Tuning topics

Super Samuri – a 140 m.p.k 240Z

Not very long ago the mass-produced sports car market throughout the world was dominated by British Leyland, but while they continued to rely on re-vamped old models the Japanese Nissan-Datsun concern stole a march on them with their 240Z. In rallying the bright red works cars captured enthusiasts' imagination, taking over from the lamented works Healey 3000s as the most exciting, brutish beasts of the forests and in the gold mine of the American West Coast the standard machine took over as the best selling sports car.

In standard form the 2,393-c.c., overhead camshaft, over-square 6-cylinder engine provides the heavy car with excellent performance, a top speed of 125 m.p.h. and 0-60 m.p.h. acceleration in the region of 8 sec. Allied to good handling and a 5-speed gearbox, this makes the fixed-head fastback a thoroughly practical and covetable motor car. However, the recipe also provides an ideal basis for extracting even more performance to create a really exciting road car.

So far the British tuners have been a little reticent in developing upon these possibilities. One who has seen the light and reacted with impressive results, is Spike Anderson, of Race Mad Services, Harbury, near Southam, Warwickshire (Harbury Wells 661). Before setting up his own business in the quiet Warwickshire village last year, Anderson was a chargehand for Broadspeed Engineering, concentrating on the modification of their renowned Ford BDA racing cylinder heads. As it would not have been economically viable to have set up in opposition to one of the best Ford tuners from a position only three miles down the road, Anderson looked around for another marque on which to concentrate and settled upon Datsun, the second largest foreign car importer, as the best proposition. The little Datsun 1200 provided the subject for his first exercise, the Samuri, as he called it, giving 105 b.h.p. and comparatively rapid performance.

Anderson's 240Z, logically called the Super Samuri (a deliberate misspelling of Samurai), is a happy medium for road use without going to the extremes of the rally cars. For £645.50 on top of the basic car's £2,535, he modifies the engine, suspension and brakes and completes the package with alloy wheels and superb coach-painting to make the Super Samuri look every inch the part for £3,180. The end product is a 140 m.p.h. car of tremendous performance and character.

Because the conversion does not affect the bottom half of the engine, Anderson can offer the parts in whole or in part for any Datsun 240Z, second-hand or new. In the case of a new car the customer would first have to acquire it from a dealer, Anderson not having Datsun retail facilities.

Naturally for a man of his previous experience, the cylinder head is the region for the major part of the performance increase; in conjunction with triple 40 DCOE Weber carburetters in place of twin Japanese SUs.

As on most production engines Anderson has found the ports of the aluminium 240Z cylinder-head shielded by the manifold gasket and the first job is to match them. Standard valves are retained but he pays particular attention to the valve throats and radiusing the valve seats for effective breathing. The compression ratio is raised from 9:1 to 9.5:1 to help improve the torque.

The Weber carburetters, inlet manifolds and necessary installation requirements such as the throttle linkage are purchased from the Cheshire tuning firm Mangoletsi, whose rolling road he used to correctly work out the carburetter and ignition settings. They also supply the six-branch exhaust manifold and competition system, which is made for them by Janspeed.

Because the engine is o.h.c., removing and replacing the head isn't a job for the average handyman, who would doubtless end up with the valve timing completely awry, while I'm told that another easily made mistake is to let the tensioner for the camshaft drive chain fall down inside the timing case with consequent difficulties of removal. Another installation job is to blank off the holes which feed the water-heated manifold on the standard carburetter arrangement, the three separate manifolds of the Weber system not being practicable to heat and cold starting and warming up being trouble-free in any case.

Anderson thought originally that he might have to balance and blueprint the engine in order to be able to use safely and effectively the extra revs afforded by the head conversion. This would obviously have added considerably to the cost, so he was both impressed and thankful when he found the inscrutable Orientals assemble their 6-cylinder engine with a care which is tantamount to blueprinting. For example, take any production engine, measure the deck heights (the heights above the pistons to the face of the block at the tops of their strokes) and they'll usually be at a slight variance to each other. On Anderson's own 240Z each of the six-deck heights measured exactly 4-1/2 thou., production accuracy indeed.

