cheap fuels

37p here in grimsby on railway street. They do all the taxis and fit systems to new cars too. 23p delivered in bulk for heating or industrial usas with a FREE tank!

Er. No subsidy. The Powershift grant has ended.

1: It will be hard to hide your take off pipe - though a visit to see a proper one could help you replicate it so it looks right. If filled by vendor they may actually have a note of tank having / not having a liquid off take. Delivery drivers have to inspect what they are putting the stuff in to. Far safer to get a tank with a liquid off take from Calor or your chosen vendor. Note with some you are contractually locked into their supply if you have their tank - they let you have the tank cheap. There are site requirements on distance to building, roads and other things - if you don't have space you can't have a bulk tank. 2: All EU counties supply the local domestic heating blend of Propane/Butane as LPG. So all UK autogas LPG is exactly the same stuff as UK heating gas - nearly pure Propane. The same "gas" tanker delivers to both LPG stations and domestic "Calor" tanks. It would make the price stupid if a separate supply chain had to be put in place to serve the road fuel users - about 1-2% of total motor fuel use in UK. 3: It's illegal to avoid motor fuel duty. When you buy cheap Propane in bulk you fill out a form declaring the fuel used as road vehicle fuel and send it with your cheque to the Tax man (+ a cut to the vat man). Liquefied petroleum gas used as road fuel 12.21 pence per kilogram (6.105p/L - less than 1/10th of petrol duty). As they don't consider it quite as clean as they did (still makes CO2 - even though that would be made anyway as by product of oil/gas production when flared off at platform or refinery), it will go up 1p this year and next year. (note section 12 they take note of where it went and what it went in!) If it's 100% for use as motor fuel then it may be simpler to get it tax paid - it's still about 10p/L cheaper in bulk but the bulk tank cost will take a longer time to recoup.

If you want a legal use for delivery of tax free LPG to a tank with liquid off take, you could take up Ballooning. It's an un-powered slow breezy sport, you should take it up as an antidote to all that hi-power stuff. Given your mobility landing will be exciting and a rush. Expect to use 80L or so every weekend.

4: You will get more than 50% of petrol mileage - about 80% is normal. Any losses due to higher inlet temps reducing volumetric efficiency are countered by near 100% of the fuel burning. A petrol engine makes soot - that's a clump of un-burnt carbon rings, LPG makes no visible soot. I've seen one back to back dyno chart that showed a slight increase in power on LPG (tuned turbo engine but no changes between runs other than flicking the LPG switch). The mixer type systems should be avoided as they place a choke in the inlet that restricts the air flow and will reduce performance on both LPG and petrol.

-- Peter Hill Spamtrap reply domain as per NNTP-Posting-Host in header Can of worms - what every fisherman wants. Can of worms - what every PC owner gets!

[snip who said what]

The vast majority of drivers have some nod towards fuel but it isn't the top priority.

You have a closed mind to diesels, that much is clear. You'll just have to accept that they're a damn sight better than you're prepared to believe.

You can't compare a benchmark power curve for a road going machine without comparing or at least considering the gearing.

Only if it has the same ratios as a petrol engine.

*big clue*

They don't have the same ratios.

Talking about flexibility in terms of engine speeds is pointless in the context of how they drive on the road. If fourth gear is good for 35 to 90 mph, does it matter if this is 2,000 rpm to 4,500 rpm or 2,500 rpm to 6,500 rpm?

No no no no no no.

Except the majority of road going machines don't extact materially more power from a turbodiesel of the same generation.

First example I think of, picking base powertrain configurations: Alfa Romeo GT.

2.0 twin spark, 165 bhp. 82.5 bhp / litre. 1.9 JTD, 150 bhp. 79.0 bhp / litre.

And will the two have the same gearing?

No. They don't.

At the other end of the alphabet we can look at the Volvo S40.

1.6 petrol, 100 bhp, 62.5 bhp / litre. 1.6 TDCi, 110 bhp, 68.9 bhp / litre.

Again the TDCi's gearing is taller.

It's repeated all of the way through.

The majority of the go-faster machines if not all are petrols. I'm not going to argue different.

As I am sure you know, the cost of manufacturing something is only partially relevant to the cost to buy it.

Because not everybody wants to use every last rpm every gear change.

Just as you do with any car so as to get the best performance.

That doesn't make any sense. You're demonstrating a complete lack of knowledge about driving modern turbodiesels, despite your claimed experience otherwise. Open your mind.

Above you're claiming that they're expensive.

Ding. That's my point.

There are plenty of rough coarse petrol engines and plenty of smooth diesels. Again, you don't know the market.

Oh you don't think it's because they're not all bad then?

That isn't an equivalent as an "on the road" vehicle.

Correct. Your answer makes less.

Except this isn't the case for modern turbodiesels, else they wouldn't be able to keep up with their peers.

Many are quieter at a cruise, thanks to taller gearing and more sound insulation.

They don't need changing down three gears from the cruising ratio to an acceleration ratio for overtakes. This makes them easier and more flexible to drive.

See above.

Now I remember you proclaiming that all front wheel drive machines are crap. You also went on to say that the less the power, the less the disadvantage.

Now you deliberately bought the 3.8 V6 rather than the less powerful and slower 3.3 V6...

...for something front wheel drive.

That makes no sense.

You don't know the turbodiesel market. You make assumptions based on your vast engineering expertise that unfortunately have little relevance by the time the Mondeo 2.0 or TDCi arrives on the road.

I have no belief system. I know and understand engines, I understand the physics and have traveled in and driven prenty of the things.

Yes you can POWER curves can be compared. Torque curves can too provided they have an rpm/mph scale along the bottom directly. You forget that mnot only did I own automotive dynamometer systems but designed and built as well as sold them in half a dozen countries in the eighties and nineties. Once you have seen enough of them its like reading music.

