diesel vs. petrol

the jew

can someone explain the differences to me. im probably wrong but what i understand is diesel are louder and slower but give more mpg and last longer.

prospect

the jew wrote:

can someone explain the differences to me. im probably wrong but what i understand is diesel are louder and slower but give more mpg and last longer.

Wrong
Wrong
Right
Right

fletch

the jew wrote:

can someone explain the differences to me. im probably wrong but what i understand is diesel are louder and slower but give more mpg and last longer.

It all depends on whether you are going for a modern diesel or not. Give us an idea of the sort of market you are in.

prospect

Just did that for dramatic effect...

Modern diesel engines have made huge amounts of progress in terms of performance and refinement. Esp. Turbo Diesel.

If you want absoloutly flat out thundering hot blisteringly fast, then petrol is really your only man, after all i have yet to see a Diesel Supercar, that sells.

But for your average Joe Soap, a decent TDi is more than powerful enough, with buckets of torque to boot.

Last year (or maybe two years ago ) i was at an Alfa Romeo day in mondello. I did three laps in a 2.0 Petrol and then three more in a 1.9 Turbo Diesel (JTD), I far far far preffered the diesel. No question about it.

ciarsd

prospect wrote:

I far far far preffered the diesel. No question about it.

that'll be the torque pulling you out of the corner and launching you into the next

DIEsels nowadays are nothing to be sniffed at. They are no longer the 'black sheep' so to speak. In fact I would consider one myself when I'm changing cars, even if just for a change-something different.

I believe the Alfa JTD's are quite good, all reports I've read - I've no actual experience - yet!

The best bang for buck though (at the moment) has to be the PD Diesel engines a la Golf TDi's - and all the VAG diesel motors

Capt'n Midnight

Diesels extract more energy out of the fuel - if they could run on petrol they would still give higher mpg than a petrol engine (spark plug). Because they work at higher pressures they need to be much stronger than a petrol engine , and so cost more. You need to be doing a lot of miles to justify the extra expense of a diesel in this country, abroad tax breaks might mean a different decision. Secondhand diesels need a full service history as they aren't as forgiving as petrol engines when it comes to skipping services. And while you can run diesel engines on waste chipper oil the revenue take a very dim view of such things.

ando

I recently went from a Focus petrol to a Leon TDi and the torque is something that took me by supprise. Even though the 0-60 aint fantastic, the in gear acceleration/torque is very nice. I can't wait for the remap

The things that I don't like about the diesel are,

1) The noise at traffic lights (is that a Transit behind me.. oh no thats me)

2) Short power range, rocketing away from the traffic lights is a bit tricky as first gear is so short but once in second your laughing, main boost of power comes in at 2000RPM and dies at just over 4000RPM

My engine aint a PD, but if I get a chance to get one reasonably cheap, I'll be upgrading as they are suppose to be superb for torque... I'd rather more Torque than BHP. Remap a Leon TDI 150 PD engine and you could pretty much beat anything on the Irish roads

Focus RS Torque, 228 ft/lbs
Chipped 150Tdi, 300 ft/lbs

prospect

ando wrote:

1) The noise at traffic lights (is that a Transit behind me.. oh no thats me)

I think that may be model specific.
My father-in-law has a 1.6 HDi 407 and it is extreeeemly quiet (although i do not know how it compares to a 407 petrol). And my brother-in-law has a 1.6 HDi 307 and it is considerably louder, although it is very tolerable , like a rumble.

lomb

prospect wrote:

I think that may be model specific.
My father-in-law has a 1.6 HDi 407 and it is extreeeemly quiet (although i do not know how it compares to a 407 petrol). And my brother-in-law has a 1.6 HDi 307 and it is considerably louder, although it is very tolerable , like a rumble.

codswallop, i have been driven in a 105000 euro s320 cdi mercedes and was far from impressed tbh, noisy bastard.

also vw diesels are very vocal, just listen to a new 35 grand one, yes modern diesels are powerful but they dont rev high up, dont sound sporty and are not very refined come back in 20 years until then petrol is the king of smoothness.

prospect

lomb wrote:

codswallop, i have been driven in a 105000 euro s320 cdi mercedes and was far from impressed tbh, noisy bastard.

also vw diesels are very vocal, just listen to a new 35 grand one, yes modern diesels are powerful but they dont rev high up, dont sound sporty and are not very refined come back in 20 years until then petrol is the king of smoothness.

Once again, It may be model specific!

Just because some dope was willing to fork out 105000 on a car, doesn't mean it will be the best at everything, and if that is what you think, then you have a lot to learn.

Peugeot/Citroen make the best diesel engine there is, and i know Ford are involved nowdays.

IMO, VW were never great when it comes to refinement of any sort, hard seats, hard ride, hard ergonimics (but that is just personal opinion)...

I agree that they don't sound sporty, but no one said they did.
I agree that they are not as smooth, but no one said they were

But as per the original post,
Diesels ARE much more refined than they used to be
Diesels ARE much better performance engines than they used to be

They may not compare to some (not all), petrol engines. But for the reliability, economy and torque, I presonally would prefer them.