The total cost of the engine conversion including fitting, tuning and testing is £396, of which the Weber kit takes roughly £200.

Handling of the standard 240Z is already very good and Anderson has found that for road use the only improvement necessary is to modify the coil springs, lowering the ride height by 1-1/2 in. and stiffening the rate, which coincidentally improves the appearance of the car, sitting as it does rather high on its suspension. Karl Shenton, better known for his racing car preparation, modifies the springs by compressing them at his premises on Malcolm Gartlan's trading estate at Pershore. Anderson feels that the standard damper rates of the front and rear McPherson struts are adequate for fast road use. This minor suspension modification sounds expensive at £52 until one considers the labour involved, made more complicated by the need to take apart the rear brakes.

Production brake material is reasonable for ordinary road use, but a hard-driven 240Z runs out of brakes quicker than any performance car I know. To combat this, the Super Samuri is fitted with special pads and linings from Old Woking Service Station, the Datsun competition people, at a cost of £32.50 including fitting.

The attractive alloy wheels are made by Midland Metallic and are of 5-1/2J width instead of the standard 5J. A customer could specify any tyre he wished, though Anderson anticipates that he would be unlikely to wish to waste the original equipment Bridgestone radials, so the normal Super Samuri specification retains these. The cost of five wheels with the tyres fitted from the original steel wheels, and inclusive of balancing is £82.50.

Concluding the specification is the beautiful paintwork completed in low-bake paint by Normandale of Southam. The original paint is retained as the main colour, with a contrasting shade on the bonnet and roofline surrounded by white coachlining. In the case of Anderson's car tested, the base was red with a metallic brown contrast, a superbly attractive scheme which won many admirers. Super Samuri is signwritten on the bonnet and rear spoiler.

The tuned cars tested by this writer of late have all been of a particularly fine standard so warranted little criticism. Once again I must turn to superlatives for the description of the Super Samuri, for without a doubt it joins the ranks of the best road cars I've had the pleasure of testing. Curiously enough it was very much akin in character to the two Alpina-modified BMW 3-litres tested recently: in handling, ride, engine characteristics and even the same rorty 6-cylinder boom it could almost have been taken for a two-seater version of the Munich products. High praise indeed for a car which costs less than £3,200 compared with over £8,000. Maybe it was slightly slower, but the performance table shows that nevertheless the Super Samuri will out-perform most other cars on the road, and maybe its interior is plasticky, but the standard of finish would almost have done justice to BMW, while the in-built strength and ruggedness is well known. The only penalty is increased fuel consumption, 20 m.p.g. when driven steadily and little more than 16 m.p.g. when fully extended.

Starting when cold presented no difficulties, the usual Weber trick of three or four priming jabs on the throttle making the fitted choke redundant, while warm starting required a modicum of throttle and one touch on the key. From cold it ran almost perfectly smoothly, objecting with a cough if too much throttle was applied within the first couple of minutes, by which time it would tick-over happily at 1,000 r.p.m.

On steady throttle openings at moderate revs engine noise was most subdued, belying the healthy unit under the power-bulged bonnet. Prodding the throttle invoked a suitably rorty retort from the exhaust and the unsilenced Webers, which also had an induction whistle on steady throttle openings in the mid range. On the whole the noise level was more pleasing than overpowering and even approaching maximum speed, conversation was still possible.

The performance table speaks for itself about acceleration, but what it fails to illustrate is the overall improvement in driveability occasioned by an increase in torque and flexibility. While the standard 240Z has little power at all below 4-4,500 r.p.m., the Super Samuri picked up cleanly from 3,000 r.p.m. so long as the throttles were opened gradually and was prefectly happy to pootle along at 2,000 r.p.m. Once above 4,500 r.p.m. the Anderson machine disappeared into the distance like the proverbial as the tachometer needle flicked rapidly round to the 7,000 r.p.m. mark (the standard car's limit is 6,500) in 1st, 2nd, 3rd and, if brave enough, 4th, while although it proved impossible to test the maximum speed, I'm almost convinced that maximum revs would appear in 5th too. If that should be so then the 140 m.p.h. figure quoted is a very conservative estimate, achieved at 6,500 r.p.m.: maximum revs at 21.6 m.p.h. per 1,000 would be 151 m.p.h.!

