Aston Martin Engine Development: 1984-2000. Arthur Wilson L.

had been agreed. There was a huge enthusiasm and spirit within the revived AML, which was just as well because the target for the new car was set for Earls Court, October 1976. Every effort was put into that car, with everyone doing whatever was needed, whenever it was it needed, I even did coach lining. We made it, just. I think that I fitted the last bit on the stand at Earls Court, the solid silver motif atop the grill. There were some other memorable Lagonda moments as well. Dennis Flather was able to make special arrangements for a Lagonda to enter the 1977 London to Brighton run and I was given the privilege. I believe that this was the first time a modern car had been allowed to enter.

      The Lagonda was a completely new car and chassis with a very low bonnet line and a new engine bay. The new engine bay layout would allow us to lower the engine but would require a smaller oil sump capacity for ground clearance and a new oil pump. But even then, the low bonnet line would still restrict the air intake system. To offset this, the compression ratio was raised and larger 2.1" inlet valves were fitted along with new camshafts to boost mid-range torque. Much work was done on the intake system to optimise the limited space available above the carburettor intakes. Various attempts at smoothing the flow by shallow trumpets and different air entry points to ensure even distribution resulted in a gauze dome or flame trap over the carburettor intake being the best, combined with a side-entry air box. The gauze domes really work, particularly in the mid-range. Top-end power was always compromised by the low bonnet line up to the introduction of the 1985 injection engine cars, which used the same engine as the V8 Coupe of the time, so had comparable power.

      A higher performance version of the V8 engine was to be developed for a new, more performance-biased version of the V8 Coupe, a return of the Vantage name last used on a six-cylinder car. The engine was developed using 48 IDF carburettors feeding through 1.5" inlet ports to 2.1" diameter inlet valves, new pistons and camshafts and higher compression ratio. A twin four-into-one manifold and exhaust system was developed specific to this engine. It produced 370 bhp at 6,000 rpm with 350 ft/lb of torque at 5,000 rpm. During the road and track development stage we had a real problem with keeping the spark plugs clean on this engine specification, although the heat range was correct for full power running. MSD ignition helped but the eventual cure was to use NGK BP6EV spark plugs, which worked very well. Thus began a long and happy association with NGK and I have always specified NGK plugs ever since.

      The car was also extensively changed aerodynamically, with front air dam, blanked radiator grill, Perspex covers on headlamps and a flip tail rear spoiler. All of which resulted in a remarkably low drag factor for such a large frontal area car. This had involved considerable night-time testing in the wind tunnel by the engineers responsible. Night time testing was cheaper. We also did track testing with short lengths of wool attached to the front and side bodywork. I can remember driving the development Vantage down the timing straight at MIRA at an indicated 170 mph, with guys at the side of the track taking photos. The suspension was developed after extensive track and road work to include Koni shock absorbers and Pirelli CN12 tyres on 7" rims.

      In those days we had no shortage of good analytical test drivers within the department. We also used the services of people like Ray Mallock and Bill Nicholson. I once had the pleasure of going testing with Bill Nicholson. For some reason I had been off work unwell. I was still feeling a little second-hand when I returned to work, only to be told ‘you are going brake fade testing with Bill, that will sort you out’. Brake fade testing is not pleasant for the copilot at the best of times, with repeated hard braking from 100 mph upwards. I survived but I have to say that I have never been driven so relentlessly hard for every inch of road between Newport Pagnell and MIRA. Compared to the trip to and from MIRA, the brake fade testing was a breeze, Bill could really drive a car. Bill also did a lot of the durability and chassis development driving on the Lagonda. If it was going to break, Bill would break it. I remember that he knocked off a number of engine oil filters while landing the other side of a particular humpback bridge on the test route before we tucked it up far enough out of harm’s way.

      The first customer V8 Vantage cars were converted from standard V8s from the production line. They were passed over to experimental to be converted individually in a small area of the experimental workshop. I was made responsible for this process and the sign-off after testing. From memory, I think that the rolling road sign-off required something of the order of 300/310 bhp at the rear wheels. All cars had to achieve an indicated 170 mph on level ground. The cars were then returned to the production line for final finish and valet. One very keen customer had his car delivered straight to Silverstone circuit to enter it in an Aston Martin Owners’ Club (AMOC) race, which he won.

      USA certification was looming again and eventually I had to go out to the EPA facility in Ann Arbour, Michigan with David Orchard, who was in charge of the safety and legislation department at AML, to certify the USA specification car. This was my first trip abroad for the company but luckily David knew his way around, having been there many times before. There were a few hiccups, not the least of which was the shipping company at Detroit airport losing track of the container with our certification car in it. But they eventually found it some days after it had arrived. After we had successfully certified the car and had our fill of Ann Arbour’s buzzing nightlife, we were invited to stay with Peter Sprague for a few days so we drove upstate, stopping off at the Niagara Falls on the way just to have a look. We enjoyed Peter’s hospitality in what is a stunningly beautiful part of America. Over the years I have had many enjoyable trips to America on company business.

      DP1054

      Engine development was ongoing for the 1980 engine range. At this time we had three different cylinder head specifications: the standard V8 with the 1.9" diameter inlet valves, the higher compression Lagonda head with 2.1" inlet vales and the Vantage with the larger valves and the inlet ports bored out to 1.5" diameter. All had slightly different compression ratios. So it would make sense to commonise engine parts where possible.

      Using the Lagonda cylinder head as the basis of the standard 1980 type would mean that all engines used the larger inlet valves and that only minor changes to build procedure and a change of camshafts would be required to produce a Vantage version. The Vantage would need new camshafts to optimise the power from the smaller inlet port and to further refine the engine. John Lipman was a camshaft consultant at that time and was commissioned to design new polynomial camshafts for development work. Further refinement to limit piston noise during warm-up would require a new common piston design with barrel skirt rather than the existing taper skirt. Support for the piston side thrust at bottom dead centre could also be extended 0.100" down the bore by reducing the chamfer at the bottom of the liner. With the new piston design we were able to reduce the clearance in the bore from 0.0045" to 0.0035".

      Dished valve heads would be part of development, as they had shown a significant reduction in hydrocarbon emissions during earlier development of the federal specification engine due to greater conformity to the valve seat. Tufrided valve stems would reduce wear particularly with the unleaded fuel required by the USA specification cars.

      Fuel consumption was improved by almost 2 mpg during the official test cycle, partly by quite a tricky modified ignition system giving part throttle advance and partly due to an improved auto transmission. The ignition system was only tricky to set up in that it used a double acting vacuum capsule for retard at idle and advance during part throttle cruise. The fact that our engine did not make enough vacuum at part throttle to advance the ignition meant that we used the air pump pressure to assist the advance side by pushing from the retard side of the capsule. This required that the advance be switched out at manifold pressure above 1" hg to avoid damage to the engine.

The Motor magazine road test of a Vantage in April 1981 obtained figures of 5.2 seconds to 60 mph and 11.9 seconds to 100 mph; they wrote that it was the fastest production car they had tested up to that date.* Comparisons were made with the Porsche 3.3 Turbo at 12.3 seconds to 100 mph and the Lamborghini Countach at 13.1 seconds to 100 mph. They also rated it as the best handling car.

      Figure 3.1 Std V8 Torque Sheet