180 km/h speed cut removal

[Guest]

While we're all hi-jacking the thread - what's the best way to test how accurate your speedo is reading?

I've got a V4 JDM WRX which I've fitted with some 215/45/17's, so assuming due to the increase of rolling diameter, that my speedo would be out, somewhat?

Given Coromandel roadtrip pending - wanting to ensure that I know how fast the car is REALLY going, so the Po-Po doesn't clock me going 105k/h when I think I'm doing 100k/p

[pedro]

205/40 17 showing 60ks on speedo = 57ks on roadside speed radar readout.

215/45 17 showing 60ks on speedo=54ks on same roadside speed radar.

So you should be getting a less accurate reading if you have gone up in tyre size/ratio.

Makes you wonder what it would show if on original 16's,might have to try it one day.

[chulozumo]

 gmeago']

While we're all hi-jacking the thread - what's the best way to test how accurate your speedo is reading?

I've got a V4 JDM WRX which I've fitted with some 215/45/17's, so assuming due to the increase of rolling diameter, that my speedo would be out, somewhat?

Given Coromandel roadtrip pending - wanting to ensure that I know how fast the car is REALLY going, so the Po-Po doesn't clock me going 105k/h when I think I'm doing 100k/p

you could try using a gps..it usually tells you the speed your going aswell as directions etc. thats how i found mine out anyways..

[quote name='pedro said:

205/40 17 showing 60ks on speedo = 57ks on roadside speed radar readout.

215/45 17 showing 60ks on speedo=54ks on same roadside speed radar.

So you should be getting a less accurate reading if you have gone up in tyre size/ratio.

Makes you wonder what it would show if on original 16's,might have to try it one day.

less accurate?? i was told it would be more accurate with bigger wheels/tires??

Im still on the original 16s...10ks out at 100km

[Guest]

I've got a Navman - have never seen the 'speedometer' option?

Where abouts can I find it?

[boon]

He means a man's GPS, not a woman's supermarket finder ;D

Most decent GPS' will show you your velocity, although it depends on the road being very flat since even a slight incline will mean your road speed vs your positional velocity will be different...

[funkytown]

 chulozumo said:

yeah my ra is about 10ks out at 100km. used spark38's gps to test this...lolol

as was my v3 sti. interesting have changed to a v9 spec c box and a v2 sti gauge cluster and now its almost SMACK on perfect.. go figure.

[Joker]

and to figure speedo-corrections try : Car Calculator V2.1 download HERE

[Guest]

 funkytown']

[quote name='chulozumo said:

yeah my ra is about 10ks out at 100km. used spark38's gps to test this...lolol

/quote]

as was my v3 sti. interesting have changed to a v9 spec c box and a v2 sti gauge cluster and now its almost SMACK on perfect.. go figure.

you running a v9 box on a v3 block?

[Guest S T E Y E]

on the topic of speed limiters...my old v2 wrx use to cut out fully just after 180 (tacho droped to 0) but i just went and tested my v3 for speed limiter and it just sounds like its doing a really early rev limiter wen it gets just a bit past 180.....this normal??

[zarnah]

Dunno, where did you test it?

[Guest S T E Y E]

in my backyard race track bro............... the idea of it cutting at a accurate 180 seems logical as mine went a bit past 180 before it cut and i have 215 35 18s

[Ninja8)]

 S T E Y E said:

in my backyard race track bro............... the idea of it cutting at a accurate 180 seems logical as mine went a bit past 180 before it cut and i have 215 35 18s

Can i come?

[Guest S T E Y E]

hahaha its strictly limited acces bro

[Guest]

 pedro said:

215/45 17 showing 60ks on speedo=54ks on same roadside speed radar.

Based on the assumption that the factory tyre size is 205/50/16:

http://www.trademe.co.nz/Trade-Me-Motors/Car-parts-accessories/Wheels-tyres/Alloy-wheels/auction-340595997.htm

215/45/17

60k/h on the speedo = 61.36k/h on the road

100k/h on the speedo = 102.27k/h on the road

Note to self...

That would've got me caught out this weekend hah!

[funkytown]

 sti8u']

[quote name='chulozumo said:

yeah my ra is about 10ks out at 100km. used spark38's gps to test this...lolol

/quote]

as was my v3 sti. interesting have changed to a v9 spec c box and a v2 sti gauge cluster and now its almost SMACK on perfect.. go figure.

you running a v9 box on a v3 block?

it would bolt up yes but only on the four bolts, not 8. I actually run an ej207 short block (and v3 heads) which is 8 bolt bellhousing.

[T.Rev]

2010..the year of the epic thread hijacks...and the longest threads about sfa...

[spark_38]

yeah my 10% error theory was not just pulled from a hat. i have throughly tested amongst many Ver 4-6 wrx/sti's using same/similar, sometimes two gps units side-by-side over the period of the last year or so. strangely once subaru got to the bug-eye model, the error was almost non-existent. one could almost say they are almost dead on.

it is a linear error, consistent error - other wise one cannot correct it with the speedo kit

now.....who is keen on that speedo correction kit ??????

i have tested this with a mates car:

215/40/17 = 10% error, (same as stock gold 16's, which i had on my car)

215/45/17 = 5-6%, so less error

[Guest S T E Y E]

got an idea how far out id be with 215 35 18s?? wana use a gps to test haha

[CUDDAS]

 gmeago said:

While we're all hi-jacking the thread - what's the best way to test how accurate your speedo is reading?

police radars are supposed to be pretty accurate i'm sure there's plenty out there to try out coming up to christmas

[Guest S T E Y E]

pretty expensive way to test accuracy...could cost u ur whole car for a month plus ur licence for 6 months

[chulozumo]

 S T E Y E said:

pretty expensive way to test accuracy...could cost u ur whole car for a month plus ur licence for 6 months

pfft who needs a license when youve got a race track in your back yard!

[QRAF]

i loved the fact when i 1st bought my car that it could do over 180km/hr but after owning the car for over 5 years now its over rated and i wish i owned a sti so i could just up the boost with more confidence that i wasn't going to blow my motor up.

[kamineko]

 QRAF']

i loved the fact when i 1st bought my car that it could do over 180km/hr but after owning the car for over 5 years now its over rated and i wish i owned a sti so i could just up the boost with more confidence that i wasn't going to blow my motor up.

[quote name='T.Rev said:

2010..the year of the epic thread hijacks...and the longest threads about sfa...

lol yup

[Guest S T E Y E]

so how can urs go past 180??

[Guest]

just keep guning it and kick the shit outa the clutch haha

mine does about 190 then cuts ah