CARS Magazine February 1979
by John Brigden & Syd Fox
After month's of hard work and development,
Ian Marshall's superb racing Esprit has started to show its worth.
The early morning mist hung lazily over the silent circuit, looking every it as though it was there to stay. On a day when the sun was shining just a few miles away, people peered at each other despondently, desperately hoping that the Modsport machinery would not be jeopardised.
The car in question was Ian Marshall's immaculate (I mean it too) Lotus Esprit, which sat on the pit lane with the predatory stance of a wild animal hungry for the kill. The sleek, red glassfibre body glistened as the early morning sunlight filtered down, barely strong enough to lift the gloom.
Syd Fox, who was to to the testing and had promised to drive me round the circuit, hadn't arrived yet, so discreet glances were directed at the entrance of the pits looking for an old nail which might bring Syd to the circuit.
Ian Jones, a Kiwi and builder of the Esprit, started the 2 litre engine, muttering about ambient temperature and whether he would bend the crankshaft before the engine was hot. The engine builder, George Wadsworth, stood by nervously. Four presses on the throttle, pumping fuel through the twin 48 Dellortos, and the car burst into life and purred its way to a running temperature. George informed me that the oil temperature needle had to lift off 40°C before it was really safe to work the engine. This cold Silverstone morning held little hope of the engine reaching that temperature so, when the mist lifted, a gentle workout was required.
The engine only turns out 225bhp at present but is highly reliable. George has fitted Cosworth pistons to the standard Esprit engine, planed 0.015 ins, so they just peek above the block. He has developed his own dry sump system, fitted only rally cams (at present) and the larger carburettors. Of course, the whole lot has been balanced but it's by no means a full race unit.
The car is sponsored by Macinnes Amcron, Ian Marshalls firm, and has been built as a full race version of the Esprit, to conform to the FIA Group 5 regulations as well as Modsports.
Macinnes Amcron Racing have been involved over the years with various classes, including Formula Ford, Prod Saloons and sports cars. For several seasons they raced the ex-Gold Leaf Team Lotus 47, with which Ian Marshall established a new lap record at Brands Hatch last October for the up to 2000cc Group 4 sports racing cars, soundly beating a host of Chevron B8's.
The money from the sale of the Lotus was the basis on which the Esprit was financed. It was built by Racing Fabrications owned by Ian Jones and George Wadsworth of Bury St Edmunds, with considerable assistance from the Lotus Factory. Ian Jones was responsible for the design of the suspension, brakes, body and chassis modifications while George's responsibility was, of course, the engine.
The car was built totally from scratch, arriving from the Lotus factory as a lightweight shell and separate chassis. There are only tow of these shells around, so if you are thinking of embarking on a similar project, then you'll have to lighten your own shell with a black and Decker.
However, once it arrived at the workshops the lightening continued and the front and rear wheel arches were cut away, as was a considerable amount of the interior glass. There was so much cut away that when Ian Marshal saw it being burnt he thought Ian Jones had put the wrong section on the fire. The chassis was fitted to the shell, then the car was delivered to Safety Devices for a roll cage and new suspension pick-up points to be added. Ian Jones has some of his own ideas about suspension design and they differ from Lotus.
By the time I had got that far with my investigation of the car, the mist had lifted enough for us to be able to see the end of the pit straight and Copse corner. Ian Marshall donned his overalls and helmet and look the car for a few gentle laps. Fairly soon his times were approaching the 1m 4 sec area (the Modsport lap record is 59.5 secs) but going any faster would mean driving be sense of smell only the fog was still heavy on the Club circuit causing him to brake at the 300 board into Becketts.
It was now about 11 o'clock and Syd had arrived, looking a little the worse for wear from a party of not the previous night, but the night before that. However, half a dozen cigarettes soon brought the colour back to his cheeks, and he was just in time for a cup of coffee. He stubbed out his Dunghill, glanced at the track, sniffed, said it looked wet and lit another.
A few more cigarettes and he was ready for the off, but still the mist created problems obviously it was time for lunch.
Over an excellent sandwich lunch, provided by Ian Marshall's French girlfriend Annalise, the reasons for the build were explained but not before Syd had expressed a dislike for garlic and frogs legs. He was told, however, that since the object of the day was speed, no snail was being served.
Ian explained: "Although initially Syd was a little dubious at entrusting the work of building the car to a less experienced firm, with my knowledge of Ian Jones, which goes back four years, I was sure he could do it and I have been proved right. Before we started the build I had a few lunchtime chats with Ralph Bellamy the Lotus designer. Although these were of some help, the basic design was left up to Ian.
"The car was built from scratch with a view to doing Group 5 racing, that is if we can get the financial backing. I have already used two years of my racing budget to get this far. Without enough money to do Group 5 we will be concentrating on Modsports this year and collect as many lap records as possible. Even now, with an unsorted car, we're within a second of most of the records and hopefully today we'll break the Silverstone record. We are already committed to doing the Donington GT Championship in 1979, and we'll also do either the BRSCC or BARC championship."
