Cerbera drag coefficient?
Discussion
chaparral said:
Has anybody ever put a Cerbera in a wind tunnel? I'm trying to calculate the theoretical maximum speed of this car in order to put together an on-paper "top-10 fastest cars under 100k" list.
Out of curiosity, how're you going to calculate this? Taking into account red-line in top gear on a standard box, or assuming it's just force vs. drag, etc?
IIRC the Cerbera is in CarTest:
www.jason.fletcher.net/tech/downloads/cartest.zip
A very useful program. A bit of tweaking with the parameters and I can get it very close to the actual figures (0-60 around 4s, 0-100 around 9s, flat out at about 190).
www.jason.fletcher.net/tech/downloads/cartest.zip
A very useful program. A bit of tweaking with the parameters and I can get it very close to the actual figures (0-60 around 4s, 0-100 around 9s, flat out at about 190).
gazzab said:
Particulary with fat americans weighing them down.
Hey Gazzab, don't knock it:
Those fabulous 5.7 litre engines, made to Detroit standard tolerances, are said to produce almost 154 SAE Hp (130 Bhp). Gee, with power like that, you need the Cd of a Honda Insight. And the C5 (original name, eh, Mr Sinclair?!) is as good lookin' as an Insate too...
I'm gonna chop the roof off, and paint a Stars and Stripes on the hood. With a coupla Jatos I'll beat the Yanks to the next Darwin awards...
Sorry, what was the thread?!
>> Edited by Tam Lin on Thursday 23 October 23:59
>> Edited by Tam Lin on Friday 24th October 00:01
Hey! Our SAE horses are stronger than anyone elses! I'm surprised to see this coming from a TVR fan - how is it that the 4.2 has as much power as a 4.5 on a dyno? Not flame-baiting here, just reminding you of this.
350 horsepower out of 5.7l isn't bad for an engine you can buy for the equivalent of 37p and have it run!
>> Edited by chaparral on Friday 24th October 03:28
350 horsepower out of 5.7l isn't bad for an engine you can buy for the equivalent of 37p and have it run!
>> Edited by chaparral on Friday 24th October 03:28
Good point chaparral
You may find that the cdA figure is more useful in trying to calculate top speeds.
Please post your findings as I would be very interested. People are forever saying that the cerbera is a 190+ or even 200mph+ supercar but to the best of my knowledge no one has got anywhere near these numbers under test conditions.
Rob.
You may find that the cdA figure is more useful in trying to calculate top speeds.
Please post your findings as I would be very interested. People are forever saying that the cerbera is a 190+ or even 200mph+ supercar but to the best of my knowledge no one has got anywhere near these numbers under test conditions.
Rob.
I've done some preliminary calculations using the manufacturer's power figures, and assuming a drag coefficient of .35 and a rolling resistance coefficient of .06, and using the manufacturer's dimensions for frontal area and weight. The results:
Cerbera 4.2 and S6 (350 bhp): 300 km/h (186 mph)
Cerbera 4.5 std. (420 bhp): 330 km/h (205 mph)
Cerbera 4.5 Red Rose (440 bhp: 340 km/h (211 mph)
I've heard that the power figures for the 4.5 are overstated- does anyone have accurate crank or wheel horsepower on these cars?
Cerbera 4.2 and S6 (350 bhp): 300 km/h (186 mph)
Cerbera 4.5 std. (420 bhp): 330 km/h (205 mph)
Cerbera 4.5 Red Rose (440 bhp: 340 km/h (211 mph)
I've heard that the power figures for the 4.5 are overstated- does anyone have accurate crank or wheel horsepower on these cars?
Power figures are overstated. Even so, having checked our power figures against the gearing of a standard 4.5 they are NOT capable of 200mph - although 195 is within reach. Power wise ours is a particularily average 4.5 (standard 17"ers all round).
Worked this out a while back and havent got the figures near me - but I think gearing is limiting it to around 195 (true GPS reading)- the speedo would show a little over 200 at that point
With the right gearing (or right wheels?) im sure a 4.5 Red Rose could crack 200mph - dont think I would want to be in it at that sort of speed though. Not bad for a sports car eh?
Worked this out a while back and havent got the figures near me - but I think gearing is limiting it to around 195 (true GPS reading)- the speedo would show a little over 200 at that point
With the right gearing (or right wheels?) im sure a 4.5 Red Rose could crack 200mph - dont think I would want to be in it at that sort of speed though. Not bad for a sports car eh?
BCA said:
With the right gearing (or right wheels?) im sure a 4.5 Red Rose could crack 200mph - dont think I would want to be in it at that sort of speed though. Not bad for a sports car eh?
Having put 245/40 ZR18s tyres on the rear (whilst switching from 16" wheels), the circumference is up by 3%. Assuming the 17" wheels have the same circumference as 16" ones (albeit with slightly lower profile tyres), and a 4.5 is geared toreach 195, that extra 3% would push it just over 200mph.
Spiders + RR conversion on order asap (when I can afford them, no time soon sadly!!)
The drag co efficient must be under 0.35 thats worse than alot of the older porkers - The Cerbera is a very slippery shape, theres no downforce, but its pretty slippery!!
Im pretty confident most standard Cerberas would crack 190mph real.
The drag co efficient must be under 0.35 thats worse than alot of the older porkers - The Cerbera is a very slippery shape, theres no downforce, but its pretty slippery!!
Im pretty confident most standard Cerberas would crack 190mph real.
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