This is a newer engine phenomenum. In the 1960s engines made good torque under 1K rpm and strong horsepower from 2K rpm thru 5K rpm. For years the Chevy 2 speed automatic was the only automatic in Corvettes. Todays engines burn cleaner and with better gas mileage by running in a real narrow rpm band hence the 10 speed transmissions.
If you look at marine engines or fire truck engines they make way more horse power because they are built to run under a constant load.... pumping water, they don't need to shift gears the load is constant so they can be tuned for more power. Which is what automotive engineers are trying to do, narrow the rpm range with many gears and make mega HP.
That is also why the clutch is almost gone. Humans cannot be trusted to manage gear selection like a computer controlled automatic transmission. Letting us pick the gear means poorer gas mileage and excessive pollution so the clutch is gone from pickup trucks. The hold outs will be the off roaders like the Wrangler and the new Bronco.
Personally, I think the whole "old engines had so much torque" but newer engines don't have torque is largely a misconception. Yes, the Powerglide 2-speed was the only auto-trans available in the 'vette for some time, in fact the first 2.5 model years of 'vettes ONLY had the 2-speed Powerglide auto. However, I'd contend that was more out of necessity than engineers thinking the 2-speed was ideally suited to the Corvette or it's engines (just a 6 cylinder in the first two years, then the original small block V8 later in the 3rd model year... when a 3-speed stick also became available). The '54 'vette made a whopping 155/223 HP/TQ. Sure, at a quick glance that looks "torquey" but by modern standards, it's not that the engine had a lot of torque... it's just that it had no horsepower. ;)
For comparison, let's look at that 2.3L EcoBoost that is the
base engine in the Bronco. It's rated at 270/310 HP and TQ. While it's the baby, 2.3L base engine it out-torques the old-school engine by nearly 100 lbs-ft. Furthermore, its peak torque is only at 3000 RPM, just 600 RPM higher than the old Blue Flame I6's peak of 2400 RPM. However, the 2.3L makes it's peak HP out at 5500 RPM and carries power well to ~6k. So it has a 3k+ RPM power-band. The Blue Flame makes its peak HP at just 4200 RPM and is all done by 4500 tops, giving it more like a 2k power-band.
In the end, if you asked me to pick between an old Blue Flame or the new EcoBoost to pair to a 2-speed PowerGlide, I'd take the EcoBoost. The fact is,
modern small displacement boosted motors make broader torque curves and have great low end torque and response. Sure, everything gets better for the "old school" when you start talking V8s... but you name an old V8 that was paired to a 'Glide or say a 3-speed TH300/400 and I promises you they didn't pick 2 or 3 speeds because it was optimal, just because that's what they've had. Heck, I'm a V8 guy... I've had something like 7 different LS-powered vehicles, a couple LT1 cars (as in the mid-late '90s Gen 2 small block LT1, not the original '70-72 LT1 everyone forgets about, and not the current direct-injected LT1), 4 different Hemi vehicles (three 5.7s, and a currently a 6.2 SC'ed Trackhawk) and picked my WJ partially because it's a V8. I just prefer V8s... but something like the 2.7L TT V6 in the Bronco is a "better" motor in every way than my 4.7 HO. With any of my V8s I'd take a 10-speed if I could just snap my fingers and make it happen. Heck, our Trackhawk makes 707/645 HP/TQ and part of what makes it so silly-fast (for an SUV) is the 8-speed auto.
Let's take another example, the tried-and-true Jeep 4.0L that is well known for being very "torquey." Ask anybody if they should buy a 4.0L Jeep and right after they finish saying how it's the most reliable motor ever, they'll praise it for being a "torque monster" that is well suited to Jeepin'. Now, I don't agree the 4.0L is a great motor, and well suited to Jeepin' in the lighter XJs and T/LJs. Still, let's look at the numbers. At it's very best ('01-06) it made 190/235 HP/TQ. I wouldn't call that a TON of torque, personally... I'd just say that it doesn't make much HP. It also has a pretty narrow peak power range, with torque peaking at 3200 and HP peaking at 4600. Anybody w/ a 4.0 knows they don't like to spin much more than 5k, though the torque even down at 2k is pretty good. Still, if anything something like the 4.0L would benefit a TON from tighter gear spacing and more overall ratios to keep it in that 3200-4600 sweet-spot when doing work. I mean, when you talk WJs with people they often poo-poo the 4.7 first on reliability (and they're not entirely wrong there... I had a super clean, well taken care of/maintenanced example that still dropped valve seats before 110k miles) but next saying the 4.0L is a "torquey" motor and better for the WJ. That's odd, with the HO like mine makes 265/330 HP/TQ... nearly 100 lbs-ft more torque, yet the 4.0L is the one known as the "torquey" motor. HP peaked at 5100 RPM and torque at just 3600 RPM. So the torque peak is only 400 RPM higher, but at the same RPM as the 4.0L's peak it's still making way more torque than the 4.0L.
Anyway... my point is any/all motors can benefit from the extra gears (if managed properly). Older stuff didn't have 2-3 (or even 4 and 5) speed Autos because they were "best", they had them because they were what existed at the time...
-TJ
