The reason why there are Toyota engines in the Elise is that these engines where bargains buys for Lotus ( a tradition on which Lotus is also very keen). To their merit are the relibale 190 HP. To their detriment is that the Toyota engine / gearbox weighs almost 100 kg more than the K-serie engine.
The main reason of gasket popping on the K-series has been found -true or false I don't know. However I want the Elise at 720 kg not at 860kg: the magic of the Elise is in the weight control, not the horsepower. If HP is wanted, I would go big engine (which I do on another car) of forced induction like the Cossie.
The shear weight of the Ford engine and its rebuild every 15000 km are once of the motifs for the "light" (78 kg) K-series.
The Toyota engine-power compensates for the extra weight when accelerating, but it doesn't while cornering and braking. There is the mere fact that the S2 receives far softer tires and bigger brakes than the orginal S1 which indicates that the weight increase is more than hurting.
Original S1= 690 kg, 2 years later: 720 kg and the S2 Toyota-engine 860-910 kg depending on the options.
I raced in former life a factory build race-Citroën AX GT: 155 HP /550 kg. It went around Spa as fast as the official Porsche 944 Turbo Cup. But the normal AX-GT (830 kg/100 HP) was left for dead on the streets compared to the 944 Turbo. I liked the race version but hated the street AX.
AX and 944 Cup met but once on the racetrack and the performance of the tiny plastic AX compared to the heavy bill-Porsche was sufficient that we were kindly given the advise never to apply again for tracktime while the Porsche crowd was there too.
A my collegue says: I won't be loosing weight, but instead I'll make my car somewhat lighter.
Tom De Moor