petrol vs diesel

BostonB

Tivoli wrote:

why are you getting so upset are you some sort of diesel fanboy


i am comparing the distance covered before reaching 60mph in a 75bhp petrol and 110bhp diesel car, and getting the same result, time taken is totally different, and pointless comparing them and the acceleration vs speed graph wold be totally different


if they are too slow for you, to make it more exciting pretend i am comparing a 150bhp petrol to a 220bhp diesel and getting the same results

I'm just correcting you. If you didn't want debate why start the thread. The diesel is faster between the two cars you are talking about thats fact. The BHP and torque is why. That you can't achieve it is how you are driving it. You said BHP was irrelevant it isn't. A diesel is like driving a large capacity petrol. You use the torque not hang on to the gears like a peaky small capacity 16v petrol. Making sweeping generalisation about diesels vs petrol is not useful. As there are fast and slow diesels just like there are fast and slow petrol cars. Can depends on the weight, how the car is geared, if it set up for economy or performance. Theres lot of factors to take into account.

BostonB

hi5 wrote:

If diesels were that good, wouldnt Ferrari,Porsche,Lamborgini et all be using them in their cars?Diesels are for tractors(and yes I know Porsche and Lambos connection with tractors):p

Thats a bit silly. Someone who spends 100~250k isn't bothered about fuel economy, and theres also the snob value.
Audi diesels seem to do ok at Le Mans against Ferrari's,and Porsche's.

Tivoli

BostonB wrote:

I'm just correcting you. If you didn't want debate why start the thread. The diesel is faster between the two cars you are talking about thats fact. The BHP and torque is why. That you can't achieve it is how you are driving it. You said BHP was irrelevant it isn't. A diesel is like driving a large capacity petrol. You use the torque not hang on to the gears like a peaky small capacity 16v petrol. Making sweeping generalisation about diesels vs petrol is not useful. As there are fast and slow diesels just like there are fast and slow petrol cars. Can depends on the weight, how the car is geared, if it set up for economy or performance. Theres lot of factors to take into account.

nice reply, you got me thinking

the hdi is deffo set up for economy, its only strong from 2000-3000 rpm, its like you got an extra person or 2 in the car at any other rpm

JHMEG

BostonB wrote:

Audi diesels seem to do ok at Le Mans against Ferrari's,and Porsche's.

Which is an endurance race.

Don't see any diesels in F1 etc.

BostonB

JHMEG wrote:

Which is an endurance race.

Don't see any diesels in F1 etc.

Don't see any Porsches or Lamborgini's either :rolleyes:

BostonB

Tivoli wrote:

nice reply, you got me thinking

the hdi is deffo set up for economy, its only strong from 2000-3000 rpm, its like you got an extra person or 2 in the car at any other rpm

Both that petrol and diesel are set up for economy. Look at the MPG and the lack of performance. The diesels simply has a different power/torque characteristics. You need to drive appropriately to get the best out of either. Adjust your driving style to suit so to speak.

JHMEG

BostonB wrote:

Don't see any Porsches or Lamborgini's either :rolleyes:

And?

They both used to. Porsche raced their own cars down through the years, and supplied engines up until 1991. Ditto for Lambo, cars and engines up till 1992.

Along with petrol stalwarths who still do, like Ferarri and Honda.

E92

JHMEG wrote:

Don't see any diesels in F1 etc.

Thats because the rules for F1 state that the engine has to be a 2.4 litre petrol V8. The reason why diesels now exist in Le Mans is because some time back there rules on engine size were relaxed, meaning that larger engines could be fitted, hence the fact that diesels can barely rev beyond 5000 rpm was less of a problem than it used to be.

