2CV turbo «
Escargot Flambי
The life and times of a 2CV turbo

By Steve Cropley

Copyright CAR Magazine, reprinted with permission.
Appeared in CAR May 1988

At the height of its career, my turbocharged Citroen 2CV produced 60 percent more power than standard – 46.4 bhp on the rolling road instead of 29bhp off the showing floor. It clocked an honest 87mph on the motorway, and might have gone faster still if we’d had the courage and cloth ears to rev its engine higher. But so agonised was its shriek at 7000rpm, and so vivid were our mind-pictures of liquorice pushrods and a spaghetti crankshaft, that we always backed off when the needle on the Hejira kart tachometer came around to the seven.

As it turned out, 87mph was plenty of speed, accompanied as it was by a 14sec reduction in the car’s 0-60mph time – from 34sec to just over 20. Speaking practically, it made a big difference to A-road journey times and to the general ease of driving a Deux Chevaux, now that it could hold on to 70mph, up the hills as well as down them. True, the boost didn’t really hit it’s stride until 3800rpm and never did span completely the gaps between gear ratios, but it still made a power of difference. So much for good sense: there is invariably a hooligan side to supertuning.

The 2CV was magnificent for its element of surprise. Sixty percent more power made the car, outwardly a standard red B-registration Special (apart from the doubled diameter of its exhaust and the load hornet’s buzz that came out), into something of a scourge on A-roads and motorways. Even Volvo estate people with Show Dogs In Transit noticed that its maximum cruise corresponded to to 93-95mph on their speedos, error included. Dudes in 205GTIs, used to looking straight through slow-lane impediments like Citroen twins, were peeved at having to do a ton-plus to put ours firmly in the mirror. Other Dyane and 2CV travellers, struggling up inclines at the standard 55mph, must have been astounded as our red car swept by at 80.

In five or siz thousand miles of driving, Struggler (as we came to call it) shocked a lot of people and made a few of them very angry indeed. The whole mad plan came from Richard Wilsher, Then development engineer at Turbo Technics, the Northampton tuning firm, now its agent in Highbridge, Somerset. He reckoned the 2CV did not cope nearly as well with road conditions in this country as it did with those of France, and it was the fault of those who designed so-called rolling English roads. Constant curves and hills prevent the unmodified tin snail from getting into its stride.

After a few years in the Arrows formula one team, and a few more developing impressive aerodynamics and extremely powerful engine of the Tickford Capri, Wilsher was widely experienced with turbocharging, and one of it’s keenest supporters. What was more logical, he argued, than equipping a 2CV with exhaust driven puffer? Paul Buckett at Citroen mentioned the idea to me. Wilsher had been on at himabout finding a suitable car to work on. After a couple of years of happy Deux Chevaux ownership, I’d contacted Buckett about Getting hold of French tuning advice, and experimenting with an anti-roll bar kit they offer over there.

Already well known as expediter, Buckett saw how everyone’s onterests could be served. He gave me the Wilsher phone number and I rang it. It wasn’t a clear-cut decision for me. I’d often disliked turbocharged engines in test cars for their lag and non-progressive power delivery – and I’d been annoyed by the priorities of turbo-tuning firms who seemd to modify engines that were merely receptive, like the Ford V6s, rather than those that needed more power. The Ford was powerful already; why didn’t somebody turbocharge a Mini? From there it was a small step: come to think of it, why didn’t somebody turbocharge a Citroen 2CV?

Everyone I talked to reacted with howls of laughter. But from the first, lots of people maintained a special interest in the car – expressly because they could visualise it beating up Rover V8s on the M4. If it worked we’d have had some fun and produced a little bit of history; if it didn’t we’d still have had the fun. And the cost was only money. At the other end of the phone I found Wilsher a cheerful, straight-talking bloke with all the technical answers and more enthusiasm than seemed decent in an accomplished engineer of 42. I commited my car into his custody one snowy day outside Milton Kaynes railway station. The 2CV is a tough subject for turbocharging from just about every angle.