The actual ratios are not too important the problem is that tey need to be closer together to allow you to try to match the motor to your desired road speeds. And closer together means you need more changes. You cant just labour it at 1000 rpm when it suits because it accelerates too slowly up to the point where it goes whoosh, or rev it higher for a few secs when there is a gap bacause it hits an rpm brick wall, etc You CAN have a 7 speed close ratio box on a petrol engine if you want but the point is you dont need to. And if you are in the wrong gear it goes anyway without having to put it in writing first.

Of course its not! Thats the whole point! In ther days of bikes in the eighties 1100s had 5 gears and were relaxed to drive. They were in a relatively low state of tune. You could pull away in second by mistake and pass a car in town in top (160mph gear). It went when you cracked the throttle regardless of what gear you were in. It was flexible and nice to ride. During the same era there were many 750s. They were basically the same bikes but were more highly tuned. They had 6 gears. Almost the same power but you NEEDED to be in the right gear for it to go. Gap in traffic - 1100 gone! Gap in traffic - 750 dance on gear lever a couple of times and - bugger the gap has vanished - wait for another one.. Less flexible matters.

If fourth gear is good for 35 to 90

2 things. Different rpms give different power levels. It may work from 35 to 90 in one gear but its far from ideal at either end of that range. The point is that a decent petrol engine is USABLE from 1000 to 1200 rpm easily. A diesel is as flat as a fart from idle to 2k when its little turbo that it needs actually boosts. And the petrol revs higher as well. So its simply more usable.

Yes unless your version of physics differes from everyone elses. There is simply no useful power below say 2k then a step, then it runs out early. It is LESS FLEXIBLE. What part of this dont you get?

I said turbo petrol! Big power from turbo deisels does not happen.

So what????

Why would they? One is flexible and can pull well from idle to redline at around 6k and one cant...

Because it uses a turbo to make the same kind of power at lower rpm. Why do you expect it would use the same gearing??? It cant rev and take advantage of the lower gearing the petrol can so it has to use taller gearing meaning less torque at the road. Power is power. Torque x rpm. The only difference is that because the diesel has less usable rpm range its less flexible so NEEDS a greater selection of ratios to try and find one that matches the engine narrow rev band to the cars road speed. For about the tenth time...

Well you cant really...

Trust me an added turbo system costs even the manufacturers a lot. They dont work free.

Then because the pertol is more flexible you would be better off with that than the petrol! If a gas turbine revs to 160,000 rpm for full power would that bother you? Do you fly? If a bike engine revs to 14k would that bother you? You rev your motor to whatever it was designed to operate at. And you will get closer to the rev limit on a diesel more often than in a petrol engine.

Every gear change is a pain, and more tiring (to go with that awful drone) and its hardly a good thing is it.

I have. Your problem seems to be a lack of understanding of engines generally.

Manual gearboxes are cheap. You said why manuals. Auto diesels are more expensive because auto boxes cost more to make. Like turbo systems... Your rattly diesels cost more and really need a fancy autobox to be user freindly at all.

Sorry but your"point" keeps changing. Where and what has a damned driving test got anything to do with this??????

No its possible to make a crap petrol engine. Not many around nowadays though. But the best diesel does not even begin to compare to the best petrols. In fact they dont even compare to non turbo cooking ones...

No as I already said. For the fuel economy. Its the ONLY thing they are better at apart from running uderwater as we discovered in another thread.

Yes it is. And in an enginnering sense.

ehh???

Every time anyone tries to defend diesels they call them "modern turbo diesels" - Wake up! Only electronic injection changed. Turbos on diesels have been fitted to everything for many tens of years - even boats and trains and generators. They are 99 percent the same as ever...

else they wouldn't be

Without the extra expence of a turbo system they cant! And in many cases based on cost they still cant even with their forced induction assistance. And they still have all the other disadvantages. If you are going to compare the two lets compare turbo petrol to turbo diesels.

You must be joking. They "may" get close at constant speed if you spend enough dosh. But at all other times they are worse. And when you drive you spend more time NOT at cruise. Like in traffic trying to find a useful gear...

Neither does a petrol engine. And especially if we compare like with like and compare a couple of 2 litre petrol / diesel turbo engines Not only is the diesel slower it would be completely blown away.

Yep.

Err no. I bought the ONLY engine the Chrysler comes with in the US rather than the uk one because it was HALF the price.

To you...

No its based on experience and knowledge. Which you seem to be a bit short of.

I have nothing against diesels for the right job. They are great for fuel economy. They are great for anything that needs fairly constant rpm like generators, pumps, boats, trains, compressors, etc They are great also in heavy vehicles like my new 4000lb dodge. I would have actually ordered a diesel auto if they did one in the US at the low price this allows. Because fuel economy overides the driving experience in a heavy van anyway. There is no real pleasure anyway - no way I would choose one for a car. I could put up with all of the above just so I could run it on kero or x oil cheaply. But I dont try to delude myself that its better in any other respect because its simply not. After I found out how cheap propane was then I was more pleased than ever I ordered a US spec 3.8 litre one though! Best of all worlds! Smooth sewing machine 6 cylinder motor and greater flexibility, and more power without the noise, smell, turbos, etc etc etc......

Your understanding is biased. You claim to have driven or been driven in lots of them and yet you're still desperately clinging to beliefs, sorry, understandings that are simply untrue.

*rolls eyes*

You don't get it do you? You don't get ordinary driving conditions?

How can I forget when you keep on resting on your laurels about how many systems... blah blah blah...

They're absolutely crucial.

There's a reason why my Accord's engine was turning over at 3,500 rpm at 70 and the Saab at 2,500 rpm.

With the same transmission but giving the diesel the taller final drive, how can the gears be closer?!

Except modern turbo diesels* don't do this.

*Your experience is from a different era. Live with me writing "modern," tough.

It goes. But very slowly.