P.S. I know a guy who spent 5 MILLION euro on a petrol car once, and it broke down, and petrol is crap, cause he spent, like, soooooooo much money, cause, like, yeah, bullsh1te, kids talk, crap

ds20prefecture

prospect wrote:

Peugeot/Citroen make the best diesel engine there is, and i know Ford are involved nowdays.

Ford buy their Diesels from PSA. I was standing outside an idling C4 1.6 HDI and I had to ask the guy was it a diesel. He's averaging 1000km from a tank, and his car has the same BHP as it's petrol alternative, with 50% more torque. There is a €1000 premium on Diesel over the petrol model, but you will most likely get that back at resale.

However I don't think PSA make the best diesel engines. The Fiat/Alfa JTD is a fine engine and the newer BMW six cylinder diesels are probably the absolute best, IMHO. Has anyone driven the BMW V8 Diesel?

Most disappointing is the 5.0 V10 from VAG. Apparently it is terribly prone to failure, is large and heavy, and not particularly powerful, smooth or economical.

prospect

ds20prefecture wrote:

Ford buy their Diesels from PSA. I was standing outside an idling C4 1.6 HDI and I had to ask the guy was it a diesel. He's averaging 1000km from a tank, and his car has the same BHP as it's petrol alternative, with 50% more torque. There is a €1000 premium on Diesel over the petrol model, but you will most likely get that back at resale.

However I don't think PSA make the best diesel engines. The Fiat/Alfa JTD is a fine engine and the newer BMW six cylinder diesels are probably the absolute best, IMHO. Has anyone driven the BMW V8 Diesel?

Most disappointing is the 5.0 V10 from VAG. Apparently it is terribly prone to failure, is large and heavy, and not particularly powerful, smooth or economical.

Drove the Alfa JTD, and was mightly impressed. But the 407 was my most recent experience, and it is obviously the same engine in the C4 you mentioned.

As a matter of fact, i spoke about two months ago with a guy who worked in Gowans (Peugeot/Citroen Importer), and he was telling me that they had a press day for the launch of the 407. One motoring journalsit seemingly came back after test driving a 1.6 HDi, and asked for a spin in the diesel version!!!!!

I wouldn't claim the car was that quiet when driving, but it is damn near close.

alias no.9

VAG are resisting the move to common rail technology because they have invested so heavily in their own Pumpe Duese (sp?) technology over recent years. Common rail diesels are light years ahead in terms of refinement and that's why the VAG engined diesels seem so noisey compared to the competition.

unkel

ds20prefecture wrote:

However I don't think PSA make the best diesel engines. The Fiat/Alfa JTD is a fine engine and the newer BMW six cylinder diesels are probably the absolute best, IMHO

Agree. the BMW 2.9 TD shocked many a petrolhead motoring journo when it came out first

Alun

ds20prefecture wrote:

Ford buy their Diesels from PSA.

Not quite ... the current 1.6 and 2.0HDi engines (Peugeot/Citroen) and the 1.6 and 2.0TDCi Duratorq engines (Ford) are the same thing (virtually) and were developed jointly by Ford and PSA. They are manufactured by PSA, but the development was a joint effort.

I've got a Ford Focus C-Max 1.6TDCi which has that engine. I test drove both that model and the 1.6 petrol version back-to-back, initially just "for a laugh" intending to go for the petrol, but chose the diesel instead.

ds20prefecture

Alun wrote:

Not quite ... the current 1.6 and 2.0HDi engines (Peugeot/Citroen) and the 1.6 and 2.0TDCi Duratorq engines (Ford) are the same thing (virtually) and were developed jointly by Ford and PSA. They are manufactured by PSA, but the development was a joint effort.

I am inclined to disagree. According to what I have read, Ford had their own development of turbo diesel engines for Europe right up to the 2.0 used in the first diesel new shape mondeo. They put a huge amount of resources into the development of this engine, which when launched was significantly behind the then standard setters VW & Fiat. They then ditched this engine for the PSA lump, thereby jumping to the fore of diesel development and saving themselves a fortune in further development costs. Previously, Volvo and Opel did the same thing with the early BMW 2.5 TD (good output, but very very rough)

Bear in mind GM and Ford designs are American led. Modern diesel engines just aren't an option in the US, due to the sulphur content of the fuel being 10 times that of diesel commonly sold in Europe. These companies have a global focus, compared with VW, PSA, BMW and Fiat. So the R & D boffins within Ford and GM just didn't invest heavily in diesel technology when it mattered most. Fiat's diesel tech was apparently one of the attractions in the doomed GM takeover. Ford solved their problem (and a lot of PSA's return on investment) by buying the engines from PSA.

Of course this is just speculation, and well off topic from the original post.

Alun

ds20prefecture wrote:

I am inclined to disagree. According to what I have read, Ford had their own development of turbo diesel engines for Europe right up to the 2.0 used in the first diesel new shape mondeo. They put a huge amount of resources into the development of this engine, which when launched was significantly behind the then standard setters VW & Fiat. They then ditched this engine for the PSA lump, thereby jumping to the fore of diesel development and saving themselves a fortune in further development costs.