Its tiny engine produces hot exhaust gasses – needed to propel a compressor wheel – in very small amounts. Its opposed cylinder layout means that the sources of the little exhaust puffs are widely separated, not centralised as they are in a decent, God fearing in-line engine. The flat twin also breaths through very long induction tracts, no help in the problem of minimising throttle lag, and the whole plot is cooled by air, a system which promises trouble with ‘hot spots’. None of this could inhibit the Wilsher energy. With after-hours help from those at TT, and propelled by laughter, he had the first version built in a couple of weeks.

The Garrett T2 turbocharger was mounted centrally in the engine bay, directly above the inlet manifold to suck through the standard carburettor. Exhaust gases were fed up to it from either side of the engine bay, siamised together in a neat piece of piperwork just before they reached the turbo unit itself, then exhausted through a 1.75in pipe equipped with a smallish central silencer. The ignition system was fitted with an electronic timing retard module, designed to react to rising induction system pressure and inhibit pre-ignition, a common petrol turbo problem under full noise.

But it didn’t work. The turbo housing, the smallest generally available, was still too large to squeeze the 2CV’s little exhaust puffs tightly and mobilise the compressor. But Garrett had built one experimental T2 with a smaller housing, and after a couple of weeks it generously supplied it. The improvement was immediate. The exhaust flow now generated boost, but no sooner did it appear, than the electronic retard-box detected it, knocked back the timing, and the extra urge fell away. Limited extra power was delivered in a most unsatisfactory kind of wave motion that had nothing to do with good throttle response – and it was accompanied by an exhaust racket that left cracks in the workshop ceiling.

Wilsher rapidly dispensed with the electronic retard and installed a Bosch breakerless ignition capsule, re-engineering the advance-retard to work on conventional vacuum advance principles. That gave conventional ignition advance for off-boost cruising and gentle acceleration, and smooth retardation to limit pinking as the boost began to increase. In went a pair of platinum-tipped NGK B7HV spark plugs (they have a wide heat range and resist oiling) and the silencer was doubled in capacity. To iron out flat spots, the carburettor was re-jetted, but that didn’t work either, so it was swapped with single-throat downdraught Weber. The compression was lowered from the standard 8.5 to one to about 7.5 to one, by filament of very tough, thicker head gaskets. I imagine that this was simply to reduce preignition; Wilsher explained that its real benefit was to increase the capacity of the combustion chambers. The bigger the chamber, the more gas you could pack in under pressure. After all this was done, the car really began to percolate. On his third run, Wilsher caught an XR2 napping, and it took the driver five miles to get past again. Early experience soon showed that the 2CV’s sure handling, and mighty front disc brakes were well up to coping with more power, even if the body roll did get a bit copious at times. The car would now get close to 90mph if your ears could stand it, and the acceleration was downright dramatic (for 602cc) if you used full revs. Beyond 3500rpm the top gear performance was almost elastic.

The problem of the engine falling off boost between second and third remained. A solution to that would have cut acceleration times even further, but it was clear that only an even smaller turbocharger – in effect a Garrett T1 – could solve it. There were some startling development problems. Once, as he was bounding down the A5 checking the ignition settings, Wilsher heard an awful rattle from the engine, the oil light came on and a large cloud of smoke filled the cabin. But it was not the expected comprehensive blow-up. Instead, half of the sump’s oil had been dumped into the air filter. It seems that the standard 2CV has a breather valve in the neck of its oil filler pipe to relieve the high crankcase pressures generated by its opposed pistons. The heat and load of the turbo engine had destroyed the standard valve and the pumping of the flat-twin’s pistons had forced oil into unwelcome places. Wilsher designed a more robust system, and used the oil returns from his new breather to flood – and - cool the exhaust valves. After about 3000 development miles I took the car away for shakedown driving in London, but had some problems with carburretor icing. The exhaust system also threatened to fall apart.

Worst of all was the failure of the new ignition system – it stuck fast with the timing at full retard. It had worked well at providing the right timing range, and at taming any pinking, but road grime had made it jam. Wilsher redesigned it, giving it a better mounting, and protection against grit. What none of us could trace was a sort of ‘hot’ smell that occurred when the engine was worked hard. With the cooperation of Keith Spenser at Turbo Technics South, Aldershot, the Struggler went off to the rolling road, where it showed 46.38bhp at 6500rpm after an hour or two’s carburettor and ignition tweaks. It might have given 50bhp had it been measured for full power at 7000rpm, but so awesome was the mechanical noise, Wilsher says, that he cried enough at 6500. At that stage, he says, the curve was still climbing steeply. For all its hard times, the Struggler seemed to run ever more smoothly. The tickover was that of a Swiss watch, and the pulses of the power delivery were smoothed by the turbo system.

