E30 top speed limiter

[nando]

Not raining on your parade, but what speed is the speedo off by 3-4mph? I ask because when speedos are off, it's exponential when they are triggered the way these cars are. 3-4mph at 45mph could be 10mph, 15mph, maybe more at an indicated 150mph.

Nevertheless, thats impressive!!! I'm assuming you were near sea level? At altitude ours cars feel weak... going down 1000 or 2000 feet feels like you just got a supercharger!! If your 325i showed 150, maybe my 335i will be able to touch 160 indicated.

Not that I have the balls to try it on the highway...

I don't think E30 speedos work that way. mine is actually decently accurate at 60+, but at an indicated 25 it's almost 10mph off! I think BMW just adds 3-5mph across the whole range to keep you out of trouble. remember, these speedos are not mechanical, the mechanical ones definitely are less accurate at higher speeds.

[euroshark]

Well... I'm not saying I'm right, I'm just going with what I think is right. If someone can do this with math, please help because I'm not about to crack open a book to help me remember this stuff! lol

The speedo sensor is triggered by the diff I think. The E28s do it that way at least, so if your tires are larger or smaller in diameter than the factory size, you will see variations that change exponentially. Mechanical or electronic doesnt matter because they are triggered by a rotating mass that is directly connected to the wheel and tire. If the wheel rotates slower for a given speed because the tires are larger than stock, then the speedo will be affected more and more as speed increases (it will show slower than your actual speed), and with smaller tires it will show faster. At least that's my understanding... I'm no math major, but my gf is :drink:

[Nick]

Are you talking about your E32? I have heard of them hitting over 175mph with the speed limiter removed.

{hard on}

Yeah they just keep pulling and pulling, and I delimited both of mine as soon as I had the chance.

I actually went so fast in my 88 that the windshield trim flew off and the window cracked. I bottomed out the speedo (170) and the tach was still flying higher.
The 94 is definately faster, but I haven't beat up on it too much because it's much nicer.

It's eerie how stable the car feels at such high speeds.

Oh yeah, I only paid $2500 for the '88 750... :)

[euroshark]

Oh hell yeah!!!

I have wanted a 750il for a looooong time.... I think I'm gonna have to spoil myself this summer :)

So... you have a '94 750 as well?? Have you put up pictures of that one yet? I think I've only seen the '88... the green one?

[Nick]

Nope.
The green one is the 94. That's the last year that they made the e32.
You can tell it's a late model by the fact that the lower lip is flared, and by the fact that it LACKS ellipsoid projectors...and that it has a radio remote, and not an IR one, AND by the fact that the rear shades are powered...all in all, a much nicer car. I could've bought an e38 740...95 or 96...for less money.

The 88 alas...

[euroshark]

Awww thats terrible! Thats cool that the '94s had some better options though, I never knew that. I think I'll probably be looking around '89 to '91 though, hopefully for one with lowish mileage and a good body for under $3000.

[02stu]

Any one know the how high the gears in a 318is w/ the 4.10 will take you? I know its around 125 at the top of fourth.

[SA E30]

I took my car to 240km/h indicated... still had sitll had around 1500rpm to go till 7000rpm.

90/5 spd

[DJB]

The speedo sensor is triggered by the diff I think.

Correct. There is a magnetic reed switch triggered by a slotted wheel on the diff. No change in any drivetrain ratio will change the indicated speed. The only thing that matters is the revs per mile of the tires. Better tire places such as TireRack list the nominal revs/miles of each tire for a typical size rim.

Mechanical or electronic doesnt matter because they are triggered by a rotating mass

Not a "rotating mass", but a slotted disk.

Detail: both the ABS and engine crank position sensors use coils and a cogged wheel. This only produces a usable signal when the rotation is fast enough. By using a magnetically closed switch the speedometer/odometer can measure even very slow movement.

BTW, the term "exponential" is incorrect. The difference between indicated and actual speed is "linear" or "proportional" with a fixed offset.

[Mystikal]

Any one know the how high the gears in a 318is w/ the 4.10 will take you? I know its around 125 at the top of fourth.

At 6500rpm on stock tires, the 318is can achieve 113mph in 4th and 141mph in 5th. Of course it will never reach the top of 5th due to drag.

With a 7100rpm MarkD chip, these numbers are 123mph and 154mph, respectively.

[silversleeper]

ive only managed an indicated 134mph... before running out of straight road. but it still had go, didn't feel any sort of limiter like i did in my old civic. stock 89 325i 5 spd.

[euroshark]

BTW, the term "exponential" is incorrect. The difference between indicated and actual speed is "linear" or "proportional" with a fixed offset.

Thank you, I knew I said something was wasn't gonna be right. At least the idea was right though!

[Dominic49]

[pineapplegti]

buried!!!

[tonytony]

what did you have to do to the car and how steep was the hill to get it to go that far past?