Well, there's a plethora of press releases and suchlike that can be found by Googling that describe it as a joint venture, so that was my source. Of course, in any "joint venture", you're never sure of how the proportion of effort was split up. Just going on what I've read, rather than speculation:). Anyway, Ford are still using some of their old engines, notably the 1.8TDCi, partly due to supply shortages from PSA. Apparently they can make their old engine Stage IV compliant easier than the more modern engines!

Rapidude

lomb wrote:

codswallop, i have been driven in a 105000 euro s320 cdi mercedes and was far from impressed tbh, noisy bastard.

also vw diesels are very vocal, just listen to a new 35 grand one, yes modern diesels are powerful but they dont rev high up, dont sound sporty and are not very refined come back in 20 years until then petrol is the king of smoothness.

Must have been the driver mate.
I've driven plenty of new mercs and a s320 CDI auto is every bit as quick as a scoobie. The sheer torque in those motors would unhinge the front seats!!

FX Meister

I was away in the U.K. at the weekend and noticed a new Vauxall/Opel Vectra with two fuel caps, and the lettering dualfuel on the back. I briefly talked to the guy about it and he informed me it was gas, which I had suspected. He said it's great for long journeys and cheap until the Russians cut them off, what ever that meant. 35p per litre compared to 70p for petrol. A huge difference as you can guess. Any ideas on this system? How come we don't have it here? I know we used to years ago but don't anymore. My mate in the UK is going to look into getting his Astra retro fitted as he does a lot of distance in his car.

lomb

Rapidude wrote:

Must have been the driver mate.
I've driven plenty of new mercs and a s320 CDI auto is every bit as quick as a scoobie. The sheer torque in those motors would unhinge the front seats!!

very quick car and is able to spin its wheels and do donuts with incredible ease. he absolutely blistered the back tyres, and considering its an auto with traction control thats impressive (it was a loaner demo for the night from the garage they deal with )
very noisy car though really lets it down. also saving 2 grand a year of fuel is irrelevent when the car is loosing 18 grand in year 1.

Balfa

Diesel engines are better at everything (from a performance point of view) than a petrol engine except for one thing. Because the fuel is injected into the cylinder after the air has been compressed by the piston, it is very difficult to uniformly fill the cylinder with semi-exploding fuel at high engine speeds. This, in addition to its longer stroke (because the compression ratio needs to be FAR higher), means diesels can't maintain their output into high rev ranges.

So at a given RPM (within the diesel's range), the diesel engine will be outputting far greater torque (and hence power) than a petrol engine, but the petrol engine will still be outputting useable torque long after the diesel has reached its redline.

This means the gears in a Diesel (remember, you can't talk about performance without talking about gears. It makes no sense.) must be longer to make up for the short rev range of useable torque. Petrol gets away with much shorter gears because each gear basically has 1.5 to 2 times the life.

Greenman

I love diesel cars, I've only owned diesel cars. My latest car is a 1990 Opel Vectra 1.7 with 120,000 km's. Its really is economical and as it is slow and drives like a tractor its very relaxing. Its easy to drive all day at 120 km/p/h on the m/way and it never misses a beat. When in Ireland I drive my fathers 1999 1.4 Golf petrol and cringe at how thirsty it is!!!

Although I don't do great distances in general I have done 880 km's on 42 litres which I feel was rather good Over here in good old Belgium diesel is about 92 cents best price but petrol is 1.20 euro so diesel is king, I would say 70% of the motorists here drive with diesel and for the people who use petrol, alot use it in combination with gas/LPG.

One downside of diesel driving in Belgium is your car tax is higher, I pay 290 euro P/Y tax if I had a 1.7 petrol I would pay about 210 euro P/Y

Give me diesel anyday!!!!

FX Meister

FX Meister wrote:

I was away in the U.K. at the weekend and noticed a new Vauxall/Opel Vectra with two fuel caps, and the lettering dualfuel on the back. I briefly talked to the guy about it and he informed me it was gas, which I had suspected. He said it's great for long journeys and cheap until the Russians cut them off, what ever that meant. 35p per litre compared to 70p for petrol. A huge difference as you can guess. Any ideas on this system? How come we don't have it here? I know we used to years ago but don't anymore. My mate in the UK is going to look into getting his Astra retro fitted as he does a lot of distance in his car.

Anybody?

lomb

FX Meister wrote:

Anybody?

3 grand grant in the uk

mike65

The gas used is CNG Compressed Natural Gas rather than LPG. CNG is an expensive system to instal in vehicles (adds about 2000 to the list price I think) it was breifly all the range with motoring journos but I think its quietly died a death as far as the mainstream market is concerned.

EuroTunnel wont allow dual fuel cars on le Shuttle which may tell you something :eek:

LPG used to be popular here (lots of old Mercs and Pugs used it in the late 70s/80s) but for some reason it fell by the wayside.

The crack about "until the russians cut them off" simply refers to where most gas will come from in the future...and the chaos that could be caused if they get upity!

Mike.