yea but cars arnt always right eather alot of cars are off on that both my brothers cars are off by like 5 and my the one in my car only goes to 45 then quits so i gota get that fixed lol
got myself a radar gun!!!
- Thread starter Stroked2stroker
- Start date
The problem with checking it against an "unknown" source like another vehicles speedometer is; what if they don't agree. Which to believe then?
The most accurate way to measure speed (by far) is a time distance trap. Like they use at bonneville. Although you don't have to spend bookoo bucks on a laser timer system like they have you're just trying to get a pretty good idea of speed not world record verification.
Get a long straight stretch of area (road, field, or basically anything flat) with some sort of marker along side of it (fence posts, power poles, trees, anything visual). Measure the distance between two points. Far enough away from each other that you (or a friend) can push the button on a stop watch and but close enough you don't have to hold your engine wide open for a REALLY long time to make it through the "trap". Once you have a known distance and a time through that distance you can use a converter to get miles per hour.
Time, Speed and Distance Calculator
Is a basic time, speed, distance calculator for free!
You can use the same principle to test the speedometer on your vehicle, mile markers on a federal highway (interstate) are predictably close to the actual distance between them (except where maybe an exit ramp is blocking them). On a straight stretch of open highway set your cruise control and time one flying mile. Using the time, speed, distance calculator that running exactly 65 mph you should cover one statute mile (US unit) in 55 seconds. If your speedometer says 65 but you cover it in 50 seconds, your speedometer is off by exactly 7 mph at 72 mph which is enough to get you a ticket!
Now, because your stop watch finger isn't going to be extremely exact (or you can't really tell how exact your friends finger is) a few passes to average out statistical errors will help smooth the results. What you'll have is like 4-5 different times for the same distance covered. Average and then calculate your speed to get a better result.
The most accurate way to measure speed (by far) is a time distance trap. Like they use at bonneville. Although you don't have to spend bookoo bucks on a laser timer system like they have you're just trying to get a pretty good idea of speed not world record verification.
Get a long straight stretch of area (road, field, or basically anything flat) with some sort of marker along side of it (fence posts, power poles, trees, anything visual). Measure the distance between two points. Far enough away from each other that you (or a friend) can push the button on a stop watch and but close enough you don't have to hold your engine wide open for a REALLY long time to make it through the "trap". Once you have a known distance and a time through that distance you can use a converter to get miles per hour.
Time, Speed and Distance Calculator
Is a basic time, speed, distance calculator for free!
You can use the same principle to test the speedometer on your vehicle, mile markers on a federal highway (interstate) are predictably close to the actual distance between them (except where maybe an exit ramp is blocking them). On a straight stretch of open highway set your cruise control and time one flying mile. Using the time, speed, distance calculator that running exactly 65 mph you should cover one statute mile (US unit) in 55 seconds. If your speedometer says 65 but you cover it in 50 seconds, your speedometer is off by exactly 7 mph at 72 mph which is enough to get you a ticket!
Now, because your stop watch finger isn't going to be extremely exact (or you can't really tell how exact your friends finger is) a few passes to average out statistical errors will help smooth the results. What you'll have is like 4-5 different times for the same distance covered. Average and then calculate your speed to get a better result.
wow a 68mph blaster. my uncle told me it wasnt possible. if i ever have an extra 2k lying around i should modify mine to go 70
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