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DL-90 a must have for the technology inclined: preliminary report
For people that don't know it, the DL-90 is a data logger from race technology, the company that brought us an interesting line of accelerometers (AC-22, AP-22). The DL-90 is the latest addition to the range.
(Disclaimer: I have no personal interest in the company and I paid retail )
The unit performs as advertised. Extremely easy to set up, plug in a GPS and you're set to go.
The main differences from my earlier unit, the AP-22 are significant:
1) No in unit display. It's truly a data logger, all computation is done on the PC. No instant gratification, and a laptop is a must if you want to { test -> interpret -> correct -> and loop } in a single day tracking session.
2) Complex GPS - accelerometer data blending is used to solve the drifting problems inherent to an accelerometer only unit.
3) Better HP calculations thru input of environmental conditions (temp, humidity, atmo pressure) on top of drag, rolling resistance, pitch, weight, which the AP-22 already did. It now calculates torque as well if using the engine rpm line.
4) Logs external variables timestamping every 10 miliseconds on top of basic acceloremeter data (lateral and longitudinal Gs) and their derivatives (speed, distance, power). The external variables include a frequency signal typically used for an rpm lead in, voltage on 2 analogue lines (can be used for anything that can be translated into a 0-5 or 12V, like throttle position, various temperature sensors, etc), one digital line for on/off events (for instance clutch or brake on/off, ABS, etc).
5) powerful software: draws tracks, flexible markers, flexible graphing (you can plot anything you want) and statistics, replay, etc... You can still download all the log data to a spreadsheet as you did with the AP-22. However the amount of data that can be logged is now overwhelming (well over 100,000 log entries)
The things that I'm missing right now, are the possibility of using a bit map as a back drop on the track graphs, which would help in studying racing lines, and the inability to combine multiple runs for comparision purposes (though you can compare multiple laps of the same run).
Some of the things that I'll be using it for:
1) Corner performance. Once you establish what the traction circle is for a given corner, it's very easy to see how far you are from the limits. So if you are far from it, you know you can either brake harder later or accelerate harder sooner, or simply turn faster. And see it in action next time out.
2) Trail braking. With a brake sensor you'll be able to see exactly what you are doing in this department. You'll be able to tell a novice (me) from a pro when comparing left and right hand corner performance.
3) Brake performance (fade) throughout a session. With a thermocouple or IR temp sensor you may even correlate it to rotor / caliper / tyre temp. Same for tyre performance. You could have a go at comparing tyre temp across the tread surface if you use more than one sensor.
4) Shifting technique, time to shift, shifting points, and, yes, you can even perfect your heel & toe technique, by inspecting how far you pushed the brake and throttle, how high the rpm went, how good the rpm match was when you released the clutch...
If you were to use an in-car camera with timecode this would be a tremendous aid for debriefing after the hands on, on track time.
Obviously you can still use this unit to measure what mods do to performance.
A few years back you'd need many tens of thousands of dollars to do something equivalent. This unit without gps is a little over 500USD.
This may sound like a copy from a pamphlet but I would have no hesitations in recommending it to technically inclined drivers though I'm just starting to use it. I will be taking the unit to Estoril in 2 weeks time and I hope to be able to provide you with a real world descriptive example, as long as I can get the sensors wired up correctly in time. Big challenge for clumsy me. In the mean time this is a picture of the unit (see how small it is, a key is there for comparision) with the GPS that I use:
And this is the header from a log file to give you a hint of possibilities. Every 10 ms a line with comma separated values with all these fields is generated :
Time [s],Accel Longitudinal [g],Accel/Brake Flag [-],Accel Lateral [g],Accel Total [g],Engine Speed [rpm],Speed [mph],Speed [kph],Analogue Ch 1 [V],Analogue Ch 1 [Units],Analogue Ch 2 [V],Analogue Ch 2 [Units],Digital Ch 1 [-],Distance [km],Distance [miles],Distance [ft],Gear [-],Power [hp],Power [kW],Torque [lbf ft],Torque [N m],Position X [m],Position Y [m],Satellites Locked [-],
Hey Luis I have a DL90 too. Here's a PIC of some of my meters...I have a few others too!! The mouse looking thing is the GPS that R-T suggests and sells. It's a magnetic thingey with a soft rubber bottom - EZ to mount and dismount. . The DL90 is a nice piece, the track mapping works well and version 3 of the software will add more stuff plus it may even be useable with the AP-22.
Have you attached any sensors yet? which ones? I am trying to see if I can source an infrared thermometer. R T recommended calex, a uk company, and I sent them an email about this sensor: http://www.calex.co.uk/OS100%20series.pdf but have no reply yet.
I have only attached normal in car sensors so far such as throttle position. Also I have used wide band O2 datalogging. I'll see if I can pull up some autocross runs.
Luis et al, here is a bunch of PICs showing some DL90 ouput. The first three are from an autocross run. The first shows the course and gs. The second my friction circle - lots of driver and car issues to work on.. The third shows the revs used. The last plot is from a botched 0-60 run, although it still returned a time of 5.87 seconds.
Im wondering about the G-tech Pro Comp. . . What is the Max RPM it is capable of? I see 8000 on all the ads and on their site but no explanation.
Other than that, how do you like it?
>>>Im wondering about the G-tech Pro Comp. . . What is the Max RPM it is capable of? I see 8000 on all the ads and on their site but no explanation.<<<
You can set it up to 15,999 RPMs. The four LEDs are red and bright enough to see in the daytime. At your set point all four blink. Below that point they progressively light up and stay on as you get closer to your setpoint.
>>> Other than that, how do you like it?<<<
The screen is readable and blue backlit. It has 3 accelerometers. This allows it to compensate for tilt, angling it towards you for a better view, etc. You have to calibrate it by tilting the unit and doing video game stuff a few times since it compensates for temperature effects. It doesn't have to be perfectly level. It has some promise but it's not yet ready for prime time. The software sucks and you can't analyze on the PC for ****. The R-T stuff totally blows it away. G-Tech says that they will have better software available this month. The stuff it comes with does not even do what they claim it will in the ads. The shift light works by counting alternator pulses. On many cars it's jumpy below about 2000 RPMs or at idle.
... and now amaze at the accuracy of the unit. A real life example:
2 runs, same stretch of road, same car, back to back, no mods.
Starting at 40km/h, after 9 seconds of WOT, in one run the dl-90 clocked 216.4 meters. On the other 216.1, a difference of 0.104%. It also clocked a terminal speed of 122.249km/h in the first run and 123.545km/h on the second, a difference of 1.049%, at which time the car, still according to the dl-90, was outputing 187.545HP in the first run and 186.324HP in the second a difference of 0.655%.
DL-90 a must have for the technology inclined: preliminary report
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on-board electronics