The high-compression route for the normally-aspirated SE was a hint of how the final Turbo models ran out of production, prior to the October 1987 adoption of a completely new and much more rounded outline for the Esprit.
The Turbo Esprit HC (High Compression) appeared at the October 1987 Motor show in London. That occasion was also used to unveil another limited edition, based on HC running gear, that was intended to celebrate twenty years of Lotus in Norfolk and up the price per Esprit.
Sharing the limited Earls Court stand space in the autumn of 1986 were two versions of the HC, both offering 215bhp at an unchanged 6,250rpm (a 2.5 per cent bonus in power). Torque (the power to pull you through mid-range blues) was more urgently tweaked: 220lb ft at 4,250rpm representing a 10 per cent elevation, and a 250rpm drop in peak torque engine revs.
To make an Esprit HC yield another 5bhp and an additional 20lb of torque, Lotus had utilized some Excel SE engine techniques. Compression could not escalate beyond 10:1 with a turbocharger huffing in its four-valve-per-cylinder ears, but 8:1 was then reasonably advanced, especically given that this was not an electronically-managed fuel injection engine. In fact, Lotus increased the size of the carburettors (specifying Dell'Orto DHLA 45M), specified a balance pipe and ensured that the intake tracts were modelled on those of the Excel SE.
Mahle-forged pistons brought the increase in ration from 7.5:1 to 8:1; Nikasil process for the liners was specified once more. Lotus rather reluctantly joined the European low-lead petrol age stating: 'The new Lotus turbo engine can be safely operated on unleaded fuel (minimum 95 RON). We recommend 4 star (98 RON) for maximum engine durability.' In other words, 'don't call us if it pinks a pistion to death . . .'
Other fundamental changes to the engine at this point included new cast-iron manifold castings 'to improve gas flow' and a replacement casing for the Garrett AiResearch T3 turbocharger. Lotus also allow the boost to increase from 8psi to 9.5psi, which was approaching boldness, given the increase in the compression ratio.
Full performance results, according to Lotus, are given below, but can be summarized as offering a lot more mid-range acceleration (plus 20 per cent, said Lotus). Maximum speed was unaffected; fuel consumption was improved at constant speeds, and acceleration was just fractionally better than the alreay sensationally rapid 0-60mph time of 5.5 seconds achieved by the 210bhp turbocharger.
Interior improvements on all Esprits now included adjustable rake for the seat backs, and you could release the rear 'hatch' from within via remote control.
longitudinally, mid, rear-wheel drive
Head/ block al. alloy/al alloy. 4 cylinders in line.
Bore 95.3mm, stroke 76.2mm,
Valve gear 2ohc. 4 valves per cylinder.
Compression ratio 80 to 1.
Electronic breakerless ignition.
Twin Dellorto DHLA 45 carburettors
Garrett T3 turbocharger.
boost pressure 9.5psi (0.67bar).
Max power 215bhp (PS-DIN) (160kW ISO) at 6250rpm.
Max torque 2201b ft (298 Nm) at 4250rpm.
Final drive ratio 3.88:1.
Front, independent, double wishbone. coil springs, telescopic dampers, and-roll bar.
Rear, independent, upper and lower transverse link with radius arms, coil springs, telescopic dampers, anti-roll bar.
Rack and pinion.
Steering wheel diameter l4ins,
2.9 turns lock to lock.
Front l0.1ins(258mm) dia ventilated discs.
Rear l0.8ins (275.9mm) dia discs.
Al alloy,7ins rims front. 8ins rear.
Goodyear Eagle NCT tyres
size 195/60VR15 F, 235/60VR15 R.
|Time mph (secs)
Standing quarter mile: 14.4secs, 98mph
Urban 15.7mpg, 56mph 35.6mpg and 75mph 28.8mpg. Grade of fuel: Premium, 4-star (96 RM) or unleaded (95RM) Fuel tank: 18.0 Imp galls (82 litres)
Pedal 15lb; Travel: 6.O ins
kerb 3052lb/1386kg distribution % F/R 51/49 Test 3434lb/l559kg Max payload 501lb/227kg
12 months/unlimited mileage. 8-years anti corrosion
Turbo Esprit Tyre News
Lotus Esprit World has managed to get a World Exclusive on testing done at Hethel on replacement tyres for Giugiaro Turbos. Lotus have now completed testing and are waiting for TUV approval, which is expect to be a formality. So any owners with Giugiaro Turbos can now buy and fit tyres tested and recommended by Lotus for their model. Below is the information direct from Lotus.
Lotus Turbo Esprit Tyres
Lotus has now completed the Tyre Investigation to find and approve an alternative to the currently specified Good Year Eagle NCT that is now obsolete. The sizes currently specified are: -
Front 195/60 VR 15
Rear 235/60 VR 15
The rear size of 235/60x15 is now a non-standard size and availability is very limited. Lotus has now completed an assessment of alternative tyres & sizes. In order to ensure vehicle compliance (tyre coverage & speedo calibration etc.) tyre choice was restricted. The new recommendation is as follows:
Front 195/60 VR 15
Rear 225/60 VR 15
The above specification has been tested & approved by Lotus. The TUV approval documentation has been completed and the application submitted to the relevant authority to cover the German Registered vehicles.
Several manufacturers tyres were tested. The following were considered to give the best handling & ride package and would be the products recommended by Lotus.
Dunlop SP Sport 01
Other makes of tyres tested did not produce the handling / ride requirements that Lotus consider desirable for the Esprit Turbo vehicle.