As some of you might know I have been working on a data logger in my spare time this year. I have done some initial testing on the system and I thought I would share the graphs with everyone here on Honda-Tech (below). I’m not going to go into the specifics of the system just yet for I’m not done with it and it’s something I work on when I have the time and I feel like it. However, if anyone cares, here are some of the basics:

Compact box that you can mount just about anywhere in the car.
Data is saved to a compact flash card for EZ transfer to a PC.
3-axis accelerometer
Remote “save data” switch so that you don’t save data when you don’t need to.
Optional data logging of (Speed, PRM, Throttle position, or any other sensor in the car.)





When I’m all done I would love to install it in others cars (HC drivers?) just to compare plots and graphs of differing cars/setups/drivers. Maybe by next summer it will be done and some of us can play around with it out on track.

 

What hardware is required for the actual device? Are you incorporating accelerometer or do you interface with something like a G-Analyst or Geez Cube?

 

As you can see from the G-G plot, I perty much never trial brake. The line from hard braking goes strait out to hard cornering, making it look like friction triangle rather than a friction circle. Something to work on. I also need to stop tapping the brake before turn 9 "l". The data shows a max cornering force while under a slight acceleration. Maybe this is becase my car is 66%/33% front to back weight?

Here is the car set up if anyone is wondering.

Front spring rate (lbs/inch): 420
Front anti-sway bar: OEM (25mm)
Rear spring rate (lbs/inch): 550
Rear anti-sway bar: Neuspeed (26mm)
Ride height (inch): ?
Total weight with driver: 2820lbs

Tires: Falken Azenis 215/45-16
Rims: 16x7.5 Kosei K-1
Front tire pressure (psi cold): 37
Rear tire pressure (psi cold): 35
Front Camber (deg.): -2.5
Rear Camber (deg.): -1.5
Front Toe (inch): 0.0
Rear Toe (inch): 0.0

Brake system: OEM
Front brake pad: Carbotech XP-9
Rear brake pad: Carbotech XP-8

I will be making changes to this set up, and I will keep you all posted on the effects they have on the G-G plot. (I know I'm a geek)


Modified by 577HondaPrelude at 4:17 PM 9/22/2004

 

Cant wait to see more, looks good

 

I'm using a chip from analog devices:

http://www.analog.com/en/prod/....html

You need to be able to make a board that will accommodate a surface mount chip, and build the proper electronics around it. Lucky for me I'm an Electrical engineer who works in a electronics lap that has the tools that makes this real EZ. I just work on it at work when things get slow, or I stay late. It's still FAR from being done to my liking.


Modified by 577HondaPrelude at 4:09 PM 9/22/2004


Modified by 577HondaPrelude at 4:20 PM 9/22/2004

 

When you are done will you make a couple of these? I would love to try one out in may car. THANX

 

thats very cool!

 

After I get it tested fully and working rock solid, I plan to make up several. I might even sell em if I can keep the price low enough, and if work does not bitch at me for selling something I developed in off hours in their lab..hehe. Either way I would not have any problem letting someone borrow it for a few times out.

 

hmm... that g-g data makes me beleive even more that a stiff ***-end may not be the best after all

 

Very Cool

Someone pointed this out to me the other day... http://www.gtechpro.com/rr.html

I am not sure how good it will be or how versatile the software will be. Also looks like other sensor input will be limited to just RPM.

I think that inexpensive data loggers could be a great tool for helping improve yourself or to reinforce what you are trying to teach someone as an instuctor.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Someone pointed this out to me the other day...
http://www.gtechpro.com/rr.html

</TD></TR></TABLE>

$300 is not a bad deal. Now I'm starting to think if I really need to log Speed/TP/temps/ect.. Because if I don't, I can just spend the $300 and move on to my next project rather than finnishing this one off

 

I saw the setup in person. Cant wait ot try it out in coupe of years.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondan00b &raquo;</TD></TR><TR><TD CLASS="quote">hmm... that g-g data makes me beleive even more that a stiff ***-end may not be the best after all</TD></TR></TABLE>

Why do you say that?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 577HondaPrelude &raquo;</TD></TR><TR><TD CLASS="quote">

Now I'm starting to think if I really need to log Speed/TP/temps/ect.. Because if I don't, I can just spend the $300 and move on to my next project rather than finnishing this one off </TD></TR></TABLE>

Yeah, but there is the satsifaction of doing it for yourself and maybe even doing it one better...looks like you are on the way there.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">Why do you say that?</TD></TR></TABLE>

well, he was commenting that trail-braking is more difficult with this set-up. i take that as meaning that the drop-throttle oversteer characteristic of a stiff rear means that he cant take advantage of the available lateral grip under braking.

you can see it on the diagram- instead of following an ellipse, the braking/cornering combination is closer to the longitudinal axis. i would say that he's doing pretty okay, but it might be easier to take advantage of that last bit of available grip with a little softer rear end.

