Geoffrey

I can get RPM, TPS, brake on/off, and wheel speed from the 993 car for a MoTeC installation but not by using RS232, OBDII, or CAN bus. Each will use one channel from the MoTeC ADL.

DaMan-993TT

I don't think anyone has mentioned the Race Technology gear, so I will as that is what I use. DL1, DL2, etc. All integrate well with Trackvision.

As the user, you need to be able to get the information out of the data you collect in a manner that is easy for you. Go to the Race Technology website and down the software (it is free) and find some sample data to play with.

I don't know if others allow you to play with the software, if they do, do the same. It is the best way to figure out what works for you.

At the end of the day, they all need sensor input, so don't worry about that right now.

SundayDriver

I think that is a bit of over-simplification about the GPS arguments. The Engineers at MoTeC and many of the professional teams will tell you that GPS is great for location, heading and speed and they use it for that. At the other end, the GPS centirc systems engineers try to claim that they can do yaw rates and slip angles with GPS. If you try to do that at 20Hz (10Hz is way too slow) then you have to be able to resolve data to ~2 inches to even get a reading. If you are 1/2" off, then your accuracy will be off by 25% in those rate of change data points.

The big issue between higher end and low end, according to a very experienced Engineer who sells and works with ALL of these systems, is that the math capabilities (in the real world, not just building some calculations for demo) are very weak in the low end systems.

If all you want is sector times and video, then why bother with data aq at all? Why not just get a good lap timer system that does sectors, or a pure GPS system and forget the data.

When you cut corners, the analysis is severely compromised. What value is brake data, if you get on/off? You know braking point, but not how hard. You have no idea if it takes you an amateurish 0.5 seconds to get max pressure or a pro level 0.2 seconds. I think you are being very smart in identifiying what you want out of the system and then buying to get that. Too many foks buy a system with little understanding of what it will really do, except that the sales buy (who only sells one of the lower end brands) promised it can do everything that any high end system can do.

svochuck

The 944-spec group seems to have choosen the traqmate system. It does everything the others do. And it can replay the race with 6 different cars so you can see where everyone is faster/slower. this is really cool with a spec class. I just made my first trackvision video and WOW i need a faster computer i had to leave it and come back ...

Chuck

Phokaioglaukos

A pure GPS system to do sector times and integrate with video is probably where I'm heading. Too bad I'm too busy at work to think about this! Larry, you've got the point.

kary993

Sorry I have been out lately ill so have not been following this thread. Here is an example set of data from my G2X of an oversteer condition at California Speedway. This is a generic G2X unit with the standard out of the box sensors. Nothing else added.

You can see from the data analysis where the oversteer starts and finished using the lateral G's, MPH graph, and the drivning line below. While this is not perfect it does show the condition. An understeering car will sometimes show a spike on corner entry as the driver tries to loosen the car up by pitching it in the corner. It will show a jump in lateral G upon entry then it drops back down as the driver chases the car through the rest of the corner.

Hope this helps.....still think the orginal poster here would benefit from the basic G2X unit as the others are much more difficult to use.

amso3

I added an AIM MXL Pista unit to my 84 Porsche this summer. I'm doing data for a Grand Am Porsche race team and work with Motec on the 996 and 997 GT3 Cup cars and if I had ulnimited funds I'd be using that. The AIM unit was under $2.5K for the unit and a few sensors. I installed steering and throttle pots and added a brake pressure pot. I am very pleased with the data I am able to obtain and the really like the AIM software to manage the system and analyze the data. There are many similarities to Motec for much less money.

Someone else in this thread mentioned that you need to be able to analyze the data. My recommendation is to get very familiar with the information available on the Optimum G website. I attended the 3 day Motec shool taught by Claude Rouelle, founder of Optimum G. The class and information provided was awesome. Their technical information on their website is awesome and free. Here is a link. http://www.optimumg.com/ There are some great articles in the old newsletters. It is really worth the time to look at every article even if you've been doing this for a while.

All that said, the import thing is will DA help you improve lap times? I've been able to isolate individual corners and try different techniques with my own driving. I've been able to take off as much as 1/2 sec in a single corner that I thought I was quite good in buy understanding the data. My braking is getting better because the data shows me the effects of late(r) or trail braking. If you're up for the challenge of learning how to analyze your data, then get AIM or MOtec and start learning.

