Date: Tue, 08 Dec 1998 06:10:27 -0800
From: Justin VanAbrahams <jvanabranopsamnet>
Subject: Re: Average speed

RCS wrote: > > Hi, > itīs normal, that the speedometer shows 5 to 10% more speed, cause you > are not allowed to be faster than the speeding limit defined by the > law!!! - so you should be on the safe (=slower) side. Also little > differences in the diameter of the tires must not cause too high speed. > Thatīs why all speedometers show minimum 5% more! The SID computer shows > the truth cause itīs more accurate for calculating distances. > Check the speed using a stopwatch and the distance index on the motorway > (1000m)! (30sek = 120kmph, 36sek= 100kmph, 45sek = 80kmph) > > (Justin - Iīm disappointed ...) > > Greetings -ROLAND- > > Charles Vaillancourt > You shouldn't be disappointed, because you are incorrect. The SID and the speedo do not agree because the SID is measuring something different. I really wish I could remember exactly what the explanation is, but I can't - it's legitimate. If you're really interested, do a search through Dejanews or something to find the answer. As for your "speedos show 5mph more" that's blatantly wrong. Speedos are *supposed* to be calibrated to take into account everything between the speedo and the drivetrain, and should be accurate at all times. US law allows a speedo to be off by no more than 10%, but this doesn't mean this is the norm. Both my '88 9000Ts are deadly accurate, as evidenced by the dyno they were both put on for their recent smog checks. At any rate, the SID and the speedo get their information from EXACTLY the same place and display it in exactly the same way. Pick up a wiring diagram for the cars if you do not believe me. -Justin

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