Why Toyota has less horsepower and torque compared to other leading brands?
Sir, it's where the "useable"
power and torque is LOCATED along the powerband (rpm-range)
that matters most, NOT the peak torque and horsepower.... Also, it's how the engines are "boosted"
Would you go by those high-boost/ high rail-pressure smaller engine like those Japanese 2.5-litre making 174 or 176 peak hp at screaming diesel-revs of 4000 rpm than the non-high boost, somewhat detuned 3.0 D-4D (1KD-FTV)
engine that makes a decent 163 peak hp at relatively low rev of 3400 rpm and distributing heaps of 343 Nm of pulling-force WIDELY from 1400 rpm all the way to 3200 rpm? That means whether you ease the throttle-pedal in between those rev-range, you are ASSURED that the peak torque is there.
In comparison to the 3.0 D-4D, one of those smaller 2.5-litre engine mentioned above will only provide you its peak torque of 403 Nm at a single-spot along the rev-range, i.e. only at 2000 rpm, and then it falls off sharply along the rev-range. The other one produces 350 Nm torque at a high-rev of 3500 rpm. And it only makes 250 Nm starting at 1800 rpm.
Also, would you substitute DISPLACEMENT for BOOSTING? ---- e.g. bigger engine that is not boosted too much against a smaller engine that has an increased or high boost pressure? The 2.5-litre Navara, as an example, its rail-pressure is NATURALLY very high such that when you tune it for more power like mating it with a diesel EFi tuning chip like RaceChip Pro or Unichip, the rail has to be strengthened/ modified.
Concerning the non-intercooled and non-VGT 2.5 D-4D (2KD-FTV)
, on the other hand, that we have here in most part of SE Asia, it's torque is responsibly placed at 1600 rpm up until 2400 rpm. Although by paper it is just 260 Nm torque, it is tappable and sizeable along that rev-range, that is why it is fuel-efficient as well. What more if Toyota mate it with an intercooler?
....The upgraded 2KD-FTV, which is equipped with a VGT, is in Thailand. It makes more power and torque than our 2.5 D-4D. Nonetheless, just like the older 2KD-FTV, Toyota located the peak torque responsibly at low-rev of 1600 rpm all the way to 2400 rpm. Compared again to the other two Japanese 2.5-litre i mentioned, this updated 2KD-FTV in Thailand is also not highly-boosted.
Now, if you compare the typical Japanese diesels that we have here in Philippines against the Koreans, the answer lies in the technology being provided by the Koreans at a cheaper production cost on their part compared to the Nippons. The Koreans are using 3rd-generation diesel CRDi engines along with 3rd-generation turbochargers (eVGT)
that's why their cars have superior powerplants than the typical SE Asian-issued Japanese diesels, AT ALMOST THE SAME PRICE.
The Japanese, in comparison, are still using 1st-to-2nd generation diesel CRDi (just like the Toyota 1KD-FTV, Mitsubishi 4D56, Isuzu 4JJ1-TC standard etc)
coupled with 1st generation VGT's while some are even using the old ones, wastegate turbochargers, like Isuzu Motors for its Philippine-issued diesel engines....