Advantages v disadvantages of a diesel!!!

I think what a lot of people are forgetting in the debate about revs vs. power is that the diesel doesn't rev much beyond 5k because it's just not working in the same way as the petrol does> Simply because they dont need a turbo just to make it drivable, they compete

Petrol and diesels are basically the same engine and cost the same to roduce. Aturbo is additional expense and technology that can equally be used on either.

Of course you can, naturally aspirated ones.

Or the three - a turbo petrol engine if we are to be fair.

They are crap, so NEED the aditional complication and expense and extra stuff to go wrong that only a turbo provides! The petrol is good enough without this on its back!

Marketing and pricing has nothing to do with which is best or the original post!

Yes but only because of the turbo, fit one to the petrol engine and see what happens!

But it runs out of steam at 4000 revs where you actually want it to go!

So what? Nothing wrong with that just change gear.

TORQUE X RPM - POWER

so it'll probably have better in-gear

No, that depends on the motors rpm flexibility (diesel = bad) and the area under the torque curve at the rpms the chosen gear ratios require, and diesels fail here as torque fall drastically as rpms rise...

But MUCH quicker if you changed down in the petrol!

eh??? Every time i leave the lights!

It needs all those gears (hard work) to keep it in the right rpm band meaning in the real world its slower or harder work.

Yes, if you want to make maximum progress, you'll have to

The economy goes down the crapper even further than it already is by comparison, and if this was not the case, car manufacturers would be doing just that to petrol equivalents... is it sinking in yet???

As you can with a number of marques (at least Volvo and VAG), that sell cars with remarkably similar discplacement petrol and diesel engines, that are both blown.

What then? Why shouldn't you compare them - isn't it a more accurate comparison of the _engines_?

They'll likely be fairly similar in cost.

I suspect you'll find that any degree of performance favours the petrol turbo'd engines. And the fuel economy will likely favour the turbo'd diesel.

In the cases of some marques, though, it is - and on a like for like basis (both lpt and hpt). Isn't that a fair comparison?

No... that's where *you* want it to go.

HTH

You're driving at 150mph?!?!

I was talking about making a petrol with the same crappy diesel turbo type power curve. Its easy, you fit a tiny turbo that strangles the top end and boosts from 1000 rpm. That way you get f*ck all power and tons of useless low down torque. Ten it would be horid to drive and have no top end or real power or flexibility just like your turbo diesels... The only reason they fit small turbos to diesels is because they dont make enough exhaust gas to drive a bigger one! Its not a good thing its something the manufacxturers are fighting!

And I already said they gave better economy, in post 1

Except it isn't 'crappy'... you apparently, just happen to not like 'it', with 'it' covering a multitude of sins, all of which come under the one specific umbrella of 'diesel engined cars', of which they're not, unlike the impression you're trying to convey, all the same.

My mileage, as it were, varies.

And happens, when I'm driving one, to be achieved more economically without any real world performance loss, than it would be in the petrol equivalent.

No point in trying to tell me otherwise, because I've come to this conclusion, as stated many times elsewhere, by using both types of vehicles, for thousands of miles, at times, back to back.

Not because I've seen a few stats on paper, and then drawn a few conclusions from them...

A few years ago I was a witness to a fata crash. Rover 600 head on into a Vauxhall Astra. The shit head in the Rover overtook a truck across double white lines on the approach to a blind bend and the cars were both travelling at between 60-70mph.

Rover driver dead, instantly. The engine came into the passenger compartment and the entire dash pushed into the back of the driver's seat. The cause of death was the spine going through the base of the brain.

Vauxhall driver had a broken ankle.

I've never been keen on Rovers, but that experience made me determined not only never to own one, but never to be a passenger in one either.

And unlike the impression you are trying to convey they are not sufficiently different to be worth mentioning.

They're all noisy, they all have a piss-poor rev range, they all have s**te service schedules, they're all too heavy, they all stink and they all release the most carcinogenic substance yet discovered in their exhaust.

Every time you change up a gear you transmit less torque to the wheels.

Power = torque x rpm

So you go slower.

No, its because bugger all happened so far and I am expecting it to actually accelerate at some pont. Bit like riding a harley... All noise no go then it wont rev anymore! Feels broken.

They think they have lots of torque too, but they are not fast because that torque is gone at the wheels due to the gearing required to keep up with a

If you have a TDi making 200bhp at 3000rpm and a petrol making 200bhp at 6000rpm and your are travelling at 60mph then regardless of the engine you are putting virtually identical amounts of power down regardless of gear or engine. The TDi will be giving better mpg.

Right, you are like those who own a chess set and therefor consider themselves as chess masters.

Tom De Moor

I have forgotten more than you know about engines, and as I already stated in the 1st post in this thread that that was the ONLY advantage. Nothing you tell me needs to sink in. Power uses fuel, turbos actually improve efficiency if well implemented because the turbo runs on almost free energy and does some of the work required to fill the cylinders rather than this coming from the crank/pistons. The same applies to both petrol and diesel, since the turbo has no idea whgat fuel the engine is using.

The only reason small turbos are used on diesels (resulting in low rev power but nothing else!) is because a bigger turbo gives too much lag on a diesel, since it has little power or exhaust gas of its own. Its not a feature, but a limitation, that you dont understand.