Given a full rebuild was needed the customer went with upgrading to a low mileage K24A3 bottom end while reusing his K20A head. As this is a road car he also wanted to be less dependant on fuel quality so the K24/K20 was assembled with reduced compression to be able to safely run 95Octane fuel. (90Octane in the USA) The original K20 baffled sump, oil pump and alloy pan was retained. The venier cam gear was modified to provide 40degs advance. During dyno tuning it was found that 35degs was adequate. The power and torque gains were significant even with the reduced compression over the stock ECU high compression K20A. Wheel Torque increased by 35% and peak power by 17% even with the reduced compression. Our tuning effort was focused on drive ability and torque under 5000rpm without spending time chasing more 7000+rpm hp which was probably hiding away in combinations of VTC, ignition and mixture tuning. I might have found another 5whp. |
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Above is a comparison of the torque/hp with the VTC locked at 0,10,20,30,40,25 degrees during optimizing the tuning. I have shown this to highlight how important optimizing inlet cam angle with engine load to create an engine with best possible torque while still getting good fuel consumption. The Honda iVtec fitted to the K series motors is an amazing system. The K20A oil pump needed a few modifications to fit to the K24A3 Australian block.
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The gearbox final drive was replaced with a 4.38 (stock was 4.76) which matched perfectly with the light weight of the Lotus Elise and the K24 motor
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I would be confident I could build either Honda engines with the right component package to produce 280Whp as a ground up built streetable NA. car.
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Jeff during business hours. 0420 355 307 email: jeff.david@quantumGP700.com.au
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