DL90 Datalogger Reviewed
Tuesday 13th August 2002
Graeme Finlayson tested the DL90 on his recent Barbados rallying experience.
Whether a trackday enthusiast, hillclimber, circuit racer or kart racer you will have heard about, seen, or perhaps used various forms of datalogging. The aim being to analyse your car and your driving to ascertain aspects that can be improved upon.
From simply recording lap times to checking how many revs you're using at various points on the circuit, datalogging is an invaluable tool. Moving deeper, you may analyse your utilisation of grip, how different braking points affect corner entry/exit speeds and perhaps begin to delve into perfecting a chassis setup through the data analysis.
But where to start? Complex datalogging systems can cost from £1,500 to over £10,000, recording everything from miles per hour to the frequency of suspension oscillations - far more than the average clubman driver requires and, in most cases, can afford.
Dataloggers use accelerometers to measure g-forces; from this they can calculate speed, distance and consequently track-maps. However, accelerometers have a tendency to wander over large distances and have trouble accurately mapping open-ended circuits (e.g. a hillclimb or rally stage). Hence, accelerometer-only dataloggers typically utilise a trackside beacon or a trigger to reset the accelerometers after each pass to give the necessary degree of accuracy.
Global Positioning Satellite (GPS) data can pinpoint your exact position to an amazing degree of accuracy and requires only a receiver to access this data. For our latest motorsport expedition to Barbados we were lucky enough to trial Race Technology's new DL90 GPS datalogger. Race Technology are well known for their popular range of G-Performance meters - the DL90 unit is their latest creation. The unit has the usual high accuracy accelerometers for measuring g-forces and in addition utilises a GPS receiver to cross-reference the accelerometer data thus increasing the accuracy further. A new concept on the datalogging market and one that is bound to create quite a buzz.
Supplied in a professional looking metal attaché case, you find the logger, the receiver, the RPM pick-up, analogue/digital input connector, DC power supply, cigarette adaptor power supply, instructions and software all nicely packaged together.
Plug and Play
Setting up the unit simply required plugging in the power supply to the cigarette adaptor, placing the logger onto a flat surface, sticking down the GPS receiver and away you go. The unit was instantly ready to record data for g-forces, speed, distance, track maps and route maps. It really is that simple. No beacons necessary, no triggers needed, no wiring to do - plug-and-play.
The unit is incredibly compact, about the size of two stacked cassettes, and feels very robust. Carbon-faced with three coloured LEDs to indicate status and two buttons - one for on/off, one for start/stop. Simplicity itself. The unit has the capacity for analogue and digital inputs (e.g. steering potentiometer, temperatures, pressures, etc.) as well as the usual speed and RPM pick-ups. The supplied RPM pick-up is taken from a spark-plug lead and is configurable within the software. Inputting your diff ratio, gear ratios and wheel size allows the software to calculate selected gears.
The software is well laid out, with a comprehensive online help manual to guide you through. Getting your first track-map on screen and plotting data onto it is accomplished within seconds. With real-time playback and a configurable dashboard displaying the recorded data beside the moving map you can relive and examine each run in detail. Moving deeper into the software, you can select an individual corner, or a user-defined sector, and plot the data - allowing you to see how you are utilising the available grip at all points through the corner and potential areas for improvement.
As a test, we took the unit out onto some of the rally stages while recce'ing pace notes. After driving through a stage noting down the corners, we then cross-referenced these with the data collected from the DL90 allowing us to confirm the notes giving us further confidence in the accuracy of them.
When used in anger on stage it enabled us to see exactly where time was being gained on each repeated run. Delving into the g-force readings it was possible to see which corners we could push harder on and how well we were utilising the friction circle. Through examining the RPM histogram we determined how appropriate the gearing was. All very accessible and intuitive to use - and this was just scratching the surface.
The most impressive aspect to me was the accuracy of the plotted maps. Having found previous dataloggers struggling with open-ended stages, the DL90 plotted perfect maps. In fact, identical to the OS map - and this was on stages that covered large gradient changes that easily confused the previous accelerometer-only loggers.
With 4Mb of memory the DL90 is able to log all these channels for 87 minutes. As the unit requires no beacons to operate, it is possible to go out on track and log data even at an event with timing/beacon restrictions.
It's difficult to get across all the features of the immensely powerful little unit from Race Technology in such a brief article. In short, the DL90 gives you accurate trackmaps and laptimes, on circuit and stage alike, without needing to wire any sensors into your car. All the data needed to analyse your car and your own performance is recorded; accessible to seasoned competitor and enthusiast alike - analysis of speed, distance, RPM, gear, wheelspin, BHP and more. All for £500.