Unless you're trying to tell me that my Accord - which has ~16% more power than my Saab don't forget - has better acceleration gear for gear at 2,500 rpm compared to my Saab. Oh and that's with gearing that's 40% shorter.

Bikes weigh jack shit. Modern cars weigh lots. Go figure.

See above.

Different engines give different power levels for different speeds. There's another variable you're omitting.

Erm, it'll *work* beyond those speeds. 35 to 90 is either the optimum or as engine speeds. It's 1,600 rpm to 4,100 rpm in fourth in the Saab come to think of it. 4,750 rpm would be ~104 mph.

Not in the higher gears it isn't.

You're living in the dark ages. They come on song plenty sooner than 2,000 rpm.

Except at 2,000 rpm the huge chunk of comparable maximum power petrols are weany. That turbodiesel is on a song.

The bit where one drives inside the speed limit and uses a gear for driving, not for checking the tacho every single time one changes speed.

The bit you seem oblivious to or are keen to ignore.

So?

D'oh.

No, one has relatively jack poke under 3,500 rpm and sings to the 7,xxx rpm limiter. The other has jack under ~1,800 rpm (for the JTD) and sings to its

5,000 rpm limiter.

Road going speeds in the gears are remarkably similar.

The effect is that you use the same gear for the same speeds, except if the tacho is over 1,800 rpm in the JTD you don't need to change down. For the other, if you want strong acceleration and the tacho is below 3,500 rpm (more like 4,000 rpm in effect) you need a ratio lower. Or two. Then it pulls nicely.

Why do you expect it to have the same gearing?

Less of a much bigger number is still more at the road.

And for the tenth time with taller gearing it's already set up to exploit more torque and a narrow rev band. Manufacturers deliberately use tall gearing to flatter fuel consumption figures in the higher gears, so your more-power petrol engine is unable to produce as much power as the turbodiesel at a 50 / 60 / 70 mph cruise.

The result is less flexibility for things like gradients.

That's why turbodiesels seemingly scoot up hills that leave their petrol engine cousins wanting a ratio lower.

But then you don't know what I'm writing about because you've not experienced this sort of thing. Or you drive with 100% power all of the time.

Why would I? We're not discussing go faster versions.

I don't deny what you're saying but what I am saying is that the difference to the end user is highly variable.

Wrong.

I don't have wings.

Bikes are for hairy fairies and as a result they bother me, yes.

But this isn't the point.

In the case of petrol engines that's often over 3,000 rpm. This is my point. Modern gearing punts too many engines at too low an engine speed most of the time.

What makes you say that? Point is that you don't *need* to use the revs.

For the short response to this, automatic.

For the long response, a u t o m a t i c.

I know. I get fed up with Acme Petrol Whine noise. Can't they do something different instead?

If you are unable or unwilling to change gear when the car requires it then you need education or an automatic.

Where?

Oh that's right. Yeah.

Instead I understand how to drive them. Petrol, diesel. Whatever.

The numbers of people buying diesels won't buy something if it's too hard to drive.

You've not been in many modern turbodiesels have you? They don't rattle on the move. Period.

And it doesn't require an automatic transmission to be user friendly full stop. It requires a driver able to change gear and work with the car to adapt.

No, you keep misunderstanding it.

If they're so dreadfully difficult to drive for people, even those inside the bottom half of average intelligence, surely people would need special training and a competence test before being let out on the roads.

I'm sure they don't let just anybody drive an F1 car or HGV, right?

Best in what respect? Best for outright power? Best for racing? Best for longevity? Best for everyday use?

If you want extreme turbodiesels, talk to Audi. They win races with them.

It isn't the only thing they're better at and you know it, you're just being pedantic because you can.

Is that what you really believe? You're further back in the past than I first suspected.

You also need to remember that a modern turbodiesel doesn't just mean the variable geometry turbine blades etc. but it also means the rest of the package. Things like noise isolation technologies, clever engine mounts, fuzzy logic transmissions or stuffing better sound proofing into a tighter space.

They're not, though; as with everything they've evolved. You'd understand this if you tried them *with an open mind* rather than "this is a FWD diesel it must be crap."

Still at least you're not producing "mini reviews" to try to persuade people that you do drive more than a collection of Alfa Romeos and a Passat, meh.

Only in some cases.

If most people drive something like a Golf petrol back to back with the same specification turbodiesel, they'll find the diesel quicker in everyday driving without having to wring its neck. That's despite it being heavier and having taller gearing.

Why not? Well the reason why not is because turbocharged petrol engines are in the vast majority of cases not sold as ordinary bread and butter models, that's why.

We could consider the Smart options I suppose.

No I'm not joking, I've tried some.

Mondeo money.

Same wind and tyre noise, less engine noise.

Erm, no.

You may not spend much time in a cruise, but don't think that an inability (or unwillingness) to cruise for your own circumstances as the same for everybody else.

Whatever car I drive spends a huge chunk of its mileage at a cruise. It's a lesser proportion of the time at a cruise.

It really isn't a problem for me or indeed anybody who is prepared to adapt to a particular car.

Here's where you're wrong.

Not like for like. Comparing a 200 bhp turbopetrol car with a 110 bhp turbodiesel is not like for like.

Yes.

Of what? Drag racing? Yeah, really relevant to modern turbodiesel stuff, that.

Get a grip.

That isn't especially heavy and is within sniffing distance of many Mondeo sized cars these days.

But you have nothing to show for this.

Smell?

Again see above. The only time you'll catch a whiff of diesel from the Saab is if you back it up into an enclosed space and start it at a low ambient air temperature the next morning. You'll get a whiff from the auxiliary fuel heater but sadly not from the exhaust.

On me, you'll get it when I smear diesel on my hands at fill up time, or just for a cheap kick. But that's something else.

I use simple physics and engineering to show why what I say is correct. I have no "belief system" and have been in and driven many diesel cars over many years including the 3litre v6 merc triple turbo of my brothers since he got it up till yesterday.

