Petrol Vs Diesel - which is better ?

[Vimeous]

A Saab 93 TtId 177 is likely to tear a Saab 93 2.0t 175 a new hole too, and it's not the 2bhp that's gonna do it.

Similarily the Civic 1.8 and 2.2TD have 138bhp but the TD has maybe 50% more torque.
On paper the diesel is faster than the petrol. I know a number of drivers who also believe their cars are faster.

Thing is it comes back to attitude and approach.
I know the petrol car eats the diesel in roundabout related situations, so-much-so the better in-gear acceleration times of the diesel have to be used attempting to catch up. By the time legal speed limits are reached the diesel is still noticably adrift.
However to achieve this the petrol powered driver must be operating at maybe 8/10's. The diesel driver could be half-awake in comparison. Perversely the harder the diesel driver tries the less the engine gives back, you want a lower gear and you'll be changing up mid-roundabout, stay in a high gear and you'll drop out of the powerband all too easily.

A diesels operating range is all too narrow.
What I would like to try is my sister or parents 530d's. Both have circa-200bhp motors and autos. I wonder if the auto can compensate for the narrow rev-range when pushing on better than a stick-shifter.
All I need now is an excuse! ......

[Zak33]

the narrow torque band is compensated for, with a very tall final drive ratio.

[dave87]

Vim - other question is tuning.

Very easy to get 190-200bhp out of the 2.2 Derv burner, but remarkably difficult to get more than 150 out of the 1.8 without significant expenditure. (This is for Honda, but remains true for most makes I believe?)

[kalniel]

So will the people complaining about narrow torque bands be heading for electric cars pronto?

[Butcher]

Vim - other question is tuning.

Very easy to get 190-200bhp out of the 2.2 Derv burner, but remarkably difficult to get more than 150 out of the 1.8 without significant expenditure. (This is for Honda, but remains true for most makes I believe?)

Only for n/a petrols really - you can get similar cheap chipping gains on turbo petrols as on turbo diesels.

[Vimeous]

Tuning is a factor Dave definitely but as Butcher points out, any FI engine can be modded in a similar fashion.
I don't know but I'd assume a non-turbo diesel will also be difficult to to extract performance above a certain threshold.

With regard to power vs engine size.
The CRX VTEC 16v pushed 150bhp from a 1.6 in 1989 (later version had 158bhp). My own 1997 1.8 had a comparatively weak 168bhp.
Yes when Honda blue-printed the engine it produced 197bhp in the DC2 so back then you'd have been right.

However petrol engine technology has improved massively in recent years (direct injection etc) so I'm sure 150bhp would be a let down for a 1.8 now.

Of course you'll not see many 1.8 150bhp engines in modern cars, they're simply not clean enough for the current market. These days FI is becoming mandatory just to pass regulations.

Sad but true

[dave87]

Sorry Vim, it was merely a pointer towards the advantage of a diesel in a range where there aren't any turbo petrols - ie Honda as an example.

The also don't seem to attract the same insurance quotations that a turbo petrol does - 2.2 Civic was group 10, a3 2.0tdi group 14, didn't bother looking at the 1.8t after that

[Konan555]

the narrow torque band is compensated for, with a very tall final drive ratio.

Which is why we have to be careful about over simplifying things with the torque from a turbo diesel. It won't be the same increase when it arrives at the wheels since the diesel ratios are that much taller.

[Vimeous]

No worries Dave you raise perfectly valid points

TBH I thought you'd be dead right about the insurance but I've just checked and the comparative petrol (1.8 SE) to the diesel is group 9.
I guess the old thinking of diesels being cheaper to insure has been leveled out with the modern motor. Until today I always assumed as much! I stand corrected