All this was achieved with the minimum of fuss and the maximum of smoothness, with instant power available at any point on the rev scale and a wide choice of ratios to utilise it properly. Although the Datsun box had a fairly wide gap between 2nd and 3rd, the torque was such that it had no adverse effect, and while overtaking acceleration from high speed could be increased by changing down to 4th, 5th could cope more than adequately.

On the subject of the gearbox, 240Zs do seem to differ widely in this respect: some are notchy, stiff and a little vague, this one was positive and easy, and a little experience made the moves from second to third and fourth to fifth in the Alfa-type arrangement (5th up to the right) perfectly natural, without confusing 3rd and 5th. Some effort was needed to pull the lever out of 5th with the gearbox hot after fast motorway runs. The hydraulic clutch was surprisingly light. Following the gear-pattern sketch on the top of the knob would have caused some confusion, for the knob happened to be from an MG-B: the car was delivered to the dealer without one and the MG-B happened to be the only temporary substitute available.

True proof of the increased flexibility came from driving the Super Samuri through heavy London traffic: it trickled along quite happily at low revs, responded instantly when taking advantage of gaps in the traffic, the temperature stayed normal and the plugs refused to soot even after the engine had ticked over for long periods.

At the time of the fifth wheel performance testing the car had covered a mere 1,900 miles and it would be safe to assume that the performance would increase with a few thousand miles more under its belt. The 0-100 figure also requires comment in that on the day of the test, repairs were taking place on the straight at the test track, so that the 0-100 m.p.h. runs had to be completed into a curve. Again an improvement could be expected under perfect conditions.

The commendable performance was complemented by extremely good handling, marred only by some bump steer which, although it didn't throw the car off line, proved a little tiring when driving hard. With power off the 240Z tended to understeer, but cornering correctly under power made it absolutely neutral. The rear suspension design was such that it proved almost impossible to disturb rear adhesion, except by flooring the throttle in the lower two gears on tight corners in the wet (in which conditions the wiper blades lifted off the screen at 100 m.p.h.). I prefer a little bit of oversteer to be provokable when required so the rear adhesion was almost too good. Traction was equally excellent, so good that I was convinced a limited slip differential was fitted, but not so. Ride was fairly firm, but tolerably comfortable, although the tail tended to leap about on bumpy roads. While the steering was heavy it was also extremely positive, which is what really counts.

Braking via the direct servo, twin-line system was much improved by the new brake material, but even so it was possible to fade them completely during extremes of repeated braking from very high speed. To perfect them would require comprehensive changes to front calipers and discs, though some sort of ducting through the front spoiler to aid cooling might help.

The Datsun 240Z in production form is an excellent and practical GT car with a good standard of appointment, which includes an efficient, if complicated to control, heating and ventilation system, considerable luggage space, heated rear screen, tinted glass, 5-speed gearbox and many other refinements which make it good value at its price. Spike Anderson's Super Samuri shows that with moderate modifications it can be transformed into a sporting car almost as fast as and more practical than a Porsche or Dino at less than half the price.

Performance

(Standard car in brackets)

0-30 m.p.h. .......... 2.2 sec. (2.9)

0-40 m.p.h. .......... 3.3 sec. (4.6)

0-50 m.p.h. .......... 5.3 sec. (6.4)

0-60 m.p.h. .......... 7.0 sec. (8.1)

0-70 m.p.h. .......... 9.3 sec. (11.2)

0-80 m.p.h. .......... 11.5 sec. (14.4)

0-90 m.p.h. .......... 14.4 sec. (19.1)

0-100 m.p.h. ........ 19.2 sec. (24.0)

Standing 1/4-mile: 15.2 sec. (terminal speed 92 m.p.h.)

Speeds in gears: 1st, 42 m.p.h.; 2nd, 64 m.p.h.; 3rd, 94 m.p.h.; 4th, 124 m.p.h.; 5th, estimated 140 m.p.h. (125 m.p.h.)

Fuel consumption 16.4 to 20.0 m.p.g.