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Engine Performance Upgrades






Wheels & Brakes


Chip Upgrade

Parts used:

    ECU Chip #2 installations based on S4s-MK5-code with the 3k stumble reduced.

This upgrade is a must for those who like to upgrade performance without having the expense to play with anything else at all.
Hint: To help you access the ECU screws we suggest to remove the Air intake hose which maybe in the way. As soon as you remove the ECU cover I suggest installing a chip base so you can remove the chip easily any time you want.

This work can take about 1 hour to complete.

  • Will also give about 210 BHP and a little more torque +5% in low and midrange
  • Gives very good drivability and is a very good and safe performance upgrade for all SE/S4

This chip is based on the improved S4s-Mk5-code but with +5% torque (and similar top end power)
Is a very good choice like the improved S4s but with that additional punch in low- and midrange
To help you with managing the ECU and getting a read out of the errors and you require a program (freescan).You need a serial cable to connect to you PC as we have. If you're unable to make the cable please contact us for help.

To install the chip simply follow the illustrated process on our mods page

Road test:
The car was found to drive much smoother with noticeable lots more power in the midrange area. This is a good start for all stock Esprit's. Running chip #2 gives you more refined running and extra performance and an all-round better Esprit over the stock chip. This would also benefit those who run their Esprit's all year round.

Chip #2 is available from our parts page.

We recommend continuing to the second stage to benefit from the ECU upgrade.

STAGE 2 Air intake and Air box Filter

Parts used:

  • Air box ram air Modification
  • K&N Filter
  • Oil catch tank
  • Chip #2

Not all Esprits use the same air ram intake size pipe, depending on the year of manufacturing as Lotus factored forever made updates while the vehicle was on the assembly line as to be expected, lucky enough ours had 100mm intake hoses pipes across the air assembly. So we only had to cut it a little shorter to rich from the intake from the body air intake panel directly to the air box and by past all the unnecessary loops (Usually the factory directs this hose to an area at the right quarter panel which causes the fresh air to go for a long trip and back with a another hose to the air box. This modification can take about 30 minutes to complete. However if your model has got an inlet smaller then 100mm you just have to make it up with any pipes you can find or make a mold out of fiberglass.

This illustrated process is available on our upgrades page

Note: Be careful not to knock out of place any of the black thin vacuum pipes especially the one to the map sensor (see pic below) otherwise you will experience a very bad start to the car with code 33 error and possibly and "check engine warning light displaying.

Note the position of the vacuum hose on the map sensor located under the right guard

K&N Filter: We managed to score the correct size K&N filter for the job as I found out they are sometimes hard to get but now available on our parts list page. This unit should last for a very long time in fact some people claim possibly for the life of the car, as the only requirement is cleaning it.

To get to the filter you need to remove the Air intake hose to the Turbocharger unit and the 2 x 10mm bolts on both sides of the Airbox.

Note: Make sure to use the original rubber seal from the old filter as the K&N filter does not come with one.

<Original and K&N air filter


Oil Catch Tank: High performance engines and race cars are routinely fitted with catch tanks to collect oil mist that is produced by pressurisation of the sump.On the Esprit there is an oil/air separator (Green plastic thing, see below) which is supposed to trap all the oil and feed it back to the sump.

We recommend to find a good place for your Oil catch tank before you start cutting or disconnecting hoses. Since we don't like drilling the Air box to fit the tank as its been suggested by others we decided to place it a little lower (see pic below).
The catch tank was fitted by Steve Tailor from " The elan factory" in a lower more natural position for any oil deposit to flow through properly as gravity is important to this mod.

If you are happy with it's resting place, disconnect the thick oil breather hose going to the air box and extended with your choice of hose into the catch tank if you require, ours did not need an extension only a small step down hose to connect properly to the tanks fitting.

You will need to block the fitting where the hose attached on the air box using a plug (see pic below). We also installed a breather filter to the oil catch tank since it must be able to breath.

