Performance figures

[steppenwolf]

John,

I think you must have got the Gross Weight (hey that's what my wife calls me! off the Subaru site.

You also raise the interesting question of why does your car accelerate so fast (it does, I've been in it! with such a relatively small amount of torque?

Having read a very good article on Torque V Horsepower (which may be the same article that Ian refers to), torque seemed on the face of it to be what was required for good acceleration but the Megablade flies in the face of this.

I also used to think that power to weight ratio was everything in the 0-60 dash but this is simply not the case and this simple ratio does not automatically resolve which car is faster on this test.

I guess some time, I must get an accelerometer and check the readings in both the Impreza STi and the SpeedSport and see what is really happening. I would have thought that the 'sensation of accelerating quickly' would be exaggerated in the Westfield and dampened in the STi because of the difference of the open cockpit, closeness to the ground and loudness of the exhaust note but perhaps this is not the case at all?

Hmmm ...... I need a nice dry straight road and a friend I can trust not to bend either steed!

[GoWest]

Nobody's mentioned wind resistance!

Though hardly svelt, the scooby (I'm sure) has a lower drag co-efficient, albeit a larger frontal area, than the Westfield. At anything over 60mph this is going to have quite an effect on the performance of each car. Also, as speed doubles, wind resistance quadruples - so (pardon me for saying this) the Westfields achilles heel becomes ever more intrusive at higher speeds.

The Scooby launches off the line because its gearing, torque and spread of torque across available revs allows it to take maximum advantage of the available grip and hang on to second gear past 60. At this point I'm guessing it's at least kept up with a well driven Westie. Then drag becomes very important (try sticking your arm out the side at various speeds if don't believe me) and it pulls past.

That said, Autocar gives figures for the 0-100 sprint for a 128bhp zetec, Seight and FW400 at (about) 34sec, 11sec, 11sec respectively.

But the 0-60's are 6.5sec, 4.3sec, 4.2 (again from memory, but the ballpark's right).

I believe that extreme power or extreme torque both allow phenomenal performance, but they have to be optimally utilised by the gearing.

[ian crocker]

The Subaru has a relatively poor power to weight ratio (compared to the Westy), but however seems to deliver the power in terms of accelerating through the gears.  For example the Subaru Impreza Turbo accelerates considerably quicker than a Honda Type R with a similar power to weight ratio

No it doesn't.  I just did some searches:

2002 WRX 14.9/90 157hp/ton (laden)

2000 Integra R 15.2/93 156hp/ton laden

The figures came from some US sites so the WRX only had 227HP.  However given that the 4WD will be worth around 0.4/0.5 seconds over the first 60ft the 'real' figures are near enough identical.  I browsed a number of sites to get a representative set of figures and not just something that fitted my argument.  These figures also bear out somebody elses assertion that the type R will pass the Impreza a long way down the road (just after the 1/4 mile, and sooner if you don't rev the Impreza to 6000 and just sidestep the clutch).

Of course, the Impreza will be quicker in the gears,but it is a bit like a V8 Westfiled.  Stunning acceleration in 5th, but then you change down and it doesn't go much faster due to the shape of the torque curve.

Ian