BRDC Tech reggs Bulletin
Discussion
I see from this:
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GT Cup Power
The most critical of these is the POWER : WEIGHT ratio for GT CUP cars. This has been changed to 0.22hp/kg measured at the wheels. This figure has been calculated as a rolling road figure comparable to 0.29hp/kg at the flywheel as published in our provisional regulations. Of course this will vary slightly according to front or rear wheel drive, but we are confident that it will not cause any of you undue difficulties
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This just about kill off any chance an Elise (or any other light car) has in the Cup class.
on this basis, at min of 750Kg's, the max power you can run is 165Bhp...
Mobile chicane anyone?
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GT Cup Power
The most critical of these is the POWER : WEIGHT ratio for GT CUP cars. This has been changed to 0.22hp/kg measured at the wheels. This figure has been calculated as a rolling road figure comparable to 0.29hp/kg at the flywheel as published in our provisional regulations. Of course this will vary slightly according to front or rear wheel drive, but we are confident that it will not cause any of you undue difficulties
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This just about kill off any chance an Elise (or any other light car) has in the Cup class.
on this basis, at min of 750Kg's, the max power you can run is 165Bhp...
Mobile chicane anyone?
It's 217.5bhp at the flywheel, then, which I realise isn't much, but the 1000kg Porsches will be running under 300, so it's not all bad.
The Elise we had in the Championship a couple of years ago was up against 440bhp Porsches, which was really silly.
Edited because it sounded like it was my Elise, which it wasn't.
>> Edited by ahonen on Friday 14th February 13:06
The Elise we had in the Championship a couple of years ago was up against 440bhp Porsches, which was really silly.
Edited because it sounded like it was my Elise, which it wasn't.
>> Edited by ahonen on Friday 14th February 13:06
Maybe I don't understand (likely) but wouldnt an Elise with 0.22bhp/kg be better off than a Porker with 0.22bhp/kg as it is designed for light weight lower power. (The Porker would have to drop more power than an Elise).
Is it the speed advantage on the faster straights that will still give the Porker the advantage?
>> Edited by mogin on Friday 14th February 17:05
Is it the speed advantage on the faster straights that will still give the Porker the advantage?
>> Edited by mogin on Friday 14th February 17:05
Yes, you're right. The Elise would just run out of steam. It's an aero thing at the higher speeds - power requred to overcome drag. Though of course the lighter cars have shorter braking distances and, providing they aren't hamstrung by really narrow tyres, the potential to be much quicker around the corners.
I haven't read the Cup rules as closely as I'd like, so I don't know what the tyre allowance is, but I think a lightweight car has best ever chance in GTs this season - just look how fast Caterham Superlights are with the same power. Okay, they are really light, but they also have brick-like aerodynamics and a small contact patch.
Does anyone know what the lap times of the now-defucnt Elise Sport Cup cars were?
I haven't read the Cup rules as closely as I'd like, so I don't know what the tyre allowance is, but I think a lightweight car has best ever chance in GTs this season - just look how fast Caterham Superlights are with the same power. Okay, they are really light, but they also have brick-like aerodynamics and a small contact patch.
Does anyone know what the lap times of the now-defucnt Elise Sport Cup cars were?
Yes,
Look at:
www.users.globalnet.co.uk/~scuffham/Silver2.pdf
and then:
www.users.globalnet.co.uk/~scuffham/22203por.pdf
This gives a 2.3 sec's a lap difference (2.5 if you compaire Mark cole with himself)
Problem with this is that they were both on 'control tyres' so it's hard to say what they would both be doing on 'competative' rubber, (and whist we are on that subject, Dunlop tyres for an Elise is a whole new learning curve!)
Big problem with power the wieght comparisons is that it takes zero account for aero drag (as has been mentioned), even if the Lotus can stop quicker, it's not going to make up for the 15+Mph difference in straight line speed.
Also,
"It's 217.5bhp at the flywheel, then, which I realise isn't much, but the 1000kg Porsches will be running under 300, so it's not all bad."
Err - no it's not, that would assume a level of losses for the transsmission of some 24+%, that's riddiculusly high (for an Elise) the real figure is ~12% (before you get onto specalist geabox stuff), so this leaves you with ~188Bhp (some what down on what the Single serise cars were running).
Simon
>> Edited by scuffham on Saturday 15th February 11:07
>> Edited by scuffham on Saturday 15th February 11:17
Look at:
www.users.globalnet.co.uk/~scuffham/Silver2.pdf
and then:
www.users.globalnet.co.uk/~scuffham/22203por.pdf
This gives a 2.3 sec's a lap difference (2.5 if you compaire Mark cole with himself)
Problem with this is that they were both on 'control tyres' so it's hard to say what they would both be doing on 'competative' rubber, (and whist we are on that subject, Dunlop tyres for an Elise is a whole new learning curve!)
Big problem with power the wieght comparisons is that it takes zero account for aero drag (as has been mentioned), even if the Lotus can stop quicker, it's not going to make up for the 15+Mph difference in straight line speed.
Also,
"It's 217.5bhp at the flywheel, then, which I realise isn't much, but the 1000kg Porsches will be running under 300, so it's not all bad."
Err - no it's not, that would assume a level of losses for the transsmission of some 24+%, that's riddiculusly high (for an Elise) the real figure is ~12% (before you get onto specalist geabox stuff), so this leaves you with ~188Bhp (some what down on what the Single serise cars were running).
Simon
>> Edited by scuffham on Saturday 15th February 11:07
>> Edited by scuffham on Saturday 15th February 11:17
Look like the goalposts are moving....
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TECHNICAL BULLETIN NUMBER 2
GT CUP CLASS
Please note a further change to the power : weight ratio for the GT Cup Class.
The figure will be 0.24hp/kg measured at the driving wheels.
We believe that this will represent a closer equivalent figure in relation to the original flywheel power figure.
Please note the following clarification in relation to the weight of the GT Cup car:
The minimum weight of the vehicle WITHOUT driver or fuel shall be 750kg.
The weight from which the power ratio test will be calculated shall be the finishing weight of the car, PLUS the average weight of the 2 drivers, LESS fuel.
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So, on this basis, if the min the car can be is 750Kg's, and we assume an average driver weight of 75Kg's, leaves us with 825Kg's = 198Bhp@the wheels
Assuming 15% drivetrain losses = 233Bhp at engine.
This is starting to look more realistic.
Simon (S)
---------------------------------------------
TECHNICAL BULLETIN NUMBER 2
GT CUP CLASS
Please note a further change to the power : weight ratio for the GT Cup Class.
The figure will be 0.24hp/kg measured at the driving wheels.
We believe that this will represent a closer equivalent figure in relation to the original flywheel power figure.
Please note the following clarification in relation to the weight of the GT Cup car:
The minimum weight of the vehicle WITHOUT driver or fuel shall be 750kg.
The weight from which the power ratio test will be calculated shall be the finishing weight of the car, PLUS the average weight of the 2 drivers, LESS fuel.
---------------------------------------------
So, on this basis, if the min the car can be is 750Kg's, and we assume an average driver weight of 75Kg's, leaves us with 825Kg's = 198Bhp@the wheels
Assuming 15% drivetrain losses = 233Bhp at engine.
This is starting to look more realistic.
Simon (S)
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