Over the past years the Espada has been upgraded and modernized to its present state, under the philosophy that only design weaknesses were to be changed and engine control could be modernized.

As shown in the brief description an Electromotive TEC-I engine management system was installed in 1993 by Pantera Specialists, Santa Ana, eliminating the distributor and reducing the carburetors to throttle-bodies and dry N₂O injectors through the old fuel inlet. The load is measured as Manifold Air Pressure (MAP), which was made much more linear by mixing the sensor signal with the Throttle Position Sensor (TPS), using a small custom designed circuit. Electromotive has later build this feature in to their unit and calls it "Super Blend", controllable in software. The crank sensor wheel is mounted on the front pulley, which is only connected to the crank through a gear, that together with torsional twisting of the crank, provide some angular position jitter. This is judged to be inconsequential. The knock sensor mounted on the block is currently disabled since the engine by design is mechanically noisy. Electronic filtering could improve on this. The N₂O system is also controlled by the TEC-I system through the General Purpose Output (GPO), which provide a pulse width modulated signal to two parallel solenoids. The pulse width is software controllable using a 8 x 8 load-rpm table and is set up to gradually inject dry N₂O between 90% and 100% load above 2000 rpm.

Other major changes include substituting the original 40 amp alternator with a 105 amp Delco (Corvette) unit and the application of reverse cooling, by rerouting the plumbing around the water-pump and provide air bleed-off on the top of the cylinder-heads.

In the Fall of 1997 I rebuild the engine with success. To properly prepare for this I decided to buy (and read) various books on engine design and get some relevant SAE papers on today's engine technology, an example of which is a paper #950938 entitled "An experimental Study of the Effect of Cylinder Bore Finish on Engine Oil Consumption". A simplified conclusion of this paper as from discussion with Jeff LeBlond and Al Burtoni would be, that newer piston ring technology (geometry and material) can take advantage of a very fine cylinder-wall finish.

I arranged with "Historic Races", Costa Mesa, CA to take out (and later install) the engine as well as provide a design for a substitution of the rubber doughnut in the drive-shaft with a CV-joint. The car and the engine were brought back to my house where the rebuilding was done. It ended up taking 4 months.

After taking the engine apart it turned out that the "only" new parts needed were pistons, rings, and bearings. There were four options for getting pistons: get some oversize Lamborghini pistons, get some from Jeff LeBlond (made by JE-Pistons, Huntington Beach, CA), have JE-Pistons custom design some for me, or buy some from Al Burtoni. To make the right choice here is probably the most important part of successfully rebuilding this engine for the following reasons. This engine has the longest combustion seal per displacement of modern automotive engines (excluding Wankel engines), which turns out to be 4/(Bore*Stroke) = 78.7 cm/l, meaning good ring sealing is very important. While the pistons might not be the most costly engine parts, getting to them is costly (and time consuming). The Lamborghini pistons were not impressive in their relatively old design, JE-piston from LeBlond or custom designed for me had at least a 5 week delivery time, so I chose to go with the (slightly costlier) ABE pistons and pins. These pistons had all the design features I would have applied namely no skirt in the longitudinal direction (reduced friction for a given weight and strength), extended skirt in the transverse direction (minimum piston rocking resulting in better ring guidance), oil groove drain directly to piston pin and crown geometry to concentrate combustion chamber around the spark-plug at Top of Dead Center (TDC). This latter feature has the advantage of better combustion probability under marginal conditions (idle) and a reduced tendency for detonation (pinging) probably due to rapidly increasing surface area as the piston moves down and the fact that combustion products burned or not are forced to move transversely. The compression ratio is machined onto the piston dome and a number of consideration were taken into account to select the best possible ratio, namely: no detonation, pump gas, a reasonable ignition timing map, combustion chamber geometry, thermal coating on piston and valves, and advanced cam timing. Only the engine computer and better combustion chamber geometry pointed toward a higher combustion ratio (the rest toward lower) than standard, so I ended up with a geometric ratio of 11.0:1. I found some good "Moly" rings from "Sealed Power" (which had just been acquired by "Perfect Circle") for a reasonable cost. The quality of the pistons I got was very impressive: I could not measure any geometric differences between them, their ring-lands had a mirror finish and the rings fitted perfectly (less than .001" height clearance).

Next in line was having the engine block bored and honed, which was done by Benson's Machine Shop in Santa Ana (who previously had done the cylinder heads). They got the block (old gasket and pistons), carefully bored it out with a torque plate and finished it with a 600 stone, with no cross hatched pattern at my request.

