NicolasW

SundayDriver (Mark)
I noticed Stack has a feature to hook into brake bias by accurately measuring pressure....does MOTEC have something like that?...or would it be cost prohibitive?

Thanks much,

Geoffrey

Let me expand on what Mark said. MoTeC software is free as are the firmware upgrades. MoTeC prices the ADL with a base cost and adds for increased I/O, enhanced logging, pro analysis, remote logging, telemetry, backlight capability, memory, etc. which are ECU or ADL enabled features. Basically they come with all of the hardware and features, but you need to buy a password to enable them which allows you to get in at a reasonable cost and expand as your needs expand. Stack for instance charges for software, but their products are less expensive to begin with. It all sort of washes out, either pay up front, or get hit on the back end.

MoTeC is not GPS based but rather uses a beacon, wheel speed, and lat/long g sensors to position the car on the track. GPS is not as accurate, and there are often times when the receiver cannot get enough sattelites to take advantage of the increased accuracy. At Sebring, the DL-90 could not communicate with enough sattelites for highest accuracy (on a perfectly clear day)

The MoTeC ADL can be configured for:
6-20 analog inputs (used for analog sensor such as brake pressure)
4-8 temp inputs (used for things like IR sensors, engine, trans, egt, etc.)
2-4 digital inputs (used for on/off type sensors such as brake switch)
2-4 switch inputs (used for on/off and display scrolling)
2-4 speed inputs (self explanatory)
0-2 low voltage inputs
4-8 outputs (shift lights, warning lights, etc.)
0-2 wideband lambda.

You can configure the MoTeC to log almost anything you want, and connection to the ECU via the Car Area Network (CAN) bus enables the ADL to log ECU information without using ADL channels. I believe CAN uses a universal language. The factory Porsche dash in the 996 Cup car uses CAN to transmit information. I believe the street cars are the same.


Any professional data logging system MoTeC, PI, CDS, etc. will give you the ability to look at driver AND vehicle performance to look for improvements. The software will allow you to look at graphs and compare numbers. For instance you might put rpm, speed, tp, lat and log on one screen plotted against time and compar lap-to-lap or driver-to-driver. This helps understand acceleration, braking, cornering for driver improvement, or vehicle performance (wheel spining under acceleration or wheel locking under braking)

They will of couse have a track map with segment times, x/y plots, g circle, and other data analysis tools to help understand what is happening with both the driver and the vehicle.

The ADL dash (and MXL dash shown above) is one of the greatest things available for serious drivers.

SundayDriver

That is a really good question, because the answer helps define the difference in many systems. Any of these systems can measure brake line pressure with the right transducer. But then what?

Let's say I get 600 psi front and 400 psi rear. Based on pressures you would say it is 60% front biased. But that has little to do with what your brakes are actually doing. That is a product of those pressures acting through pistons of different sizes (front and rear). In fact, you may actually have more force on the rears with those pressures.

Motec has a very strong math package and what I do is run those pressures through calculations, in real time to produce the forces on the front and rear. (that would be pressures times piston areas). That is what I use for brake bias, so 50% means equal clamping force front and rear. Without such a math package, the brake bias number is rather meaningless, but is significant for one setting vs. another. Stack and Pi both claimed to be close to adding math when I bought the Motec some months ago. As a side note, I think you could be really clever and mis-calibrate the pressure channels so you read real bias.

Another example is that I measure shock travel. Not only high frequency for tuning, but I filter that data and measure ride height. As the height changes down the straightaway, at various speeds, I calculate how much downforce is being produced by looking at how much the height drops with speed. This is stuff that neither Pi nor Stack could do at the time I purchased, in their club level gear. This is why Motec has the kind of pricetag it carries.

Frankly, I would probably not purchase another Pi or Stack. If the needs were simple, I would go with AIM or something in that price range or make the step to Motec. For the kind of system I did, with full suspension, brake bias, steering, throttle, etc - Motec, Stack and Pi were very close to the same price. There is an amazing amount of $ in the sensors, brackets and wiring harness for such a system.

Hope that helps.

mitch236

Geoffrey, since Sebring is my main track, I guess the GPS based units are not useful? What is the beacon method and does that mean that something has to be available at the track? Can you provide links to MoTec and other companies? I only want to buy once so it pays to get the most upgradable, cost effective unit first.

I would like to be able to analyze:
g-forces
brakes
throttle position
steering input
tire temp
brake temp
track position
segment time
speed
tach

NicolasW

Interesting...I never even thought about the calculations with respect to the piston area.

Now when you do calculations real time, can you display the results on the ADL? Or do you have to download the data and analyze it later on your computer?

Geoffrey

As I said before I think the DL-90 for $700 represents a good value but falls short of the systems costing 10x. It will do all you listed but tire temp and brake temp. I did this as a favor for a good customer, however I mainly do MoTeC installations. Useful? I guess that depends, you can do some basic analysis and for some that would be useful. We are talking about $700 vs $7000 entry into MoTeC.

