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stevem
26-02-08, 03:14 PM
Hi, Just received a form from Swansea asking for photographic proof of amateur build evedence and photocopies of major parts ect. One thing they have asked for is for me to confirm the actual max road speed of the kit car as the speed stated on my form is rather low for a 3500cc engine. The tyres on the car are speed rated R (106mph) so i put down 95 mph. Has anybody else come across this. Cheers Steve..

tonym
26-02-08, 03:29 PM
My only suggestion is to get better rated tyres, you'll quite probably go faster than 106mph (I'm making an assumption here, my apologies if you have no inclination to ever go that fast) and if you do then you'll be exceeding the tyres safety. The sva people are aware of this which explains there letter.

dingocooke
26-02-08, 03:31 PM
As VOSA read these forums, its safe to say theyre already more than aquainted with the various things folks can put on the forms to get around some aspects of the regs.
R rated tyres do seem very low for a V8 powered car

stevem
26-02-08, 03:33 PM
Hi Tone, The tyres i have got were supplied by pilgrim when i ordered the wheels. Maybe they dont expect a Sumo to go that fast.

Miket
26-02-08, 03:40 PM
Just write back and tell them the National Speed Limit is 70 mph and you don't intend to break the law. ;) ;) :D :D so the tyres should be fine.

Noel
26-02-08, 04:16 PM
Get on the phone to Pilgrim. Sounds to me like you have been "done", not by Pilgrim, but the supplier of the tyres. They out source the tyres and fitting to someone else and usually get them to deliver on their behalf. Maybe just a mis-understanding but I would presume that you have paid for higher rated tyres. Swansea have probably picked up on the low max speed and decided to carry out further investigation. Talk to Tony at Pilgrim and he will advise what to put on the forms to satisfy them.

HTH

stevem
26-02-08, 05:18 PM
Get on the phone to Pilgrim. Sounds to me like you have been "done", not by Pilgrim, but the supplier of the tyres. They out source the tyres and fitting to someone else and usually get them to deliver on their behalf. Maybe just a mis-understanding but I would presume that you have paid for higher rated tyres. Swansea have probably picked up on the low max speed and decided to carry out further investigation. Talk to Tony at Pilgrim and he will advise what to put on the forms to satisfy them.

HTH

Like it has been said R rated tyres do seem a bit on the slow side for a V8. I paid pilgrim 370 for the four tyres. does that sound right for R rated tyres 15".

Purple AK
26-02-08, 06:17 PM
Like it has been said R rated tyres do seem a bit on the slow side for a V8. I paid pilgrim 370 for the four tyres. does that sound right for R rated tyres 15".
Steve. What tyres have you got? And where did you get the "R" from?

stevem
26-02-08, 06:23 PM
Hi Chris. Front P215/60R15. Rear P235/60R15. Cooper Cobra Radial G/T. Cheers Steve..

Chimeara
26-02-08, 06:23 PM
Are you sure there is not another letter before the R for example Z. It strikes me strange that your tyres would only be R rated.

Toddy
26-02-08, 06:24 PM
Steve, the photographic evidence and receipts is normal now, sorted mine last week.

stevem
26-02-08, 06:28 PM
Its just the speed rating on the tyres that is worring me now. The photos and receipts i have got them. There always seems to be something to worry about.

Purple AK
26-02-08, 06:33 PM
Hi Chris. Front P215/60R15. Rear P235/60R15. Cooper Cobra Radial G/T. Cheers Steve..
Ahha. The R in the middle of the size denotes "Radial" There will be 93T on the fronts and 98T on the rears somewhere, The T is the speed rating which is 118MPH ;)

stevem
26-02-08, 06:40 PM
Hi Chris. You are correct 93T Front & 98T Rear. Cheers for that. Im just going to stand in the corner with a pointy hat on for ten mins.. (bugger)

Purple AK
26-02-08, 06:47 PM
Hi Chris. You are correct 93T Front & 98T Rear. Cheers for that. Im just going to stand in the corner with a pointy hat on for ten mins.. (bugger)
Nothing to be ashamed of ;) I've been in the tyre game 30 odd years, and still managed to measure the offset wrong on my rear wheels :( :rolleyes: At least you can up your top speed by 20mph now ;)

stevem
26-02-08, 06:56 PM
Can i just say i would be lost without the help from you guys on this site, Thanks Steve..