Meanwhile I was checking the (previously rebuild) cylinder heads and designed a simple test for their functionality. Plexiglas plates to cover a pair of exhaust ports and intake port were made. Each plate had a tube that could be connected to a vacuum pump. One by one, vacuum was applied to the ports, and the time, it took for the vacuum to change from 20 inHg to 10 inHg, was recorded. If the cams are on the heads, they have to be turned to close the valves in the runners to be measured. This test will then show the summed leakage from valve guides (non standard seals were installed previously) and valve seats. The results are shown below.

The time is shown in minutes : seconds

These numbers show very little leakage of the cylinder-heads, but still three of the valves (I1, I2 and E3) were taken out for inspection and found OK, their seats lapped, seals improved a little and re-installed.

After the engine block had been machined to a piston skirt clearance of about .002", the rings were measured for end gap, which was slightly larger than the minimum of .013".

The engine was then assembled with the only major new components being pistons, piston pins, main and connecting rod bearings, chains and a throw-out bearing for the clutch. The 25 year old chains were actually OK but were stretched to the limit of the tensioners. All parts except pistons and piston pins were supplied by GT Car Parts, as usual promptly and at a very competitive price.

Timing the cams was an interesting activity. I had previously been told that the engine could benefit from advancing the cams relative to standard and had run some simulations using a program called "Engine Analyzer Pro" to investigate this and arrived at the result shown in fig.1.

Fig.1 shows the torque and horsepower increase gained by advancing each of the four cams 6 degrees.

As can be seen the low end torque gain is substantial. So are there better settings of the cams? I investigated many other possibilities and it turns that advancing the cams further will continue to increase the low end torque, but decrease the high end, but interference between the (intake) valves and pistons sets a limit and should be checked in each case. It should be noted that the minimum valve to piston distance occurs between 5 and 10 degrees after TDC and is different from engine to engine. Calculations show that a 6 deg. cam advance will reduce the valve-piston clearance by about 1 mm. Another minor complication is that the cam timing mechanism is quantized to a 1.6 degree adjustment, but fortunately once non-interference is verified, the separation will increase as a function of normal wear (chain stretching and valve and seat height reduction). So why wasn't this done from the factory? Probably because of the potential valve-piston interference and since it does not affect the maximum horsepower the engine was equally attractive on paper. I ended up with a 4 to 5 deg. cam advance.

After having assembled the engine I performed a leak-down test with the results shown below.

As can be seen the sealing could be better on cylinders # 6, 11 and 12, but overall very good for an engine just out of the machine shop.  Many small details were attended to such as painting the engine block, new gold-plating where necessary, thermal coating of header and exhaust system, etc.  The engine was installed, now with a modified drive-shaft and the computer re-calibrated.

Overall rebuilding this engine is quite easy, but the outcome (and cost) depends on some sound engineering decisions, that can only be made once the engine is apart, such as selection of cylinder finish, pistons, rings, clutch, re-grind crank or not, etc. The basic design of the engine is very fault-tolerant, meaning that for some serious problems this engine still functions while others might not. Also strength-wise many components are over-engineered including gearbox, differential and CV-joints. The only weakly designed parts for this engine/transmission are: bronze valve seats, no valve seals, weak water-pump seal, low power alternator, heavy A/C compressor, weak clutch and rubber doughnut in the drive-shaft.

So how does the car run? I brought the it to the Lamborghini club meet at Death Valley in January with initially only 200 miles on the engine and realized that it ran perfectly well on 87 octane without pinging. All the hills in Death Valley (except the very end of Dante's Peak) and in my neighborhood have been easily climbed in 5th gear without breaking a sweat some even down at a leisurely 1000 RPM. I even had to block off part of the radiator to keep the engine warm when cruising (no thermostat). The engine sound is as expected very impressive and the exhaust does not smell, due to well controlled combustion and catalytic converters. After 3000 miles the engine is even better, with less than 1% misfire at a steady 900 rpm idle. Later the nitrous system may be reconnected.

Summer 2000.  A little bit of quick history seem to be missing: I purchased the car in 1986 (40 kM), had it repainted in 1990 from silver (turned gray) to tangerine (candy color with clear-coat and a little gold-pearl), added engine management system (incl. Polishing and plating) summer 1993, had the engine "rebuilt" in fall 1994 and finally rebuilt the engine myself in fall of 1997 (76 km).

The car now has done 88 kM and does 19-20 MPG cruising on the freeway. It fires uniformly on all cylinders at all times, sounds wonderful and is very powerful even without the nitrous. It actually is a little scary with the nitrous. The handling is very predictable, but I miss the sticky racing tires. The power, torque or leak down of the engine has still not been measured, but I am sure that the combustion chambers have sealed uniformly to less than 4% and frankly I doubt there are any better running 4-liter V12 Lamborghini in the world.