How relevant is BHP per tonne

Power to weight is probably the most relevant factor for performance.

The fastest car I've driven had around 80bhp, but my daily driver has 192.

The fast car had about 300 bhp/ton and my daily driver only has about 135.
 
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BigglesPiP said:
Power to weight is probably the most relevant factor for performance.

The fastest car I've driven had around 80bhp, but my daily driver has 192.

The fast car had about 300 bhp/ton and my fail driver only has about 135.
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what was the 300bhp/ton car? at 80bhp it musta weighed ~260kg, I know humans that weigh half of that lol, was it like an atom or a lotus 7 or something?
 
I find BHP per tonne, although theoretically fine, real world prooves different.

My GFs Suzuki Swift Sport has a bhp/t of 113.6 given 125bhp @ 1.1tonnes

My 530d is what? 1800Kgs, so 235/1.8 = 130bhp per tonne. Yet there is worlds apart in performance, the Swift would never stand a chance. Can 17bhp per tonne really make that much difference?
 
BHP/Ton does tell the majority of the story except for top speed, just look at bikes where anything with about 60bhp is capable of a modest 130mph top end but a monster 3-4s 0-60. Even then despite the horendous aerodynamics of a bike you need far more power in a car to reach that top end due to far more drive loss despite the better aero.
 
Lucero said:
I find BHP per tonne, although theoretically fine, real world prooves different.

My GFs Suzuki Swift Sport has a bhp/t of 113.6 given 125bhp @ 1.1tonnes

My 530d is what? 1800Kgs, so 235/1.8 = 130bhp per tonne. Yet there is worlds apart in performance, the Swift would never stand a chance. Can 17bhp per tonne really make that much difference?
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If you are going to calculate it on the back of a fag packet, sure, it's not great.

However:

Swift: 125 HP, 1105 KG = 113 HP/ton
530d: 235 HP, 1580 KG = 149 HP/ton

So, your 530d has a 32% greater power-weight ratio. I bet in the 0-60 dash, if you could eliminate the FWD vs. RWD difference, that would translate about right.
 
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robskinner said:
At normal road speeds then you can pretty much eliminate air resistance and pretty much most things that are outside effects like tyres etc.
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Air resistance is surprisingly high at "normal road speeds", and this is were power/weight falls down. A very lightweight car with modest engine power and poor aerodynamics (e.g. an original Lotus 7) will be disadvantaged even at "normal road speeds", compared to a heavy car with similar power/weight.

robskinner said:
Old motorsport saying "BHP sells cars, Torque wins races".
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Old motorsport saying is a load of crap!
 
Hi there

For me I'd want the Merc in a straight line race, especially run rolling where 90% of the time you'd feel the benefits.

For me BHP, Engine Displacement and lets not forget torque is what effect acceleration plus rolling. Another major factor is aero-dynamics.

An example would be a Corvette C6 (1450kg) against a tuned EVO 9 (1450kg) so both running circa 400BHP.

Only difference is once moving the Corvette is gonna walk away from the EVO even though they have similar power?

Reasons are:-
1. More power getting to the tarmec
2. Corvette is very very slippery (aero-dynamics)
3. Engine displacement!

When I drove a Z06 I was shocked how bloody quick it accelerated into three figures, was mind bending the acceleration, made the Mustang feel slow into 3 figures, thats how fast it was. Yet the Mustang had more power, for me what made the Vette faster was mainly its slippyness compared to the Mustang brick like design. Then it had displacement, a whole 7.0l of goodness. :D

However when racing off the mark, then lightweight, traction all come into play but for real world usage give me BHP, Torque and engine displacement every time, unless its a racetrack, then lightweight all the way.
 
Gibbo said:
Hi there

For me I'd want the Merc in a straight line race, especially run rolling where 90% of the time you'd feel the benefits.

For me BHP, Engine Displacement and lets not forget torque is what effect acceleration plus rolling. Another major factor is aero-dynamics.

An example would be a Corvette C6 (1450kg) against a tuned EVO 9 (1450kg) so both running circa 400BHP.

Only difference is once moving the Corvette is gonna walk away from the EVO even though they have similar power?

Reasons are:-
1. More power getting to the tarmec
2. Corvette is very very slippery (aero-dynamics)
3. Engine displacement!

When I drove a Z06 I was shocked how bloody quick it accelerated into three figures, was mind bending the acceleration, made the Mustang feel slow into 3 figures, thats how fast it was. Yet the Mustang had more power, for me what made the Vette faster was mainly its slippyness compared to the Mustang brick like design. Then it had displacement, a whole 7.0l of goodness. :D

However when racing off the mark, then lightweight, traction all come into play but for real world usage give me BHP, Torque and engine displacement every time, unless its a racetrack, then lightweight all the way.
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A 'Vette should be your next car Andy. It really should.
 
DogsBody said:
Yeh the maclaren was waaaaaay quicker off the line, the veyron only caught up when the speeds got up into the higher figures.
It took the veyron a lot longer to pass the F1 than I thought it would.
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The Veryon didn't get a good start compared to the F1, because they didn't use launch control, and the race was bascially in 50C heat, and the Turbo's aren't as efficient in that kind of heat. The F1 is N/A so not a problem.

The Veryon is 2.5 to 60, the F1 is 3.2 at least. A veryon would never loose to a F1 im afraid.
 
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