Quote:
Originally Posted by serialk11r
The guys who are saying keep it under 2000 or whatever, are you sure about this? These small engines tend to hit peak efficiency at slightly higher rpms. My 1ZZ is not a Honda D16 but the 2 are quite similar (91.5mm stroke vs. 90mm stroke, I have 1.794L though), and while there are no published complete BSFC charts that I know of the peak thermal efficiency at maximum load is at 3200rpm or so.
Additionally, I can't go up a very (emphasis on the very) slight incline in 5th below 1600rpm, because the engine bogs. If I hold at 1600rpm (about 30mph) on flat ground my mpg is only so so, high 30s ish. When I go up to 2000rpm or about 36mph then I'm getting 45mpg or so. If I try to hold 1000 rpm, I need so much load that I only get 30mpg according to Torque. Hence, I try to not dip below 1700 unless I'm coasting in gear to a stop. For those pesky 25mph roads I tend to accelerate and then put it in 5th and give barely any throttle so it doesn't DFCO on me. That way I don't need to put in neutral and idle (depending on the ECU's mood the idle can be as high as 1200rpm sometimes :/, or as low as 600), which consumes only marginally less fuel than having the engine do a tiny bit of work in 5th, and makes rev matching a downshift easier, as well as giving me the option of DFCOing.
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I know it might seem counter-intuitive but it seems to work well. Look at Palemelanesian's PaleCivic fuel log. He accelerates between 1500 and 2000 rpm at about 80% load. I do about the same, often 2200 RPMs. A distinction worth something might be that we're not at "maximum load" as you say, if by that you mean WOT and 100% load. We are at maybe 30% throttle and seeking about 80% load, which is generally regarded as the best region on the BSFC map for fuel economy purposes. I'm not claiming expertise, just experience. It works, and lots of guys here argue this is why.