How does S mode work?

The 3.5L V6 powered Tacoma trucks with automatic 6 speed transmission have the following gear ratios:

1st – 3.60
2nd – 2.09
3rd – 1.49
4th – 1.00
5th – 0.69
6th – 0.58

Maximum horsepower is 278 HP at 6000 rpm, while maximum torque is 265 lb-ft at 4600 rpm. The 2GR engine (V6) has different redlines, depending on the three alpha codes following 2GR- designator. However, I thought I read where Toyota initially had the redline for the 2016 Tacoma at 6400 rpm, but increased it to about 7000 rpm on later year models. Please correct me if I have it wrong.

Anyway, let’s assume you are driving up an incline with the AT selector in the S position. Also, let’s assume your engine is at or near normal operating temperature and that the ambient temperature is above freezing. So, you start out in 1st gear and rev up to 6000 rpm. This is maximum horsepower, but beyond optimal torque. Then you shift into 2nd gear. At that instant the engine will drop to 3480 rpm, [mathematically 6000 x 2.09 / 3.60 = 3480, rounded to nearest 10 rpm]. Note that now the engine rpm is operating about 76% of optimal torque. Same thing once reaching 6000 rpm in 2nd and shifting to 3rd, the engine drops to 4280 rpm, 93% of optimal torque. Then once reaching 6000 rpm in 3rd and shifting to 4th, the engine drops to 4030 rpm, 88% of optimal torque. In all cases the engine performs from just below, to through the top, and into the flatter portion of the torque curve.

I did this exercise to show that driving above 4600 rpm, where the torque curve is maximized, can be beneficial. The torque curve for the 3.5L V6 has the greater slope on the rpm low side (not ideal) and flatter on the rpm high side, and by shifting at 6000 rpm the vehicle will come up to speed quicker (normal, loaded, and/or pulling a trailer). Driving this way will maximum your speed about as quickly as possible without redlining the engine. I’m in the camp that says you should never drive at or above redline.

If you were to shift at 4600 from a lower gear to the higher gear, the rpm would drop significantly back into the steep sluggish range of the torque curve. For instance, 3rd to 4th at 4600 rpm would result in staring in 4th gear at 3090 rpm, which is a back from optimal torque. It will take longer to come up to 4600 rpm, where the torque is optimal. Note that starting the next gear at 3000 rpm and significantly better performance than lugging back to 2200-2500 rpm. In that case, you may as well stay in automatic.

I don’t recommend driving on the high end of the engine rpm all the time, as most times there is no hurry to achieve the desire road speed, and the engine is designed with fuel efficiency in mind (lower rpm). But at times when you are pulling a heavy load and impeding traffic behind you, or you just need to quickly come up to merging speed on a busy on-ramp, then this would explain how to achieve it.

This may be better said somewhere else on this forum, but I didn’t see it addressed in this thread.

 

I primary used the S mode for engine brake going down hill and high way merge. Work great for me.