Note: This modification does may not comply with road regulation in some countries including Australia. Your other choice to comply is to fit the breather oil catch tank hose back into the Airbox.

This process is illustrated in our mods page. This process is referenced from LEW. LEW has used a different unit than ours but you will get the idea.
If there is any interest in this Catch Tank Kit, then it can be supplied as a package by us. e-mail us for details.

Road test result:

This completes the 1 stage of the project. We road test the vehicle with a K&N Air filter installed and the car felt and sound so much more like a super car. You can hear the turbo and Air box working well that's if you don't mind those kinds of sounds, the power and power response feels like it has increase up to 20%. We can now notice wheel spin after 3000 revs, power is almost constant during the rev range, some turbo delay is to be expected however this should be solved on the next stage.

Dyno results: 203BHP

Note: measuring Horse Power at the wheels. (on 4rth Gear)

On a dyno you will always see very strange Hp-figures when you put an Esprit on it. The main reason for this is the fact that MAT (= mass air temp) and coolant temp will be too high on a dyno and for that reason the ECM will retard ignition and as a next step it will also lower max. boost. There are also some other parameters that will have an influence especially when you do these dyno runs. For all the above reasons the final figure on Horse Power can differ up to 40% less from what the vehicle can do on the road.

DYNO Graph ECU Chip #2


  • Chip # 5installation.
  • Manifold updates
  • Fuel Injector service/test
  • Back Pressure Valve

Installing a BOV at this stage the Esprit will perform better through changing gears by reducing turbo lag. The turbo will also spin up quicker when back on the throttle as it will now keep spinning. This kit will also protect your turbo from wear, by releasing pressure which would normally stall the turbo causing increase wear and tear.


However we have done some cosmetic work to the inlet manifold after consulting with many experts regarding powder coating the area, however powder coating was not recommenced for our project due to the heat transfer characteristics the coating provides and remember we are trying to cool the area as much as possible here, so we ended up with the next best solution of plastic media blasting which was done by CAR-STRIP in Melbourne. Plastic media blasting apparently does not leave any particles which can harm the engine and its also easy to clean with water after the process has finished.

We finished the job with a special red VHT wrinkle paint and PPC protective clear coating for the inlet manifold.

The 4-cylinder models (SE, S4, S4s & GT3) use an air/water heat exchanger (chargecooler) to reduce the air inlet temperatures and so increase the density of air leaving the turbocharger compressor before it enters the intake plenum chamber. The chargecooler is flexibly mounted to the engine, and uses flexible high temperature hoses to connect the intake and outlet to the compressor and plenum respectively. Air passing through the chargecooler flows past a matrix of tubes through which water is circulated in a closed system by an engine driven pump. Heat is transferred from the intake charge air to the water which is pumped via alloy pipes routed through the chassis backbone, to a chargecooler radiator mounted ahead of both the air conditioning condenser and the engine cooling radiator.

The system is prone to many problems and it is vital for the optimum performance of your car that this system is in tip top condition. Lowering the inlet air temperature is a very safe and easy way to increase engine performance. You gain approx. 0.5 - 1 hp for every 1 C you can lower the inlet air temperature.

Our initial upgrade is to achieve a better results with the factory assembly. Revolution Racegear provided us with a special heatshield material for the chargecooler, this product provided sufficient heat protection from the T3 turbo generating heat using the stock pump. All these products worked well supporting the heat transfer we wanted to achieve and help the engine to run cooler.

Our team is also working on a temperature controlled Johnson CM30P7-1, Part Number 10-24504-03, 12V which we will test on a later day.

* Recommended position for the Johnson pump (no need to drill the body. Use the solenoid screws coming through the boot panel

The Johnson pump can be wired to the system a couple of ways showing in our upgrades page and more importantly this solution is also supported by Lotus Factory. However our team will develop a temperature controlled circuit at a later stage to improve the operation of this system even more, this mod will help the chargecooler to run at its optimum temperature while circulating the water as the engine requires during higher temperatures. That way the pump will not run at full power as per the original tests. This pump was tested at 30lts/min.