The beacon method contains a beacon receiver in the car and a beacon somewhere on the track that indicates start/stop of a lap (in simple terms). The base MoTeC will do what you are looking to do +

mitch236

Since I don't want to spend 7g's for DAS, I think the AIM will be the way I'll go. But the GPS thing is worrying me. This may sound really stupid but my nav system in my car works at Sebring, why won't the GPS DAS?

Stu Waterman

Mitch236 wrote: Now I need to decide what info I need. They claim the GPS is accurate enough to tell differing lines through a corner. Is this true? That would be amazing accuracy. I was at an AIM-sponsored seminar recently, where they showed sample track maps from the MXL with GPS option, and you could indeed see differences in the line taken through the corner on different laps. However.... I have concerns about accuracy (how much of the difference between the mapped driving lines is due to inaccuracies in the data vs. the actual position of the car)

For the true nerds in the audience (we know who we are! ), this is probably more of an issue related to the precision of the measurements, rather than their accuracy. But let's not go there...

Also, if you are really interested in using the data to look at the driving line, you will need to spend some time to make a map of the edges of the track. The most straightforward way to do this is to make a slow lap of the track hugging the left side of the track, followed by a slow lap hugging the right side of the track. Using these two laps as reference laps in your data analysis software will show your driving line at speed vs the edges of the track. Personally, I think ColorChange has the right idea - using video sync'd with the data show how you drove the corner.

Geoffrey - thanks for the really useful comparison between low end and high(er) end systems! Geoffrey wrote (about the DL90): I was able to break up Sebring into the straights and corners to get segments, then compare the different laps times in total and in each segment. You can then add all of the lowest times to arrive at the best "theoritical" lap time. This is a manual effort where a true DAcq system would do this for you. The AIM RaceStudio software is much stronger in this regard - it automatically generates segments (or you can do it manually), and generates tabular reports of segment times, also showing your fastest rolling lap and your theoretical best lap (the sum of your fastest segment times). The "predicted lap" display on a STACK dash works the same way - calculating segment times and comparing them with previous laps "on the fly."

Maybe the DL90 users out there can comment on this, but I believe that before the DL90 can calculate lap times, you have to manually mark the start/finish line on the track map (sort of like placing a "virtual beacon") in the data analysis software? Perhaps this is one reason why the system doesn't support a real-time dash display.

While the GPS systems are cool, I think I agree with Geoffrey - I'll stick with a beacon-based system for now.

NicolasW wrote (about the ApexVisualizations system): He said that you should be able to use any data in CSV format so I would imagine data obtained from the AIM systems would work? Yes, the AIM data analysis software can export data in CSV format.

Brian P

My understanding is the DL90 uses the GPS signal combined with the accelerometers to derive a fairly accurate set of position coordinates. Even then, I seem to remember them saying that it still wouldn't be good enough to show differences in the line. (Unless your changes were hugely different)

Geoffrey

I think that track position (left-right) is less important than the set of vehicle dynamics data that accompany a position on the track. You are interested in what is happening, not necessarily where it is happening left-right.

SundayDriver

It does this real-time. In fact, I have a temperature displayed in race and practice mode, but when the system sees brake pressure, it changes that area to show brake bias. Just to be clear, when I say "I" do this, it was with a lot of help from the suplier - Veracity Racing Data.

ColorChange

Sunday: Does the Motec interrogate my ECU in my 2004 tt like it does the other ECU's?

SundayDriver

Sorry, I don't know anything about those connections. Check with Motec or Veracity at 408-732-6606. I'm sure they can get you that answer.

ColorChange

Here is a page of data from Schumi's F1 car. I have more. This came from an older F1 magazine issue. If you guys want more, let me know. It really shows some benefits of left foot braking. Too bad I don't have a sequential tranny in my tt. I t also shows how much trail braking Schumi does. You will also notice, as is common but not often understood, that the fastest drivers often make their speed by being faster in the first part of the turn, not on the exit.

mitch236

This is where you get in trouble Color, your statement is too simplistic. The fastest drivers make speed in all parts of a turn, that's what makes them fast. And I can assure you that Shumi is maximizing his exit speed, the graph is to contrast the benefit of left foot braking. But for us mortals who want to be as fast as we can given our limitations, the best way is to first learn how to exit a turn. Once a driver can be consistent at the exit, then entry must be perfected. After the entry and exit are consistent, then braking is worked on. Nobody is advocating going slow on entrance, but the phrase "slow in fast out" is used because most novice drivers enter a turn too fast and then spend the first part of the turn scrubbing off speed to collect the car, which is definitely slow. Better to go a little slow on entry and concentrate on exit speed at that level of the game. As one progresses then attention to entry speed given. Maybe you are taking the phrase too literally?