3 ms·
It's guaranteed they are using some sort of variable valve timing, however I wouldn't dismiss a non-timed 14:1 motor. If they toss in some forged internals and
by cullenking 16y ago
It's guaranteed they are using some sort of variable valve timing, however I wouldn't dismiss a non-timed 14:1 motor. If they toss in some forged internals and keep the displacement small, they don't even need any sort of VVT to lower the dynamic compression ratio. My R6 has something like a 13.1:1 compression ratio with no VVT. Granted, the cam probably has some overlap.
- Construct 16y agoGood point. Motorcycle engines, with their smaller cylinder sizes and thus lower combustion chamber surface area vs. volume, have a much easier time cooling their cylinders and heads. This reduces hot spotting, making it easier to get away with larger displacements. I'm sure there was a healthy amount of overlap in your cam, since that motor was designed to rev to the moon. Still, I did have a 14:1 piston in my single-cylinder, 450cc dirt bike motor and ran 91 Octane in it all day long without problems. Granted, I never took it below 4000ft altitude, which probably helped, but the cylinder, head, and valves were all designed for excellent cooling. And I had a really aggressive cam setup. Either way, kudos to Mazda for pushing the limits here.