BostonB wrote:

Don't see any Porsches or Lamborgini's either

Thats because a lazy engine that can barely rev to 5,000 rpm is no good for a supercar. I'm not directing this at you BostonB because I've noticed that you have pretty much said a good bit of what I'm about to say, but to the OP.I'll put the question another way.Why do trucks, trains, buses etc only run on diesel? Because lazy engines are much better suited to heavy vehicles because of all the torque. The heavier something weighs, the more force(torque) thats needed to overcome a vehicles resistance to motion. You dont need a whole pile of torque in something that doesnt weigh a lot, and lets face a supercar, while they do weigh up to 1.7 tonnes isnt that heavy on the whole scheme of things. I dont know what a bus or a truck weighs, but I'm sure they weigh a heck of a lot more than 1.7 tonnes. Bhp is what matters when going from 0-60, and in general when racing, but when overtaking, which is what is what happens in the real world, what you need is torque,and diesels have it in spades. For instance in the E60 5 series, the 530d with 218 bhp is 1.1 seconds faster from 50 -75 mph in 4th gear than the 545i which had 333 bhp. In other words in the real world a 3 litre diesel is faster than a 4.4 litre V8. If you were to race the two cars around a track the 545i would destroy the 530d, or if you were just going flat out on German autobahn then the petrol model is a better choice, but when you're on a motorway or overtaking, you want to be in the 530d. The reason is because the 545i had 332 lb ft of torque and the 530d had 369 lb ft at the time(it now has more needless to say). There are other reasons too why the diesel is faster, its not just torque, but unless you really want to know,I'm not going to discuss it(its to do with gearing and what the engine speed is and where it is in its power band, and where in the rev range the most power available is).

There are other reasons why Porsches and cars like that would be totally unsuited to diesel power. Cars like that should sound good, and no diesel does. The sound should make those who know nothing at all about cars sit up and take notice. The engine should be extremely smooth, and you should have to rev the sh*te out of the engine in car like that, for the sake of it. Theres absolutely no logical reason why anyone would or should want a supercar, its all emotional reasons, and because of the badge they carry. Diesels weigh up to 100 kgs more, meaning that they would be less fun to drive than a petrol version. Fuel Consumption is hardly an issue in a supercar. As the old saying goes, 'if you have to ask the price then.....'


Getting back to the OP I don't see how the petrol model is better value. You're comparing a car that has 75 bhp vs a car with 110 bhp. Now if both were petrol, the 110 bhp car should be a good deal quicker than the 75 bhp model. But its a 110 bhp diesel, which is like having a smallish 6 pot petrol, without the financial pain or smoothness and refinement(that includes the added aural refinement that only a 6 pot has). A petrol engine with about 160-170 bhp would provide the equivalant real world performance. Dont fall for the trap of 0-60 times.Add to that an engine which is at least 14 mpg more economical, a company that has a reputation for making diesels that are as good as their petrols are bad(the 1.4 'TU' engine in the 307 has been around in one form or another for > 20 years its the same basic engine that was used in the Citroen AX, Peugeot 106 and many others), I think it would be mad not to choose the diesel. For only €1,220 extra its a steal. Buy the diesel.

Just so you know 0-60 for the 1.4 petrol is as mentioned 14.1 s and max speed is 104 mph and the 1.6 HDi takes 11.2 s from 0-60 and has a top speed of 117 mph. In other words the diesel is 2.9 seconds faster fom 0-60 and 13 mph faster at the top end. Incidently the 1.6 petrol(which has an identical 110 bhp but only 147 as opposed to 240 lb ft of torque) goes from 0-60 in 10.7 s and has a max speed of 118 mph, because its 56 kg lighter(kerb weight of 1279 kg vs 1335 kg).

BostonB

JHMEG wrote:

And?

They both used to. Porsche raced their own cars down through the years, and supplied engines up until 1991. Ditto for Lambo, cars and engines up till 1992.

Along with petrol stalwarths who still do, like Ferarri and Honda.

Ah used to? They still run in Le Mans and endurance racing, and as so do diesels. So it makes sense to compare them there. Why draw comparisons between Porsche/Lambo/Diesel in F1 when there none in it currently. Makes no sense. Theres no reason why you can't race a diesel, they are quick enough, the Audi R10 proves that. The limitation is the rules . Same way the rules changed in the past to allow turbos and NA engines side by side. A big disadvantage the diesels have is they are generally a lot heavier than the petrol equivalent.

8k2q1gfcz9s5d4

diesel giver better fuel economy. its all about milage

maidhc

cjt156 wrote:

I'm with bo-bo & Gerry here, there's a reason the redline is at 7k, and you've probably got another thousand or so rpm over that.

