Am i restricted

[toombzy]

can anyone help me on this, i have a jap n/a supra on a '93 plate, i was recently dragging my mate in his brand new civic type r, as soon as my car hit about 125 mph it didnt seem to have any more to give, is this a speed restiction or is my car toppin out. if so how do i remove it?http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/rock.gif http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/cry.gif

[The Restorer]

Most likely it is restricted at 112mph (Speedo does overread by 10% at high speeds). Contact Thor who should be able to sort you out. Their details will be in members discount somewhere.

[toombzy]

well i'll be trying that asap many thanks, cant wait to wipe the smile off my mates face http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/cool.gif

[Chris Rocks]

you should be able to head way north of that speed unrestricted http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/smile.gif

on a private road of course http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/wink.gif

-c-

[toombzy]

ok just had a powerflow decat full stainless system, apexi induction kit an irridium denso spark plugs put in so the cars running smooth, now to buy a speed deristrictor, anyone know anydifference between the ones on ebay at ?30 an the ones from thor ro ?100? dont wanna waste more cash as some nice guys relieved me of my headunit an passenger window!! http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/down.gif

[Martin F]

The ones from Thor will defenitely work, 100% guaranteed.

Pete (Director) is a Supra owner and developed the DSC initially for the MKIV Supra, so there is a good support for this product. Also the product has been fitted to many MKIV's over the last 5 years or so.

The MKIV has a lot of auxillary circuits which make use of the speed signal so its important to make sure that you use the correct type of converter\delimited and wire it as instructed.

[toombzy]

the car is converted to mph from kph, an everywhere i seem to read always say the mph convertors delimit the cars anyway! is this true cause i see thor sell a seperate convertor for both mph an speed restrict an one unit that does both.

[Martin F]

No it doesn't unfortunately. The 110mph speed limit is internal to the ECU, so the only way to get around it is to clamp the signal going into the ECU just before the 110mph cut off point.

A standard kmh to mph conversion would just divide the signal going to the speedo by approx .625 and then your speedo would read in mph. However on a MKIV supra after going to the speedo the speed signal then goes on to a few other ECU's as well as the main ECU, so you can see if you kept accelerating you would eventually hit the speed limit again.

But unfortunately sending a divided signal to some of the ECU's can cause problems, active spoiler doesn't deploy at correct speeds, power steering assistance is incorrect, autobox gear changes are incorrect or harsh, etc. Thats why converting and delimiting the MKIV often catches people out (especially importers who think one box fits all).

Take a look at this diagram borrowed from Thor and it should help explain things.

http://homepage.ntlworld.com/peter.betts/supra/TechTips/dsc_speedo_mph.jpg

[toombzy]

well u've convinced me to buy the one from thor, last thing , do you know where these delimiters are mounted because i want to check to see what type of convertor has been used. ive found that everything that has been done to the car is of very shoddy workman ship and wouldnt be suprised by anything, an does every mk4 have cruise control cause mine certainly does not niether abs!! doh! thanks for the great diagram.

[Martin F]

They are mounted behind the speedo\rev counter cluster. If you remove this you should find the converter spliced into some of the wires behind there.