The debate between petrol-heads & diesel heads are unending. Both these engines have their own advantages & disadvantages. In this thread I have put the power & torque graphs of similar sized naturally aspirated petrol & CRDi with almost similar power ratings. Due to confidentiality issues I have removed the power/torque scale. Please don't ask anything regarding which engines, where etc.
Point 1:
Starting from 1000 RPM to all the upto 4500 Diesel rules. Diesels can produce almost twice the torque at certain RPMs. However in the lag zone 1000-1500 the petrol performs better (except a few lag free diesels) inspite of having the same torque. Why? Firstly the gearing of diesels are taller and then they also suffer from higher kerb weight. In real world Diesels pull 1.5X times harder after the lag zone.
Point 2:
Now where does the petrol score? Inspite of having shorter gearing, the petrol pulls longer. Thanks to its 6500 RPM which can even be enhanced to touch 7000 at your own risk. For example in the 2nd gear the diesel is fine till 65 but runs out of breath at 75. The petrol on the other hand will pull all the way till 85. Similar story extends in all gears.
So it is only post 4500 that petrol has the advantage. Not only because it delivers more torque in that region but also coupled with shorter gearing gives a tremendous advantage.
Point3:
Now in case of normal driving, where the RPM is limited in the range of 1000-4000 it is diesels by a huge a margin. Lets say for example on a diesel car you are traveling at a speed of 100kmph in 5th gear. It will have better acceleration than a petrol traveling in 4th gear. So to emulate the oil burner the petrol needs to fall back in the 3rd gear which IMHO is impractical.
Point 4:
The increase in acceleration on downshifting in a petrol is much more than a diesel. That is because in a diesel when you downshift, you get the advantage in gearing but you loose out on torque as diesels produce less torque at higher RPMs. In other words if you see the power graph of the diesel, it is almost same in the 3000-5000 Range. So if you are in 3000 RPM and you downshift to get in the 4000 RPM zone there is hardly an increase in the available power. In a petrol it is not so. It is only 5500 RPM there is no point downshifting.
At the end of the day it is a personal preference regarding petrol and diesels. I like the characteristics of the diesels and I stand by it.