Back on the track, which was now drying, but which never dried completely throughout the day, Syd was out again remorselessly eating away at the record and was very soon down to the 60.3 secs. Then came the magic occasion when he did a 59.2 and within a couple of laps had got this time down even further to 58 seconds dead. As he leapt out smiling, he remarked that when the engine has its extra power, and a hot dry day comes around, then an amazing 55 seconds will be possible.
Just to put some of these figures into perspective, the times for Sports 2000 are 59.5, and for FF 2000 58.5.
Despite these good lap times Syd was still driving well within himself, as he was not even using the clipping points on corners like Woodcote and Copse.
When he came in Ian Marshall took a turn at the wheel, but his times started climbing to the 1 min 8 second mark which was very puzzling 'til he came in to say the rack had seized. And that meant no drive round for me! Oh well, I had enjoyed watching anyway.
AT THE WHEEL
I first made contact with Ian Marshall through another more famous law officer by the name of Gerry. We were all testing various cars at Snetterton around about the middle of the 1977 season, and Ian was having trouble getting his Lotus 47 down to respectable lap times. He approached Gerry to see if he could give him any ideas on what was wrong with the car. Gerry made a valiant effort to get into the 47 but found he was a wee bit too large, so suggested to Ian that I drove it round for a couple of laps to see what I thought. It took only two laps to confirm that the car was difficult to drive as it tended to wander in a straight line, and seemed to have bump steer under braking. Taking a quick look around the car most things seemed to be OK but by raising the rack .75 inch we cut seconds off the lap times. Ian's last drive in this car broke the lap record at Brands Hatch.
As with a lot of testing, these results led to Ian requesting my help with his next project. Looking at it in retrospect it was quite an awesome prospect. His basic idea was to get hold of a Lotus Esprit and make it a high runner in Group 5 races, which meant taking on the might of Porsche and BMW. Not only that, but he was starting from square one, as no previous attempt had ever been made with a car of this sort.
With the Esprit it was possible to go in one of two directions. One could go for a full blooded Group 5 car immediately which, loosely put, means that you can do anything including a full monocoque chassis, a rear wing, and so on, as long as you end up with something that looks like an Esprit. Alternatively, one could start the car off in a Modsports configuration, for which the rules are much more stringent eg it's necessary to carry a roll hoop/cage, but you may not carry the cage forward along the top of the car and down towards the front wheels. You may semi-spaceframe the side sections by the doors, but not forward into the front T-bone section of the car. I must explain this T-bone section. Imagine a T made up of a box metal design where the front wheels are mounted outside the two outer edges of the T. This, for road use, seemed to be reasonably adequate, but looking at the car for the first time we felt that there was a possibility of flexing, simply because in its Mod-sports configuration you couldn't carry spaceframe strength forward to this T section to make a complete bracing job. Another problem was that by Modsports rules one has to use the original gearbox, which in this case was a Citroen Maserati. Here Ian had to make two sets of rose-jointed rods one for leverage left to right and another for leverage fore to aft quite a tricky job. In spite of all these problems it was agreed that it would be better to take the latter option which would at least give the car a few competitive outings in Britain as there were hardly any Group 5 races scheduled for the UK during 1978.
When you are building a car from scratch, reality is taking the amount of time you think is needed and quadrupling it. Thus instead of the car making its Group 5 debut in May 1978, having had a couple of Mod-sports races, it was not until July 6th 1978 that the car made its first showing for test at Snetterton. Now I'd never seen this car before and as I like to live to another test day, I quite naturally spent some time doing my own checkout on the car. It was an amazing piece of workmanship and for the first car of its type ever to hit the track it was a work of art. Even so, there were the inevitable niggles which can never be cured until the car turns a wheel. The throttle cable was extremely stiff easily rectifiable for another day. The steering was very heavy, but this was also easily remedied. I was concerned that we were going to suffer a lot of flexing from the front section T-bone chassis and I also felt that the spring rates were well adrift. This showed up when Ian Marshall was about to take the car round for a couple of laps, to check out the car, and failed to make the end of the pit lane because the front spoiler was scraping the deck, as the front springs had collapsed. One thing which showed up very badly was the gear selection. Unless you were extremely precise in selection, you could end up in any one of five gears and not know which you had. This resulted in Ian having to construct a whole new gear selection gate. But after removing the front spoiler we were to do about ten laps that day, which was enough for an initial shakedown.
The second test took place a week later, again at Snetterton. We changed the springs, Ian had re-routed the throttle linkage, the steering was better and so we were able to go out to see what else would show up. Brakes were the first major thing. The rears were overheating so much that the grease in the CV joints was boiling. This was not just a case of changing the brake bias, although for the moment it helped. It was vital to introduce some ducting to get air in for cooling. At this stage we didn't even need to use a temperature gauge on the brakes we could see how out of balance they were. Also, we were using a second hand set of tyres which we were trying to run-in to the cars Roadholding, and the rears were overheating considerably. By then we had covered about thirty laps and had gained enough information to consider minor modifications to the suspension. By now our lap times were in the region of 72 seconds which was just off the lap record for any Mod-sports car.
