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 tuned so that all its components are matched. This means that if you want to change one thing in the name of performance, you may have to make ten other chances to take full advantage of any modification.

Blow Off Valve

Although the Esprit is equipped with a Dump Valve, properly installing a Blow Off 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.

Carburetors

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 something larger (as much as 62's) which helps with the 3k RPM transition.

If you still need to pass emissions, make sure you keep those 52's on hand, you might be too rich to pass emissions on the larger idle jets.

A rebuild kit from http://www.dellorto.co.uk/ will cost about $175.

Engine internals

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

If you have to open up the engine anyway, you should invest in a set of JE pistons to replace the OEM pistons. The JE pistons will increase your compression ratio to 8.5:1. The JE pistons are custom pistons, but companies like JAE usually have a number on hand. The set of four should run around $750. It has been suggested by a few owners that ceramic coating the pistons, however the folks at JAE say that ceramic coating doesn't really gain anything for you (the assumption is that there are many weaker links than the pistons). Lotus engines can safely make 350HP+ without ceramic coating.

You could replace the cast piston liners with the newer HC liners, but the cost of the new liners is about $1000 (per liner). 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 very 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.

Since this is beyond your average tinkerer (especially the lightening and balancing,) you should talk to other performance enthusiasts and car shops in your area. Find a quality engine builder who is familiar with building turbo charged small displacement engines.

Valves

For US models Lotus changed the M.O.P. (Maximum Opening Point) for emissions reasons. You can swap the 110° intake cam sprocket with the 104° auxiliary cam sprocket. Green dots are 104°, red dots are 110° (there is actually a small painted dot on the gear.) Another option is to install an adjustable cam gear which means that you can return the cam to 110° for emissions testing (but of course this is more expensive than simply swapping cams gears.) Also on US models, you should also swap the stock 107 intake cam with the higher lift 104 cam. This does sacrifice a little power at the low end (below 3k RPM) for top end performance. The stock heads can be ported almost 1/4" and allow much better flow. If nothing else, the head should be port matched. The extreme would be to port the head, intake and exhaust manifolds. Along with this, You may want to do a 3-angle grind done to the valves and added bronze/silicone valve guides and thin wall higher lift springs (especially if you are going to the higher lift cam.)

Timing

Have the distributor recurved to apply full advance (16°) @ 2,500RPM. And advance the static timing from 1° BTDC to as much as 13° BTDC (you will need a little trial and error to find the best timing for your engine.)

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

Intercooling

Intercooling is vital above 10psi boost, but there is no easy way to add intercooling to a mid-engined car. Lotus opted for a liquid-to-air intercooler (i.e. the chargecooler,) but you may also want to investigate an air-to-air intercooler (which is actually a bit more efficient but has it's own pitfalls.)

Some owners have opted to remove the A/C and use the A/C radiator and lines for IC.

Boost

Your biggest danger in increasing boost is detonation. With the right components you can run 10psi on pump gas without intercooling. The 910 Engine is a very capable platform which can exceed 300HP with the right components.

Knowledge

Take advantage of the user groups and forums online. There are a number of people who have explored this ground before and can help guide your choices.

based on various postings :
re:horsepower chips
race actuator now...
flat spot
84 esprit turbo