Quicksilver!

Wringing 100 bhp per litre from a production-line car would once have seemed an absurd target, incurring all sorts of unreliability and intractability. But that figure is exactly what a limited-edition version of the impressive Porsche 944 Turbo now achieves. For £36,900 the standard Turbo offers 220 bhp; the newest variant, called the SE (for Sport Equipment) jumps to 250 bhp from its blown 2.5-litre four-cylinder engine, and gets a package of handling and equipment additions which together pitch the car up to £41,249, well over the cost of the cheapest 911, the Club Sport.

Most of these extras are already available from the options list, but the one which is not, and which really sets the SE apart, is the more powerful engine developed from the specification used in the Porsche 944 Turbo Cup race series which has been a feature at continental race circuits over last season.

A race engine on the road may sound dubious, but the engine changes are anything but radical; maximum boost pressure goes up to 0.82-bar (11.9 psi) and the electronic rev limiter is tweaked another 500 rpm to 6500. These small “black-box” adjustments provide an extra 30 bhp, and a smaller gain of 15 lb ft of torque which also now peaks 500 rpm higher at 4000. This slices over half a second from the 0-60 mph time, down to 5.5 seconds, and pushes top speed towards 160 mph. Otherwise the specification is as before, the KKK turbocharger feeding through a large air-to-air intercooler behind the main radiator, with a knock-sensor to retard the ignition or reduce the boost if any pinking is detected.

Heat problems, always a special risk in turbo engines, have been carefully attended to: sodium-filled exhaust valves are fitted, and the turbo casing carries a water-cooling system for the bearings which continues to operate after the engine has been turned off. The turbo itself is mounted on the cooler intake side of the block so as to avoid picking up extra heat from the exhaust manifold, at the cost of increasing the length of the pipe run which feeds it.

Digesting the power is a rear-mounted transaxle which in SE form includes a limited-slip differential. Unlike Alfa Romeo’s transaxle, Porsche’s clutch is on the engine end of the prop-shaft, which may help to explain the quicker action of the change. it is not light, but it feels solid and sure; the gearsets have been strengthened to resist the stresses of Turbo Cup racing, and a separate oil cooler keeps the transmission comfortable. Nor is that rear under-bumper spoiler merely a stylist’s whim: it helps to channel more air between the wheels and past the transaxle.

Though the Turbo has always had four-piston calipers and ventilated discs, the SE gets a transplant from the 928S4 of the complete ABS system with its massive discs, a full foot across at the front, with gleaming bronze caliper castings shaming through the gaping holes in the special forged-alloy 16in wheels. It is a visible signal of the “regardless of cost” approach which characterises much of Porsche engineering, and which the company’s image of technical excellence allows it to sell successfully even at ever-increasing prices.

Like many other specialist companies, Porsche is tending to rely on the value per unit rather than number of units sold to keep profitability up, which has helped to soften the effects of its market shrinkage. Perhaps fewer people are buying the car, but those who do seem not to be worried about the cost. Hence limited-edition specials such the SE tested here; with 1000 being made, of which only 70 will be imported to Britain, exclusivity is added to the extra performance.

All of these SE cars will be finished in the same colour scheme, a dusky rose-pink exterior which is very acceptable, and a burgundy cockpit which falls rather short of Porsche’s usual standards of taste; the colour oozes over fascia and steering wheel alike, looking like a refugee from one of Mazda’s colour charts. Better news is that the rear backrest is split to fold independently, a small practical gain over the single backrest on standard 944s.

Another SE feature is the word “TURBO” fading in across the offside front wing; some onlookers felt it was rather ostentatious, but I rather approve of it as a reminder of the original 924 Camera GT Turbo, the 1980 homologation special which demonstrated Porsche’s intention to develop the staid 924 into something more exciting. That car carried the word “Carrera” in the same place.

Though the unadorned Turbo already has prodigious grip, this one gets the Sport suspension pack (optional on other 944s) and yet more rubber: the old rear size (225/50 VR 16) moves to the front, while the back jumps to 245/45 to make sure that 250 bhp actually has something to bite against, while the limited-slip differential ensures that both wheels can be made to spin at the same time.

In fact it takes a pretty slippery surface and maximum boost showing on the little dial in the tach before the Goodyear Eagles let go; in almost all normal cases full throttle brings a mild surge as the needle heads for 3500 rpm, at which point the tail drops a fraction, the car seems to stiffen and the seat tries to swallow the driver’s body.

That central rev-counter becomes momentarily crucial, for in third gear the 3000 rpm left on the way to the red line are gone in a blur; thump fourth home and the boost needle stays glued to 1.8-bar pressure as the 100 mph mark flashes past. Even when fourth runs out at 130 or so, the turbine is still cramming pressurised air through the Bosch L-Jetronic injection system to propel the car up to and beyond 150 mph.