Jerry Austin
84-911 3.6

jlucas

No one is saying Motec isn't great stuff. It's just not even remotely entry level (for cost or complexity).

Bang for the buck (<$1000) it's hard to beat the amount of driver improvement that can be had from an entry level dual axis accelrometer+GPS based system; like the Race Technology DL1 (10hz GPS w/WAAS) and the RacePak G2X (4Hz GPS). What you don't get yet with the entry level products is some of the slick ECU interfaces (but it is being worked on at Race Technology) or data logging rates above 100Hz. RacePak can add up to 12 sensors/inputs on it's CAN-bus based sensor network; the DL1 can add 7 sensors/inputs, besides RPM and wheel speeds which have thier own inputs, and/or one of the optional DASH displays that include predictive lap timing. A lot of the time on modern cars your just tapping into what is already there like the TPS (throttle position sensor) instead of adding a new sensor.

A lot of people place too much emphasis on the line position data from GPS systems because they do not understand the relative and absolute accuracy available. The main advantage of GPS is true speed and beaconless lap and segment times. BTW, GPS speed is combined with accelerometer data to interprolate speed & position between GPS readings. One additional benefit of GPS based systems, that DE drivers might appreciate, is how easy it is to swap between cars and still get some basic data; without GPS you just can't do that.

I'm looking forward to trying out the AIM GPS module as it becomes available this spring (just announced that it's finaly done at PRI). BTW, Motec sees the benefit too and has been testing their 20Hz GPS module all year; AFAIK it is not yet available for sale. I was sold a long time ago on the benefits that GPS adds to data acquisition, no matter what brand you are considering.

All the brands work with Trackvision.

Lot of information out there. Google is your friend.

Jeremy Lucas
FastTechLimited.com

bnewport

We at trackpedia have given our G2X loggers to over 40 drivers in 2006 and everyone has been able to use it and get decent entry level data. Everything seems to work with trackvision also, search on youtube for trackpedia and you can see all our vids, many with data.

It does get expensive when you add in sensors but for RPM and GPS, Gs, speed, it's cool also and stays portable.

kary993

Absolutely, I beliieve too often we all try and provide good feedback but if everyone were to read what larry is asking for it becomes obvious he is not going to buy a Motec system. There are some great pieces of information here in this thread though I do not find it all that useful unless one is going to spend $4000+ for a system.


I cannot agree more about the relative nature of GPS. I tend to only make comparisons in line between laps within a session or in that day when deciding upon differences in turn entries for example. Even then I tend to use my own markers in my mind versus thinking that the GPS logged line is it. I know it is not, but does provide a nice relative reference when testing corners or segments for fastest lines during analysis. Features like track edges to see where you are in the track are relatively useless.

jrotsaert

Sorry for being thick but would you mind explaining to me how you get to see where the oversteer started? To me it looks like a long left hander followed by a straight and a chicane and i just can't see how i can tell over or under steer. i have a stack system and would love to understand it.
many thanks
JM

kary993

Your last sentence could be interpreted a few different ways though my initial thought was you are having difficulty with your stack system, is that what you are saying?

In terms of what I was trying to show folks here is that an oversteer condition shows itself with a GPS based system. The upper graph showing lateral G load and MPH shows an increase in G's and a lose of MPH at the point where the cursor is. The lower right graph which is magnified shows the driving line which takes an abrupt right turn not because it is a turn but because the car is over steering. Drinving line and car attitude change which is picked up bythe GPS based unit. The graph on the lower left shows the overall track position.

While this is not a definitive method to tell when a car is over or under steering all the time (smaller correction of the chassis) it does show that these "less expesnive" units can display some of the characteristics of the much more expensive units.

I know that the resolution of the pic I posted might be hard to see though it is easily seen when using the analysis software directly.

924RACR

Yeah, that's an interesting graph - though I think you could illustrate your point better if you focused in on the chicane itself (off the straight), rather than showing the whole lap. I notice there is also that speed peak then drop; this brings up an interesting comparison between GPS vs. speed sensor based data. If it were my car, with a speed sensor on the rear axle, I'd know I was spinning the rear wheel; of course that's decidedly not the case here. I would like to see the lateral g curve in a little more detail there - perhaps add a level of filtering though to cut down slightly on the noise level.