We suggest if you ever get to this stage to also improve the internal surface of the manifold, there is a lot of air flow lost from the turbo to the throttle body inlets. International tests have shown that the standard inlet system lost over 30 cfm of airflow from turbo to the inlet ports. However with a little matching up of the inlet manifold to the ports, gas flowing the nozzle and plenum you could get this down to about 7-8 cfm loss. The entry of the nozzle to the plenum is quite restrictive.  Over 5mm can be machined from the entry of the nozzle to the plenum and all the edges can be reduced off and matched to the individual gaskets. Thanks to Steve from "The elan factory" showing us the way it's done. Next step is to polish the manifold internals and cut the casket to the new shape of the manifold, this will help to gain the air flow and complete the job right.

matching the portsFinished Product

Fuel Injectors Service: Both stock primary and secondary (Bosh) injectors were tested and passed. At this stage we will not make any upgrades to the injection system till we complete all the dyno stages. In case of an upgrade the only recommendation is to replace only the secondary injectors (see stage 6) as the primary will work very well up to 350+ HP.

Stock Secondary Injectors measured at 17ml flow, Primary Stock Injectors should be at 36ml flow

Back Pressure Valve: Since we had clear view to the inlet manifold during this stage we were able to remove the exhaust back pressure valve assembly attached on the manifold including the pivot arm showing on the picture below. We also had to make the appropriate modifications to the vacuum lines to trick the ECU that the system is still connected.

You will also need to install a spacer at the exhaust where the back pressure valve is located as the valve will now be closed (Don't go anywhere before you do this) If you don't have the appropriate exhaust spacer at the time you can wire the valve open for the time been to hold the butterfly open or If you don't want to install the spacer you can also take the butterfly off from the assembly which will cause you to disconnect part of the exhaust to get to it and remove the butterfly from the assembly. If you are able to do this you can re install the original butterfly body back to its original position to act as an spacer this time.

Exhaust spacer is available from our parts list part seen below.

This process is illustrated on the mods page.

Road Test: The first thing we notice is all the new sounds coming from the BOV valve and the Airbox. it's like driving a different vehicle, this is not quite car any more and it takes time to get used to from the stock system, forget about turning the stereo on there is a better song at the back end. The power is more noticeable at the top end as the boost has been increased so plenty of pull from the 2.2ltr engine.

Dyno results: 209 BHP

Note: measuring Horse Power at the rear wheels. (on 4rth Gear)

On a dyno you will always see very strange Hp-figures when you put an Esprit on it. The main reason for this is the fact that MAT (= mass air temp) and coolant temp will be too high on a dyno (up to 20 degrees celcius noted in our tests.)and for that reason the ECM may retard ignition and as a next step it will also lower max. boost. There are also some other parameters that will have an influence especially when you do these dyno runs. For all the above reasons the final figure on Horse Power can differ up to 40% less from what the vehicle can do on the road.

NOTE: This tests were focused on the performance produced by #5 ECU ship installed in a stock engine with the original Exhaust system.

DYNO Graph Chip #5 results


Parts installed: (Mark I) Sports EXHAUST SYSTEM fitted with a Catalyst
testing Chip#2 and #5 with a K&N filter.

Road Test: The car was much stronger across the rev range with the turbo coming a little faster. The sound of this system is perfect for those who don't want to attract to much attention. This system is totally legal and now the car sounds as it should.

Dyno Results: 227 BHP

ECU Chip #2 and #5 with the Mark I sports exhaust system produced clearly 218 and 227 BHP. See more detailed tests with many other ECU chip configurations in our Exhaust page


DYNO Graph ECU Chip #2 Vs #5


Parts Installed: ECU PROM UPGRADES Chip#6, (Mark I) Sports EXHAUST SYSTEM fitted with a Catalyst, K&N filter.

