Tuning topics



Firenza made good

Blydenstein exploits Vauxhall potential

VAUXHALL have always retained a sedate image since the last 30/98 rolled sadly away from the craftsmen’s hands. The Luton firm has scorned the temptation to produce sporting motor cars and, not surprisingly with a range of stout-hearted but mediocre family saloons, has shied away from the shop window of competition. Until recently, that is, when the General Motors offshoot found themselves with a powerful but compact overhead camshaft engine and a good handling saloon in which to place it, an amalgam which produced the Viva GT. Sadly, that lack of a sporting image betrayed Vauxhall, who found a dispiriting lack of custom for a car which, though nothing spectacular, performed well and had obvious potential from an engine badly strangled in production form. The Viva GT was withdrawn and the men of Luton, with fingers burned, got on with the job of producing more mundane family saloons, but not before Bill Blydenstein, the Hertfordshire tuner, aided by the driving ability of Gerry Marshall, had started to work wonders with a GT on the circuits, the beginning of a revitalisation of the Vauxhall image which gathered such momentum that Vauxhall had a re-think and resurrected the Viva GT in the guise of the fastback Firenza.

Unfortunately, some people never learn and the 2-litre Firenza and the current 2.3-litre Sport SL which superseded it, together with the mechanically identical Viva 2300, again lacked that performance edge to distinguish them. A big engine in a small car sounds fine in theory, particularly when the car has the excellent brakes and handling of this Vauxhall range, but what use a big engine when the power output is restricted by inefficient breathing? Fortunately, the 2.3-litre Firenzas and Vivas are so close to being right that very little work on the engine is required to transform them into extremely rapid cars indeed, as we found when we tested the foremost Vauxhall tuner Bill Blydenstein’a own Firenza Sport SL fitted, of course, with his own performance equipment for road use.

Undoubtedly this is one of the most effective and pleasant road conversions we have ever tested, yet at £150 extremely reasonably priced for the improvement gained. All that it entails is the substitution of a big-valve head, different needles and damper bushes for the twin Zenith-Stromberg 175 CDS carburetters, a fabricated 4-branch exhaust manifold and an Aerofan. Power improvement is in the region of 22 b.h.p., lifting the DIN figure from 110 b.h.p. to over 130, but more especially raising the torque correspondingly to provide the real effectiveness of this conversion.

Bill Blydenstein has no time for the tuners who churn out road conversions capable of endowing a car with spectacular, wheel-spinning, standing-start acceleration and a high top speed at the expense of power where it’s really needed—in the middle ranges. He feels that to cope with present-day traffic conditions the ideal road car must have ultrasmooth flexibility under all conditions and tremendous urge in 3rd and top gears, while maintaining a high standard of through-the-gears acceleration. This Firenza was a perfect example of his thinking put into practice; indeed, the results are better than even he expected and the normally stoical Blydenstein is overjoyed at the results obtained when a weekly contemporary journal compared the 3rd and top-gear acceleration figures with those of known performers like the Capri 3-litre, BMW 2002 Tii, Datsun 240Z, RS1600, and even the hefty Rover 3500S and Citroën SM, to find that the modified Sport SL excelled them all considerably. Standing-start acceleration figures, as an added attraction, show a massive improvement over the standard car; the 0-60 time of just over 8 sec. is sufficient to see off most cars in the traffic-light grand prix, and top speed is raised from a shade over 100 m.p.h. to 113 m.p.h.

However, figures are only a small part of the story, for the most impressive virtue of the Blydenstein Firenza is that the torque gain gives a vast improvement in flexibility, making the car easier to drive generally and much more pleasant, not just at high speeds where one would expect it, but in the lower ranges too. One would hesitate to hand most tuned cars to the wife for shopping and taking the children to school, but this Firenza is one example where even she would find the car improved and completely vice-free.

There are literally no snags whatsoever with this ideal conversion, which would give worthwhile change from £1,500 fitted to a new Viva 2300 SL 2-door or be about £30 over the £1,500 mark on a Firenza Sport SL, yet give performance the equal of cars costing several hundreds or thousands of pounds more. Another convincing proof of the efficiency of the Blydenstein modifications is that fuel consumption is actually improved by approximately two miles per gallon to an economic figure of 25 m.p.g. overall. Such exceptional characteristics are not unusual when they stem from the know-how of Blydenstein, one of the most respected and competent tuners in the business. They denote a subtlety of tuning craftsmanship far removed from the “bang in a hot camshaft, open out the ports and stick on some bigger carburetters” brigade. Perfection is the name of Blydenstein’s art, so his products undergo considerable testing and development. Not until their road performance meets the high standards of this former BARC Saloon Car Champion and Fellow of the Royal Aeronautical Society, or, in the case of racing modifications, have achieved circuit success in the hands of Gerry Marshall, are they released for public consumption.

