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Peformance Cookbook

There's a lot more to performance than just making more horsepower, and there is a lot more to making more horsepower than just “turning up” the boost. Remember that the Lotus shines at handling, if you want straight line speed there are better cars to be modifying (and they are cheaper to modify too.) That said, getting a little more kick in the pants is part of the reason we own these cars.

Since the Esprit's handling really can't be improved dramatically (your best bet is sticky low profile tires on larger wheels,) this cookbook is for horsepower and torque.

Most cars come from the manufacturer tunes so that all it's components are matched. This means that if you want to chance one thing in the name of performance, you may have to make ten other chances to take full advantage of any modification.

Engine internals

The stock short block is pretty strong and you shouldn't need to “upgrade” beyond many the OEM parts.

Ceramic coated JE pistons is a worthwhile investment (especially if you need to do a rebuild anyway.) This will increase your compression ratio to 8.5:1. JE pistons are not off the shelf for this application so you will have to have them custom made. You can work with the folks at JAE to get the right pistons. Piston cost is about $750 plus another $150 for the ceramic coating.

You could replace the cast piston liners with the newer HC liners, but the cost of the new liners is about $1000. The alternative is to hone the cast liners and coat the skirts with a wettable dry lubricant (molybednum disulphide) to increase oil carrying capacity. Although the HC liners are certainly good insurance, the “upgrade” if fairly cost prohibitive.

Lastly, you should balance and lighten many internal components as possible. The crankshaft and the connecting rods are very robust and are many times larger/stronger than needed. A good machinist should be able to dramatically reduce the weight of these items.


The stock heads can be ported almost 1/4“ and allow much better flow.

There two valve head sizes available. The first is 36.8mm: which is the largest valve that will fit on the standard valve seat insert. Alternatively, it is possible to have 38mm valves; which is the size used in the ultra big valve heads of the “works” Lotus Sunbeams. These valve sizes will require the cylinder head to be fitted with oversize inlet valve seat inserts; but offer the ultimate in airflow.Both size valves have the stock 9/32” (7.14mm) valve stem size. Both also feature an undercut stem in the area that protrudes into the port - this assists air flow at low lift and lightens the valve a little. These valves are ideal for a tuned naturally aspirated 2.0L or 2.2l engine; the cost is less than a standard OEM valve and changing to the larger valves gives a significant gain in air flow; even without any gas flow work; although obviously the valve seat will require re-cutting to suit the larger valve. The 36.8mm valves would also work in a tuned turbo engine; Lotus used a 36.5mm valve in the S300 and S4s engines; these valves are a fraction larger than the S300 valves and the valve head shape flows better too.


You should rebuild both carbs replacing the needle valve and seat, accelerator pump diaphragm, springs and all gaskets. You might also rejet your idle jets from the stock 52's to 62's (which helps with the 3k RPM transition.)


Even better, replace the rotor and cap distributor with an electronic one, like Pertronix.

Blow Off Valve

Although the Esprit is equipped with a Dump Valve, properly installing a blowoff valve should reduce turbo lag between gear changes as well as reduce stress on the turbo (thereby increasing life.) Not to mention this “upgrade” actually increases the reliability of your turbo. On Bosch CIS Injected cars, the BOV must vent back to the duct between AFM and compressor intake. Any leaks will cause engine running problems.

other/performance.txt · Last modified: 2021/12/21 17:44 by driestone