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Esprit Engine Upgrade
Power Upgrades for NA and Turbo Engines now Available from www.Lotusbits.com


For years Lotus enthusiasts have enjoyed un-paralleled driving pleasure from their cars. The excellent dynamic behaviour and the superb chassis of Lotus's has always suggested that the cars can take significantly more power. With the later turbo 910 engines and of course the V8, Esprit owners eventually got the power their car deserved. However, when the turbo waste gates stick and boost the engine to destruction, ownership often ends in tears.

Lotusbits.com have over the last year been working closely with Ultimate Performance LTD to come up with a properly engineered engine upgrade that would take the 900 series engine to a new level of performance. Today we are pleased to be able to offer a range of up-grades that can take your 160 bhp 907 or 912 engine from 200 bhp all the way up to 270bhp without having to turn to turbo's, Nitrous Injection or any after market add-on. Our conversions are based around getting the best from the existing engine while minimizing all the stresses and potential damage added by the often fatal after market add on's.

Our engine upgrades have been competition proven with 100% reliability in our own Lotus Sunbeam Rally car. Our performance engine has taken us to second in class in the Rally of The Midlands and has successfully out performed all the other Sunbeams (4) on the promenade stages, not to mention the 5 Subaru's and 6 Escort Cosworths that where left standing.

The up-grade options come in a number of stages. Depending on your budget you could start with the bare performance head, gas flowed and ported to perfection with the latest CNC machines to guarantee an error free and repeatable result. This always comes with a matched inlet manifold to ensure the head delivers its best. The next stage will add cams with increased lift that will aid the delivery of max gas flow to the cylinders. Beyond that we are now working on up rated and lightened valves that will allow us to apply even higher lift cams to push the performance even further.


The graphs below show the increase in power and torque on our own Sunbeam engine. This engine was fitted with an Ultimate Performance Ltd head, L14 cams on both Inlet and Exhaust, 10.9:1 Mahle pistons (as on SE High Compression engines) and a Tony Law exhaust manifold. The figures are a little hard to make out, but yes, that 219.8bhp @ 7246 revs and 171.1 lbft @ 6232 revs

The real petrol head's will appreciate the increase in gas flow. The basic head will flow 126cfm, our performance head comfortably exceeds 170cfm.

The table below gives a cost guide.

Cost (£)
Ultimate Performance Ltd. bare head & Inlet manifold – With original guides – only replaced if badly worn with matched manifold
+vat £100 surcharge if donor head required
Ultimate Performance Ltd. bare head - new guides
set of standard valves (used, standard 907 0r 912)
Pair of L14 high lift cams (freshly reground)
Mahle pistons - used - 10.9:1
SE cam carriers and lids
Freshly balanced rods
Freshly balanced crank - 2.2 cross drilled
Freshly balanced crank - 2.0 cross drilled
912 non SE block set
912 SE block set
Ultimate Performance Ltd “Ultimate” head - big valves - 6mm stems, ultra high lift radical billet cams, light followers, up rated valve springs spring caps and collets

Cost really depends on how far you want to go, but the head and manifold set start at £1000. From just supplying the parts to completing a full engine build and rolling road tuning, we can work with you to define the best package that suits your requirements and budget, so please give us a call and lets work together to give your Lotus the performance it has always been crying out for.

For more details or to discuss your requirements contact Mike Taylor at Lotusbits.

Email: lotusbits@hotmail.com
Tel: 07866 255614 or 01788 815158
Fax: 01788 815036.

For lots of other Lotusbits, take a look on the web at www.Lotusbits.com .

Model Information
The engine upgrade packages have so far been developed for and tested on Naturally Aspirated Carburettor engines and are equally suitable for S1,2,3 and Stephens type NA Esprits. In addition to this there is no reason why the same head could not be applied on Turbo cars (obviously with the Turbo valves fitted) since these engines too would benefit from the major increase in flow into the combustion chambers.

All variants should gain a major power lift from making the head swap, but in order to exploit the increased flow fully, the carbs should be re-jetted and preferably fitted with larger chokes as well. The vehicle should then be road tuned.

Injection variants
Unfortunately the Lotus choice of throttle position sensing rather than mass airflow metering means that the engine management would not know that more flow is being drawn into the engine and hence the fuelling would be weak. These engines MUS%T have the ECU re-mapped or some other method of enrichment applied (eg variable pressure regulator). We have not yet ventured into re-mapping of ECU's.

Simon at Ultimate Performance Limited is truly an expert when it comes to extracting more power from engines and working with Lotusbits.com, we can together advise potential customers of the best way to deliver the engine upgrade package that best suits their needs.

If you have any comments, feel free to e-mail me with at admin@lotusespritworld.com


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