Photos by Kevin DiOssi and Corey Stephens
Last week, we explained the history of data capture—Discovering Data: Emergence of Data Acquisition <<HERE>>. We are back this week to help you plan, purchase, install, and use your own data capture system on your car.
When you start to plan your data capture system, the first decision you’ll face is whether or not you’ll use a standalone data logger such as those from Racepak, or an integrated logger in an existing ECU like those offered in the Haltech Elite series, AEM Infinity, FuelTech FT600 or Holley Dominator systems. Advantages to using your EFI or Ignition ECU include a slightly simpler installation and all functions integrated into one box. The downside is that each additional sensor ties up an input, and you need to make sure you have the appropriate input type available for the sensors you want to use. For example, Pressure and Position sensors require analog inputs while magnetic pickup driveshaft speed sensors require specific Inductive or Digital Frequency inputs. It’s a good idea to have spare inputs available during the planning stage, so that you have room to grow as you add more inputs in the future.
Using a standalone logger such as a Racepak V500SD has the advantage of being able to use both dedicated inputs, as well as V-Net modules that share a single input. You can run as many as 75 sensors on a single V-Net input on systems like this! Racers who aren’t using an existing EFI ECU will likely want to choose this route. You can also build a hybrid system that combines both types: VP Racing Fuels Street Outlaw and X275 Racer Rob Goss uses his Racepak V500SD to capture data from V-Net channels as well as data from his FuelTech FT500 ECU, which gives the best of both worlds and a nearly limitless supply of inputs. We suggest having more inputs available than your initial plan requires, as there always seems to be a reason to add more channels later on. Basic inputs most drag racers start with are engine rpm, coolant temperature, intake air temperature, barometric pressure, crankcase pressure, engine oil temperature, manifold vacuum, crankcase vacuum, throttle position, accelerometer, air fuel ratio, and driveshaft speed. More advanced channel inputs include GPS speed, nitrous bottle pressure, exhaust backpressure, air fuel ratio and exhaust gas temperature per cylinder, and fuel flow. The list of things you can monitor is almost endless, so you can see the point of planning for future inputs.
Once you’ve decided on your hardware, the next thing you need to consider is data capacity. The number of channels you want to capture, the rate at which you need data to be captured, and the length of time you need to record, all affect the space you’ll need to store the data. Eric Lowe at Racepak explains that memory cost has gone down so far that it’s rare to run out of space to store data, but you still need to make sure your system has the capacity to move the quantity you’re capturing fast enough for it to be written to memory without over running the capability of the system. What this means is: your data logging system is taking snapshots of data at a speed that you configure. You probably are not concerned with measuring coolant temperature 500 times per second, as it only wastes storage space. However, you will want to capture items such as suspension travel at that higher rate. The benefit of systems like RacePak’s V500SD is that you can configure individual channels to record at different rates, letting you preserve valuable storage space. Many EFI ECUs only allow you to choose a single sample rate for all channels, so if you want to capture suspension travel at 500hz, you’re stuck with coolant and air temps also at 500hz: just more to consider when planning your system.
Other things to consider before you decide whose system you’re using are manufacturer technical support, system complexity, and cost per channel. Are you going to install the system yourself, or will you have a professional installer handle the task? What about training, are you comfortable tackling the learning curve by yourself using just the manufacturer documentation and online forum support, or do you have friends using that system who’ll help you get up to speed? Some manufacturers provide onsite support at the races, which can be very handy if you have questions during an event. What about integration with other systems, do you require a dash with gauges that can read these sensors? Racepak interfaces all mainstream EFI ECUs out there and offers a number of different dashes that plug into the V-Net network with a simple connection, allowing you to display any parameter available on the network, which eliminates the need for a large number of mechanical gauges and clutter in the cockpit.
Hopefully this gets you thinking about your system and what data you want to capture. Next week we will talk about installing and testing your system before you go to the races. Until then, check into what other racers are doing and be thinking about what data YOU need to capture to improve that et and mph!