With Euro-4 homologated bikes already hitting showroom floors, potentially there could be bike tuning problems ahead for the industry. Rapid Bike add-on tuning models allow you to "open-the-loop" and take control of the impact the 02 sensor signal has on the injection map, making conventionally pre-calibrated mapping obsolete.
Italian performance and tuning technology specialist Dimsport's Rapid Bike branded range of motorcycle tuning modules are ahead of the game when it comes to the implications of the new generation of Euro-4 homologated motorcycles.
At the heart of its technology is the ability to work with, rather than fight against, the data captured by the stock Lambda sensor (O2 sensor) and use the signal to dynamically modulate the fuel injection map to keep the air fuel mix at the optimum setting.
All three of the Rapid Bike modules - EASY, EVO and RACING - are based on this technology, and all three automatically and instantaneously return an air/fuel ratio that is either too lean (too much air for the fuel) or too rich (too little air for the fuel) back to the optimum setting.
Rapid Bike modules turn the Lambda sensor signal into the tuner’s friend - and turns every rider into a tuner. The dynamic modulation of a signal designed to work with a pre-installed map, with its pre-set, all conditions and all circumstances fixed calibrations, opens up the 'Closed Loop' and renders the concept of a set injection map obsolete.
Adopting electronic technology for engine management has always required a number of sensors to control the amount of fuel being injected and to maintain a balanced carburetion.
 |
| The AUTO-ADAPTIVE feature built into Rapid Bike's EVO and RACING modules will fine-tune the map of injection values while the bike is being ridden. Seen here for a twin cylinder engine (2015 Ducati Multistrada 1200), in which the module is reading and modulating the signals from both the stock Lambda sensors in order to generate a correction map specific for each cylinder. In this way the module is self-learning and responds to the constant change of external factors such as temperature, pressure, riding style, etc., and also to the installation of additional aftermarket components affecting directly the injection values |
The amount and quality of intake air coming through the engine and being mixed with fuel is affected by different factors such as temperature, pressure and humidity rate - this is the reason why bike performance changes considerably in operation even after it has been in the hands of the best tuners, to say nothing of the remapping required by changes to the stock set-up such as aftermarket exhausts, air filters etc.
The stock Lambda sensor measures the quantity of oxygen in the exhaust gases, while the OEM Engine Control Unit (ECU) determines the air fuel ratio (air quantity in proportion to one unit of gasoline) in the context of the value pre-set in its memory, and then modifies the injection timing to achieve its pre-settings based on the signal it receives from the Lambda (and other) sensors.
The technology at the heart of Rapid Bike's modules achieves a very simple result, yet is highly innovative since it actually takes advantage of the stock Lambda sensor signal to improve engine efficiency while optimising fuel consumption.
The goal is not to eliminate the stock Lambda sensor, but rather to perform a dynamic modulation of its signal in such a way that the results of doing so are fully compatible with the new injection values set by the add-on module.
This solution helps the whole system (OEM ECU + Rapid Bike Module) to be more reliable, and to prevent the benefits of improved fueling from being perceived by the ECU as a mistake requiring correction.
Rapid Bike's add-on modules change the amount of injected fuel (and they can directly control up to 8 injectors) while modulating the stock Lambda sensor signal in such a way that the OEM ECU will not detect any difference in the air fuel ratio.
Its new "auto-adaptive" feature allows Rapid Bike modules to compare the air/fuel ratio target value (set within the module's map) with the signal reported by the stock Lambda sensor. The result of this continuous comparison determines whether the fuel being injected needs to be increased or decreased - making sure the engine always delivers the best performance.
This is even more useful when performing modifications to the bike (such as the installation of a free-flow air filter or a racing exhaust system) that require the injection map to be modified. Rapid Bike modules are able to develop and implement these changes automatically, while the rider is using the bike.
Rapid Bike says its module will complete the injection auto-remapping process within a 200 km ride, even when starting with a 'zero' value map.
The company says that its "technology re-maps the most critical section of the power delivery curve - the low and medium rpm range where the Lambda sensor is in full control of the fueling parameters".
The so-called 'closed loop area' that typically remains 'off-limits' for conventional add-on module technology becomes tunable, putting the tuner and the rider in full control without any sort of limitations.
RAPID BIKE/DIMSPORT
www.rapidbike.it
Test case study - Ducati Multistrada
The Ducati Multistrada was one of the first Euro-4 compliant street bikes to reach showroom floors. This dyno chart shows the behaviour of the air/fuel ratio (at 25% Throttle Position Sensor) with the 2015 Multistrada 1200 in stock configuration (no aftermarket exhaust or air filter, etc.).
It shows the Multistrada starting with a very lean mixture (almost 16 points, that means 16 parts of air for 1 part of gasoline); with the Rapid Bike EVO module this value comes down to 14 points and maintained at a value between 14 and 13.5, meaning the fuel mixture is richer, the throttle response is more reactive, the engine no longer suffers from the sudden power drops caused by interruptions in the supply of gasoline, and the torque is more consistent.
When the stock ECU reacts by trying to 'correct' this (and re-set the AFR value to around 12 points - meaning that the mixture is becoming too rich), the EVO module and its technology of Lambda signal modulation continues to work effectively and keeps a steady AFR target value around optimum at 13.5 points. This means the corrections to the injection values performed by the EVO module (and RACING version) directly connected to the injectors create a stable AFR value as close as possible to the ideal target of 13/13.5 points (depending also on other factors such as gasoline octane percentage content etc).
The end result in this example is that at 25% TPS there is a gain of almost 5 hp and the torque is also improved (from 6,5 kg.m at 8845 rpm to 6,9 kg.m at 8520 rpm).
The real-world riding impact of the numbers is that the bike’s handling and engine response are greatly improved at lower and mid rpm - the most important and most used part of the power band.