A Modsports co-driver race was scheduled for 25th July at Oulton Park and as I was already racing there that day, Ian asked me to do the first stint. We made middle of the first row in practice and after three or four laps following a Porsche, took over the lead which we held until handing over to Ian. Unfortunately the car would not restart, but nevertheless we felt that we had proved a point. However, certain things had shown up
1. The Citroen gearbox in competition was nowhere near as effective as a Hewland would be it was very heavy and the ratios were wrong. In the race we were using only third and fourth.
2. There was some bad vibration under braking due to "winding up" the front T section to which the suspension was fixed. Or maybe the car was going down on the bumpstops of the shockers.
3. Although the car didn't feel bad through slow bends it was very skittish in the medium ones, and positively horrific through the fast sections. I could feel the weight transfer and roll, so we could attempt to up the springs tightening the roll bars made it worse. The fast bend problem was easier as the downforce at the front would naturally increase with the speed and thus the car needed either a rear spoiler for Modsports or a rear wing for Group 5.
The last session with the car was the track test, and we chose Silverstone club circuit mainly because it had slow and medium pace bends which we felt we had sorted, but had not yet put on a spoiler/wing for the fast bends exit speeds in excess of 100mph. We could also do a good check on the brakes as it was all straight line braking. The braking was much improve but still skittish. We now had reasonable ducting but temperatures showed that we still needed to get more bias on the front. We propose to use different size front master cylinder as we are running out of bias adjustment. We are definitely bouncing on the front shock absorber rubbers and will have to relocate the top pickup point to a higher level to allow more movement this proved positive when we raised the front ride height and the conditions improved. Front tyre temperatures were very good but rear inside temperatures showed overheating and a tendency to grain 30 laps of that would shatter the tyre on a warmer day. We knocked off 0.5° of rear camber and the problem was cured. We finished off the day with a lap time of 58.0 seconds which is approximately 1.5 seconds under the existing lap record.
Conclusions well, we started off the day with a wet track and although conditions improved, the track never dried completely, so we can allow half a second for that. The engine is still a cooking version 225 bhp and getting tired. The next step is 280bhp which must be worth a second or, of course, turbocharging. The brakes will be better balanced next time, and with higher front spring/shocker location should give us another half second. The gearbox is still lousy, but there has been talk of allowing Hewland boxes into Modsports. There would be two main advantages here it would be cheaper over the season and would allow the correct choice of gears for each circuit another second a lap.
A rear spoiler is required for fast bends, and I reckon that this car could do a 55 second lap at Silverstone club circuit in Modsports trim in Group 5 trim it should be really something!!
CLASS: Modsport/Group 5.
OWNER/DRIVER: Ian Marshall of Macinnes.
BODY: Lightweight Lotus Esprit with wheel arches and much of the interior cut away. The Lotus backbone chassis is employed, with fabricated suspension pick up points.
INTERIOR EQUIPMENT: Safety Devices roll cage and fire extinguisher.
INSTRUMENTS: Chronometric tacho, oil pressure gauge, oil temperature gauge, water temperature gauge.
SUSPENSION: Front; There are top and bottom unequal length wishbones with March 763 uprights. The roll bar is 7/8 inch tubular steel and there is a tie bar for strength on the lower wishbone. Spax shockers with adjustable shoulders.
BRAKES: Front; Ventilated discs and 4 pot calipers. Rear; Formula 2 Lockheed discs.
WHEELS: Speedline Formula 2 10in x 13in front and 14 x 13 rear.
TYRES: Goodyear G64 slicks
STEERING: Jack Knight magnesium GRD rack, which means the steering column is canted towards the centre of the car.
ENGINE: Lotus. TYPE: OHTC. No and configuration cyls: 4 in-line. Bore: 95.2mm. Stroke: 62.9mm. Actual capacity: 1973cc. Comp ratio: 11:1. Valves per cyl: 4.
CAMSHAFT TYPE AND POSITION: Twin overhead.
CARURATION/INJECTION: Weber DCOE 48's
INLET MANIFOLDING: Standard Lotus, polished
EXHAUST MANIFOLDING: by Mike The Pipe.
EXHAUST SYSTEM: Mike The Pipe 4 into 1.
OTHER DETAILS: Dry sump system by Racing Fabrications using Vega oil pump, mounted on the offside of the block driven off the crack pulley. The distributor is driven off the back of the inlet camshaft and the alternator is driven off the exhaust camshaft which would normally drive the air conditioning.
TRANSMISSION: Lotus Citroen Maserati gearbox.
GEARBOX RATIOS: 1-0.76; 2-0.97, 3-1.32; 4-1.94; 5-2.92.
FINAL DRIVE RATIO: 4.375. LSD: No.
FUEL TANK: 4 gallon.
FUEL PUMP: Bendix Blue top.
COOLING: Front mounted radiator and oil cooler fitted at rear.
ELECTRICAL: 12 volt Varley battery and Lucas Opus ignition.
OTHER FEATURES: Twin plate racing clutch by AP.