How fast is a quick mini?
Discussion
Hi,
Strange question....
What sort of performance stats would you expect from a quick but roadable A-series powered naturally aspirated mini? In other words, whats the quickest you could get without spending mega bucks?
I have to confess this isn't strictly mini related. I'm looking at buying a GTM coupe which weighs about the same as a real mini and has an A-series in, yet to my astonishment they're only said to be as quick as an X1/9. Surely with a tweaked 1380 you'd be looking at fairly reasonable performance?
CP
Strange question....
What sort of performance stats would you expect from a quick but roadable A-series powered naturally aspirated mini? In other words, whats the quickest you could get without spending mega bucks?
I have to confess this isn't strictly mini related. I'm looking at buying a GTM coupe which weighs about the same as a real mini and has an A-series in, yet to my astonishment they're only said to be as quick as an X1/9. Surely with a tweaked 1380 you'd be looking at fairly reasonable performance?
CP
Chris71 said:
Any idea what'd be realistic for 100mph gearing?
0-60 in 6.5 secs?
0-60 in 6.5 secs?
was thinking about this earlier, trying to remember cars my brothers could thrash as a datum. I'd say 7 to 8 would be a reasonable guess at what his would do - but it is just that, a guess! could be 6, could be 9
GTM Coupe recommends to turn down and de-rate the front cones to soften the suspension as it uses a Mini front sub minus the engine in the front (albeit with the fuel tank neatly sat in the hole). Weight distribution is biased rearward and the thing handles like a genuine mid engined car (i.e lose it and it is gone!!!).
My Brother had GTM Coupe with a Mild tuned 1275cc and 3.44 final drive. It was very quick up to about 110 and could easily have pulled longer gearing (on 12" wheels). With a 1380cc motor you'll pull well over 120-125 due to the reduced frontal area compared to a Mini.
Comparison to a Fiat X19 - Wouldn't even have seen in which direction the GTM had gone. Bl88dy blasphemous.
1380cc - Decent head (1.4" inlets) - Swiftune Sw5 Cam (torque) - 3.2 final drive - 5x13" Rims (Cause a GTM looks bloomin' great on them)mmmmmmmmm. Bruv's car got rear ended by a dozzy bugger on his mobile.... it was standing still and the chappie was doing 30mph. The rear spaceframe structure was very solid and stood up very well to the impact. The whole thing is a metal tub from memory with high thick sill sections.
My Brother had GTM Coupe with a Mild tuned 1275cc and 3.44 final drive. It was very quick up to about 110 and could easily have pulled longer gearing (on 12" wheels). With a 1380cc motor you'll pull well over 120-125 due to the reduced frontal area compared to a Mini.
Comparison to a Fiat X19 - Wouldn't even have seen in which direction the GTM had gone. Bl88dy blasphemous.
1380cc - Decent head (1.4" inlets) - Swiftune Sw5 Cam (torque) - 3.2 final drive - 5x13" Rims (Cause a GTM looks bloomin' great on them)mmmmmmmmm. Bruv's car got rear ended by a dozzy bugger on his mobile.... it was standing still and the chappie was doing 30mph. The rear spaceframe structure was very solid and stood up very well to the impact. The whole thing is a metal tub from memory with high thick sill sections. Edited by fwdracer on Tuesday 17th October 16:48
With an 'A-series' engine the maximum for any sort of reliability is around 100 bhp. The aerodynamics will always prevent high maximum speed and ultimate acceleration is limited by wheel spin.
Thus, the realistic optimum performance will probably be something like 0-60 in c.8.5 seconds and a max speed of 105 mph. That would be with a diff ratio of,maybe 3.44 or 3.76.
To go to higher power will just bring on the legendary unreliability, although if you accept that you could bring those figures down/up a bit, but not by much really. Remember, aerodynamic drag increases as the square of the speed. So, if you double the speed you quadruple the drag and hence the power required to achieve this. To best illustrate this, if a 30 bhp Mini will do 70, to do 140 would require 120 bhp. It's not quite as straightforward as this, as to do the 140 would mean the same gearing, i.e. a 3.76 diff, and then you'd need to pull c.10,000 rpm. To change the gearing to a higher ratio would then mean not comparing the true drag/speed/engine characteristic (the torque curve, for ecxample).
It's a complicated area.
Thus, the realistic optimum performance will probably be something like 0-60 in c.8.5 seconds and a max speed of 105 mph. That would be with a diff ratio of,maybe 3.44 or 3.76.
To go to higher power will just bring on the legendary unreliability, although if you accept that you could bring those figures down/up a bit, but not by much really. Remember, aerodynamic drag increases as the square of the speed. So, if you double the speed you quadruple the drag and hence the power required to achieve this. To best illustrate this, if a 30 bhp Mini will do 70, to do 140 would require 120 bhp. It's not quite as straightforward as this, as to do the 140 would mean the same gearing, i.e. a 3.76 diff, and then you'd need to pull c.10,000 rpm. To change the gearing to a higher ratio would then mean not comparing the true drag/speed/engine characteristic (the torque curve, for ecxample).
It's a complicated area.
cooperman said:
Remember, aerodynamic drag increases as the square of the speed. So, if you double the speed you quadruple the drag and hence the power required to achieve this. To best illustrate this, if a 30 bhp Mini will do 70, to do 140 would require 120 bhp.
