Torque curves - which do you prefer?

onomatopoeia99

Today I drove to work in a 2.5l TDi , earlier in the week I was using a 3.2l petrol. There is no comparison, the power delivery of the petrol engine is so much better.

diesel is nothing...nothing...ooh 1800 revs, here's the turbo kicking in and off we go ... puff puff out of breath by 4000 revs, better grab another gear, and another, and another, and another.

petrol is smooth from 1000rpm all the way to the rev limit at 7300 and feels like it wants to keep pulling even then. Also, a flat six petrol engine sounds so much nicer than a v6 diesel.

Both cars have six forward gears, but I need to change gear far more often on the same journey when I use the diesel.

Petrol for me.

onomatopoeia99

gary_jules wrote: »

Race cars in general have flat torque curves; it makes it easier to modulate power at any speed on track.

Mine doesn't, it climbs very steeply between 5000 and 6000 rpm (it's like the "shove in the back" effect that a high boost turbo gives when it comes on boost, except it's a naturally aspirated petrol engine) and then stays high although it falls away gradually after 8500. Peak power is at 8800, the decrease in torque is more than offset by the increase in rpm until that point so the power increases, then the torque falls away more steeply. Still usable to 9500 or so though, if I don't want to change gear when cornering.