Blydenstein’s absolute integrity is illustrated particularly by the conversion fitted to his own Firenza. As tested it was fitted with a Stage 4 big-valve cylinder head, only slightly removed in detail work from the full race item used on Marshall’s Thames TV Firenza special saloon. Because of the work involved in final finishing of this head the conversion kit at the time of the test cost £175, yet uneconomic for Blydenstein. By clever development he has since altered the specification so that less hours are required for machining and the kit can be retailed economically for only £150. For many years he had believed that rough-finished porting would give better results on road engines than the highly polished finishes necessary for racing engines, but had always been unable to achieve a uniform rough finish. He has found the answer in the Guyson Beadblaster machine, which blasts minute glass beads at high pressure much in the same way as sandblasting. The Stage 3H big-valve high-compression heads which replace the Stage 4 are thus treated after machining, saving many man-hours, while proving Blydenstein’s beliefs by giving the same performance as the more expensive hand-polished head with the advantage of even better flexibility and economy.

Nevertheless there is still a considerable amount of effort put into the head modifications; ports and valve throats are opened out and considerably larger valves fitted (47 mm. inlet, 41 mm. exhaust), while the gases are able to escape more freely with the aid of the extractor exhaust manifold connected to the standard system. The compression ratio is raised from 8.5 to 1 to 9.5 to 1 by skimming the head, which creates complications in itself because the belt drive to the overhead camshaft is slackened as a result. Blydenstein’s answer is to compensate for this by fitting a thicker gasket between the cam carrier and the head; an oversize jockey wheel is the alternative on higher compression ratio racing engines.

The husky standard Firenza engine is supposed to be quite torquey, but in practice the gearbox has to be used energetically to obtain reasonable performance from lower speeds because of a lack of low-speed torque, whereupon a further drawback shows up in that the 97.54-mm. bore, 76.2-mm. stroke four-pot runs utterly out of breath at 5,500 r.p.m., making higher-speed performance better in top. On the other hand the gearbox could almost be dispensed with on the Blydenstein car, which would accelerate with verve and smoothness from as low as 20 m.p.h. in top, the almost flat torque curve creating a distinct improvement throughout the range. Alternatively the same torque improvement also made 3rd more useful so that for ultimate acceleration it paid to use this gear up to 80 m.p.h. The better breathing lifted the usable rev, band by a good 500 r.p.m. Noise lever, if anything, was reduced and there was a noticeable improvement in smoothness by virtue of balanced combustion chambers and better balanced mixture charges to each cylinder. The most obvious advantage of all these improvements was the wonderful ease of overtaking without the fussiness which is inevitable when trying to push the standard car quickly.

There is little need to delve into the pedigree of Blydenstein’s Vauxhall modifications, for as the technical kingpin behind Dealer Team Vauxhall his successes on the circuits speak for themselves. Along with Chris Coburn on the rally side he has done much to lift Vauxhalls to the forefront of National competition, for which they have been rewarded by Vauxhall under the new Sportpart scheme whereby their wares have been made available to the general public through a network of 12 Vauxhall dealers. Indeed, 98% of Blydenstein’s conversions are now sold through these dealers, though they remain available direct from his works at Shepreth or from Coburn Improvements at Banbury.

The great pity is that Vauxhall themselves can’t build similar improvements into their production cars, for surely it would cost little on a mass-production scale. The result would be a reasonably-priced Sports saloon of great merit, which with adequate publicity and marketing could do much for Vauxhall sales. Such a move would not worry Blydenstein, who has many other modifications up his sleeve for the solid, reliable 2.3-litre engine. C.R.

(Standard car in brackets.)

0-30 m.p.h. 2.4 sec. (3.1 sec.)
0-40 m.p.h. 4.0 sec. (5.2 sec.)
0-50 m.p.h. 5.6 sec. (7.5 sec.)
0-60 m.p.h. 8.3 sec. (11.2 sec.)
0-70 m.p.h. 11.4 sec. (14.8 sec.)
0-80 m.p.h. 14.7 sec. (21.4 sec.)
0-90 m.p.h. 21.0 sec. (32.2 sec.)
Maximum speed: 113 m.p.h. (105 m.p.h.)
Speeds in gears: 1st, 39 m.p.h.; 2nd, 58 m.p.h.; 3rd, 92 m.p.h.
Standing 1/4-mile: 16.0 sec.