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ferswin
Member
ok done some research heres the max. speed
5th gear ratio is 0.82
diff ratio is 3.44
wheel circumferance is 1.8726m
max engine speed is 6250rpm
6250/0.82/3.44=2215.68349 is the wheel rpm @6250rpm engine
2215.68349*1.8726= 4149.0889 metres per min
4149.0889*60/1600=155.59mph
actual top speed would be slightly lower because i didn't take
into account the tyres sinking a little making the wheel circumferance
lower thus the top speed.
so after all that i guess my speedo is wrong.
but i im not a liar.[/b]
5th gear ratio is 0.82
diff ratio is 3.44
wheel circumferance is 1.8726m
max engine speed is 6250rpm
6250/0.82/3.44=2215.68349 is the wheel rpm @6250rpm engine
2215.68349*1.8726= 4149.0889 metres per min
4149.0889*60/1600=155.59mph
actual top speed would be slightly lower because i didn't take
into account the tyres sinking a little making the wheel circumferance
lower thus the top speed.
so after all that i guess my speedo is wrong.
but i im not a liar.[/b]
S
si21
percentage of error
like i stated b 4 all speedos are not acurate thats y when you get mags doing articals they have special timing gear to get real figures you dont see em reading it off the speedo how many cars think they are doing 120 i bet they are only doing 110 LOL
si21 :wink:
like i stated b 4 all speedos are not acurate thats y when you get mags doing articals they have special timing gear to get real figures you dont see em reading it off the speedo how many cars think they are doing 120 i bet they are only doing 110 LOL
si21 :wink:
lyn21turbo
Active Member
in most of the test articles i have read on the 21T,,, the vast majority give the true reading of 100mph, when the speedo actualy read 105mph.
J
Jamie
My wife was following me today in her car.Thought i better be sensible and stick to 70,she said she was showing 80 and could'nt keep up!Whats all that about?
lyn21turbo
Active Member
speedo out,,different wheel sizes(rather than std 15") etc
DaveL485
Staff member
Well...
....I guess we need an anorak with some numbers to settle this....
...and here I am.....
With Std gearing the R21 Turbo, on the rev limiter (6300 rpm) with 55 profile tyres it is capable of 150.8 mph. Renault book top speed is 141mph, although they had one to 147mph on a test track i believe.
It IS possible to gear one (and believe me it wouldnt be easy, cheap or sane) for 171mph with a certain set of parts and mods, getting the car there power wise though would cost just as much again.
Certainly an almost std car with 18psi would not be able to break the 160mph barrier, personally i've made 150 twice (albeit on the std speedo) and expected to see half my engine vaporise doing it....
Also the std speedo is far to inaccurate to be depended upon at these speeds.
Draw your own conclusions from that everyone
....I guess we need an anorak with some numbers to settle this....
...and here I am.....
With Std gearing the R21 Turbo, on the rev limiter (6300 rpm) with 55 profile tyres it is capable of 150.8 mph. Renault book top speed is 141mph, although they had one to 147mph on a test track i believe.
It IS possible to gear one (and believe me it wouldnt be easy, cheap or sane) for 171mph with a certain set of parts and mods, getting the car there power wise though would cost just as much again.
Certainly an almost std car with 18psi would not be able to break the 160mph barrier, personally i've made 150 twice (albeit on the std speedo) and expected to see half my engine vaporise doing it....
Also the std speedo is far to inaccurate to be depended upon at these speeds.
Draw your own conclusions from that everyone
S
si21
so with any luck then
my 17's will put my true speed on the speedo lol dont think it makes that much difference to normal legal speeds running 17's any comments to the contary? you stick with 16's dont you Dave ? i know that you arnt supposed to have quite the acceleration that you do from standard wheel size on a 17
si21
my 17's will put my true speed on the speedo lol dont think it makes that much difference to normal legal speeds running 17's any comments to the contary? you stick with 16's dont you Dave ? i know that you arnt supposed to have quite the acceleration that you do from standard wheel size on a 17
si21
DaveL485
Staff member
17's
Si mate, as long as you use the right profile tyres on the seventeens (40) the rolling radius of the wheel will stay the same and not affect your speedo.
It does affect acceleration a little, because more of the weight of the wheel sits further out of the centre of rotation.
Changing the tyre profile will affect your speedo, bigger puts your reading low, smaller profile will put your reading high. Approx 7% per profile increment.
Si mate, as long as you use the right profile tyres on the seventeens (40) the rolling radius of the wheel will stay the same and not affect your speedo.
It does affect acceleration a little, because more of the weight of the wheel sits further out of the centre of rotation.
