Lies, damn lies and speedo readings
Lies, damn lies and speedo readings
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Discussion

Martin_S

Original Poster:

9,939 posts

269 months

Saturday 8th May 2004
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Just had the Elise wound up to an indicated 142mph on the speedo, which I reckon is good going for a near standard S1 (sports zorst and CRP, big throttle body etc. - call it 130mph max, downhill with a following wind?).

Has anyone out there had bigger lies from their speedo than this, I wonder?

Fairly intense, whatever the true speed was, I must admit. The wind roar and induction noise were phenomenal and both mirrors folded themselves flat against the bodywork!

Dave.B

58 posts

267 months

Sunday 9th May 2004
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Up untill recently I have a GPS unit in the car (bloody thing broke) anything above above 30 would indicate that the speedo in the car was approx 10% out. Speedo would read 77 & GPS 70 etc. So your indicated 142 you'd be looking at around 128. Think this is pretty standard fair for car speedo's.

Martin_S

Original Poster:

9,939 posts

269 months

Sunday 9th May 2004
quotequote all
Yep, that sounds about right.

Begs the question how long it will be before manufacturers start fitting GPS calibration to speedos as standard. Obviously, they would still need a 'mechanical' ststem as back up, cos it can take a few minutes for the GPS to aquire the satellites on start-up, can't it?

...and I'm still waiting for some enterprising company to come up with an portable GPS system that gives me both navigation and hazard (ie. revenue camera location) warnings. Anyone have any contacts with the manufacturers that they could give a nudge?

bogie

16,927 posts

296 months

Sunday 9th May 2004
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if I bounce mine off the limiter in top I can get a genuine (on GPS) 141Mph - the speedo shows about 150mph ish. This is with the CR box and a 7000rpm limit. With the longer 5th I should be able to get a genuine 155mph ish ...but to be honest the Elise isnt really a high speed cruiser and its not comfortable at those speeds - it would just be nice to have a longer 5th gear for cruising

Martin_S

Original Poster:

9,939 posts

269 months

Sunday 9th May 2004
quotequote all
bogie said:
if I bounce mine off the limiter in top I can get a genuine (on GPS) 141Mph - the speedo shows about 150mph ish. This is with the CR box and a 7000rpm limit. With the longer 5th I should be able to get a genuine 155mph ish ...but to be honest the Elise isnt really a high speed cruiser and its not comfortable at those speeds - it would just be nice to have a longer 5th gear for cruising


That's about 7.1% error, in your case, then?

The S2 is a close ratio box as standard, isn't it? IIRC, the standard S1 box is geared for someting stupid like 156mph@7000rpm in top. Would be interesting to know how the TT230 performed on that - maybe the stanard box would even be better suited, given the extra torque of the supercharger. Do you have any power/torque curves, to do the sums with?

bogie

16,927 posts

296 months

Sunday 9th May 2004
quotequote all
Martin_S said:

bogie said:
if I bounce mine off the limiter in top I can get a genuine (on GPS) 141Mph - the speedo shows about 150mph ish. This is with the CR box and a 7000rpm limit. With the longer 5th I should be able to get a genuine 155mph ish ...but to be honest the Elise isnt really a high speed cruiser and its not comfortable at those speeds - it would just be nice to have a longer 5th gear for cruising



That's about 7.1% error, in your case, then?

The S2 is a close ratio box as standard, isn't it? IIRC, the standard S1 box is geared for someting stupid like 156mph@7000rpm in top. Would be interesting to know how the TT230 performed on that - maybe the stanard box would even be better suited, given the extra torque of the supercharger. Do you have any power/torque curves, to do the sums with?


yep - CR as STD and yes it would be far better with the S1 box - hopefully Im swapping with a friend soon. I ran my power/torque curves (225/192) through Cartest 2000 with the new gearbox and it does say it should pull 155mph at 7000rpm - I really just want a longer 5th for more relaxed motorway cruising

tupolev

89 posts

293 months

Sunday 9th May 2004
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have you considered the 111s (s2) box -doesn't that have shorter 2nd/3rd (for traffic light grand prix) and longer 4th 5th for cruising?

cheers

tupolev

fergusd

1,250 posts

294 months

Sunday 9th May 2004
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Mines has been compared to a GPS up to about 120 . . . and speedo and GPS agreed within a couple of mph . . . only car I've ever had that's like this . . .

fd

DanH

12,287 posts

284 months

Sunday 9th May 2004
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If any of you are using an Origin Blue i for measuring speed, its out by at least 7% by design -so that it matches your speedo I'm told. Of course my Elise speedo always reads about 7% under the blue i!