 100% throttle chart of my bike from a dyno probe that shows it at 16:1 from idle to 4,000 rpm where it changes to 14.7 through the mid range and then all the way to 12:1 at high rpm.
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A real BSFC map of my bike would be nice but there is no dynos in my area. So I guess at least putting a scan gauge on would be a big help.