Another interesting find - BHP performance calculator

It's a crock of s*it.

"Power at Flywheel (BHP) : 100 Weight without Driver (KG) : 1072 Power to Weight Ratio (BHP Per Ton) : 94.78 Invalid Entry : Power to Weight Ratio must be between 95 and 1300 BHP/Ton"

Hmm well, it worked to within a fractionth of a second for the cars I have.

Adjust the weight down a little bit then just for interests sake.

It just doesn't like low powered cars - but then, who does :)

Seems ok to me, certainly as good as you could expect from mathematical guesswork. Assuming a lardy 1550 kilos for the 4x4 running gear I get this;

Power at Flywheel (BHP) : 276 Weight without Driver (KG) : 1550 Power to Weight Ratio (BHP Per Ton) : 180.92 0 - 60 (Secs) : 5.55 0 - 100 (Secs) : 14.97 Quarter Mile (Secs) : 14.27

A run of the TI stats seems fairly accurate too;

Power at Flywheel (BHP) : 197 Weight without Driver (KG) : 1350 0 - 60 (Secs) : 7.21 0 - 100 (Secs) : 18.97 Quarter Mile (Secs) : 15.62

Isn't that just the official figure, though?

Yup, 280PS / 276BHP.

To be perfectly honest, I know it's a Scoob and all that and at the risk of being controversial I don't actually rate them 'off the line' without a huge amount of revs and a hammer foot, which I have no inclination to do (and why I sparked the initial comments off regarding the WRX performance figures). I suspect this is largely due to the inherent problems of the twin turbo setup though, which is a bit ham-fisted and pretty much fails to achieve every major goal in its design brief.

Lordy? Controversial? Surely not! Whatever next?

To a degree that's the all wheel drive aspect combined with the twin turbo-ness. Unless you use the limiter-step-off-clutch technique, they get bogged down very easily. Okay okay at least the Impreza does.

It feels mechanically very unsympathetic. And indeed it is!

I think that's a bit strong. It does produce lots of power. It is easy to tune. Once the move I expect it's stupidly rapid.

Does it shower its internals with petrol to keep everything cool, i.e. have an enormous thirst? :-)

Oh the premise is sound - two turbos; one spooling up at low boost=20 providing low down power, the other kicking in at high boost to provide=20 jollies.

The problem is in its implementation - the second turbo is closed off by=20 an ECU controlled valve which doesn't open until after 4,000 revs. So -=20 when you floor it - after a short period the ECU decides to open the=20 exhaust valve and bring the second turbo to the party. All well and=20 good. Unfortunately both turbos are fed off the same intake so my=20 understanding of what happens is that all the air that is currently=20 feeding the first turbo suddenly finds it has an extra length of pipe=20 open to it and loads of room to move about, disrupting the first turbo=20 and resulting in a flat spot whilst the second spools up.

So basically you don't end up with a smooth acceleration curve, it=20 launches, pauses at 4,000, then goes ballistic at 5,000. No-one has ever=20 managed to successfully eliminate this, even with aftermarket ECU=20 upgrades. The first turbo isn't as strong as a T25 either, so in normal=20 use it isn't as flexible as a TI for instance.

Another effect of this is that when you are running on a feathered=20 throttle getting ready to overtake, if you back off the pedal and the=20 revs drop slightly the valve snaps shut and the car gives a kangaroo=20 kick (That's what I meant about them being a bit of a pig to drive, it's=20 not a 'waft around on a wave of torque' kind of car, you have to pick it=20 up by the scruff of the neck and throw it down the road). However, I have found that 99 Ron fuel has had an astonishing effect on=20 this. With normal 97 super the Valley of Death (as it's called) was well=20 over a second. On 99 it's reduced it to something like a quarter of a=20 second under full throttle. It's made the car *so* much more fun to=20 drive and a lot more flexible, especially on the first turbo.

It's astonishing bad, even on light use - which again makes a mockery of=20 using a small initial turbo to keep fuel costs down. Put it this way, I=20 reckon on one trip I used =A350 to travel about 200 miles. And that was=20 mostly motorway without dipping into triple digit speeds.

I've not actually taken any proper readings other than keeping an eye on=20 the odo, but in the TI I reckoned I was averaging 17 mpg on hard use. In=20 this I reckon I'm averaging 17mpg on light use. Again that does seem to=20 have improved on 99 but I haven't driven much over the last week or so=20 so can't really guage it well yet.

--=20 Lordy.UK

It's a known diff killer on WRX.

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

Well he set limits so it won't work for cars that don't have any performance to speak of. Your is very close at 94.78bhp/ton. Get an induction kit or take the spare seats / wheel out.

Power at Flywheel (BHP) : 100 Weight without Driver (KG) : 1069 Power to Weight Ratio (BHP Per Ton) : 95.05

It's based on analysis of reported data. Given a data set you can interpolate but have to be very careful when extrapolating. Cars that fall outside his data set are correctly excluded. 95bhp/ton is very arbitrary I'd have set the limit at 100bhp/tonne. Or a bit higher as one TV road testing of the Hyundai V6 Coupe described it as "adequate". Ergo anything less is inadequate.

Power at Flywheel (BHP) : 165 Weight without Driver (KG) : 1424 Power to Weight Ratio (BHP Per Ton) : 117.73

They clearly set low standards for an "adequate" sports coupe, personally about 140bhp/ton giving a sub 7.5sec 0-60 and under 16sec

Power at Flywheel (BHP) : 170 Weight without Driver (KG) : 1190 Power to Weight Ratio (BHP Per Ton) : 145.15

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!