i noticed this at a recent track day. because my car has a somewhat 'soft' rear (and isnt so prone to snapping at dropped throttle), i am able to carry my braking further into a given corner than some of the other cars with drivers of similar skill. this is, of course, very much opinionated and i can offer no proof. so just beleive me

i guess all im saying is that i am not convinced that a stiff rear is the fastest way to go. and i wont be convinced otherwise until ive gone out and experimented for myself :D

 

Awsome

If you want to compare, here are some of my graphs from Beaver Run (ITR expo 4) in a firends stock ITR. I am currently using a DL1 logger, so far I really like it.
Beaver Run Lateral Accl and Speed vs Distance
Beaver Run Track Map and G-G Circle

 

Nice looking graphs. I would say that a steering pot would be the next sensor I would want to look at. It would be easier to pick out handling characteristics of the car at specific turns (entry understeer at F and pretty loose through J), but it helps to know what the driver is doing.

Where did you mount the accel?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondan00b &raquo;</TD></TR><TR><TD CLASS="quote">you can see it on the diagram- instead of following an ellipse, the braking/cornering combination is closer to the longitudinal axis. i would say that he's doing pretty okay, but it might be easier to take advantage of that last bit of available grip with a little softer rear end.

i noticed this at a recent track day. because my car has a somewhat 'soft' rear (and isnt so prone to snapping at dropped throttle), i am able to carry my braking further into a given corner than some of the other cars with drivers of similar skill. this is, of course, very much opinionated and i can offer no proof. so just beleive me

i guess all im saying is that i am not convinced that a stiff rear is the fastest way to go. and i wont be convinced otherwise until ive gone out and experimented for myself :D</TD></TR></TABLE>

While I agree that a compromise is always necessary for drivability vs. grip, the physics behind a rear-stiff FWD car shouldn't take into account driver ability IMO. The fastest car should require the fastest driver (cuz Ferrari could pay me a whole lot less than MS to drive if that's not true).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by canuckr &raquo;</TD></TR><TR><TD CLASS="quote">Awsome

If you want to compare, here are some of my graphs from Beaver Run (ITR expo 4) in a firends stock ITR. I am currently using a DL1 logger, so far I really like it.
Beaver Run Lateral Accl and Speed vs Distance
Beaver Run Track Map and G-G Circle
</TD></TR></TABLE>

Cool, what type of tires were on that car?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Nice looking graphs. I would say that a steering pot would be the next sensor I would want to look at. It would be easier to pick out handling characteristics of the car at specific turns (entry understeer at F and pretty loose through J), but it helps to know what the driver is doing. </TD></TR></TABLE>

good idea, I was thinking about that also. I will add that to the list.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Where did you mount the accel? </TD></TR></TABLE>
In the rear of the car (trunk). With the car on flat ground I adjusted the height of each corner, of the box I built, via adjusting screws till the X and Y axis read zero, and the Z axis read 1G.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondan00b &raquo;</TD></TR><TR><TD CLASS="quote">well, he was commenting that trail-braking is more difficult with this set-up.</TD></TR></TABLE>

With a good rear-stiff setup, its just not necessary and probably slowing you down if you're doing it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">i noticed this at a recent track day. because my car has a somewhat 'soft' rear (and isnt so prone to snapping at dropped throttle), i am able to carry my braking further into a given corner than some of the other cars with drivers of similar skill.</TD></TR></TABLE>

As the experience level increases you will be more comfortable with a loose car, and it is faster.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">With a good rear-stiff setup, its just not necessary and probably slowing you down if you're doing it.
</TD></TR></TABLE>
says who?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by elgorey &raquo;</TD></TR><TR><TD CLASS="quote">says who?</TD></TR></TABLE>


i too would like to know why trail braking is slow

 

If you do not need to trailbrake to rotate the car you can get on the throttle earlier, and carry more speed out of the turn.

It "feels" great, but many people I have asked about it say "no I dont trailbrake there, why do you ask?"

 

I think trailbraking is pretty corner dependent, sometimes its faster, sometimes its more trouble than its worth.

 

As a LONG-time trailbraker, I'm only beginning to understand what a band-aid technique it is - with way better tires and real suspension pieces for stock-tub race cars.

&lt;geezervoice&gt; Back in the old days (like the '80s), a person had to be able to do clever stuff with the pedals to get sloppy FWD cars to change direction. That is not nearly the case anymore. A car that we would have thought was wicked loose then would seem like a shopping cart to someone used to a modern FWD race car. &lt;/geezervoice&gt;

Kirk

(who is pretty sure that Uncle Catch is going to think the Golf is a plow, even with the biggest bar in the US on the back end and the front bar in the garage)

 

I need to install my 1" rear bar... maybe loosen up my front endlinks.