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Thanks for the confirmation on the window tint, I assumed it would help but it is nice to have some reassurance. On the shift points, to make a long story short, I have found the best shift points are as follows: (note I have non-stock tire size, ymmv)
Eco minded shifting- Shift near 3100 rpm, land closer to 2400-2600 rpm, thus staying in this assumed low bsfc region. Also giving the engine around 1/3 throttle (approx. 3 gallons per hour rate typically) seems to be the most efficient as you get up to cruising speed at a reasonable rate.
Quicker but still semi-eco shifting- Shift around 5000 rpm, landing around 4000 staying in the main camshaft peak torque curve region. Give the car half or more throttle. This method typically uses more fuel, but not an extreme amount, as you get up to cruising speed quicker. Best used for merging into traffic on the interstate or getting up to cruising speed while climbing a hill.
Non-eco shifting. Shift as close as you can to 7800 rpm without hitting the 7800 fuel cut of point. Land in the 6000 region trying to keep the secondary camshaft engaged at all times, using 100% throttle. Uses more fuel as compared to the other methods. Best for occasional use only when necessary, such as getting out of someone’s way or passing on back roads with limited space available. (It is hard to get used to taking the car out of sixth and putting it into second to complete a pass, I have never driven a car like this before.)
A little background on the long story I made short. The 2zz is an interesting motor as it was designed to be a high revving engine. The powerband on the car is from approximately 4000-5000 on the main cam profile and then from 6200-7800 on the secondary camshaft profile. The engine doesn’t have much power below 2000 rpm, and it ends up lugging if you try to keep it that low under a load. I don’t have a bsfc map for this engine, but from reading around and doing some testing I have found the engine appears to have two bsfc sweet spots at 2400 and 3100 rpm. These spots correspond to localized dips in either the torque (3100) or HP (2400) curve of the engine. I am guessing these correspond to the third and fourth order of some sort of harmonics in the engine as additional dips can be seen as a set spacing of approximately 780 rpm, but that is purely a guess. I don’t have the bsfc chart, but I am assuming the region around these two points is the lowest area of the bsfc chart.
Note that the engine is geared very low factory (4.56 final drive, 0.70 overdrive, 24” stock tires) and that I have already upped tire size by 10% (26.5”) to assist cruising rpms. With this oversized tire, it puts my bsfc spots on the car at 2400=57 mph and 3100=74 mph. On the interstate, I set my cruise at exactly at74 mph, which on my stock speedometer is about 1/32 of an inch below the 70 mark. I have to read this on the stock speedometer as the rpm gauge is too small to discern this accurately. I also have to check my setting against the gauge, and try again if I am even a little off. If I get the engine in this exact spot (+/- 20 rpms) I get really good mileage compared to similar speeds aka 73 or 75 mph. I have to go around 65 mph to get better, 70 is actually worse. Similarly, the 2400 rpm or 57 mph is useful on the side roads, I don’t cruise as I can P&G, but if I have to climb a large hill I shoot for this spot.
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