Most times, the engine seemed as sweet as a good four – sweeter, perhaps, because it did not suffer the in-line’s four’s typical 4000rpm tingle. The exhaust, within legal limit, had a rasp and boom to it when on boost to it that would have done justice to a big BMW bike. Wilsher fitted the engine sump with Shell’s Gemini oil (claimed to ‘stay in grade’ at extremes of heat and hard use) and the gearbox with Amsoil gear oil, the last-a-lifetime stuff they put in grand pix cars. Then, after an outlay of something like 1400 Pounds, it came back to me for a life in London traffic.

There was nothing fair about this. Though the bones of the car, and the outlay were mine, the idea and the inspiration, the thought and the sweat, were Wilsher’s. It had been no ordinary job. I could see that in his eyes as I drove away. Apart from my enjoyment of the finished car, this should have been the end of the story. The Struggler worked well. It burst into life hot or cold, it beat it’s share of 1100cc hatchbacks at traffic lights but behaved as docilely as an ordinary Deux Chevaux. Its turbocharger managed to avoid abuse because Wilsher had incorporated a little red warning light in the dash that winked at you when the turbo housing was too cold to call up the boost, plus the little Hejira tachometer, down near the driver’s right knee. The Struggler was always popular with friends. A lot of miles were accumulated in demonstrations of its prowess. The chicken shed-on-wheels felt faster than a greased Ferrari. For one thing, whenever your right foot was properly nailed to the floorboards, there was no reliable indication of speed. The needle of the matchbox-sized dial tended to wind so far beyond the highest graduation (70mph) that its only use was a belly-button indicator. In the absence of a speed guide, your imagination tended to run away with you. It was easy to project yourself beyond the magical 90mph – the sound barrier as far as twin-cylinder Citroens are concerned. What brought you back to Earth were a variety of aural and visual speed indicators. At 75mph, the tops of the front doors were sucked outward by the slipstream. By 80mph, the din of the wind, road, and engine made communication between occupants, even by shouting, impossible. We learned to signal would-you-like-to-stop-at-the- next-Happy-Eater? by hand. Above 82-83mph you would suddenly recall, whatever your train of thought, conversations with other Citroenistes about the strength of 2CV bottom ends.

By 85mph you’d be praying that it was as true as this day as ever. We always intended to write about the Struggler. Too many people had shown interest to for us to sweep it away uncelebrated. One day in summer, Mr Richard Bremner and a photographer set out to capture the car on film and to make some sensitive studies of Wilsher, brains and impetus behind the whole thing. They accomplished all this and were cruising quietly home along the M1 at 80mph when green-brown smoke began to billow from under the dash and bonnet. They pulled rapidly across two lanes of traffic, but in time it takes to read a sentence, orange flames were shooting six feet in the air. Fool that I am, I had never bought a fire extinguisher, but it probably wouldn’t have helped. Nobody with a brain opens a the lid of an engine bay when there’s a fire underneath. And so it burned. Luckily the car was at the southbound entrance to Scratchwood services on the M1 – ironically, right next to a huge sign advising drivers to ‘REDUCE SPEED NOW’. Fire fighters arrived quickly. Bremner told me as much on the line to Germany where I was that day. He and the photog where unscathed, and a good few thousand pounds’ worth of photographic gear was saved too, but the car burned out completely ahead of the windscreen. The Weber carburettor melted away quietly, as did the alloy brake clippers, and the master cylinder. The engine appeared OK, but its oil seals and the pushrod tubes had been well cooked. The plastic dash and trim hung down inside the car, like carefully arranged spaghetti. The trim, once fawn, was black.

Nobody knows what caused the fire, but the likelihood is that the two pieces of ventilation trunking across the top of 2CV’s engine bay got so hot that they ignited, even though they have been carefully heat-shielded. They were probably the source of the ‘hot smell’. Made of kind of glorified cardboard, these tubes are widely thought to have caused fires in many a standard Citroen twin, too. Wilsher, having heard of the news on the phone from me, went out and got drunk. He said it wasn’t the first time months of his work had been wasted in an accident, but it was a profound blow, just the same. I contemplated a hefty financial loss because I have been to stupid to tell my insurers that the engine had been modified. There was no question of making a claim.