If you make any comments please show your "reasoning" rather than your "opinion"...

Yes of course I do. But I have power and turque curves here by the dozen that prove you are wrong, and totally agree with what my senses tell me. You are confusing the "bump" in power production at 2 to 4k revs as flexibility because at these rpms only when you compare (unfairly) a non turbo petrol to a turbo propped up diesel then the diesels torque curve wins. But as you yourself have already said, because the diesel has to have taller final drive because it only makes good power at low to medium rpms there is far less available at the wheels at any given roadspeed. You also confuse flexibility with the fact that at your chosen cruise speed the diesel turbo is more likely to be in the rpm band (narrow that it is) that means good acceleration. Initially. But a gear change required soon after... Engine flexibility refers to the fact that it pulls and can be used over a wide rpm band. Diesels cannot.

Plus if you have to compare a diesel to a petrol then its also unfair to try and compare a naturally aspirated petrol to a forced induction diesel. The only reason that we do is because a normal cooking type car (shopping golf?) does not need the aditional expense and complication of a turbo system to be perfectly usable and cheaper as it is. Even so it can compete well.

If you took a non turbo diesel and produced a dyno curve it would make far less power and torque EVERYWHERE on the graph from idle to its low rpm maximum compared to a similar design / size of petrol engine. And it would be less flexible too.

Add a tiny turbo to the diesel so its going to boost at a lower rpm as poss (typically 1800 to 2200) and you get the same crap power from idle to boost, then an improvement over both the diesels original figures and the petrols figures (in some cases) up to a point. Then as it peters out due to a) the small turbo strangling it at higher rpms b) the slower burn speed the petrol engine continues on and can make very good power by 3k to typically to 6k plus.

You cant. And I am please you cant.

Individual ratios are pretty unimportant, final drive ratios are the one that matters. Whats more important is a graph showing (as my own and dynojet dynos provide) power or torque at any given roadspeed in each gear. This shows that having big dollops of torque at 2500 rpm gives EXACTLY the same power and torque at the wheels at 70mph as an engine that makes half the torque at 5k rpms. It also shows why a large spread of torque is important if you are not to spend most of your life changing gear.

Because... (figs are exagerated for simplicity in maths)

1k to 3k Dies engine 100 bhp peak 100 mph flat out. Same gearbox. 1k to 6k Petr engine 100 bhp peak 100 mph flat out Same gearbox

The final drive has to be twice as tall in the diesel since it produces peak power at 3k The final drive has to be half as tall in the petrol since it produces peak power at 6k therefore half the torque at this rpm.

The Diesel however has only half thevrev range. So it needs double the amount gears to get the same level of flexibility because the torque curve is shorter by 50 percent..

If you disagree show your working out.

For what its wiorth the dyno, and real life observation shows the same thing although the maths is plenty clear enough without it.

They all do it. Dyno one and watch the graph. They cannot burn the fuel fast enough. Its why they dont rev out like petrols do. And because they rely on a turbo for power there is always the off boost low rpm problem. With small enough or variable/multi sized turbos this is minimised to a degree but its always there. You either ignore it, doint have the feel or experience to recocgnise it or deny it.

The word "modern" has no effect on the engines performance. Turbo diesels have been on the go rather a long time. Their performance has changed. They still have off boost and rpm and overev problems as well as a short usable rev range. The addition of microchips end electronic fuel systems served to cut enmmissions and save more fuel but certainly has no effect on power production or usable rev range. Diesels induct air. Turbos help them induct more air at lower revs (since they cant burn the fuel fast enough at higher revs) to help them. It does not matter about finesse of fueling on a diesel. if you doubled the fuel flow you get black smoke and make sure no air goes unused. If you half the fuel flow then you get half power and much of the air goes through unburned. "Modern" is marketing for both sales and emission control. And we had multi sized turbos and variable geometry turbos years ago.

OK but it just shows you igniorance of the engineering and workings.

A non turbo pertol ALWAYS makes MORE power than a non turbo diesel at ALL rpms. And an off boost diesel is just exactly that. The petrol engine will pull properly and without a step when it finally gets on boost from idle.

If you disagree show me your logic and explain why? Your "experience" appears biased and totally illogical.

I NEVER said that. It most likely has. But its also possible that it only feels like it has. If theres bugger all up top it makes the low down power seem better! But its only at this point in the rpm range that this will occur. Look at the graphs. As soon as you begin to accelerate the saab will run out of steam and the accord will leave it. But it just tells me you were in the wrong gear. And at the same ROAD speed rather than revs the honda would already be at higher revs in any given gear...

Plus theres the fact that even here you are trying to compare turbo to non turbo!

You are showing your lack of physics again. The bikes weight has nothing to do with it. In fact the 750s were lighter. Their problem was lack of flexibility meaning too many gears needed. WTF has the fact that "cars are heavier" got to do with anything. It was just an analogy of the rev range problem that diesels have.

Yes I did. You didnt seem able to understand complicated stuff again.

Torque curves on most road cars are pretty much the same shape. Only shorter and at lower rpms on the diesels turbos. I didnt omit it. The final drive ratio squares things up pretty nicely.

Its not optimum, its usable. But the petrol one is FAR more usable!

Again. It is if you choose to and even here it will make more power than a diesel. And theres no "step£ where it goes from totally useless to boost where it puls as in diesels. Check powercurves if you dont believe me.

Some may. The earlier they do then the smaller the relative size the turbo or its exhaust housing nozzle is. At which point it strangles it more at the higher rpm end!

I agree that at 2000 rpm once they are on boost they are better in most cases for a few rpms than petrol. But so what? As you begin to accelerate you one point in the rev range where the diesel was good is past! And the petrol takes over all the way to the 6k red. But you need another gear... And again, you are comparing a blown engine with a naturally aspirated one that costs less. If you really wanted to cream the diesels small earea of glory you just fit a small turbo to a petrol engine and it too would do the same and then some. But to do so would limit its rev range like the diesel (because of the small turbo) so the manufactures in there wisdom correctly choose not to!!! Insread they let it rev and get "free" power...