Changing the tyre profile will affect your speedo, bigger puts your reading low, smaller profile will put your reading high. Approx 7% per profile increment.
S
stevenford_uk
the rolling radius of my 17"s is not the same as my 15's, i put them side by side on level ground and my 17" 40 profile wheels and tyre was bout an inch higher than my 15, the 15's were 195,50,15.
the highest i have had mine is 145mph (private road of course), still pulling well, geoff h who had it before me has had it to 155mph running silly boost and full stainless with the 17" wheels.
if i can i will get a cordless pushbike speedo, goes to 200mph accurate it programmed correctly to bout 0.3 mph, and ill take piccys of that if i can.
the highest i have had mine is 145mph (private road of course), still pulling well, geoff h who had it before me has had it to 155mph running silly boost and full stainless with the 17" wheels.
if i can i will get a cordless pushbike speedo, goes to 200mph accurate it programmed correctly to bout 0.3 mph, and ill take piccys of that if i can.
J
Jamie
That's one fast push bike :wink: Are you gonna stear with your knees as your doin 155 with a camera in your hands :shock: Hope the phone does'nt go at the same time :lol:
DaveL485
Staff member
*Sigh*
I Wish people would pay attention.....
Stevenford, yes you are right the rolling radius of your 15's is different to your 17's because your 15's have the WRONG SIZE TYRE ON. Std size in 195/55/15 as stated in a previous post, not 50/15 as you have stated yours are.
SO, with the right profile on a 15, ie (55 profile) they would near as dammit match up in rolling radius. The biggest variation will be from tread depth/wear factors.
I Wish people would pay attention.....
Stevenford, yes you are right the rolling radius of your 15's is different to your 17's because your 15's have the WRONG SIZE TYRE ON. Std size in 195/55/15 as stated in a previous post, not 50/15 as you have stated yours are.
SO, with the right profile on a 15, ie (55 profile) they would near as dammit match up in rolling radius. The biggest variation will be from tread depth/wear factors.
S
stevenford_uk
oh, sorry dave, meant no harm
BIG MVS
Well-Known Member
Going back to the 21 Turbo against RS6, can I just say that there is no way that a 21 Turbo can keep up with one of these things, i was out in one we have at work(Car Rental company with an Audi contract - they give them to people when their Lambourgini Breaks down!! :shock: ), to best describe the performance was that it pulled my foreskin back!
G
graham
sorry to say but me mate had an audi 100 s4 and my 21 beat it off the lights and then pulled away from it
G
graham
well we would like that sort of power
DaveL485
Staff member
LOL
Stevenford-mate I think you took my post the wrong way, I apologise, it wasn't meant to be :evil: it's more :roll: :wink: :lol:
Big MVS, yes mate, i'm one of the unfortunate's who's tried it on with an RS6....I know my car ain't slow man but Jesus he just said SEEYA!
By the time I made 120 (from 40ish) which takes about 12-14 seconds, the thing was fcukin offski, I was gobsmacked. Ain't been beat so bad since I tried it on with an F40 just for comedy value :lol:
Stevenford-mate I think you took my post the wrong way, I apologise, it wasn't meant to be :evil: it's more :roll: :wink: :lol:
Big MVS, yes mate, i'm one of the unfortunate's who's tried it on with an RS6....I know my car ain't slow man but Jesus he just said SEEYA!
By the time I made 120 (from 40ish) which takes about 12-14 seconds, the thing was fcukin offski, I was gobsmacked. Ain't been beat so bad since I tried it on with an F40 just for comedy value :lol:
S
STEVE KENTISH
just like to say..........
when u "race" on the streets with a complete stranger you dont no what he is doing or how hard he is driving. just because you are trying your hardist dont mean he is.
plus racing off the line also depends on how well you launch, i once kept up with a ferarri testerossa (0-60 in 5.4sec) from the lights up to 80mph at which point the aero-dynamic brick that is the 21 got well and trully wasted.
the only true way to say you have beaten someone, or a perticular car, is on the strip or track.
(oct.30-31 avon park, putting money where mouth is. )
when u "race" on the streets with a complete stranger you dont no what he is doing or how hard he is driving. just because you are trying your hardist dont mean he is.
plus racing off the line also depends on how well you launch, i once kept up with a ferarri testerossa (0-60 in 5.4sec) from the lights up to 80mph at which point the aero-dynamic brick that is the 21 got well and trully wasted.
the only true way to say you have beaten someone, or a perticular car, is on the strip or track.
(oct.30-31 avon park, putting money where mouth is. )
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