rs10

I've recently started a thread with a very similar title in the performance modifications forum, here:
https://rennlist.com/forums/racing-a...l#post13898932

EDIT: I understand this link isn't (always?) working. You should also be able to get there by copy and pasting the following text into this forums search tool: "things you can do to your car that will affect the aerodynamics"

Then someone posted that I should have started it in this forum, and they're probably right.

Too late now, though. I can't move the thread. All I can do is mention it here. So if you're interested, please click on the link!

rlm328

Your link doesn't work. The only way that I know to get true empirical data is with a wind tunnel.

Depending on much you have set up for data collection, you can work with linear gauges on your suspension to measure how changes to aerodynamics effect any given corner on the car under a given set of circumstances.

Frank 993 C4S

I have been successfully working with well calibrated shock pods and AIM math channels over the past two years on lift/downforce measurements. In the wind tunnel you really need a rolling road set-up to deal with boundary layer effects.

It's tough to do reliable drag measurements outside the wind tunnel. We also use flow visualization techniques with tuffs.

Matt Romanowski

There are ways to do this, but your threads are tough to follow since they are in about 5 forums.

The data systems are not $6k to do this. The sensors would run around $250 each, data logger would be around $1,700, then install on them. You may be able to tap into the stock sensors or decode the CANbus info if you wanted to and then you wouldn't need the sensors. AEM would not be a good choice for this.

A wind tunnel would be the best bet, but would be expensive working through all the configurations. You can rent A2 for $500/hr with a 2 hr minimum. That would be accurate enough to get you info on what works better and worse. http://www.a2wt.com/

rs10

Indeed. I did my best to direct all discussion to just one forum, but it didn't quite work that way. Perhaps rim328 is not the only one for whom the link didn't work ... .

Otherwise, A2 isn't really an option for me. I'm not a race team, and I can't change the configuration fast enough to use 2 hours of time. Indeed, in many cases I wouldn't be able to change the configuration myself at all ...

Any idea what data loggers would be a good bet to use with the stock height sensors?

Thanks!

rs10

Thanks for your post - shame I didn't see it sooner!

I don't know how to fix the link. But as I just added to the first post, another way to get there is to seach this forum for some text from that thread, such as:

Matt Romanowski

If you just wanted to log, an AiM Evo5 would be a very good choice. Then you would have to either see if you can get the CAN info to make a custom profile (read lots of time and effort) or tap into the stock ride height sensors. If neither of those work, then you can add your own sensors.

Let me know if you want to do something along those lines and I'm happy to help you out. I'm an AiM dealer, but I might direct you to someone else depending on where you are.

wanna911

Is A2 the one in NC? I've thought about that one. 500/hr isn't bad at all.

You need to make for quick swapping with some low torque power tools and maybe use quick release pins on your wing. An extra set of hands would work wonders.

rs10

There may be a way to get even more data in less time: Once a car is ready, how long does it take to put it in the tunnel and measure it? 10 minutes?

If so, then if 12 guys go together with their cars, each of them different, you can learn a lot in just two hours.

(But please share your data when you do, because I can't join. I'm nowhere close.)

Chris P Lewis

Airplane guy.......

rs10

Any reason you didn't use the stock height sensors?

ProCoach

Not enough accuracy or resolution, I would imagine.

rs10

Interesting, but I'm not entirely sure how to understand your post. Do you know they do not have enough accuracy or resolution (and imagine this is Frank 993 C4S's reason)? Or do you imagine they might not have enough accuracy or resolution?

(If it turns out that they are not very good height sensors, then my question would be whether they are good enough for me. I would be satisfied if I could reliably pick up a change in lift of as little as 5 kg (possibly a bit more in the rear). This might be tough to measure on my car, as my springs are significantly stiffer then the standard Carrera sport suspension. On the other hand, since I have the opportunity to get up to pretty high speeds on long, flat stretches, 5 kg could result from relatively small changes.)

ProCoach

I am clear.

I also know that the ONLY way you could achieve close to your desired resolution is by strain gauges at the spring perch. I recommend these: http://www.raetech.com/Instrumentati..._Load_Cell.php

rs10

Looks impressive. Does not look cheap. (The site does not show the price, which contributes to it no looking cheap.)

How about 10 kg differences? With standard Carrera springs? :-)

Well, I can definitely test at high enough speeds that 7.5 kg would tell me what I need to know. Not sure about 10 ...