But the fact that a diesel has a shorter rpm usable range means its the DIESEL driver that needs to keep checkingh the tacho! Your logic defies logic!!!

No see above. Its you that does not seem to quite get it. The rest of the engineering and motoring world already recognise the diesels lack of flexibility. You seem to want to ignore every graph and every test!

Compare curves. # With a non turbo petrol v a turbo diesel both power curves are a different shape. The petrol one is not as good at 2500 rpm (which is a spike/bump inthe curve on the diesel.) But the petrol is way better from idle to say

1800. And way better from 3.5k onwards. And continues well after the diesel has run out of revs. And you are still unfairly comparing a cheaper less complex non turbo petrol! And whats good for the goose etc....

Only because the diesel has and needs taller fimal drive to do the same speed. And the usable minimum and maximum in each gear is about 20 percent lower.

Err All petrols go well and most are at or around peak torque at 3000 rpm! And maintain this about to 4.5k on a nice flat torque curve motor! So You get MAX acceleration at 3k or close and max power at about 5.5k as the torque curve tails off slowly.

So what happens if you want to accelerate in your diesel from 3k? Its worse, and you need another gear much sooner. And we are talking about your unfair comparison with a naturally asp petrol!

I dont. Its lumbered with torque reducing higher gearing because it makes its power at lower revs. Net result is the same apart from the need for more gears to suit the narrow band.

No its exactly the same. Its why POWER is directly comparable.

100 bhp is always 100 bhp no matter if it is derived from a hight torque diesel or a 14000 rpm bike engine.

Gearing simply reduces the torque until the same power is applied to the road regardless of the ammount of torque x rpm it was derived from. And final drive ratio - taller or not does not make a less flexible engine more so! There a hole in you physics again. Only multible gears (or more gears) and more work matching them as you drive can do that.

If you had a motor that only did fized rpm you would need an infinite number of gears. Same applies no matter how you try to describe things!

Manufacturers deliberately use tall

Rubbish. The best gear ratio for fuel efficiency is usually the same one that gives the highest BMEP providing the injection system is correctly set up. This means a top gear that would give the best brake mean effective pressure at the chosen test roadpeed.

so your

The amount of power an engine produces has absolutely nothing to do with gearing anyway. Unless you mean driving around in an overdrive top at low speed? In which case you are in the wrong gear.

What you mean is not flexibility. That refers to usable rpm range. You mean torque at a specific rpm I am sure. So a turboed diesel with tiny turbo can make more torque at a single small area of the torque curve? At low revs. But nobody argued that this was not the case. And remember your torque advantage on the dyno graph is torqe v rpm Unfortunately its small advantage is all but completely gone on a torque v roadspeed graph compared to the petrol due to the taller final drive your diesel needs precicely because it makes all its torque and power at low revs. Thats why power is directly comparable and torque isnt. Unless you compare it at a given roadspeed AT THE WHEELS!

No its not. Its because of the shape of the torque curve and because the diesel is already more than halfwar through its useful usable power band at

2500. And because again you are comparing a blown motor to a cheaper more flexible naturally aspirated one.

But I do know. The difference is that I understand it. And have experience of it. And yes I do use a lot of power lots of the time...

You cant the diesel is already the go faster version! How will you turbo it? It already is just to compete with a cheap non turbo petrol badly...

At the end of the day it has to be paid for. Its not free so if you are going to compare petrol to diesel you must make a fair comparison. Either allow for a bigger capacity, more cylinders, or a turbo just like the diesel.

Only if you stick it in top too early! Modern gearing... (How pray tell is gearing "modern"???)

You cant. It wont. It cant. You are stuck with tall gearing to try and get some roadspeed with the torque reduction that this means.

4000 revs IS high revs and theres no power there anyway. Thats why they are inflexible.

Its still a pain.

I cant even hear most petrol engines and to see if its running you need to open a window and listen carefully. No diesel is like that.

If you reduce the rpm range enough you would need 75 gears to reach 30mph. The only difference between this and a diesel as they are now is that its not so extreme. But its not a nioce thing.

Well thats all thats left. To suffer the consequences while being ignorant of why???

Most dont care and they are not HARD to drive (trucks need many gears but are easy to drive but just hard work and tiring)

Yep they do. You just dont hear it as much as before on the indide due to mountains of sound padding etc...

If you say so. I cant be bothered any longer...

I never said "difficult" just anoying.

for people, even those inside

Clutching at straws????

Because of size in the case of HGV and because of risk of death through speed/lack of ability in F1.

All of those yes. And more. Diesels are only good for economy.

Errr ENDURANCE races! They are better on fuel... But I said that already. Now you are arguing my case for me??? I am still worried about your "logic"... They dont win any outright race type races full stop.

I can because its entirelt true! Not being pedantic.

That does not change the engine and can apply to petrol too!

That does not change the engine and can apply to petrol too!

That does not change the engine and can apply to petrol too! In fact it does to my 9 year old van...

That does not change the engine and can apply to petrol too!

As I said the last one I tried recently was an expensive triple turbo 6 cylinder brand new merc. All the previous still applies.

Quite!

Most.

Debatable. It depends on your definition of quicker. If you mean it "feels" livelier with a quick prod of the throttle then most likely. But try and actually pass a few cars or get through a gap where you actually need some performance and the illusion dissapears....

That's despite it being heavier

But thats because they dont NEED a turbo. And it keeps them cheaper. But try comparing like for like...

Sorry but my neibour has one it sounds like a truck every morning.

Ermm yes and its easily proved.

No its because rod systems and traffic simply dont allow it...

