Diesel Vs Petrol

[Number Six]

Considerably more - torque is really irrelevant as cars have a gearbox that will alter the published figure considerably.

 

BHP will be what determines the top speed, and combined with the vehicle mass will determine the acceleration. The torque figure is largely irrelevant, a motorcycle with a very low torque figure will easily out accelerate a car due to a combination of it's gearing and low mass for example.

 

I've never *quite* got the difference, but I sort of understand it.

 

I've owned two cars with similar power. The diesel was 140bhp/224lb-ft. The petrol is 130bhp / 131lb-ft.

 

The diesel accelerated, if not like a stabbed rat, the certainly like a rat that's been poked with a stick. The petrol accelerates ...... eventually.

 

A motorbike will accelerate quickly, but only if you rev the beejesus out of it - which seems to suit bikers for some reason. For those of us who like our ears not to bleed though, acceleration lower down is more useful. I used to own a Sportka (handles brilliantly, not a whole load of power or torque, but a gorgeous gearbox) and it was great fun in town and on country roads. It's the last car I drove simply for the pleasure of doing so. But I drove it to Skye once and the motorway bit was not so much fun - hour after hour of incessant engine whine gets dull after a while - and it barely cracked 30mpg. On the other hand I did Manchester-Glasgow in the 140bhp diesel in 3 hours dead, at over 40mpg - and when I got out at the other end I felt as relaxed as if I'd just popped to the shops. Driving a car where the engine is so unstressed at normal (ish) speeds that you don't really even feel the inclines, and if you slow down at all you can accelerate almost just by thinking about moving your foot is much less stressful than in a car where the engine is buzzing away at 2000 rpm more and generating so little torque that you feel like you're carrying it up the hills!

[Adamss]

I've never *quite* got the difference, but I sort of understand it.

 

I've owned two cars with similar power. The diesel was 140bhp/224lb-ft. The petrol is 130bhp / 131lb-ft.

 

The diesel accelerated, if not like a stabbed rat, the certainly like a rat that's been poked with a stick. The petrol accelerates ...... eventually.

 

A motorbike will accelerate quickly, but only if you rev the beejesus out of it - which seems to suit bikers for some reason. For those of us who like our ears not to bleed though, acceleration lower down is more useful. I used to own a Sportka (handles brilliantly, not a whole load of power or torque, but a gorgeous gearbox) and it was great fun in town and on country roads. It's the last car I drove simply for the pleasure of doing so. But I drove it to Skye once and the motorway bit was not so much fun - hour after hour of incessant engine whine gets dull after a while - and it barely cracked 30mpg. On the other hand I did Manchester-Glasgow in the 140bhp diesel in 3 hours dead, at over 40mpg - and when I got out at the other end I felt as relaxed as if I'd just popped to the shops. Driving a car where the engine is so unstressed at normal (ish) speeds that you don't really even feel the inclines, and if you slow down at all you can accelerate almost just by thinking about moving your foot is much less stressful than in a car where the engine is buzzing away at 2000 rpm more and generating so little torque that you feel like you're carrying it up the hills!

Yep so diesel wins on the motorway but how do you find the turbo lag around roundabouts does it catch you out?

[Number Six]

Yep so diesel wins on the motorway but how do you find the turbo lag around roundabouts does it catch you out?

 

No - it's barely perceptible - and even so, I can drive properly using the gearbox and anticipation.

 

I generally only stop at roundabouts if there is heavy traffic or lights.

 

The turbo kicks in at such low revs (1800rpm or so) that I suspect most drivers don't even notice it come in at all.

[shims]

Another option for lower running costs is a petrol car with an LPG conversion.

[Adamss]

No - it's barely perceptible - and even so, I can drive properly using the gearbox and anticipation.

 

I generally only stop at roundabouts if there is heavy traffic or lights.

 

The turbo kicks in at such low revs (1800rpm or so) that I suspect most drivers don't even notice it come in at all.

 

Which car and engine was this if you dont mind me asking?

[Greengeek]

Which is better though torque or bhp?

 

BHP Sells cars, Torque wins races.

 

I think it's something along the lines of : You have to do at least 20k per year for a Diesel to be more cost effective than a petrol, once you factor in :

Cost of fuel

Purchase price.

[convert]

BHP Sells cars, Torque wins races.

 

I think it's something along the lines of : You have to do at least 20k per year for a Diesel to be more cost effective than a petrol, once you factor in :

Cost of fuel

Purchase price.

 

When you add in depreciation, due to the increased resale value of Diseasels it becomes a little less cut and dried though.

[Number Six]

Which car and engine was this if you dont mind me asking?

 

I had in mind my first diesel - an Alfa 156 2.4 JTD, but the same is true of the other common rail diesels I have driven - a Fiat Multipla 1.9 JTD, a Vectra 1.9 SRi (much the same engine albeit in a different state of tune) Even the old Focus TDDi (older tech than the TDCi) I borrowed was perfectly driveable; albeit noisier than 'modern' diesels.

 

The mass-air-flow meter failed on the Alfa (as they always do eventually on all cars) and that gave it a massive flat-spot around 3000 rpm until I had it replaced (actually I just unplugged it for a few months because I was skint and it was almost as smooth with it unplugged as it was with a new one) but basically they're very good. The number of people putting petrol in diesels is proof of the fact that a lot of people can't tell the difference.

 

Manufacturers rarely put out cars that are hard to drive these days!

[Number Six]

BHP Sells cars, Torque wins races.

 

I think it's something along the lines of : You have to do at least 20k per year for a Diesel to be more cost effective than a petrol, once you factor in :

Cost of fuel

Purchase price.

 

My diesel car cost me £1700 and does 45mpg.

 

My petrol car cost me nothing and does about 27mpg.

 

I spend some money getting the £1700 car serviced - say £300 a year. The free car I spend nothing on.

 

Even if I write off the entire cost of the £1700 car in the first year, it's still cheaper over 22,375 miles.

 

If you ignore the cost of the car, which seems fair as the amounts are so low, the diesel is cheaper if you do a little over 3,400 miles.

 

It depends very much on the servicing costs and the depreciation as to when the break even point will be.