Will the Digital speedometer have a fast refresh?

[Dadhawk]

Originally Posted by timurrrr;3428237
Surprisingly on that occasion it was 100% accurate [I

when driving at constant speed[/I] on a straight flat highway.
I'm not talking about a single sample, I'm talking about hundreds of samples across multiple drives on different sets of same spec tires.

Well, you are fortunate. I've tested all cars I've owned since GPS became common, and they all have been 2 to 8 miles an hour off in the same condition.

[ermax]

Originally Posted by timurrrr

But I do agree that this is not worth 8 pages of a discussion lol.

I just hope that it's ~10 Hz from the factory, or at least that someone comes up with an easy tweak for the software.

In the worst case, I'll try to I find time to make a DIY speedo with blackjack and HUDers.

Okay I’m not familiar with blackjack or HUDer and a quick Google turns up nothing for either of them. Do you have any links?

[Kronk]

Here accuracy panels: 10% faster
But it’s not a problem. Your circuit references are based on your speedo. And legal road limits are based on this wanted poor accuracy.

[Ernest72]

Digital is fine, no issues in 5 years of ownership. Only looked at the needle speedo once and it’s too small. You are way overthinking this.

[Dake]

They're talking about the digital speedo and their superhuman ability to notice that it might be a quarter second off of where it should be while negotiating the Forrest Elbow at Mount Panorama.

Semi-serious though Timurr, I get what you're saying. You're saying it doesn't matter so much that the speedo is inaccurate, just that it should be consistently inaccurate. But let's look more closely at your example from the last page:

See above my comment on this thread a few pages ago: track driving.
When I track out from T6 at Laguna Seca and I see 78 mph on the speedometer, does it mean that
I've nailed that corner ... or does it
mean it's still showing the speed I had before the corner?

You are introducing a number of variables into this and the potential refresh rate of the digital speedo isn't even the biggest one. I'd say the biggest is, how are you managing to look at the speedo at the exact same moment every time so as to have exact comparisons (or exact enough to then be wrong due to the quarter-second refresh)?

So T6 at MLC... you've entered, headed for the apex, and you've picked up your exit point, your eyes are now looking up the hill to get the car in position for the corkscrew. That's where you should be looking. Looking at the speedo in any of those instances is taking your eyes away from where they should be. Furthermore, you should be able to tell whether you're on speed because you either hit your targets or you don't. You're either in the power band, or you're not (that's why the tach is the right in the center of our display).

Your eyes should be outside the whole time at most every point on that track aside from maybe the front straight when you're just WOT and heading for the line. I will bet you'd see better overall time gains if you put a piece of cardboard over the instruments, drove outside the whole time and just focused on hitting your entry/apex/exit every turn through feel and engine sound, than you'll ever gain from worrying about 1 mph (+/- .025 seconds) at any given point along the track.

[timurrrr]

Originally Posted by ermax

Okay I’m not familiar with blackjack or HUDer and a quick Google turns up nothing for either of them. Do you have any links?

https://knowyourmeme.com/memes/im-go...ck-and-hookers

Originally Posted by Dake

You are introducing a number of variables into this and the potential refresh rate of the digital speedo isn't even the biggest one. I'd say the biggest is, how are you managing to look at the speedo at the exact same moment every time so as to have exact comparisons

I use the end of the track out curb as a time reference.
The timing is as precise as any reference people use for braking.

Originally Posted by Dake

(or exact enough to then be wrong due to the quarter-second refresh)?

I have to admit: the more I think about it, the more it seems that at points where it is useful for me to know speed the speed doesn't change that much.
But just the second thoughts that I don't know if the speed I'm looking at, when I do look at it, makes me doubt the speedo.

Originally Posted by Dake

So T6 at MLC... you've entered, headed for the apex, and you've picked up your exit point, your eyes are now looking up the hill to get the car in position for the corkscrew. That's where you should be looking.

This is where I am constantly scanning towards with my vision.

Originally Posted by Dake

I will bet you'd see better overall time gains if you put a piece of cardboard over the instruments, drove outside the whole time and just focused on hitting your entry/apex/exit every turn through feel and engine sound, than you'll ever gain from worrying about 1 mph (+/- .025 seconds) at any given point along the track.

Just to clarify, I'm not just staring at the speedo every time I take every corner of every lap.
It's more of a sampled data check as I go, primarily used to sanity-check/calibrate my seat of pants.
Looking and thinking ahead is still the priority, of course.

Originally Posted by Dake

Semi-serious though Timurr, I get what you're saying. You're saying it doesn't matter so much that the speedo is inaccurate, just that it should be consistently inaccurate.

It's funny that nobody in this 9 page (lol) discussion has even mentioned the biggest source of inaccuracy.
Not theoretical, but happens every time when you're "on it", affects all speedometers of all cars, and easily affects the reading by up to 5 mph when driving on the track.
Curious when someone brings it up

But again, a fairly consistent/predictable/correctable one.

[p1l0t]

What about a Nixie Clock? These are pretty sweet, retro but fast.

https://eshop.3dsimo.com/collections...c13nXZoAUAJieE

You can crank some of these puppies up to like 100,000hz!

https://hackaday.com/2019/12/12/cust...-100000-hertz/

Sent from my SM-G975U using Tapatalk

[JuniEdith]

A car with a digital speedometer uses a speed sensor, which usually consists of a magnet surrounded by a wire coil, quite like the pickup on an electric guitar. The sensor is mounted directly next to a gear on the transmission, and as the gear spins, its teeth whiz by, interrupting the magnetic field on the sensor.
Nobody loves slow speed refresh,this may occur due to faults the speedometer should try to show exact speed.

[Blighty]

It will be predictable.

You also have revs and gear you are in displayed without the same keep and hold as the speed, and these have an much more optimal layout for racing as per the new visual mode.

It should be one of the better cars for track day information.

[soundman98]

i don't think i've ever heard of people at track days talking about their speed through corners. it's usually references to rpm and/or gear selection. 'should be topping out 3rd there, but instead of shifting, hold to redline, that'll be the braking zone point for the next turn'...

[ls1ac]

I too wonder about the value of a speedo on the track. Several of my track cars had NO speedo. Reviewing telemetry after a race or practice run was instructive but not while driving. Too much else going on to be looking at a speedo.

[HKz]

OP is professional driver from italy.

[Kronk]

Nope, I’m just a software analyst in love with cars and technologies.
But you must to be a pro comedian, thank you for your contribution.

[timurrrr]

Originally Posted by JuniEdith

The sensor is mounted directly next to a gear on the transmission, and as the gear spins, its teeth whiz by, interrupting the magnetic field on the sensor.

I believe on our cars it uses the ABS sensors integrated into the wheel hub assemblies.