YOURS might be accurate, but most simply are not. On OEM wheels/tires, mine reads roughly 4.5% too high. So I could probably get mine to read 160mph, since 153.1 is within the acceptable range of top speeds

I haven't tried for that speed. To nervous financially.

And if even 1 RX-8's speedo is off, then you have to assume that more of them are as well, and it throws into doubt anyone who makes a statement outside the accepted range by using their speedo.

 

Exactly. I'm not saying the stock speedo can't be accurate. I'm just saying that there's frequently slight inaccuracies and the faster you go, the bigger the gap. In an instance where someone's car shows a speed that has not previously been seen on a stock RX-8, the assumption should be speedometer error (if the run was on a flat surface with no winds).

So when motorcycles are accelerating with their front wheel off the ground, they can't tell how fast they're going?

 

Many car makers actually build their tachometers to be inaccurate by a rough 3-5%. This helps the dumb users to stay within the speed limits

 

The AP will register correct rpm, will it do the same for the speedo ?

 

I can test, but I think no. The speedo is already digital, so it probably just grabs that number. The tach, and the speedo in other cars, being analog signal has inherent inaccuracies from the ECU to the display. Taking the number from the ECU removes those additional inaccuracies. I'd bet the Speedo is already from the ECU, and the inaccuracy is between the sensor and the ECU.

 

No the AP does not give you the correct speedo and neither does GPS. You need to get the vehicle properly timed then re tuned.

 

So I'm curious, why do you say that the GPS doesn't give you accurate speed?

 

and speedo's. that tiger's speedo is 6mph faster throughout the range.

huh?

 

I have had a car timed by the SCTA I had a GPS in the car at the time. It was the microsoft streets and trips GPS this was in 2008. The SCTA required that I do a calibration run at 135 MPH so that they could tell me how far off the speedometer was for the run I was doing. My car read 135, my GPS read 132, the SCTA told me I was doing 131. Now all being that said it was off by 1 MPH but it was still off.

 

6mph consistent is odd. Usually it's off by a percentage. 4.5% in my case (roughly). So 1mph high around 20mph, 2mph around 40, 3mph around 65, 4mph around 90, etc...

A 6mph consistent off would mean that he would show 6mph while stopped.

 

eek! 6%

note to self: must not multitask

 

I have always shown a consistent GPS speed between multiple devices running all at once, and they match what a stop-watch and math does. (there is a marked and signed official Measured Mile near me that I tested against)

Though 1mph at 135mph is a 0.7% variance, which could easily be explained by rounding and/or timing. For example if your GPS was rounding up, the SCTA rounding down, and maybe they were only 0.1mph different.


I wouldn't use that to say that GPS is off. The SCTA could have been off as well.

In fact, I'd trust the GPS before any other medium, given how accurate the GPS system has to be, and how it works makes speed calculation a cinch, and VERY accurate. The inaccuracies with it typically come about from delays between the processing time and the display time.

 

Gotcha

 

The only guess I could make on that assumption is that the GPS had a display lag time.

 

keep in mind your in dash speedo also suffers from tire size, tread wear, tire inflation(intentional and inflation due to tire temp) etc etc

 

with all the technology we have today you would think they could rig the speedo to run off gps, and the tire speed guages as a back up

 

Pivacy there. Think about all the privacy nuts that would go crazy when they heard that "a GPS sensor is installed on their car".



Even ignoring how it's used, and if the data goes anywhere.

 

The only one I wouldn't use is the one for car insurance purposes. Most cars come with a nav system now, cant they just move that over the gauges on speed. Its already in most new cars as a stock option. Don't a lot of new cars already record data for crashes?

 

heres a nice one that allows you to set colors, font, and other things.

http://www.speedhut.com/custom_gauge...number-820.htm

 

119 mph in a 65 mph zone in my 2004 4-speed automatic RX8

I found out my new GPS caught my speed too



i live too close to work, so im only on the highway for work two days a week

 

I did 115 in a 4 cylinder '98 Nissan Altima. 100 in a Suburban is scary on a country road. I haven't put the 8 over 85 yet. I tend to grandpa the 8 for some reason.

 

I went over 100 mph in my sebring convertible after me and my dad repaired the water pump 300 miles before.. she blew up. now i have an 8. hoo-rah?

 

120 in an 4 speed AT must have taken a while...

I got my top speed urge out when I was younger with the 8. I hit 155-ish. I dont think I'd do something like that again unless it was on a closed course of some sort. I very rarely go over 100 in the S4. Been up to 120 or so but don't really feel the need to go faster. Another S4 with similar mods has hit close to 180, and I have no desire to come close to that.

 

In my blown C5 I went over 160mph a couple times.

On my sportbike(fully modded 954rr) I did 185+ indicated many times. Was -1 on the front sprocket though so it was probably a fair bit lower. It so easy on the bike since it gets there so quickly. I've been busted doing 140 on one wheel...that was a fun phone call to the wife...

Not sure the fastest in my Rx8, though I've posted logs of me exceeding 120 on short bursts while testing my turbo.

 

mawnee, you sir, have gigantic nuts