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Discussion Starter · #1 ·
PLease can someone shed some light on which one of these is best at determining how
quick a car is , when your comparing cars on the road and their figures are printed in
mags ;
Cars Maximum power
Cars Maximum engine torque
Power to weight ratio.

When looking at maximum engine torque the lower the revs to acheive maximum torque,
the more likely it goes like **** off a shovel !!!.
When they print 0 to 60mph figures , EVO mag stated not to many people dump the clutch
at 3500rpm ( do they !! ) on the road , so these figures were unrealistic.
regards Richard
 
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Discussion Starter · #2 ·
Richard

It`s a combination of all three, if you improve any one of these it will increase performance, a lot of the time the answer to your question is which of these can be done / achieved the most cost efficient way.

It mite cost thousands for serious HP/TORQUE gains on some engines but shedding **** loads of weight will give a cheap way to increase the cars performance!

Regards Dave
 
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Discussion Starter · #3 ·
The trouble is there is not just a single point that you can use to match cars together but as a guide I think it is best to look at the power/weight ratio and then the maxium torque and power figures.

A power/weight ratio over 150Bhp/ton is good and usually means sub 8.0 sec 0-60mph runs and sub 18.0 sec 0-100mph runs.
(I know 30mph-50mph or 50mph-70mph are better indicators but nobody prints these in the back of mags!)
After that check to make sure there is not a vast difference between the max power and torque figures.

For example:

Lotus Elise
Power/weight |EQU| 164Bhp/ton
Max Bhp |EQU| 118Bhp
Max Torque |EQU| 122Lbft
Result:
0-60mph in 6.1 secs, 0-100mph 18.5secs.
A prime example of light weight meaning you don't need bucket loads of power. Obviously the low power means its starting to run out of steam towards the top end but still manages a very creditable 126mph top speed.

Honda S2000
Power/weight |EQU| 191Bhp/ton
Max Bhp |EQU| 237Bhp
Max Torque |EQU| 151Lbft
Result:
0-60mph in 5.5 secs, 0-100mph 14.6secs. Even better performance from a NA 2 litre engine. The problem with this is the very low torque compared with the power meaning you have to keep the engine in the power band to get any real performance out of it. Still manages to get to 150mph top speed though.

Evo VI GSR
Power/weight |EQU| 204Bhp/ton
Max Bhp |EQU| 276Bhp
Max Torque |EQU| 274Lbft
Result:
0-60mph in 4.8 secs, 0-100mph 13.5secs. Turbo power means huge lumps of torque so the its pretty effortless to get the performance out of it. Only manages 152mph top speed (140mph according to Evo mag?) but don't forget gearing and drag (Cd) effect the Evo considerably.


Looking through other performance figures it does seem that lightweight is the way to go for super performance. The Audi TT 225bhp for example has exactly the same power to weight ratio as the Lotus Elise listed above but it gets the same figure by being heavier but more powerful. It is 1.5 seconds slower to 100mph than the Elise! Obviously there are quite a few variables in the testing and the cars will have different gearing and Cd etc. but that is a fair difference in performance.

Instead of upping the boost or adding performance exhausts and filters perhaps we should just rip the back seats out, dump the carpets, headlinings........
 
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Discussion Starter · #4 ·
For standing start acceleration , it's power to weight , traction and gearing , see under Dragster for further info.
For other driving it's flexibility of the engine combined with power to weight.

The more the torque and the wider the band of high to maximum torque the faster the car will be on in-gear acceleration for a given power and weight , time over 40 mph increments in a given gear is a good indicator of this.

This is a complex subject though and some other factors , such as aerodynamics , also have an influence , for instance , F1 cars juggle gearing and engine maps like magicians to optimise performance for specific tracks.

One thing I will say though , Evo's are FAST
 
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