It is if you change speed now and again. You do abouty 20 percent more gear vchanges than the more relaxed petrol driver due to limited rev range.

Any info or power v roadspeed graphs to back up your opinions because I really am not wrong.

Same capacity, both turbo? Seems fair in both complexity, cost, etc to me... The turbo petrol makes half the power because and this is the bit you dont like they are pretty crap!

I have not been drag racing for 8 years. Based on many bmw (new) merc (new this year) and the diesel chrysler voyager (admitedly a daimler mercedes sourced 2.8 common rail) one this year alone.

Pop over this side of the river and have a listen to mine...

I don't think I've ever been in a car where you can't hear the engine running. Either, that's bollocks or Burgerdude has bad hearing from all those drag bikes heh.

Lexus LS430. Merc S500. BMW 760i. Eerily silent. You can't hear the engine of the E280 over the aircon.

I have had one or two like that as well! As you know... But they sound nice rather than like a ignition setup ptoblem,,,

Err well yes I do have a slight hearing prob in one ear! Happened suddenly out of the blue. But really in some good (read expensive) cars you really cannot tell if its running without checking tacho...

Cobblers. You waffle endlessly and vaguely in an attempt to justify your prejudices and to wind up Dervman. :)

ok, example. Take the VW 140BHp 2.0 TDi engine and the VW 150BHp 1.8T petrol engines:

The TDi produces >175nm of torque FROM TICKOVER to 4700rpm (ratio 5.8) The 1.8T produces >175nm of torque from 2300 to 6000rpm (ratio 2.6)

The Tdi produces >100BHp from 2200rpm to 4800rpm (ratio 2.18) The 1.8T produces >100BHp from 3700rpm to 7000rpm (ratio 1.89)

The TDi produces >90% of peak power from 3100rpm to 4200rpm (ratio 1.35) The 1.8T produces >90% of peak power from 5300rpm to 6400rpm (ratio 1.2)

These are all taken directly from dyno plots. In each of these cases the TDi is actually *more* flexible than the more powerful petrol lump.

I know that it's possible to find counterexamples, but I'm only trying to show that TDs are not the weedy, inflexible things that you seem to think they are. Bear in mind that I *prefer* the petrol power delivery

- but I can see that the diesel IS better for an equivalent peak power. It's simple physics.

But again it only torque at the wheels that counts and because of the different final drive ratio the petrol has better and greater torque at a given road speed. You cannot compare torque curves without knowing the speed at which this can be achieved so this is meaningless.

Ok but the petrol is entirely usable below 3700 and it may make less power here but its making more than the diesel below its 2200 point and as you go further down the rev range the more this is the case. Those figures only work if you choose 100 as your reference point. And its only a 1.8... And a crap example of one!

But its a greater peak power! You should be comparing engines of the same size and a specific hp number not a percentage of each! But then your flexible diesel would look inflexible again wouldnt it compared on equal terms...

What are the figures for say 50, 70, 90 bhp which is still most of the power? Suddenly the diesel looks bad again? I dont have those graphs that your looking at but I would almost garantee it.

Plus you chose a specific pair of motors that show the turbo petrol up badly. Since the Diesel is pretty good and the petrol is weedy for a 1.8 turbo. And the petrol engine is smaller!

Only by your chosen power level, smaller petrol engine, chosen percentage etc By others the smaller petrol engine even though its a bad example still wins.

Post the graphs and I will choose some different specifics!

I dont think they are, they are!

Bear in mind that I *prefer* the petrol power delivery

No its not "better" at all. Its different and suited to heavier vehicles, towing, etc or for those that dont drive in a very spirited way and to save fuel.

And you are 100% right.

It seems that most here (NA petrol >< Turbo Diesel) do not grasp the meaning of turbo-charging.

However Turbo-petrol >< Turbo-Diesel and the diesel-engine is blown away.

TDM

At 70mph a petrol V8 5 series is producing 68 decibels of noise in the cabin. At 70mph, a 535d 5 series is making 66 decibels. So it's actually quieter than the petrol one :-)

Yep but who WANTS to hear a diesel! And thats the only time its as quiet...

Absolutely, except, the examples of "ordinary" vehicles that have a comparable* turbodiesel or turbopetrol engine in the range are very limited.

*comparable in end user cost.

If there were a 2.0 litre BMW turbo petrol model that could compare with the Alpina D3 we could be laughing.

But you change what you claim to suit.

I struggle to understand this, how you have such extensive experience and yet don't understand the changes over the years.

This is Usenet.

Except that this "bump" is between ~1,750 rpm and 4,750 rpm

It is only unfair from your Ivory Tower engineering perspective. In the manufacturers' line ups it's perfectly fair.

Far less available? No there isn't far less available. There's proportionally less available. Yet you'll still find the turbodiesel has significantly better acceleration in the higher gears compared to the petrol.

You change down in the petrol to match the acceleration. That's *less* flexibility.

Correct. You confuse flexibility in the real world with some engineering term. Or available engine running speeds. I see, so you reckon that the

1,500 rpm or whatever engine speed advantage that the petrol has makes a real difference to everyday driving, given that it's impossible to cruise (not) and you need to use those extra revs every gear change.

Right.

No it isn't. If there's a useful amount of power from as low as 1,750 rpm such that one doesn't need to change down on a motorway gradient in top gear, and this usable power continues to a pessimistic 4,000 rpm, where's the compromise here?

You're tackling this from an engineering perspective, which is flawed when we consider the real world. Unless you tell me that you drive around, up and down gradients, overtaking other vehicles, in top gear in your petrol because it can be used from 800 rpm to 6,500 rpm. If that's the case then you _desperately_ need an automatic.

Why so?

You keep on going on about this hugely complicated and expensive turbocharger and how it's a disadvantage to a diesel, or bleating that it isn't fair. Tough, because the majority of model ranges have a range of normally aspirated petrol engine and turbodiesels in the line up, typically with maximum power levels at or just below European power / tax bands. And yes turbodiesels typically cost a little bit more. But they are also typically quicker in everyday use for a given maximum power output.

