Well, too much traffic to do coastdown testing.
But I did get to do a fair amount of low RPM loafing. And... 1300 RPM is doable with this engine, but
barely. And if
I'm saying something is barely doable for increased efficiency, then you know there's not a lot of wiggle room
I wouldn't say the engine is lugging, but there is increased vibration.
Also, consider that 1300 RPM in top gear is happening at about 50 km/h with my current set up. Which takes about 2.5 horsepower to maintain. 75 km/h would take about 6 hp. (Per the default values for my unmodded car in the
aero/rolling resistance tool.)
The good thing is that
IF I can get a new 5th set made out of a 2nd set, I still have the original transaxle that I can put back in. That would give me the third from top gearing scenario in the chart, rather than the bottom scenario:
Anyway, I'm going to see if I can acquire an extra 2nd and 5th gear set and go visit my machinist.