200mph - Is it possible in theory?
Discussion
OK, this should provoke an interesting thread 
Is it theoretically possible to get a 6.0 VXR to be able to achieve 200mph? I am having a bit of an argument with a friend of mine and I am not convinced it is possible within reason (ie not strapping 6 Jet engines on the back!).
If I knew how to calculate theoretical maximum speeds using gear ratio's then I would be part of the way there but alas I haven't a clue on the calculations
With the current top speed in the region of 180mph it would need to be increased by 11.1% which does not sound that much, however, the wind resistance at that speed would be huge.
>> Edited by GSI_Daz on Wednesday 17th May 12:51
Is it theoretically possible to get a 6.0 VXR to be able to achieve 200mph? I am having a bit of an argument with a friend of mine and I am not convinced it is possible within reason (ie not strapping 6 Jet engines on the back!).
If I knew how to calculate theoretical maximum speeds using gear ratio's then I would be part of the way there but alas I haven't a clue on the calculations
With the current top speed in the region of 180mph it would need to be increased by 11.1% which does not sound that much, however, the wind resistance at that speed would be huge.
>> Edited by GSI_Daz on Wednesday 17th May 12:51
my monaro does 40 mph roughly at 1000 RPM
so 200 = 5000 RPM
so gearing not a problem
the idea is to find out what the top speed is with the power you have ie if 300 bhp = 150 mph then resistance increases with the square of the velocity so 200 / 150 = 1.3333333
1.333333 squared = 1.77777777778
1.777777777779 * 300 = 533 bhp
now these are just rough calculations and there are some factors you have to take into account
the 200 mph point and max power of the engine may not be at the same point
you have to put down that amount of power at a long time to acheive this this leaves no spare power for acceleration
this is a lot of power to put through the rear wheels this generates heat
more grip is needed to handle all this force through the back wheels which genetrates more drag
hope this helps but 900 bhp should do it
so 200 = 5000 RPM
so gearing not a problem
the idea is to find out what the top speed is with the power you have ie if 300 bhp = 150 mph then resistance increases with the square of the velocity so 200 / 150 = 1.3333333
1.333333 squared = 1.77777777778
1.777777777779 * 300 = 533 bhp
now these are just rough calculations and there are some factors you have to take into account
the 200 mph point and max power of the engine may not be at the same point
you have to put down that amount of power at a long time to acheive this this leaves no spare power for acceleration
this is a lot of power to put through the rear wheels this generates heat
more grip is needed to handle all this force through the back wheels which genetrates more drag
hope this helps but 900 bhp should do it
don't know how accurate the figure can be taken to be but Dave52's car registered 180mph on a rolling road with room to spare and that was a 410bhp modded base Monaro with the 5.7l engine. I'm sure given a long enough straight stretch of road there will be a few owners on here that could achieve 200 or very close to it. Of course the really fun bit would be to see what the mpg figure was at that speed 
Power required goes up with speed cubed, so increasing the speed from 180 to 200 mph would require about 40% more power. If you're trying to do this in the real world you are probably trying to get the maximum peak speed within a finite distance rather than comparing terminal velocity, this is a much harder nut to crack and would potentially need a lot more than 40% extra power.
GSI_Daz said:
With the current top speed in the region of 180mph it would need to be increased by 11.1% which does not sound that much, however, the wind resistance at that speed would be huge.
>> Edited by GSI_Daz on Wednesday 17th May 12:51
There is something you need to look into with this & thats the 'square of airspeed'. It works VERY basically like this:- 10 men can pull a 100lb weight at 1 mph but it would take 30 men (not 20!) to pull the same weight at 2 mph! The effect of not only drag, but also pressure build up at the front of the car is also doing it's thing! I've heard it said that you need an another 100bhp to give you an extra 20 mph, over 180! Don't quote me on that last bit, but thats the idea anyway! I know Brian said that his car (now mine) was on the dyno & he saw 180 mph on the clock....no wind resistance & no drag either!
Paul.H.
