[sixpot]

I assume from various sources of information that the 335i is limited to 155 MPH?
After a recent test on a private runway I found my car exceeding this amount, and the car has no remap/tuning box fitted?

[jjbirch530d]

Originally Posted by sixpot

I assume from various sources of information that the 335i is limited to 155 MPH?
After a recent test on a private runway I found my car exceeding this amount, and the car has no remap/tuning box fitted?

i think its a EU rule that they should be limited to 155mph unless its a supercar,but how do you know its not remapped, how fast did you go down this runway

[phil200tdi]

I think they are good for 180mph with a tune so gearing is fine... What did you get to??

155mph isn't a mandated limit as far as I know. Plenty of none super cars have no speed limiter, case in point wasn't vauxhall vectra VXR top speed 161mph...

[neil@JuicedUpTuning]

It is thats why we sell the BMS SLD (Speed Limit Defeat). You'll need to cross check with a reading from a GPS device (More satelites the better)

Stock tyres and pressures? changes in diameter, pressures can +- the accuracy of the speedo

[phil200tdi]

I heard this may be incorporated in to jb4 at some point..?

Not that it's of much use to me!!!

[neil@JuicedUpTuning]

Not seen any threads Phil?

Generally if BMS feel that the majority of customers want and need the feature it will be builtin. They dont want to charge for features that most people wont use.

BMS currently have two options:-

1) CPS/SLD (Cam Position Off Set/Speed Limit Defeat) combined module

2) SLD (Speed Limit Defeat) Module. (This can be used on its own tuned or not tuned)

[M3-FAST]

Originally Posted by sixpot

I assume from various sources of information that the 335i is limited to 155 MPH?
After a recent test on a private runway I found my car exceeding this amount, and the car has no remap/tuning box fitted?

When you say it exceeded it, by how much?

All speedo's read optimistically, mine does by 5% when compared with pogo alert GpS speed reading.

Up at that mph, you clock would have gone to 163 ish before hitting the limiter at true speed of 155

[phil200tdi]

Wouldn't the limiter be based on the speedo? So that you hit 155mph on speedo and stay there.

I wouldn't have thought that they would add a limiter based on gps true speed.

Lots of limited cars 'break through' the limiter on occasion.

[JJD]

According to Autotrader's Performance and Economy stats. an Alpina B3 (360BHP) is good for 177mph link and a B3s (400bhp) is good for 186mph link.

Both these cars are based on a 335i but afaik are de-limited. Based upon this I like to think that at 420bhp a 335i is capable of 190mph

[doughboy]

Originally Posted by sixpot

I assume from various sources of information that the 335i is limited to 155 MPH?
After a recent test on a private runway I found my car exceeding this amount, and the car has no remap/tuning box fitted?

They are a 'soft limiter' AFAIK, ie its not a sudden limit, more a gentle backing off as you pass the limit, so a little creep will be permitted.

Also they probably run off the exact speed, rather than the optimistic speedo readings.

I've fitted the BMS delimiter ready for a Vmax do last year, but had to drop out, still be trying it out next spring though.

[BanziBarn]

Originally Posted by doughboy

They are a 'soft limiter' AFAIK, ie its not a sudden limit, more a gentle backing off as you pass the limit, so a little creep will be permitted.

Also they probably run off the exact speed, rather than the optimistic speedo readings.

I've fitted the BMS delimiter ready for a Vmax do last year, but had to drop out, still be trying it out next spring though.

But where does the car get the exact speed from? If it knows the exact speed, why wouldn't the speedo read it?

[Laney]

It can't give you the exact speed because the car can't factor in certain variables such as drag, Traction and tyre/wheel size.

It is therefore a calculation based on rpm and gear ratio. It has to be over stated in order to make sure you are never going faster than the Speedometer says.

I suspect the limiter is driven by the RPM/Gear ratio calculation.

So if the RPM/Gear Ratio calculation works out as 155 MPH the Speedo's slightly over stated reading (which can be as much as 10% over) could say 170 MPH

[doughboy]

Originally Posted by BanziBarn

But where does the car get the exact speed from? If it knows the exact speed, why wouldn't the speedo read it?

Car speedos HAVE to over read by law to ensure they don't under read in any circumstances (new tyres etc)

With modern electronic speedos they just add about 5% on the actual measured speed from the gearbox sensor.

This ensures they stay on the right side of the law.

BTW The false over-read law only applies to the speedometer reading. The odometer and mpg's etc all run off the ACTUAL speed / distance.


Traction only causes a problem if you drive around wheel spinning all the time, so not really an issue IMO!

Regarding tyre sizes, they know these exactly (barring wear etc). If you work out the overall diameter of every type of factory wheel and tyre combo on a E9x they are ALL the same (620mm +/- 1mmm)

This means a single speedo / odometer setup will cover the entire range regardless of wheel option - this should be taken into account when fitting non standard size tyres.....


My tyres are worn now, which makes it worse, but at an indicated 100mph, my GPS road angel and GPS phone both say 91mph actual.

[m1bjr]

Tech:
The speed signal is generated by a pulse counter.
Although it can be done in a combination of ways, I suspect all of the ABS (wheel speed) sensors and module is employed.
I'm not 100% of how BWM do it, but the principles are largely the same on any modern car.
It used to be read by reading the gearbox output shaft speed on some old RWD cars - as the diff ratio is known and fixed.