Other interesting things I note in that trace... in Turn 5-6, 180 deg LH-er, seems like you're double-apexing it. That's probably appropriate, particularly in a race situation, and I assume the course is basically flat and level since it's a roval... but looking at your speed and lateral combination there, I gotta wonder if you could carry more speed in there - the reason why is it seems like your lateral drops off a bit after turn-in, then builds to make the second apex. I'd be interested in seeing what your steering input is there too.

It's also interesting - though not 100% clear at this level of resolution - that you appear to pull some opposite lateral for quite some time exiting that corner. Does the track actually curve a bit to the right there? Again, kinda hard to tell; I'd be wondering if there were a way to straighten that out, though if it's much of a RH bend, you could end up sacrificing some track out and overall speed.

Turn 7-8 is a little perplexing; entry seems quite agressive/good, but after the first RH (not the king in your braking zone, but the first tight radius) and before the 2nd tight RH turn there seems to be a lull in the action; basically 0 lateral, yet the acceleration seems weaker than out of the hole in the first/slowest part of the turn. Is that a shift point, on track-out after the first turn? Also, your lateral on tracking through and exiting 8 seems a bit lower than the slower turn - perhaps the line could be more agressive here, you could push the car harder?

Finally, the esses leading onto the banking... Looks like you're having no problem getting the car to turn well going in - seems like you're getting lots of lateral on those first two. But I have to wonder, from looking at the speed trace, if there's a combination of line and setup that could improve your exit onto the banking - which would no doubt reap huge benefits in lap time - because of the substantial amount of speed that has to be taken out of the car on entry of 10. Yet at the same time the speed is being killed off, the laterals achieved are declining - only 0.8-1.0g vs. the full 1.4 or so on entry of the esses. Perhaps this is just another example of fast-in, slow-out? Because again on exiting the banking, in what should be a single, presumably increasing-radius LH turn, I see two distinct peaks on the lateral, before it tapers off on the banking and you're just cruising.

HTH, feel free to rebut!

924RACR

One more general suggestion - tighten up the range on your G display there... If you're going to be exceeding 2 g's, I don't think we're gonna want to see data so much as pics of the car when you're done! We'll all be able to see more if you increase the resolution...

kary993

Yes, I have a graphing set up template defined for this track that scales each of the channels to a reasonable range for my car (and my capabilities). Unfortunately I did not apply the scaling as I was focusing on the over steer example since many here felt it could not be demonstrated using GPS and lateral G's. Nonetheless, you are correct I could have exploded the graph and data to look at turn 3 and 4 with better resolution, but then I would not have received the valuable information/feedback regarding my entire lap had I of only provide one or two turns

Turns 5 and 6 are interesting in that the following straight is the important thing to focus on. Turn 6 actually falls away a bit outside of the apex and the track actually runs out quite wide to the right. Cutting that off will not be good for top speed down that straight to the difficult decreasing radius off camber turn 7 (on this track map, actually turn 9 on the real track). So I choose to give up turn 5 and try and get more speed in turn 6 for the following straight. Perhaps I can go faster in to 5 without sacrificing setup for turn 6?

Turn 7 is probably the most difficult turn on the track as you enter it at over 100 MPH in my car and it turns right gradually until it turns sharply into a decreasing radius final right turn. At the same time the last part in the brake zone id off camber failing away from the turn adding additional difficulty. What appears to be a lull is indeed a lull as I could not get my car (last year) to turn in quick enough there forcing me to wait. Not waiting would have really ruined the next straight which is as important as the previous straight because it is acutally longer. I am working on a different set up for this year so hopefully it will improve turn 5 and 6 and definitely turn 7.

There are two major G pulls in turn 9 on this graph. The first one and second are ok but open to suggestions. At turn 10 is the critical left turn because it is the speed that is carried onto the oval (first through the sweeper though) and all the way around to turn 3. Turn 10 is a 90 degree left with tire barriers lining the trackout point. Being aggressive there pays well but missing is not fun. So the big G load at the end of 9 is that key turn. You see the lose of MPH and the higher G loads there but then it is actually a long sweeper which does not require a big G load. Maybe I am missing something here? It seems the MPH are coming up well from the 90 degree turn 10? Suggestions?


Open for any suggestions and can post more detail of any or all turns however it would be much easier if you had the software and I could send the data