Speed limiters

[Frank]

I just tried out today how fast my car (Impreza 2.0R) goes. Up to 200 km/h is easy and fast, then I switch to fifth gear and the acceleration slows down. It goes further to 215 km/h and stops there, at 6250 rpm (max is 7500).

Well, that was about as expected, but it stuck there no matter what. Going downhill: 215. Going back uphill: still 215! And considering that the maximum power is delivered at 6400 rpm, it should at least be able to go 230 km/h, probably a bit faster than that, as medium hills seem to be no problem.

It's simply limited to 215 km/h

 

[DJ12]

I guess it'll be the drag.

Seeing as the top speed is listed as 130 mph you are actually getting a bit more out (133 mph) of it than Subaru say.

They aren't very aerodynamic cars.

I maxed out my STi before I got it tuned to about 155mph, I haven't dared try it since I got it upgrade.

 

[Frank]

Yes, but you should see a difference going up- or downhill, shouldn't you?

And considering that the speed gauge only goes to 220 km/h, I suspect they simply limited it.

 

[DJ12]

Not being a physicist I couldn't tell you.

I would've thought the drag would be the limiting factor and your car isn't developing more power just because it's going downhill.

There still won't be enough power to push the car through the air any faster.

 

[Frank]

Ok, that makes sense. But I would still expect to see even a small difference going up or downhill.

But that they aren't very areodynamic is definitely true. The air noise increased all the way quite a lot, and when I passed 200 km/h, the right front window started to vibrate (no frame). I had to roll it down and up every time it did that. Although I think oiling the rubbers would fix that.

 

[DJ12]

I have that problem with mine, mine starts doing it at about 130mph though.

Opening the window just a touch gets rid of it though not that I can hear it that much. All I hear is a whole lot of noise out my rally spec exhaust.

 

[digitalwanderer]

Sounds like a restrictor, that would explain the up/down hill bit.

Just for practical concerns, after 120mph it's kind of redundant. Seldom need much more than that.

 

[Ateo]

I just tried out today how fast my car (Impreza 2.0R) goes. Up to 200 km/h is easy and fast, then I switch to fifth gear and the acceleration slows down. It goes further to 215 km/h and stops there, at 6250 rpm (max is 7500).

Well, that was about as expected, but it stuck there no matter what. Going downhill: 215. Going back uphill: still 215! And considering that the maximum power is delivered at 6400 rpm, it should at least be able to go 230 km/h, probably a bit faster than that, as medium hills seem to be no problem.

It's simply limited to 215 km/h

Get it Chip-tuned and unlocked, it's locked electronical at that speed

Welcome to 2007, overclocking you car

 

[DJ12]

My car (when it was standard) only does about 155 mph (25 mph more than Franks) despite having at least 100bhp more.

The car will be restricted by the drag nothing else.

The fact it's the same going uphill or downhill really doesn't make any difference. I may make it a little quicker/slower accelerating but the top line won't be affected.

I guess we need someone with a physics degree to properly explain it.

Subaru, as far as I know, do not restrict any of their vehicles in foreign markets (in Japan they are limited to about 150 kmph or something like that)

 

[Simon F]

Yes, but you should see a difference going up- or downhill, shouldn't you?

The wind resistance goes up with the square of the speed which means the power required goes up with the cube of the speed. I should think it'd have to be a really steep hill for it to make much difference (and then would you get grip from the tyres?)

 

[Frank]

Ok, thanks. So it's simply drag, bad areodynamics and nothing else. I can live with that.

And yes, digi, I agree: when I entered the German highway, I was wondering if there was some speed limit there, until I was overtaken by a Mercedes 530i at high speed. So, I planked and overtook it, and only had problems with slow cars overtaking while they really should have seen me coming in their mirror after that.

 

[suryad]

It is electronically limited. I dont think it has to do with drag. I have an 07 Scion tC and it is limited to 127 mph....and a stock tC makes it to that speed. So I doubt it is drag and horsepower cause a tC at the engine makes 160.

 

[Ateo]

It is electronically limited. I dont think it has to do with drag. I have an 07 Scion tC and it is limited to 127 mph....and a stock tC makes it to that speed. So I doubt it is drag and horsepower cause a tC at the engine makes 160.

Agreed, it's quite common today that they lock cars that way...

 

[_xxx_]

Ok, that makes sense. But I would still expect to see even a small difference going up or downhill.

It's deliberately limited for safety reasons. The cars are built to drive up to the certain max speed, and that is flashed into the ECU's at the end of line during the final diagnostics.

You can gain speed downhill if you can switch to neutral, but I definitely wouldn't recommend trying that, might end badly.

 

[Rainbow Man]

It's deliberately limited for safety reasons.

No. People want t odrive at speeds where the only way they'll survive when they crash is out of sheer damn luck. (Let's conveniently forget about any passengers or people in the other vehicle(s) they hit etc.)

It's their human rght. Or that's what they claim anyway.


Peace.

 

[_xxx_]

Dude, it's about staying within the (safe) limits of the materials involved in the construction, nothing more than that. There is always a max speed limit in the engine ECU (electronic control unit) for exactly that purpose. The gearbox might have it's own internal limits for different situations too, depending on the manufacturer/model, and the instruments have their own limits as obvious. Those are not coincidentally chosen as you may imagine.

 

[Frank]

It's deliberately limited for safety reasons. The cars are built to drive up to the certain max speed, and that is flashed into the ECU's at the end of line during the final diagnostics.

You can gain speed downhill if you can switch to neutral, but I definitely wouldn't recommend trying that, might end badly.

That's what I expected, considering how it works. I do know about electronics, microcontrollers, programming and such. And that's how it felt.

Hm.

 

[nutball]

Overclock it

 

[Frank]

Overclock it

I doubt that would work.

But it would be really interesting to hack into that program! I might just do that.

 

[Frank]

Btw:

Dude, it's about staying within the (safe) limits of the materials involved in the construction, nothing more than that. There is always a max speed limit in the engine ECU (electronic control unit) for exactly that purpose. The gearbox might have it's own internal limits for different situations too, depending on the manufacturer/model, and the instruments have their own limits as obvious. Those are not coincidentally chosen as you may imagine.

While that is absolutely true, every part used has an additional safety margin of at least 10%, as produced by the subcontractors. It goes on down the line. And I have a whole lot of confidence in the competence of the Subaru engineers. I think only Porsche and a few other top brands spend more attention to the engineering and production quality than Subaru.

Between Mercedes, BMW and Audi, I think only Audi is comparable, and only for their prototypes and speciality systems.

That's not to say that BMW or Mercedes make bad cars (although the materials and production quality of Mercedes is pretty bad since the last few years, I'm sure you'd agree), but they have a quite different focus.

In cornering, grip and stability, I would want to see one of them compare to an equal Subaru (as long as you forget about the stupid Justy. That's not a Subaru).