Road Test: This is the first time that we noticed considerable deference in Horse Power using deferent chips. The #6 chip is the way to go for maximum performance however it will require some extra mods to the fuel injection as we have noticed the car running lean across the rev range and the turbo lucking of top end power due to its factory limitations. This was expected ....!!!

Factory Turbo
The 1990-1993 SE and 1993-1996 S4 were fitted with a Garrett T3 with a 40 or 50 trim compressor wheel. It has a maximum flow rating of 30 lbs/min at a pressure ratio of 2.2 (1.2 bar boost) with 58% efficiency.
The bottom line is that once you start producing a very free flowing engine setup; air filter, ram air mod, exhaust mod, de-cat pipe the turbo then become the weak link in the system. The turbo in the S4 cannot flow enough air at the top end, the result is that the inlet temperature (MAT) raises very dramatically and boost drops away. In fact there is a condition in which increasing the boost will actually produce lest power this is clearly demonstrated from the graph below.

As mention above the graph is also showing drop of power due to fuel starvation which will be fixed on the next stage.

Dyno Results: 247 BHP Stock turbocharger

Dyno graph ECU Chip #5 Vs #6 with a factory turbocharger.

Stage 6

Parts Used: High Flow Turbo, high volume secondary injectors, (Mark I) Sports EXHAUST SYSTEM fitted with a Catalyst, K&N filter, High pressure fuel pump.

Fuel injectors _ Secondary: Although the two plenum secondary injectors are similar in construction to the primary injectors they are actually high impedance (16 ohm) 190 cc/min or 18 lb/hr saturated type injectors. These injectors operate at a fixed frequency of 128 Hz, with the quantity of fuel delivered dependent only the pulse width sent by the ECU.

The stock S4 ECU fuel mapping only triggers the secondary injectors over 4800 rpm and 0.7 bar boost. We have fitted 270 cc/min (25.7 lb/hr) RC Racing high impedance injectors. If you are undertaking major engine mods it is very important to think about the correct fueling.

The ECU goes into "open loop" mode above 94% throttle openings, in open loop mode there is no feedback to the ECU from the lambda sensor, under these conditions fueling is based on pre-stored fuel maps in the ECU.

Our first Dyno run with the new local made experiment turbocharger and secondary injectors showed the engine running lean across all the rev range. At that stage we introduced a high pressure fuel pump to correct this issue.

< Secondary Injectors

Picture above is an image of the 2 secondary RC injectors on the bottom compared to the standard Lotus Bosch injectors.

High pressure fuel pump: As shown in the previews Dyno graph at this stage the vehicle is showing running lean at the top end. To correct this we have installed a local supplied high pressure racing fuel pump can support engine up to 450 HP.

The standard S4 fuel pump is a roller vane type, high pressure electric fuel pump mounted within the right hand fuel tank. The pump supplies fuel at 30.5-55psi to the fuel rail. On the Sport 300 the fuel pump was upgraded to a higher capacity pump as fuel starvation was experienced in testing. Unfortunately the Sport 300 pump is now obsolete and so an alternative up rated delivery compatible in-tank pump was purchased locally.

< High Pressure Fuel Pump.

The removal and installation of the pump is available here.



After 8 months R&D and testing recommended solution on turbocharger units available, our team has installed a ball bearing unit modified locally to produce the minimum satisfactory results used on a stock internals engine producing 250 HP at the wheels on the dyno.

We noticed a better performance on the road as the Mat sensor is running much cooler producing an estimated 20 HP more due to cooler Mat temp.

On the dyno the car was much stronger and delivery smoother power in the top end.

However we will continue testing all the solutions available in the near future to improve the results we have achieved using our local and overseas experts/suppliers.

Over all including stage #6 we have managed to increase the HP power of a stock internal engine by 40% by adding the quality parts as shown above. We will be happy to discuss any of your upgrades or concerns with you regarding any of the stages shown.

More info on the turbo results


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