Lotus Eleven/Elise/Exige. Manual

Lotus Service Notes

Exige S/C

Page 6

Supercharger & Ducting

Connection to chargecooler inlet

Connection to chargecooler outlet

New inlet manifold

Chargecooler

inlet duct

Supercharger outlet connector

Supercharger outlet elbow

Supercharger

outlet adaptor

Mounting lug for

supercharger

Fixing point

Swan neck

Chargecooler

to manifold

adaptor ﬁxings

outlet duct

(supercharger

inlet)

Fixed to engine

mounting plinth

By-pass valve

capsule

pl4207ls/pl4209lr

Strut to clutch

Alternator anchor

slave cylinder mounting

Lotus Service Notes

Exige S/C

Page 8

Air is drawn from the standard air cleaner through the throttle body and adaptor and into the supercharger

axial intake port. From the outlet port on the compressor top surface, the air is directed through a 'U' bend duct

to the LH end of an air/air chargecooler rubber mounted above the engine, where airﬂow gathered from the roof

duct is used to cool the compressed intake charge. The chargecooler uses four rubber bobbins attached to two

mounting brackets themselves secured to the inlet manifold and cam cover. A charge air temperature sensor

is mounted in the outlet tank of the chargecooler. The cooled air exiting from the RH end of the chargecooler

ﬂows via another 'U' bend duct into a cast alloy intake plenum/manifold. The whole intake tract has been kept

as short as possible, and uses large diameter ducting and generously radiused bends to optimise airﬂow and

efﬁciency to the particular beneﬁt of throttle response and fuel economy.

A re-shaped breather pipe is used to connect the crankcase breather spigot to the cam cover and circum-

navigate the supercharger.

On the 240R and Cup cars, a stainless steel 'level one' sports exhaust mufﬂer (LOTAC05334) is ﬁtted to

provide an acoustic enhancement and features enlarged, slash cut tailpipes and a near 20% weight saving

over the standard system. Exige S models use a stainless mufﬂer with a single, oval shaped, tailpipe design.

240R models use 4 standard port fuel injectors together with an additional 5th injector mounted in the

intake end of the inlet manifold. Other 240 and upwards versions, and all USA cars, use 4 special high-ﬂow

port injectors. The Lotus engine management system is reprogrammed to suit each engine speciﬁcation and

incorporates additional functions to control the ﬁfth injector (240R) and supercharger by-pass valve. The boost

characteristics have allowed the switching point from low to high lift cam proﬁle to be modulated between 4,500

and 6,200 rpm (at normal running temperature). The airbox ﬂap valve opens at 4,500 rpm. 240R models use

a mechanical cable operated throttle body, whereas the Cup and Exige S cars use '06 model electronic throttle.

Twin front mounted oil/air coolers are ﬁtted to all supercharged Exige.

Accusump - 240R & Cup 240

To provide protection against the possibility of oil starvation caused by the extreme g-forces possible with

track use on slick tyres, the 240R and Cup cars are ﬁtted with an Accusump oil storage system.

A 2-litre Accusump reservoir is mounted in the rear luggage compartment, plumbed into the LH oil cooler

return hose at the front of the engine bay, with the connecting hose routed over the RH rear wheelarch. The

device comprises an alloy cylinder divided by a sliding piston, one side of which is connected to the engine

oil supply, with the other containing pressurised air. With the engine running, the cylinder is charged with oil

provided by the engine oil pump, but if the pressure should drop for a short period due to oil pump pick up pipe

exposure during extreme braking or cornering events, the accumulator air pressure forces the stored oil into

the engine lubrication system to maintain continuity of oil supply until normal conditions are resumed.

A one-way valve at the oil cooler connection of the 'T'- piece ensures that the oil discharged from the Ac-

cusump is directed into the oil pump and not the cooler. An Electric Pressure Control (EPC) non-return valve is

ﬁtted at the connection to the Accusump cylinder, to allow cylinder charging when oil pressure is above 35 - 40

psi, and cylinder discharging at engine oil pressures below 35 - 40 psi. The EPC is also linked to the ignition

switch such that with the ignition switched on the valve is open to allow oil ﬂow, and with ignition off the valve

is closed to retain oil within the reservoir.