Now this REAL speed value can be read at the BUS, or the OBD2 diagnostic port.
This 'real' speed signal is passed to the instrument cluster circuits where it is modified UP by a few percent as others mention, and it then drives the speedometer.
The REAL speed signal is employed by the limiter program.
So Banzibarn, you can see why the clock still over reads - your limiter really IS working at a calcualted 155mph, but the clock still over reads.

At a real 155mph (SiRFStar3 GPS chipset accurate to roughly 0.5mph) my clock reads a shade over 160, full deflection.
So its likely you still have the limiter in place, its very subtle and feels like the engine is siezing up
It can be removed in the software, or as part of the flash tune process. Piggybacks cannot do it alone.

Would you want to?
On a UK road car personally I didn't think there was a point to it - I find that I can hit it VERY quickly however.

[doughboy]

Nice bit of detail steve.

Piggy backs could do it, the BMS delimiter I have just wired into the JB loom with 3 wires, so it could be integrated if they wanted to do it.

Not much use on the road, but as said I bought it for a VMax day at Bruntingthorpe.

[emre]

Other than BMW PPK, my car is also stock.

Fuel is cut off when the speedo reads a bit more than 265km/h (165mph) and a bit less than 270km/h (168mph). I cannot see exactly what km/h at those speeds :-) Actual speed must be 250km/h (155mph) though.

My Audi S3 had a digital speedo and fuel was always cut off at 266km/h

[Alpina_B3_Lux]

Originally Posted by JJD

According to Autotrader's Performance and Economy stats. an Alpina B3 (360BHP) is good for 177mph link and a B3s (400bhp) is good for 186mph link.

Both these cars are based on a 335i but afaik are de-limited. Based upon this I like to think that at 420bhp a 335i is capable of 190mph

I went with mine up to 310 km/h speedo before I ran out of straight road and had to let off; the car was still accelerating.

The limiting factor for manual transmission cars is rather the gearing, as it is much shorter in 6th gear than the AT. Therefor at around 290/300 km/h it's in a region rpm wise where the turbos are out of their efficiency range and hp starts to decrease.

Alpina_B3_Lux

[Falmouthboy]

Originally Posted by jjbirch530d

i think its a EU rule that they should be limited to 155mph unless its a supercar,but how do you know its not remapped, how fast did you go down this runway

I believe the 155 mph thing is to do with tax in some EU countries. Clearly if you are buying a supercar, that additional tax isn't an issue, however it is sufficiently punitive to motivate car makers to limit their cars.

[doughboy]

Makes me want the Hartge 200mph speedo conversion even more now.....

Looks good too without the ugly km/h sub scale.

[Carrera RSR]

Originally Posted by jjbirch530d

i think its a EU rule that they should be limited to 155mph unless its a supercar,but how do you know its not remapped, how fast did you go down this runway

Originally Posted by Falmouthboy

I believe the 155 mph thing is to do with tax in some EU countries. Clearly if you are buying a supercar, that additional tax isn't an issue, however it is sufficiently punitive to motivate car makers to limit their cars.

Merely a gentlemans agreement between MB, BMW & Audi to avoid potential German legislation in imposing/reducing speed limits on certain unlimited Autobahn sections in clear and dry weather. 155mph = 250kph which is why it appears to be an odd figure. Porsche never signed up to it.

As it is a non binding or legal agreement it doesn't matter whether its limited on an accurate reading, an inaccurate speedo reading or just ecu software via rpm/gear calculation. Being likely the later it will be a 'soft' limiter gently limiting the car circa 155mph. Therefore its very plausible to have a speedo reading of 160++mph before it runs out of 'virtual' steam.

[kaishang]

There's a similar gentlemans agreement for bikes, but it's 300km/h.

[Dackelone]

ALL modern day BMW's have a speed limiter.

ALL BMW's are limited to 210 kph unless they have "option #840" Increased top speed limiter Option #840 comes with the M-sport package or sport packge.

When your car has option #840 - the car is now limited to 250 kph.

ALL //M models are also limited to 250 kph. On a //M model, you can pay extra to raise your speed limiter to 280 kph. But only when you have gone thru a M Driving school and pay $$$$ to your dealer to raise the speed limiter.


Now... what you see on the car's speedo is not the car's true vehicle speed. Typically the car's speedo reads high by about 5 to 10%. It has to by German law - bc a car can not report a speed slower than the car is actually traveling.

For instance on my 135i my speedo would say I was going 155 mph (250 kph) while my true vehicle speed (check with GPS) wa actually 240 kph.


Now that I have a German flash tune I can peg my speedo needle. I have also had my car coded to have the M3 digital speedo - it reads true vehicle speed btw(you can choose to have it read actual or a "buffered" value that teh speedo sees). Anyway... now that I have a tune and the M3 speedo I have seen speeds as high as 280 kph. That was about 6,300 rpms in 6th gear with my 225/255's PS3 summer tires on.

You can see my M3 digital speedo here... while the car's speedo says I was going faster than 80 mph, the M3 speedo clearly shows that I am only traveling at 130 kph (80 mph) as does my GPS Navi also confrims.