plantman
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 posted on 29/7/08 at 07:14 PM |
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SVA, top speed and tyre ratings
i am nowhere near going for the sva yet, but i am thinking about buying wheels and tyres.
I am sure that the calculated top speed assuming the engine runs to 6500revs and i use 195/50/15 tyres, 3.62 diff is 173!! no my sums are correct and
yes i now it will not do this speed.
the question is what speed rating do the tyres need to be???
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Paradoxia0
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| posted on 29/7/08 at 07:19 PM |
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Going by the guide I have here....
149mph - V
168mph - w
186mph - y
There are some other quirks about loading on each tyre at different speeds that I will try to post up if you need it, but I would say go for Y or Z
rated tyres 
There is no replacement for displacement...
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britishtrident
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| posted on 29/7/08 at 07:22 PM |
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Try calculated top speed in 4th at peak power RPM -- it will be more realistic
Remember a Locost has the aerodynamics of brick privy.
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plantman
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| posted on 29/7/08 at 07:23 PM |
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BUUUUtttt i thought you had to put the top speed you thought it would be on the sva form..... ie locost,s are brick shaped and don't go through
the air very well so i would say the top speed will be 140 mister sva man honest
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r1 locost
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| posted on 29/7/08 at 08:35 PM |
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brick shaped? i geared mine to do 121mph and it does 121mph so....mmmmm
[Edited on 29/7/08 by r1 locost]
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02GF74
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| posted on 30/7/08 at 07:18 AM |
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Big RON suggests:
1100 cc = 90 mph
1300 cc = 110 mph
1600 cc = 130 mph
(or thereabouts - I need to check the book).
as long as you put something reasonable down you'll be fine for SVA and you tyre rating is correct.
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Lars
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| posted on 30/7/08 at 07:55 AM |
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I just put the engine donor's top speed on the SVA form, which was 129mph for a 2l zetec.
My tyres were h rated (130mph).
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alistairolsen
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| posted on 30/7/08 at 08:16 AM |
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also remember your tyres are a continuous rating, sitting on the boards on the limiter is not.
dont know about sva specifically, but for the mot you can buy a modern tin top and fit poo tyres to it and so long as they all match its fine? surely
seeing as its illegal to exceed 70..........
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David Jenkins
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| posted on 30/7/08 at 08:30 AM |
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I put 125mph down as the max speed, and have H-rated tyres.
As for the max speed - what happens if you take it over to Germany on the ferry? Nothing like 100km at max speed for knackering the tyres!
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britishtrident
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| posted on 30/7/08 at 11:40 AM |
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quote:
Originally posted by 02GF74
Big RON suggests:
1100 cc = 90 mph
1300 cc = 110 mph
1600 cc = 130 mph
(or thereabouts - I need to check the book).
as long as you put something reasonable down you'll be fine for SVA and you tyre rating is correct.
Even Ron's figures are optimistic for a car running a windscreen. Most Sevens type cars will actually have a lower top speed than the engine
donor.
For a standard 2 litre Zetec powered Locost with windscreen 120 is in the right ball park. Wide tyres will increase drag, removing the windscreen
reduces it significantly.
Caterham's claim top speeds of between 104 and 140 for their various models from the 104bhp 1.4 K series powered Classic up to the 210bhp
Caterham Seven Superlight R400.
The 265bhp Caterham Seven Superlight R500 is significantly faster but that has no windscreen.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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plantman
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| posted on 31/7/08 at 09:53 AM |
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All very good but does the sva man look at the gearing, and then check your tyre rating.... I don't want to spend loads of money on the wrong
tyres........
i will have no windscreen and hopfully get in the region of 325-350bhp
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Marcus
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| posted on 31/7/08 at 11:43 AM |
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SVA bloke will not know power of motor (unless you tell him) he doesn't know what it's geared for either. Just tell him it's geared
for 120 (or whatever you decide) at max revs and buy tyres accordingly.
[Edited on 31/7/08 by Marcus]
Marcus
Because kits are for girls!!
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plantman
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| posted on 31/7/08 at 12:34 PM |
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so you don't enter the gearing on the sva form
seems like a very good idea not to tell the sva man the whole truth
thank you
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smart51
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| posted on 31/7/08 at 02:29 PM |
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The theoretical speed in top gear at max revs irrelevant. The SVA wants to know the highest speed the car can achieve and make sure the tyres are
rated above that speed.
My Peugeot is geared to reach 143 in top gear at max revs but it won't even to 100 because the power is too low.
That said, 350 BHP might be enough to reach your 174 MPH, so start saving up for your expensive tyres.
BTW, the life expectancy of tyres at the quoted speed is a matter of a minute or two
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plantman
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| posted on 31/7/08 at 04:15 PM |
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cheers
i think that will just about what i needed to know
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