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The mkiv Supra Owners Club

Removing the 180kph restrictor.


SIMON LC

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Guest steve982

That is also what I have been led to believe!.....As I still haven't done mine either, perhaps you have now found out?

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I had a restrictor on when i bought my jdm supra from UK it diden´t cut at all, I was driving maybe 160-165mph and no cut. However as soon as i removed the little box the speed cut appeared at 180kmh. I have got this gadget in the garage, if someone needs one it´s for sale, cheap.

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no it wont do it even if you place a km to mph converter. thor do it or u can get a

hks sld

http://www.qjp.jp/catalog/images/product_images/L_2129.jpg

or a pivot v speed meter like mine

http://carview-img6.bmcdn.jp/carlife/images/UserCarPat/781889/p1.jpg

 

or if ur a nutter ;) apexi rsm

image

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I like that apexi one:d how does that get rid of the speed limiter?That pivot one you have is smart how does it work and how much it cost?Sorry for all the questions i hate my 180kph limit need it gone:d

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Speed delimiters work by fooling the ECU that you're going slower than you really are. On an unlimited car, an electrical signal goes from the speed sensor to the ECU, and this tells the car how fast it's going. If it reaches 180kph, the ECU will prevent it from going any faster (by limiting the fuel feed possibly, the details don't matter for this discussion).

 

Top Speed delimiters (TSDs) are small electronic box of tricks that usually work in one of two ways:

 

1) the best way is to make a ceiling speed that is passed to the ECU. The output of the speed sensor is intercepted by the TSD, and if it goes above, say, 170kph, then an electrical signal equivalent to 170kph is passed to the ECU no matter what your actual speed is. The car is fooled into thinking it's going at 170kph, so the ECU allows it to go faster.

 

2) the not-so-good way is to divide the speed signal from the speed sensor before passing it to the ECU. Let's say we have a TSD that divides the signal by 2. If the speed sensor reckons you're going at 100kph, then the ECU will be passed a signal for only 50kph. When you're going 180kph, the ECU thinks you're doing only 90pkh, so will allow you to go faster. Of course, the limit would still be reached if you ever get to 360kph, but that's unlikely to ever happen. :)

 

The 2nd way is worse because there are other electrical circuits in the car that rely on the speed signal, for example the power steering. Below a certain speed (let's say 30mph) the driver gets full power steering assistance. The 2nd TSD method would mean that the driver gets full assistance at 60mph (the ECU thinks you're doing 30, remember?), which would make the steering feel too light and skippy.

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Righto chaps, I hearby promise to finish off my "How To...Fit a speedo convertor and top speed delimiter" guide during this week. I've had it half finished for ages and I can see there's quite a need so I'll crack on and post it up during the week. :thumbs:

 

It's a pretty simple and easy DIY job, takes a couple of hours to half a day depending on how competent you are but anyone could do it.

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