VLG archive ยท Message 498
[VintageLambo] Jalpa Twin Turbo Project
Author: lgpdk
Message
Jack has on a prior occasion urged me to post the progress of my Jalpa Twin Turbo project so here is the first installment. Since my primary focus is actually getting things done, I will only be able to answer very few questions. Some information on my Jalpa can be found on my web-site: http://home.earthlink.net/~laust/jalpa.htm I have found the Jalpa to be an extremely enjoyable car, it attracts positive attention, makes wonderful Lamborghini noises and (with racing tires) handles like a go-kart. I have once had it on Willow Springs Raceway and found the handling to be surprisingly predictable and so far I have not found any major engineering deficiencies in the design. The only weak point is the lack of power relative to today"s cars. Having had success with my Espada improvements, having purchased and raced a Porsche 944 turbo and realizing that the Jalpa has a 9.0:1 compression ratio, the thought of turbocharging came very easily. The emission equipment on the engine is very voluminous and antiquated, so that also leaves a lot of space for the turbochargers and intercoolers. I previously had a chance to do leak-down testing of the back four cylinders (could not get to the front four) and found the numbers very encouraging. Furthermore the engine has always felt very healthy, so I have decided not to go deeper than the peripheral components. I have purchased the vast majority of the peripheral components which are: 1) Electromotive TEC-3 engine management (with sensors and actuators), 2) a pair of turbochargers from a Mitsubishi 3000GT (3Liter, 320HP), 3) intercoolers, 4) electric water pumps, 5) water injection parts and a number of other components. Since the engine is not specifically designed for turbocharging, I intend to use boost "only" up to1 bar relative (14.6 psi). With a 9.0:1 CR, full control of the ignition timing and possibly efficient intercoolers (I have not 100% decided on those), I should be able to run at that boost level without detonation and have purchased a 2 bar MAP sensor for that. The water injection will be an extra safeguard (or intercooler alternative). My Espada shows that full timing control can do wonders since I there am running 87 octane with a 11.0:1 CR. The engine is relatively "broadband" (1k โ 7k rpm) in contrast to turbochargers, which are narrowband. To overcome this, I have devised a (somewhat complex) scheme to switch between serial and parallel connection between the two turbochargers. The intake and the exhaust sides can be switched independently and the switching will be computer controlled. The serial-parallel switching scheme is likely patentable, but hardly commercially viable (= costly). So until I have decided whether or not to patent it, there will be no details. Should I in the future desire more horses there are directly replaceable aftermarket turbochargers for the Mitsubishi 3000GT, that brings that car up to 450 HP. Attached is a picture of the TEC-3 unit and note the slim "coil on sparkplug", that I intend to use. They fit perfectly and will be a "neat" feature. However the spark energy is not impressive, but if I have ignition on all cylinders under all conditions they stay, otherwise I will have to sacrifice aesthetics for function (upgrade to the transformer coils also in the picture). My Jalpa had a gear-whine, which I am 99% sure is from the differential, so I have taken the crown-wheel out for analysis (as can be seen in the 2nd picture). I was surprised to see that it has straight cut gears and appears "quite beefy" (27 mm wide with a 68/17 ratio) and I found the teeth in perfect condition. However the wear-patters would indicate a 80% mesh, while I would expect a 90% mesh. I am seriously contemplating moving the crown-wheel about 1 mm closer. There is also a picture of "Suspension Cosmetics". The shocks (and springs) are in perfect
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