Quote:
Originally Posted by Ecky
Honda has been building ~40% thermally efficient engines for two decades. The engine in my Insight is ~39% efficient over a pretty wide band, and it's not hard to stay in that band. Honda achieved this efficiency in an engine without forced induction, without variable valve timing (thought it still has variable lift), and without resorting to the Miller/Atkinson cycle which robs torque, and these engines will generally run reliably for 3-500k miles before needing any kind of service. The Accord hybrid's engine peaks at over 40%, but I haven't seen any BSFC numbers for it. Which is not to say that Mazda significantly exceeding that isn't an amazing accomplishment, but comparatively speaking the current Skyactiv engines are not that great.
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Eh, I love Honda but they are not over 40%. The reason why it may seem like it though is Honda has always been very lightweight with very great aero and low accessory drive losses and were the only ones who could get lean burn to pass emissions until they finally gave up on it. I wanna see some sources lol. Hilariously I have a recent report from a group at Stanford that tested the 1997 LS1 and did a report on it. That damn engine hits 35% thermal efficiency at load at 2000 rpm lol. There are a lot of 35% thermal efficiency engines from the 90s forward though. Makes you wonder if manufacturers stagnated on improvements on purpose to save money and just sell cars until here recently when the regulations went up.