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SVreX
SVreX MegaDork
11/12/15 4:05 p.m.
AaronBalto wrote: I read an old review of one of my cars--a '92 NSX--and the writer mentioned that the weight distribution is exactly the same at 168MPH as it is standing still. Apparently, the engineers tuned the shape of the car to maintain the same dynamics at any speed. Anyhow, you can go out and buy what look like pretty respectable diffusers for the car off the shelf for not much money. What I am wondering is whether it is really a good idea to tinker with the work of the gods?

Aaron Balto:

I think it is important to note that weight distribution is not the same thing as downforce, grip, or even balance.

An F1 car can generate 5g's of downforce (that's 5X the downforce), without changing the weight distribution.

Weight distribution is generally expressed as a percentage. Downforce is expressed as a weight. A 3000 lb car with a 50/ 50 weight distribution that develops 1000 lbs of downforce would have 1500 lbs on each axle standing still, but 2000 lbs on each axle at speed if it maintained the same distribution.

The NSX has 58% on the rear axle. Your statistic only means that it also has 58% on the rear axle at speed. It does not mean it has the same downforce.

It also does not mean 58% is the optimum distribution for autocrossing, or drag racing, or hotlapping, or land speed records. Each of those would have an optimum distribution AND an optimum downforce for a given grip.

The designers were not gods, and did not design the car to do all things. Feel free to improve on anything they did for a particular purpose.

AaronBalto
AaronBalto Reader
12/5/15 9:49 a.m.

In reply to SVreX:

Um, no. The NSX was set up by some guy named Ayrton Senna. So I would take issue with your final premise. This car was, in fact, set up by a god. Screwing around with fluid dynamics in the shadow of the people who developed this car could very likely be a fool's errand.

At least until I finish the grassroots rolling floor wind tunnel in my basement.

MrJoshua
MrJoshua UltimaDork
12/5/15 12:02 p.m.

In reply to AaronBalto:

Setup by Senna to do what? Achieve the highest speed possible? Do the best on a wide open road course or a tight one? Autocross? Drive down the highway at 70 mph? Go over speed bumps? Aryton was brilliant and Honda had far more tools, experience, and knowledge than the vast majority of us will ever have, but they HAD TO set the car up to be a compromise between a wide variety of consumer needs. Thinking that no body can set up the car to do ONE thing better on a car that was designed to to MANY things well is limiting yourself.

SVreX
SVreX MegaDork
12/6/15 7:32 a.m.

In reply to AaronBalto:

I'll let Mr Joshua respond for me on this one.

The gods are fallible. Well... the gods design for different parameters than we generally do.

Smitty
Smitty New Reader
3/23/16 6:13 p.m.

A car is a rolling compromise. Ayrton Senna had some input into the setup, but in reality, probably not as much as the EPA, NTSB, the bean counters, and the product liability lawyers. Most of the people on this web site would prefer to maximize Mr. Senna's influence, and minimize that of the others. There is always room for improvement (for a particular purpose). and Not A TA Dork should try CAD (Cardboard Aided Design)

NOT A TA
NOT A TA Dork
3/24/16 9:12 p.m.

I've been a cardboard aided design fabricator for well over 40 years! ahahaha Box in the bottom pic is for my undertray.

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zps5amashnq.jpg.html][/URL]

[URL=http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002_zps4j5lzgo9.jpg.html][/URL]

sleepyhead
sleepyhead Mod Squad
4/18/19 9:19 a.m.

wow, I'm a search idiot... is this the article that's referenced in this thread:
https://grassrootsmotorsports.com/forum/grm/diffusers-demystified-article/63859/page1/

?

Tom Suddard
Tom Suddard Director of Marketing & Digital Assets
4/18/19 9:40 a.m.

Yep, that's correct!

sleepyhead
sleepyhead Mod Squad
4/18/19 9:52 a.m.

In reply to Tom Suddard :

thanks for the subtle smack-upside-dehead, by pulling it up in "The Latest" feed

note: I've moved it into the Aero section

Tom Suddard
Tom Suddard Director of Marketing & Digital Assets
4/18/19 10:06 a.m.

Nicely done. Thank you.

 

BA5
BA5 Reader
10/16/19 10:37 p.m.

Wait, no one honed in on the fact that blown diffusers hour an honourable mention in the article?  

I've been planning on giving my car a blown diffuser and have been bracing for the nay sayers on that because the on/off characteristic of them is kind of dangerous.

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