There are good reasons why manufacturers don't use a 1.0 litre, three cylinder, turbopetrol engine back to back with a 1.6 litre, four cylinder, turbodiesel in a model line up with comparable maximum power outputs. For the most part it's because many people won't buy a 1.0 litre Focus / Golf /

307.

So? Is this you trying to change the goalposts without reference to the real world again? There are so few examples of model ranges where a naturally aspirated diesel is paired up with a smaller capacity petrol engine. I can think are some VAG models.

Meh, no, you'll find that this is not the case from a real world perspective.

Lower. Lower. If you'd bothered to keep pace with how modern turbodiesels have benefited from improvements and refinements in their turbocharger(s) you'd understand that they start to produce boost at the 1,400 rpm point upwards.

Chip. Shoulder. Go figure.

In many cases.

The point where the petrol engines starts to come on song and the turbodiesel starts to go off song.

Right. So what you're saying here is that the petrol's power band is 3,000 rpm to let us suppose 6,000 rpm. That's 50% of the rev range. Then we compare this with our turbodiesel and for arguments sake we'll say 1,750 rpm to 4,750 rpm. If the diesel is limited at 5,000 rpm, vote now on the percentage of overall rev band where our turbodiesel produces high power levels:

(a) turbodiesels are noisy, smelly and s**te (b) sixty percent but see above (c) turbodiesels are noisy, smelly and s**te

Hmm.

So? Unless you want to compare family car with hot hatch?

Enter lots of naturally petrol engines, where their output is jack under

3,000 rpm.

Yes.

Why are you taking a text book and replicating it on Usenet to try to demonstrate your years of experience?

You're making some pretty huge assumptions about the torque curves of both engines, though. Plus you're also sticking with this engineering definition of flexibility. On the road things are different. That lump of torque available from a turbodiesel arrives at around the one third of maximum engine speed. It arrives later in a petrol engine, for arguments sake I'll work on half maximum engine speed. At a motorway cruise or driving through a village at 30, where do the engine revs typically sit? Somewhere between one third and one half of maximum engine speed...

'Course you could drive along at 30 in second in the petrol to benefit from the revs being closer to 3,000 rpm rather than 1,800 rpm, so as to better match the turbodiesel's acceleration.

On paper you're absolutely right, but you're ignoring what happens out there

*waves at real world* and sticking with what your data says. What happens in the real world is what happens when people drive them. This is the bit I'm most interested in.

I don't need to, though.

That's at the top end of the rev range. You're ignoring what happens elsewhere.

Yes, except you are interpreting some data on a chart as how it drives on the road. Ivory Tower.

You need to drive more cars with a variable geometry turbocharger set up, then. There are plenty about.

Whereas you simply pull off some charts and translate this into how they drive on the road?

Re-read what you've said, on the one hand you say that modern stuff has no effect on performance but on the other, you claim that things have changed.

No.

Wrong. You'll find that, just as with petrol engines, some modern designs will rev much higher than older generation engines *and* produce more output at the bottom end of the rev range.

Yet have only seen relatively widespread use in the last eight years or so.

Tough. You show your ignorance of live outside your tower elsewhere.

One, I don't believe you and two, if the driver is daft enough to try to drive any turbo car outside of where it produces boost, then he or she need to be educated or be given an automatic.

Petrol engines are worse under where their turbocharger produces material boost. Low compression engine, no torque, nothing absolutely nothing.

Erm, no, it just *feels* smoother. There are still bumps in acceleration.

One of the reasons why I bought the Accord was because too many four cylinder normal engines are too compromised and feel plain weany at low engine speeds. The F-series engine in my Accord is a SOHC VTEC, a means of flattening the torque curve across the rev range. It worked well, to a point, but there's still a definite hike in acceleration at 2,500 rpm (so much so that it's utter gutless under this engine speed) and again at 4,500 rpm (the change of camshaft lift profiles and intake tracts). My theory is that I wouldn't have to rev it hard for strong overtaking acceleration. Unfortunately in practice, it needed 4,500 rpm for strong acceleration and the reason why it was geared to 20 mph / 1,000 rpm is because under 2,500 rpm, try to accelerate in the upper gears and tumbleweeds roll past.

Doubtless you'll claim that it's s**te or something and you're entitled to your opinion.

Absolutely not, even with 40% shorter gearing. Accelerate at 2,500 rpm in top at 50 mph and it does nothing. Accelerate at 2,500 rpm in top in the Saab at 70 mph and its acceleration is far stronger. Indeed accelerate at

50 mph in top in the Saab (engine speed ~1,800 rpm) and it pulls much better than the Accord.

Inside the speed limit in top gear the Saab has materially stronger acceleration.

But that isn't what happens. The Saab is producing ~91 bhp at 2,500 rpm.

If the Accord's gearing were shorter in top then it would have stronger acceleration but a lower top speed.

Because the Accord isn't as flexible it needs a downchange (to third) to out-accelerate the Saab.

Would you like me to discuss towing stuff in the Saab versus the Honda, too?

Bingo. All too many modern petrol cars will drive in a certain gear but have such limited acceleration that they require a downchange.

This is a lack of flexibility. It isn't something turbodiesels suffer from in the same respect. You don't need to downchange as much. You have superior flexibility.

And producing less power for the majority of the time, because when cruising one uses the highest gear possible. I don't drive through 40 mph speed limits in second gear in the Accord... I'll use fourth or perhaps fifth. I'll use fourth in the Saab. Accelerate the far side of the limit, the Saab goes much better. The Accord, well, shift down to third or second...

Irrelevant.

You are showing your lack of understand of real world driving (riding) once more.