Tell you what - I'll read ALL the reply's first before trying to be a smart arse!!!! lol
>> Edited by Paul.H. on Wednesday 17th May 15:19
Well_Fans said:
don't know how accurate the figure can be taken to be but Dave52's car registered 180mph on a rolling road with room to spare and that was a 410bhp modded base Monaro with the 5.7l engine. I'm sure given a long enough straight stretch of road there will be a few owners on here that could achieve 200 or very close to it. Of course the really fun bit would be to see what the mpg figure was at that speed
so if you strapped a caravan to the back and continued testing it would also do 180mph?
rolling road top speeds are therefore largely irrelevant.
a monaro is relatively slippery shape, my old 456 did a supposed 194mph with 450bhp so I would guess a Monaro would need somewhere between 500 and 550bhp to crack 200.
Bennno
there was power left to use but the operator bottled out when it hit 180mph - the caravan comment is completely irrelevant. If anything from what I've read the speed as measured by a rolling road is more accurate than the speedo in most vehicles. The rolling road though is a false environment - no aero drag and consistent "road" ie roller surface - conditions you wouldnt achieve on any stretch of tarmac. I would go along with your estimate though of 500-550 bhp to approach the 200mph figure.
Speed measured on a rolling road is completely useless.
You may as well jack the car up in the air, and put it in top gear, and floor it....
You would probably achieve a theoretical top speed in excess of 250mph, as top gear has a pretty big overdrive.
Not a chance in hell will you ever do that on the road, certainly not one with any air there.
I would highly doubt a Monaro would achieve 200+ with only 500bhp. Even with an endless road, I doubt it would happen.
I'd say you would need closer to 650+ to achieve 200mph+ within a reasonable stretch of road.
It might also be worth checking the propshaft is capable of spinning fast enough safely for that speed.
You may as well jack the car up in the air, and put it in top gear, and floor it....
You would probably achieve a theoretical top speed in excess of 250mph, as top gear has a pretty big overdrive.
Not a chance in hell will you ever do that on the road, certainly not one with any air there.
I would highly doubt a Monaro would achieve 200+ with only 500bhp. Even with an endless road, I doubt it would happen.
I'd say you would need closer to 650+ to achieve 200mph+ within a reasonable stretch of road.
It might also be worth checking the propshaft is capable of spinning fast enough safely for that speed.
In Europe I have seen 'over 200mph' on my Stack Unit. The speedo was reading around 220 but swinging wildly. On my way to the Nurburgring in July, all being well, I intend to 'go as fast as safely possible' on the same stretch of road and get a speed printout / video the reading. I didn't before as frankly had no intention of trying it but decided to have a go as it was accelerating like a plane taking off That was with circa 650 English BHP (with the NOS install I still have), I now have another 100 BHP thanks to Monkfish Will be interesting to see what blows / falls off LOL!
That was with circa 650 English BHP (with the NOS install I still have), I now have another 100 BHP thanks to Monkfish Will be interesting to see what blows / falls off LOL!Well_Fans said:
250bhp over a 6.0 VXR to gain the extra 30mph or so over Vauxhalls claimed top speed seems a bit steep.
Aerodynamics...
Ive been to several events were cars do top speed runs ( admittedly over s relatively short distance ). You would get your eyes opened at how incapable some supposedly fast and powerful cars are at actually achieving high top speeds, in real life, with proper speed measurement equipment.
Think about how many genuine 200+ cars there are out there, and you will start to see that it isnt easy.
My father in law has a 550hp AM V8 and it was tested to 191mph on the Michelin test track at Ladoux - don't know if it was restricted by space/aeros etc. But they do not think it will go much faster in terms of VMAX - car weighs 1920Kg - so heavier than Monaro
Standing Km in 13 secs at 155mph gives an idea of how much room you need for a run I guess. Intersting bit would be time and distance between 155 and 191.
Don't know how long Top Gear runway is but the Z06 went from standing to 175 all in 5th gear and they had to bail before reaching top speed in 5th.
And that is a 500hp car that weighs less than than our cars and has race prepared aero package.
Any one got HSV/Monaro equivalents?
Kev(Tiler) may be able to offer a view on top speeds of Monaros......
Standing Km in 13 secs at 155mph gives an idea of how much room you need for a run I guess. Intersting bit would be time and distance between 155 and 191.
Don't know how long Top Gear runway is but the Z06 went from standing to 175 all in 5th gear and they had to bail before reaching top speed in 5th.
And that is a 500hp car that weighs less than than our cars and has race prepared aero package.
Any one got HSV/Monaro equivalents?
Kev(Tiler) may be able to offer a view on top speeds of Monaros......
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