Strictly speaking the drag relationship is speed cubed not speed squared. Double the speed requires eight times the power to overcome aerodynamic drag.
It must have changed since my days as an aeronautical engineering student then. When I graduated the relationship was that 'Aerodynamic drag increases as the square of the true airspeed'.
With automotive applications there are certain variables which do have a direct and an indirect effect on that relationship. These include ground effect, distortion due to airflow disturbances, shape, etc, but I used the basic formula as an illustration.
The popular misconception is that if you have, say, 50% more power, then you'll go 50% faster at maximum. A graph of x=y squared will easily show the error of this, taken in its simplest form.
In the case of the Mini, it is likely that the disturbed airflow off the back of the vehicle at the higher end of its speed range will have a major negative influence on the drag/speed relationship. With the square basic shape, no amount of rear aero-d aids will help much, if at all. Also the airflow across the roof will not be as smooth as that on more modern cars with a much more sympathetic screen to roof panel shape.
It's certainly a very complicated and technical area.
With automotive applications there are certain variables which do have a direct and an indirect effect on that relationship. These include ground effect, distortion due to airflow disturbances, shape, etc, but I used the basic formula as an illustration.
The popular misconception is that if you have, say, 50% more power, then you'll go 50% faster at maximum. A graph of x=y squared will easily show the error of this, taken in its simplest form.
In the case of the Mini, it is likely that the disturbed airflow off the back of the vehicle at the higher end of its speed range will have a major negative influence on the drag/speed relationship. With the square basic shape, no amount of rear aero-d aids will help much, if at all. Also the airflow across the roof will not be as smooth as that on more modern cars with a much more sympathetic screen to roof panel shape.
It's certainly a very complicated and technical area.
GreenV8S said:
cooperman said:
Remember, aerodynamic drag increases as the square of the speed. So, if you double the speed you quadruple the drag and hence the power required to achieve this. To best illustrate this, if a 30 bhp Mini will do 70, to do 140 would require 120 bhp.
Strictly speaking the drag relationship is speed cubed not speed squared. Double the speed requires eight times the power to overcome aerodynamic drag.
The drag relationship is squared, hence you need four times the torque at the wheels to get twice the speed. However, as this will also be at double the RPM, the power requirements are actualy cubed.
It's so much simpler with aeroplanes where to get, say, a 30% increase in top speed you need 1.3 x 1.3 = 1.69 times the power.
so, if 800 bhp gives you 300 mph, to go to 390 mph will require 1352 mph. The gearing is taken care of with the CSU (Constant Speed Unit)
If you look at the performance increases for the Supermarine Spitfire, probably the most-developed aeroplane ever, this ties in very nicely, although the increase in MGW does have some effect as well, since the wing-loading increases too.
Too b****y complicated - I think I'll buy a book!!
(Cooperman retires to bed with a sick headache!)
so, if 800 bhp gives you 300 mph, to go to 390 mph will require 1352 mph. The gearing is taken care of with the CSU (Constant Speed Unit)
If you look at the performance increases for the Supermarine Spitfire, probably the most-developed aeroplane ever, this ties in very nicely, although the increase in MGW does have some effect as well, since the wing-loading increases too.
Too b****y complicated - I think I'll buy a book!!
(Cooperman retires to bed with a sick headache!)
pete
just go and buy a copy of max power.
a set of plug leads will give you 10 bhp.
changing the oil will give you 6 bhp
fitting a air filter will give you 15 bhp
before you know it youve doubled the power of you car, then you need to buy a big spoiler, to stop it taking off...
...innit...........
just go and buy a copy of max power.
a set of plug leads will give you 10 bhp.
changing the oil will give you 6 bhp
fitting a air filter will give you 15 bhp
before you know it youve doubled the power of you car, then you need to buy a big spoiler, to stop it taking off...
...innit...........
I used to have one with about 90bhp, not that quick in a straight line but the handling and grip in the dry was fantastic. i had friends with a 205 gti and a golf gti and they couldn't even get close down a twisty road. It had coil-over front suspension, a quick rack and extended negative camber bottom suspension arms, the seat mountings all broke because of the cornering forces.
ive got a coupe jammed in my garage, and found the gtm lot to be most un-helpfull, their normal method of helping was to either rubbish the car so much that i started to think it wasnt worth bothering, then they would either offer to buy it cheap, or just buy the screen! (which are very rare and expensive). i do wonder if this a tatic employed to ensure the price of them remains low??
after i had remade all the floor and cross members i got bored with it and its sat for years.
shame really as its a really pretty little thing, but im just not prepared to let it go for 100 quid - id rather scrap it.
after i had remade all the floor and cross members i got bored with it and its sat for years.
shame really as its a really pretty little thing, but im just not prepared to let it go for 100 quid - id rather scrap it.
GURU_1071 said:
they would either offer to buy it cheap, or just buy the screen! (which are very rare and expensive). i do wonder if this a tatic employed to ensure the price of them remains low??
Surely not??
Hmm, either way I think I'm more inclined to go for a K3. The question is would it send me in to the hedge? Everyone says 'with relatively little power and the engine in the back, all you'll get is unstopable lift off oversteer'
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