One of the reasons why diesels have generally outlived their petrol counterparts is because they are a much slower running engine. There will be more stress on a engine doing 7000 rpm than on one doing 4000rpm. If you drive a petrol sympathetically it will far outlive a engine that spends its day at the red line.

Stark

neuromancer wrote:

Seriously, what are you talking about? What have skangers, in the Motors Forum , got to do with alloys. Almost every purchasable car these days has an option for alloys or they come as standard. Please stay on topic.

I was on topic. The OP was asking whether he should go for car A or car B and one of the differing criteria was that the diesel car didn't have alloys. I was giving my opinion that alloys wouldn't be a must have for me.

what_car

Tivoli wrote:

i am lucky enough to access to 2 peugeot 307s

car 1
1.4 petrol, 75bhp


car 2
16 diesel turbo and anftercooled 110bhp


both cars reach 60mph at the exact same point from standstill ( when i pull out the drive to the 3rd tree down the road ) I can't make it sooner in either car no matter how many times i try!

car 2 is a lot better for overtaking (its srtong in high gears), but €6000 dearer to buy, €100 dearer to tax, and comes without alloys, car 1 comes with alloys as standard

the diesel car gets twice the mpg the petrol one gets,
so if i buy the petrol car (and use less then €12200 on petrol :eek: in its life time) i am getting free alloys and a longer service interval

P Vs D
in the case of which is better.....

well depends what you are looking for in a car.........
for example..... i recently changed from diesel to petrol..... i wanted an auto car but couldnt find a new reasonably priced auto car in diesel... so went petrol........

i like diesels, but my requirement was auto...........so i had to compromise...


unless you are doing 20,000+ miles a year.... go with petrol......

or

if you are planning to hold on to the car for 4-5 years go diesel....

ventre

let me clarify this one for all of you,desiesel cars should be outlawed!there for people who are too cheap to run a petrol car,they pretty much all preform like crap in comparison to their petrol counterparts and sound like somebody hitting a hammer off an anvil.why would you do it to yourselves.not cool!!!

bo-bo

ventre wrote:

let me clarify this one for all of you,desiesel cars should be outlawed!there for people who are too cheap to run a petrol car,they pretty much all preform like crap in comparison to their petrol counterparts and sound like somebody hitting a hammer off an anvil.why would you do it to yourselves.not cool!!!

is this what this thread has been rduced to

Marcus.Aurelius

ventre wrote:

let me clarify this one for all of you,desiesel cars should be outlawed!there for people who are too cheap to run a petrol car,they pretty much all preform like crap in comparison to their petrol counterparts and sound like somebody hitting a hammer off an anvil.why would you do it to yourselves.not cool!!!

Another aul fella who refuses to try anything new! Try driving a new Audi A4 2.0 TDi vs the 2.0 petrol. theres sweet FA difference. And the TDi will do 40-60% better MPGs. And quit your ignorance, TDs cost more to buy and are nearly as quick if not quicker than their modern petrol equivalents! And they're getting quieter by the day! Try driving an Accord 2.2 CDTi and tell me its crap.

what_car

ventre wrote:

let me clarify this one for all of you,desiesel cars should be outlawed!there for people who are too cheap to run a petrol car,they pretty much all preform like crap in comparison to their petrol counterparts and sound like somebody hitting a hammer off an anvil.why would you do it to yourselves.not cool!!!

you just displayed your ignorance on the issue!

diesel cars have fewer emmissions than petrol.. are cleaner ...

with the torque in a diesel you can accelerate faster than a petrol car...
they give better fuel economy

gyppo

ventre wrote:

let me clarify this one for all of you,desiesel cars should be outlawed!there for people who are too cheap to run a petrol car,they pretty much all preform like crap in comparison to their petrol counterparts and sound like somebody hitting a hammer off an anvil.why would you do it to yourselves.not cool!!!

Welcome to the forum - we need posters like you so we can smile sometimes.:)

JHMEG

what_car wrote:

diesel cars have fewer emmissions than petrol.. are cleaner ...

Less CO2 per mile than an equivalent capacity, but unless it has a particle filter it's substantially dirtier than petrol.

what_car wrote:

with the torque in a diesel you can accelerate faster than a petrol car...

Oh no, not again...