This makes total sense, although I was hoping to get a far more clear answer by using Brake Specific Fuel Consumption. However obtaining a contour plot would require some dyno time and a fuel flow meter.Regarding 6th gear ratio:
You don't really need to physically test the gearing to know how it will perform. You can calculate/model the whole thing extremely accurately. All that is required is accurate Coefficient of drag, Frontal area measurement and torque curve for the engine. It's best to perform a coast-down test to get numbers on the rolling resistance of your specific vehicle, but that's only needed when you are looking for super accurate results.
Most engines produce the highest efficiencies at low rpm, and high load, generally in between 2000 and 2500 rpm. Do we (the consumers) know this is the sweet spot for the 2J, probably not. Obviously the engineers that were programming the shift schedule of the auto knew this.
(If anyone could provide a contour plot of the stock 2JZ-GE for reference that would be great)
This also can't be more accurate since speed is a measure of velocity squared. 45^2 is just over 3x less than 80^2....Then consider that sustaining 80mph requires three times the torque of sustaining 45mph. Ask yourself if you think the engine had 3x more torque than it "needed" when you floored it in 5th @ 2000rpm @ 45mph.
Nope, hahaIf the answer to this question is a "yes" (which I'd disagree with)
Since the car was built and designed with a W55/A650e, I would also agree. Even though I'm not exactly familiar with the stock tuning parameters. Now if we subjected the stock configuration to this type of abuse, I would be interested on how the stock ECU would manage the setup....ask yourself if it'd be a good idea to put the engine into that speed/load condition in a steady-state situation - for hours on end. Say, 2000rpm at 90+ kPa of MAP. I haven't put a wideband on a stock IS300, but I'd be willing to bet Toyota has it calibrated to start enriching the AFR for MAP over ~80kPa. Engines under high load require a richer mixture to keep combustion, exhaust temps, and catalysts within acceptable temperature limits.
Again, I can see this as well, makes the marketing teams job pretty easy, most likely is their target audience. However even using a generic BSFC countour plot, I wouldn't say it's unreasonable to get 15-20% gains over 25 to the gallon (29-30 MPG hwy). Although this is yet again subject to scrutiny with what the exact engine efficiency parameters of our engine are.Regarding improved fuel economy
The 30% improvement Tremec mentions is probably aimed at the folks that have a Chevelle, with a 454 big block, with a non-overdrive transmission and a 4.11 rear gear - that currently gets 13mpg. For them, a 30% improvement would take them up to 16 or 17mpg, which is reasonable.
I did want to touch on this with a separate post, but I can just do that here. Yes it will require the same amount of power, although that power can be achieved in multiple gears. (i.e. 100kW power at the wheels can be found in 2nd, 3rd, 4th, etc., but the lower the gear, the higher the consumption.) It's really just about finding that top island on the BSFC contour plot.As GGM_IS mentioned, the same power is still required to go a given speed. Air resistance and rolling resistance remain the same, regardless of gearing - so what you save is the friction associated by the engine, trans input shaft and countershaft spinning more slowly in their bearings. This is gonna be worth 1 or 2mpg in our cars.
When GGM_IS stated we will need the same amount of power, nothing could be more true. I'm just curious as to what that magical gear ratio would be for optimal efficiency. It's probably just slightly under 0.63:1 with all else being stock.
And lastly, the graphs. I was able to get some similar results in excel before seeing yours, but you appeared to layout your data with RPM on the Y axis, and speed on the X axis. Mine are reversed when I was generating the tables to get a sense of the different ratios between the transmissions.Regarding graphs
I made those in Excel. I just created a basic table with 7 columns: Vehicle speed, 1st gear, 2nd gear...6th gear. I populated the vehicle speed column with mph figures, from 1mph to 200mph. I populated the gear columns with a basic calculation based on the gear ratio of trans in question, the diff ratio and the tire circumference. Then pulled the table of values into a graph.