markr
26-02-08, 07:15 PM
A guy from Vosa actually phoned me to check the top speed details. As I had a Granada V6 in it he wouldn't accept anything below 135mph which was the top speed of the Granada. Luckily my tyres are Z rated which should be good for 160 (steep hill with the sails up)

TonyD
26-02-08, 07:47 PM
A guy from Vosa actually phoned me to check the top speed details. As I had a Granada V6 in it he wouldn't accept anything below 135mph which was the top speed of the Granada. Luckily my tyres are Z rated which should be good for 160 (steep hill with the sails up)


Well thats my plan for using "Romanian Remoulds" effectively buggared then !!:)


If a Lexus has an electronically limited top speed of 155, and you remove the limiter, but put the motive power into something with the aerodynamics of a brick, such as a Cobra, I wonder what would the top speed be?

Anyone know the Cd factor of a Cobra ?

Cheers,

Tony

tonym
26-02-08, 10:12 PM
If a Lexus has an electronically limited top speed of 155, and you remove the limiter, but put the motive power into something with the aerodynamics of a brick, such as a Cobra, I wonder what would the top speed be?


But are you using the Lexus diff Tony??

ps I still can't find the wheel supplier's details in Burton, perhaps someone else can help??

TonyD
27-02-08, 09:42 AM
But are you using the Lexus diff Tony??

ps I still can't find the wheel supplier's details in Burton, perhaps someone else can help??

I'm using the 3.54 Jag diff versus the Lexus diff which is 3.64 so only 3% difference in Ratios.

The Lexus engine will redline at 7800, top gear is overdrive 0.8, wheels should be 245/55/16, with just over 300bhp at 6500rpm the flexiplate, with torque converter locked up so say 20% driveline losses, the question is would the Cobra aerodynamics stop max revs being attained?

I'd say 150mph max and the car would run out of grunt to push the air out of the way before it runs out of revs, what say others?:confused:

Cheers,

Tony

dingocooke
27-02-08, 09:49 AM
Anyone know the Cd factor of a Cobra ?

Cheers,

Tony

Maybe you could calculate it yourself??? (My brain hurts just lookiing at it)

The Drag Coefficient (http://www.grc.nasa.gov/WWW/K-12/airplane/dragco.html)

dingocooke
27-02-08, 09:57 AM
I'm using the 3.54 Jag diff versus the Lexus diff which is 3.64 so only 3% difference in Ratios.

The Lexus engine will redline at 7800, top gear is overdrive 0.8, wheels should be 245/55/16, with just over 300bhp at 6500rpm the flexiplate, with torque converter locked up so say 20% driveline losses, the question is would the Cobra aerodynamics stop max revs being attained?

I'd say 150mph max and the car would run out of grunt to push the air out of the way before it runs out of revs, what say others?:confused:

Cheers,

Tony

You could theoretically get max revs in any shape, you just need a lot more hp as the shape gets worse!
From the (cobra clone) cars Ive been in or driven or owned, my take on it is you need approacing 300hp to reliably crack 140mph, and Id guess closer to 350-400hp for everyday 150mph ability; thats not speedo miles per hour though :-) It takes a very good engine in a cobra to see those sort of figures, the drag of the open cockpit and screen at speed is immense, and the main reason Shelby went Daytona.

TonyD
27-02-08, 10:05 AM
Maybe you could calculate it yourself??? (My brain hurts just lookiing at it)

The Drag Coefficient (http://www.grc.nasa.gov/WWW/K-12/airplane/dragco.html)


Nope couldn't see a Cobra amongst that lot.......

Although the vortex theory helped to explain why an open but full beer bottle when lifted out of the relative calm of the Cobra cockpit and held aloft in the airstream over the top of the widscreen by ones passenger is able to deposit its entire contents in a second or two on the inside of the drivers glasses.

Personally I had put it down to the passenger being a prat. :mrgreen:


( Sending me to a NASA page for Gods sake........last time I saw equations like that I was pretending to understand my daughters maths homework)

Cheers,

Tony

dingocooke
27-02-08, 10:12 AM
aw cummon where your spirit of adventure??? I'll lend you my old tech college slide rule and log tables if you like.....