From the September print issue of AE
Lotus claims that its bioethanol fuelled Exige
265E is the most powerful road version of the Exige to date, and may well
be the “world's quickest road-legal E85 bioethanol car”.
Ethanol’s high octane rating, combined with the pressure charged engine in the 265E, allows more power to be produced in the engine than with a conventional petrol fuel. The 265 in the name refers to the approximate horsepower developed.
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| You can't buy an E85 Exige because Lotus made only one |
The unit produces 268 ps (197 kW) at 8000 rpm and 249 Nm (184 lb/ft) of torque at 5500 rpm. This is an increase over the standard petrol Exige S of 21 per cent – 47 ps (34 kW) in terms of power, and 16 per cent – 34 Nm (25 lb/ft) of torque. The total weight to power ratio of the 930 kg unladen car is around 287 ps per tonne.
The engine is a four-cylinder, 1.8-litre 2ZZ-GE VVTL-i, featuring a roots-type Eaton M62 supercharger, run from the crankshaft with an integral bypass valve for part load operation and a “sealed-for life” internal mechanism that means it does not require the use of the engine’s oil.
It will rev up to 8000 rpm – or 8500 transient for up to two seconds. An electronic drive-by-wire throttle enables the “quickest engine response possible” and keeps emissions down. Four enlarged fuel injectors have been fitted on the 265E to increase the fuel flow under normal conditions, and two additional injectors are included in the supercharger inlet to increase the amount of fuel injected under higher engine speeds.
This also allows the greater latent heat of the ethanol to be used to further cool the charge air prior to combustion, in turn reducing the amount of power required to operate the supercharger, a smart double-use of the properties of ethanol.
In bioethanol vehicles, the additional oxygen atom attached to the ethyl alcohol molecule helps the combustion process in the cylinder to burn more effectively and provide more power – but with the drawback that fuel economy is slightly less than with regular petrol.
The engine also has two cam profiles – high and low speed – with a switch point that is completely variable depending on driving conditions and engine load. Lotus claims that the driver will be unaware of which cam is being used at any point in time. The result is to supply a smooth surge of power from idle to the full 8500 rpm limit.
The downside is that the Exige 265E is purely a research vehicle, and Lotus is saying that there are no plans for production.
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