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Modifying a Lotus Esprit S4

To modify or not, that’s the question, one for which Dermot O'Hare had only one answer. Richard Lofthouse reports

By / Monday, October 31, 2005

O'Hare's Lotus Esprit S4 (the red one)

O'Hare's Lotus Esprit S4 (the red one)

Dermot O’Hare is amongst the most dedicated Lotus modifier you’ll meet, but to many Lotus enthusiasts, modifying is a black art best left to the Max Power brigade.

45 years old, with a wife and two kids, however, Dermot misses the average modding demographic by a mile. Plus — wait for it — he’s a mega boffin, specifically a professor of inorganic chemistry at Oxford University, hailed as one of the 50 leading young scientists in Europe.

He was featured in the Sunday Times last year on account of his home-brew fuel, 98 RON Optimax uprated to an estimated 101 RON through the addition of various additives, a very simple process when you spend the rest of your life specializing in exploratory synthetic organometallic chemistry.

The Lotus Esprit S4


In the flesh, however, O’Hare is the plucky Irishman from Newry, Co Down, who made good on the mainland and then bought a bright red, 1994 Lotus S4 only to decide that it wasn’t nearly fast enough. 

The resulting Mk 1 O’Hare-modified S4 included arguably tacky cosmetic additions such as the gear stick cap imported from an Honda S2000, but mostly comprised mechanical changes such as a dump valve and an uprated turbocharger.

Disaster struck last September when he was ‘out on a burn’ and blew the car up, fuelling speculation that the mad professor had done what most modders do best, ruin an otherwise excellent car by messing around with stuff they don’t fully understand.

O’Hare recalls his ‘moment’: “I had tinkered around with re-circulating air from the dump valve. I had installed this plastic 90 degree piece of plumbing from B&Q, but there was an internal sleeve that I didn’t silicon in correctly.

"It came out at speed and was immediately sucked into the turbo, which was probably operating at 100,000 rpm; the plastic disintegrated into a thousand bits, and the turbo blades were wrecked. However, the engine was completely untouched. All the debris was collected by the charge cooler, which has a very dense matrix. We later shook a lot of metal bits out of it.”

Prior to this, O’Hare told me he was getting itchy for a Ferrari, but thankfully his modifying instincts prevailed, and he figured he’d upgrade everything and go in search of Modena 360 territory – about 400bhp – despite only having the Lotus’ four cylinder, 2.2 litre, sixteen valve engine, and all of it for a budget of approximately £10,000.

The Mk 2 O’Hare S4 emerged earlier this year, and it achieved 165mph at the Pistonheads VMAX day at Bruntingthorpe, plus a sub-five second 0-60 sprint.

For a truly detailed -- and truly impressive, it has to be said -- account of the project, go to O’Hare’s Web site (see link below). But the basic project was to achieve the additional performance without fraying the car’s mechanical resilience to the limit or making it look daft.

Current modifications

Working through the list, the following modifications define O’Hare’s thorough approach. With the ignition system he’s added iridium spark plugs for better throttle response, and Magnacor KV85 competition spark leads and a high output MSD ignition coil.

On the fuel delivery front, he’s added an uprated Sytec fuel pump capable of track work, and he’s re-proofed his fuel tanks inside and out, using Melksham-based Arrow Radiators. He’s also opted for RC Racing Injectors, based on the obsolescence of the original kit and its poor quality. And he has made complex adjustments to the nozzle, plenum and throttle body in order to prevent loss of air flow from the turbo to the throttle body inlets.

He had the cylinder head taken to bits, de-coked and polished, the only modification being to cut the inlet seats to accept larger valves. He then added a custom ground inlet camshaft, and revised cam timing to open it up a bit from the originals, which were retarded owing to emissions constraints.

Crankshaft, flywheel, clutch assembly, pistons were all dynamically balanced and lightened by Steve Smith at Vibration Free.

Induction mods

A central modification was O’Hare’s decision to double the size of the charge cooler, based on the simple physics of lowering air temperature to increase power. As he notes: “You gain approx 0.5 - 1 hp for every 1 °C you can lower the inlet air temperature.” First time around he fitted the Craig Davies pump available from Demon Tweeks. But second time around he opted for a 12V magnetically driven, marine specification pump with twice the pumping capacity, with the essential charge cooler blanking plug to prevent potential loss of oil pressure.

O’Hare has also imported a bespoke turbocharger from WC Engineering in the US, apparently a fountain of knowledge on Esprit-related turbocharging issues and staffed by serious specialists. It incorporates simple but extremely effective, state of the art components such as a ceramic ball bearing assembly.

There are too many mods to list, but there is plenty of advice for the novice resting on nothing but basic physics. For example, Lotus fitted the original charge cooler directly above the engine, dramatically reducing its thermal efficiency, apparently owing to lack of funds and time.  

O’Hare has come up with two very simple solutions to this problem, neither of them costing more than a few pounds and a couple of hours in a garden shed. First, every Esprit owner should use the ‘dummy’ air intake on the near side to pipe air to the charge cooler, using any piece of tubing they can lay their hands on. Secondly, they should buy a slice of Nimbus GII heat shield – a simple piece of aluminium sandwich with exceptionally low thermal conductivity productivity – to separate the charge cooler from the engine, thereby greatly enhancing its performance. 

Of course, O’Hare has suffered the normal trial and error along the way, and the Lotus dealer responsible for the basic work, Peninsula Lotus Devon, went through a few sleepless nights themselves trying to get the whole package together.

But at the end, it is a beautiful result, with all new parts powder coated in the right shade of red, as the pictures of the engine bay so clearly demonstrate. The result is a purist’s modification or a very special car, eliminating most of the problems of the original car but also taking it to performance thresholds it was never designed to go.

This has left O’Hare with two residual head aches: upgrading the brakes and suspension to match the new power. Just a year ago, O’Hare said that on no account would he alter the original suspension set up, the one thing Lotus got right at the outset. 

Lotus - the modder

Yet Lotus itself is, according to O’Hare, preparing aftermarket kits for Esprit owners based on its admission that the original suspension, although brilliantly set up, was based on cheapo Munro shocks and springs rated for a measly 20,000 miles. O’Hare got away with 40,000 on his, but now they’re sagging, especially with the power upgrade that causes acceleration squat. 

So Lotus is now the modder, and looks set to offer all S4 owners Eibach-Bilstein kits for each incarnation of the Esprit back to 1985. This is perhaps an official seal of approval on O’Hare’s project, given that Lotus engineers drove his car recently to see it for themselves.

Yet the idea that the more softly sprung, original car, built according to the pre-track day era when a supercar was meant for the public road, will be lost forever in a haze of upgrade frenzy…well it’s sacrilege, isn’t it?


Images by Matt Watkinson

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