With the boost high, the Turbo SE has almost unrivalled overtaking povvers, but it is less flexible than before. The correct gear is vital: off boost there is a noticeable gap in the action, and joining main-road traffic from a side-road standing start means looking for a bigger gap than a normally-aspirated sportscar would need. Those few seconds while the turbo gathers steam can seem a long time, if only in contrast to the bullet-like reaction when the car eventually lets fly.

In the upper half of its performance chart the car remains completely stable, with no yaw to deflect its direction, and the leather wheel feels exactly, in fact uncannily, like it does at 30 mph. So well matched is the power-assistance to the speed and the load on the tyres that there is no real change in the sensations absorbed by the driver’s hands between the urban crawl and the open road; indeed at high speeds the servo effect dwindles to zero, leaving all the tiny darting and pulling movements to come through direct. It would be a tenable proposition to suggest that this system is actually superior to unassisted steering for fast driving, because of this absolutely constant level of response and the ideal, slightly weighty, feel.

Yet the 944 is not perfect on this front: lean on the firm brake pedal and the broad front ryres instantly start to dart around bumps and cats-eyes, twitching the blunt nose away from the line. It is distracting rather than worrying, a racing car trait which is the penalty for the sort of lateral bite which has inexperienced passengers gasping through roundabouts.

At the same time a terrific thumping and roaring emanates from the suspension to disrupt an otherwise peaceful interior where the turbo’s whistle is virtually inaudible. In fact there is not much to be heard of the engine at all; its twin balance shafts make it smoother than any big four ought to be when spinning fast, and what to onlookers is a pleasant exhaust growl is lost on the occupants.

At low revs, though, the unit begins to grumble. It really does not like trickling down to less than 2000 rpm, becoming lumpy and uneven, and its relatively high gearing means taking second and on occasion first gear to keep the car rolling in traffic queues where most cars would be happy a gear higher. Yet this is the only indication that this is a 250 bhp road-burner; resuming fast driving, the unit pulls away without hesitation and with the temperature needle unmoved.

During a week’s trial, the only time I was aware of triggering the ABS was over a severe hump where I would otherwise have momentarily locked a wheel; I simply do not believe the scare-stories which say that people drive faster because they have antilock brakes. As far as I am concerned, it is the single most valuable safety feature, after seat belts, now offered, and a great comfort when the spray-coated tail-gating third-laners stream past on a wet M1.

Tramlining aside, braking performance is superb, locking the seat-belts around the crew and pinning both ends of the chassis to the road. Partly this is due to the four pads which seize each hollow disc, but also by the normal excess of work done by the front brakes is offset by the rear weight bias of the transaxle layout. Incredibly, the weight distribution of the Turbo SE is virtually the same as that of a rear-engined Porsche 911, with 59% over the rear axle. Happily the polar moments, or resistance to turning, are very different: if the back of the 944 steps out, a moment, flick of the wrist is enough to hold it until the tyres lock on to the line again.

Helping the driver to feel so in control is the excellent relationship of seats, pedals, wheel and gear-lever, though the skinny handbrake lever is much too far away, down by the driver’s right calf, and the electric tailgate release is buried in the footwell.

Some of the minor controls, set in an uninspired line along the dash, are hard to find behind the steering wheel, but the air-conditioning controls the system is standard) are exemplary, with temperature being controlled by a rotary knob, and push-button demisting. The softly-curved grilles in the stylish fascia (revised for the first Turbo and now common to all 944s) provide plenty of air — if you can get them set up to suit you.

Electrically-adjustable seats are part of the SE package, manipulated by neat inset circular rockers in the side of the squab like those on the V8 Porsche, and they do a good job of gripping the occupants without being tiring. There is no doubt that one could drive from Calais to Stuttgart where this car began its life and be quite relaxed and composed at the other end as long as the route avoided any poorly-surfaced roads. With its stiffened damping (though relatively pliant springing), hard bushes and unyielding low-profile tyres, the SE will make its driver grit his teeth at the approach of another manhole cover at town speeds; but it is naturally less harsh as the speed rises, and the sheer accuracy of the chassis through a sequence of left-right-left esses is enough to forgive its low-velocity rumbles.

As usual, the overall package which Weissach’s engineers have marketed is beautifully balanced: there is traction to cope with the huge power, sensitivity to match the tenacious road-holding, and top rank assembly quality to go with the impervious mysteries of black-box engine control. There is little drama — indeed almost disappointingly little — to the staggering acceleration, and in some ways the car’s sheer competence makes it appear less stimulating to the senses. But at the end of a full day of hustling along B-roads, the driver’s smile of content tells all. GC