Normal Operation

When the ignition is turned on, the EPC valve is opened, allowing the pressurised oil stored in the reser-

voir to ﬂow out into the engine and prime the oil galleries and bearings ready for start up. When the reservoir

has been emptied, the pressure gauge on the end of the reservoir will indicate the pre-charge pressure which

should be 7 - 15 psi.

When the engine is started, engine oil pressure will force the reservoir piston back, such that the reservoir

air pressure gauge will indicate engine oil pressure. At pressures above 40 psi, the electric valve is switched

off, enabling the non-return function to allow oil ﬂow only from the engine to the Accusump. The pressure of

stored oil will accord with the highest engine oil pressure achieved until either; a) pressure falls below 40 psi,

at which point the valve opens, or b) the ignition is switched off, and then on again, opening the valve as de-

scribed above.

With cold oil, 80 psi may be generated, but idling at normal running temperature should produce around

30 - 40 psi. Note that the pressure reading on the reservoir gauge is damped and will lag behind the actual

instantaneous pressure. A pressure relief valve in the end of the reservoir protects the equipment from over-

pressure damage. If oil is seen to escape from this valve, a fault in the lubrication system is indicated, or

excessive rpm have been used with cold oil.

When the ignition is switched off, the electric valve closes and the oil stored in the Accusump at that time

is retained in the cylinder ready for re-starting.

Page 9

Lotus Service Notes

Exige S/C

Routine Checks

Be aware that the indicated oil level on the dipstick will depend on the amount of oil stored in the Accu-

sump, which itself is dependent on the both the Accusump pre-charge air pressure and the engine oil pressure

when the ignition was switched off.

Before checking the oil level, the Accusump pre-charge pressure should ﬁrst be checked; turn on the

ignition to open the EPC valve and allow the stored oil to be discharged from the Accusump. The pressure

gauge reading will drop during this discharge, but should then register 7 - 15 psi representing the pre-charge.

If necessary, adjust the air pressure using tyre inﬂator equipment on the Schraeder valve adjacent to the gauge

and set to 15 psi.

The oil level should now be above the top mark on the engine dipstick. To check for correct oil level, the

engine should be started at idle to charge the Accusump until the pressure gauge registers 40 psi. If idle oil

pressure is below 40 psi, increase rpm until 40 psi is achieved and then switch off. This pressure should then

be retained in the cylinder. If idle oil pressure is over 40 psi, the engine must be run to normal running tem-

perature before switching off and then re-starting as above.

After a suitable oil drainback pause, the sump oil level may then be inspected on the disptick, and the

level corrected to the top mark. It is important to maintain oil at this level to accommodate the oil transfer into

the Accusump at pressures greater than 40 psi. Be aware that checking the oil level under any conditions other

than 15 psi pre-charge and 40 psi oil pressure will produce inconsistent results.

Oil Changing

Before draining the sump, the ignition should ﬁrst be switched on to open the EPC valve and allow the

Accusump to discharge the stored oil into the sump. Check that a pressure of 7 - 15 psi remains in the Ac-

cusump at the end of this process, and if necessary top up the pressure using tyre inﬂating equipment on the

Schraeder valve next to the gauge and set to 15 psi.

The oil can then be drained in the usual way, with the quantity contained in the oil cooler lines disregarded

for the purposes of routine maintenance. If an engine failure has occurred, with possible debris contamination

of oil hoses and coolers, it is recommended to replace both oil coolers, and to replace or thoroughly ﬂush the

feed and return hoses. At each service interval the in-line ﬁlter gauze in the hose between the Accusump and

'T'- piece, should be renewed.

After renewing and pre-ﬁlling the engine oil ﬁlter, and replacing the in-line ﬁlter gauze (see above), reﬁll the

sump to about 10mm above the top mark on the dipstick. Start the engine and allow to idle. Do NOT rev the

engine or drive the car. The Accusump will take up to 2 litres of oil from the sump to store within the cylinder.

Accusump reservoir Air pressure gauge

EPC valve

assembly FRONT

Mounting clamp to

boot ﬂoor

In-line

ﬁlter To LH port From oil

on sandwich cooler

plate

pl4015cLR

Lotus Eleven/Elise/Exige. Manual - part 125