I nearly sold the ruins to a bloke in the pub for 500 pounds. In the end we made the only sensible decision – to build a Turbo 2. It was exciting the enthusiasm grew all over again. The fire had been a sort of a friendship test I suppose; the fact that we could contemplate doing it all over again told us things we liked. Peter Jackson of Brampton Garage, an enthusiastic Citroen dealer, was an immediate help in rescuing the car from Scratchwood, and offering to find parts for the rebuild from his extensive second-hand cache. He also helped in relocating the car to Wilsher’s new headquarters at Highbridge, Somerset.

Wilsher, after a short period of mourning, went to work on the ruin. His wife, Leslie, stripped the fabric upholstery out of the car and washed it repeatedly until the color scheme came back. We made various attempts to get a newish 2CV write-off to strip for parts, but affordable examples were rare. In the end, Wilsher settled for an old but healthy Dyane to provide the needed electrics, instruments, brakes, driveshafts, tie-rods and an engine (it had a label which read: ‘Next service 97,000miles’). A local panel man rejuvenated the burnt and rusted skin to a better-than-new state, and a lighter, non-standard grille was fabricated to plug the ugly hole that remained in the nose.

Just for the heck of it, Wilsher gave the car a facia of his own design, (to go around the Dyane instrument pack) and, bless my soul, a flour change using a lever ‘won’ from an old DS. A big, white-faced boost gauge was given pride of place in the middle of the dash. The ‘black armband’ was my idea; we painted a single black stripe horizontally across the offside wing to commemorate the Scratchwood Inferno. There had been talk of building an intercooled turbo engine with water injection this time. But it made little sense on an engine of this age – and the budget couldn’t stand it, anyway. Our official reason was that the charge-cooling benefits wouldn’t be best utilised by an air-cooled engine. Still, the new suck-through system, really a third generation design, used previous experience in relocating the turbo unit to give a shorter travel for gases between exhaust ports and turbo. The heater was redesigned, the ‘cardboard’ trunking replaced with modern, fireproof ducting, and the whole engine bay was smothered with shiny fireproof material.

The turbo was overhauled by Turbo Technics and fed this time by a 1.5in SU carburettor on a modified TT adaptor. Wilsher reckoned the SU’s constant vacuum characteristics would give better flexibility down low. And so it has proved. Today the engine lacks a little of the bite of the old Weberised version (particularly since Wilsher is loathe to allow it quite the boost pressure of the younger engine).

It runs about 5.0psi now; in the old days it had various boost guises up to about 8.psi, while the driver watched like a hawk for pre-ignition on hot days. The Struggler Turbo 2 lived with me until late last year, putting in a trouble-free 4000miles. The ‘new’ old engine uses oil, and it needs watching, but the car will still do 80mph plus on the motorway. And its extra torque really tells on long hills and on give-and-take roads. It will rumble along at a steady 70 where other Citroen twins are hard-pressed to average more than 50-55. You can drive without any of the brain-curdling concentration on saving momentum which quick progress in standard 2CV demands. The performance is of the order of a 950 Fiesta’s – useful and flexible. I can’t remember any previous hot-up project interesting people as much as this one. It broke a general rule: it provided performance for a car which previously didn’t have any, instead of starting with something that was good anyway. How good it could have been if there had been a small and cheap turbocharger truly suitable for small engines (Garrett marketeers, answer please).

We’ve learned lessons out of this, Wilsher and I. His is that doing one-off projects for people never makes your fortune; mine that true engineering skill will probably have a good result on the most unlikely project. I’ve also learned to carry a fire extinguisher and to tell my insurance company. I’ve made a good friend too. Nowadays, the Struggler lives at Wilsher’s place, which is where it belongs. The engine has lately turned 119,000 miles and will need to be replaced one of these days. The gearbox groans a bit and the ancient dynamo has a struggle keeping the halogen headlights alight. But the turbo installation continues to be reliable. And in the cabin there’s not even a funny smell.

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