A lack of flexibility for road going purposes has all to do with power to weight. More weight needs more power for effective acceleration. That's pretty basic mathematics. More power needs either more torque or more revs.

See above.

Unless you've driven a 2000 Saab 9-3 TiD you'll just have to take it as assumed that it's usable from idle to 5,000 rpm, it just happens to have superior acceleration in the above range.

It's smeared across a few hundred revs.

Point is though that there's such a compromise involved in a manual petrol, then. I can either keep the engine where it produces plenty of power but it's noisy and thirsty, or I can use a higher gear to keep it quieter but accept I have significantly less flexibility and acceleration.

I don't have this compromise with the turbodiesel.

No point.

All do. There is no may about it.

What kind of crude technology do you think is used for diesel turbochargers these days? Update yourself before making such assumptions.

More power, greater flexibility, fewer down changes.

And here you're assuming one decides to use all engine revs when accelerating. You don't.

So?

And yet so few manufacturers do this.

And force drivers to make a much bigger compromise on the gear selection for a manual.

Erm, no. I don't need to use the tachometer. Actually I can turn it off most of the time. It's easy. If you are in a driving gear you have enough acceleration. End of.

Hardly.

Compare road speeds and gear selections.

I don't give a stuff about the increased cost of the turbocharged donk when my earned money can buy either.

No, it's because the petrol engine gearing has to be much shorter. You have this backwards.

Most?

Point is that you'd drive it such that you'd accelerate lower down in the rev range, though. Just as you'd change down in the petrol for better acceleration, you don't bother changing gear in the diesel.

Neither is wrong nor right, just different.

If you insist on trying to drive a turbodiesel like a petrol engine, no wonder you struggle.

If I try to drive a petrol like a turbodiesel I find it well slow.

Now I wrote this earlier and you denied it.

Or in the case of the petrol it's used to increase the torque at the road.

Blah blah. That's the engineer in you. This isn't how machines are set up, they're set up for low carbon dioxide / low fuel consumption / low noise levels. That means keeping engine speeds down over a broad range of commonly driven speeds.

This is exactly how petrol stuff is set up... though.

Hence compromise comments above.

Which is precisely where cars spend most of their time at.

You do.

So why oh why do turbodiesels out-accelerate their petrol peers in the higher gears inside the speed limit?

See above. Nearest to this is in gear acceleration times. People don't think, "oh at this speed range my engine is producing X bhp" instead they care more on the acceleration between points, like accelerating on a motorway slip road.

Or 2,000 rpm. Or 1,800 rpm. Right at the bottom of this bump you talk about.

And again you're citing a technological advantage, but thumbing through most model ranges we see naturally aspirated petrol engines sold alongside turbodiesel peers.

Well there you go then.

Eh?

I'm not entirely sure what you're on about so I'm going nod slowly and smile.

Hopefully it's subsidised by petrol engine car buyers.

Or alternatively we can look through a What Car? with a budget in mind and spend the same amount of money.

Go back twenty years and a typical family car had a top gear of say 20 mph /

1,000 rpm. It'll be closer to 25 if not 30 mph these days, depending if it's a five or six speed transmission. I assume you remember what cars were like going back many years.

The reasons for this? A combination of noise, emission and consumption compromises and since modern stuff has improved aerodynamics and more power, so it is geared to reach a higher maximum speed.

But speed limits if anything have gone lower over the last twenty years.

Where once our cruise of 70 meant 3,500 rpm it'll be 2,800 or even 2,350 rpm these days.

It may be technically correct to cruise at 70 in fourth or fifth gear rather than sixth, but people can and do cruise in the highest possible gear.

You don't need to. You do in a petrol.

4,000 rpm is not such a high engine speed for diesels these days given their improved willingness to rev beyond this point.

How so? It does everything for you.

Then you have a hearing defect.

Okay just read another thread and you do have a hearing defect. Listen harder. You can tell that the engine is running.

Except you don't need to do so if you adapt to the car.

I don't understand what you're trying to say.

I don't care if my neighbours can hear my diesel's rattle in the morning if I can't.

Better than banal generic petrol murmur whine.

So you're lazy. You can't blame the car for your laziness.

Earlier in this post you commented that you were quoting technical reasons and facts.

Now you're saying that it annoys you.

So really you're just trying to annoy me. Bet you wish it was working.

You do appear to be doing so.

Right, because, speed kills, yes?

Diesels are easier to drive and quicker in everyday driving.

Endurance means combining pace with range. Something slow but able to drive for eight hours won't win.

You're just speculating that. Unless you reckon that an endurance race isn't really a proper race?

You're being pedantic.

They win races so you claim that these are not real races.

I point out that they have better flexibility in the higher gears inside the speed limit and you say that the petrol driver is in the wrong gear.

Other people point out that some diesels are quieter than comparable petrol peers and you claim that they're only quieter at that exact speed and at no other times, even though you've never tried 'em back to back.

So?

So?

So?

So?

Oh so you tried ONE?

Great experience there.

Only if you do it using the wrong gear. You don't change down to overtake.

We are.

Not from inside the vehicle it doesn't.

I'm sure he doesn't idles the engine for a few minutes each morning just to annoy you in the morning, it'll be to ensure all those delicate and expensive turbocharger oily bits are properly lubricated.

Nope.

Strange that I seem to manage it. Oh and I commute over 20 miles each way, most days, in rush hour.

No you don't. Somebody used to driving a petrol car will change gear far more frequently in the turbodiesel than he or she needs to.

Conversely, somebody used to a diesel will find the petrol car remarkably unflexible and unforgiving to drive over a hilly piece of road.

You really are wrong.

Except the 200 bhp turbopetrol won't cost the same as the 110 bhp turbodiesel.

Eh? I don't think turbopetrols are crap. They're great. What I disagree is the chip on your shoulder where you claim that all turbodiesels are crap.

So you have limited experience then?

Point is that you hear it less, though.

Nonsense.