trvyyz
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Diesel Or Petrol Cars?

Thu Dec 14, 2006 10:02 pm

Which is better?
I like Petrol ones. For the same engine size, they are
Quieter,
more hp
faster
smoother
less maintanence
...

I've driven only some low tech diesel cars of India eg. ambassador,Indica, fiat uno
and i've heard praises about turbo diesels of german cars, are they really better than petro cars?

Just curious
 
cosec59
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 10:05 pm

I have recently changed from a 2.0 litre petrol Mondeo to the 2.0 litre 130bhp turbo diesel. The diesel is far smoother, offers much better economy and is, believe it or not, quicker.
Rules are for the obedience of fools but for the guidance of wise men
 
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WildcatYXU
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 10:25 pm

It's tough to say. Diesel cars are now better at fuel mileage (although the TDi Jetta I once rented wasn't all that impressive) and deliver a quite respectable amount of torque. OTOH they are very complex, lot of expensive technology employed, deliver less hp and despite of all efforts, are still bad on environment and use much heavier fuel (a part of better mileage comes from here).
Diesels are the european choice because of heavily taxed fuels and very often much lower tax on diesel.

Gasoline cars are usually simpler, environment friendlier, deliver more hp. With higher displacements and more cylinders they usually run quieter. This is why gasoline's are preferred in North America.

With some hi-tech gadgets we can have gasoline engines delivering some really respectable results. One of them would be a super-turbocharged VW engine, delivering 170 bhp from 1.4 l of displacement. The 2.0 l GM engine used in SKY Red Line delivers 260 bhp and 260 lbf of torque.
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CPDC10-30
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 10:34 pm

When you have cheap fuel like you do in Canada, you will see few benefits to a Diesel. However try beating this rental car I had a few weeks ago:

-Vauxhall Vectra (about the same size as a Chevy Malibu)
-1.9L Turbo diesel (150PS)
-6 speed automatic transmission
-Carrying driver and three passengers + bags

Average mileage over the span of three weeks and 2400 miles (in hills, towns, major cities and motorways): 55 MPG imperial, 45 MPG US . Holding 75mph using cruise control on the motorway the car would get about 61mpg. Show me a petrol that can do that in the same size class.
 
trvyyz
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 10:38 pm

Quoting CPDC10-30 (Reply 3):
Show me a petrol that can do that in the same size class.

I have no doubt that a same size diesel engine gives more mpg(kmpl) than a petrol. But I feel the comfort in a diesel is less and also its engine runs hotter and is also noisy.
 
cosec59
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 10:40 pm

Quoting Trvyyz (Reply 4):
But I feel the comfort in a diesel is less and also its engine runs hotter and is also noisy.

The diesel is smoother and more comfortable. Yes, the engine is louder when it's cold, but once it's warmed up and when on the move, you don't know it's a diesel.
Rules are for the obedience of fools but for the guidance of wise men
 
trvyyz
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 11:18 pm

Quoting Cosec59 (Reply 5):
Yes, the engine is louder when it's cold

That brings me to the next question. How do you start a cold diesel engine? do you still have to electrically heat the engine for a minute before starting in the mornings?

Also, another thing about diesel, i never fully understood about the gear shifts(manual). ie,
Upshifting is done at higher speeds compared to a petrol and hence it takes longer to reach the top gear. Is it really required although i followed this way with diesels?
 
cosec59
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 11:23 pm

Quoting TRVYYZ (Reply 6):
That brings me to the next question. How do you start a cold diesel engine?

Turn the key like a petrol car.
The diesel has glow plugs fitted. In older models you had to wait until the glow plug light had gone out. These days it's much different. The only time you need to wait is if it's REALLY cold.

Quoting TRVYYZ (Reply 6):
Also, another thing about diesel, i never fully understood about the gear shifts(manual).

Same as a petrol car.

Quoting TRVYYZ (Reply 6):
Upshifting is done at higher speeds compared to a petrol and hence it takes longer to reach the top gear. Is it really required although i followed this way with diesels?

Diesels rev much slower than petrol engines. I would say that changeing gear is done at roughly the same time as petrol. I tend to change gear at around 2000rpm in order to maintain the turbo boost.
Rules are for the obedience of fools but for the guidance of wise men
 
trvyyz
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 11:26 pm

Quoting Cosec59 (Reply 7):

Thanks for your replies. Very informative and updating for me.
 
Superfly
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 11:35 pm

I like diesel cars a lot and wish that there were more availible here in the United States.
They last longer, get better fuel economy and can run on cooking grease.

I not a big fan of German cars but they are excellent when it comes to making small diesel motors.
Bring back the Concorde
 
Kay
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 11:54 pm

Diesel is torquier, but you can't take it up the rpm's. It's also cheaper in miles per gallon.

So, small non-sporty cars can be ok with a diesel, because they already are crap euroboxes or whatheverboxes. Trucks are better as Diesel's too.

For drivers that require any refinement at all, a big petrol engine is what it takes.

Kay
 
Kay
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RE: Diesel Or Petrol Cars?

Thu Dec 14, 2006 11:57 pm

Quoting Superfly (Reply 9):
I like diesel cars a lot and wish that there were more availible here in the United States.

I must say this is surprising for someone who usually praises classic american V8 cars..

Kay
 
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WildcatYXU
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 12:04 am

Quoting CPDC10-30 (Reply 3):
Average mileage over the span of three weeks and 2400 miles (in hills, towns, major cities and motorways): 55 MPG imperial, 45 MPG US . Holding 75mph using cruise control on the motorway the car would get about 61mpg. Show me a petrol that can do that in the same size class.

Apparently GM has much better diesel engines now that some 6 years ago. I used to drive an Opel Astra B 2.0DLi. Wasn't the most powerful ever and the gas mileage was quite poor. I Compared to my own Suzuki Baleno, which is approx. a same size and had a slightly more powerful engine. The Suzuki's mileage was way better.

Your results are impressive. I drove my G6 to Space Coast and back this August. 4 passengers (including me), our bags. Average mileage 30 mpg. Even realizing that the car was basically brand new when we took off , the G6 is larger and heavier than the Vectra and the diesel is a heavier fuel, this difference in mileage is astonishing.
But still, this is Canada here. The only non-luxury cars with diesels around here are VW's. VW's are quite pricey around here. A diesel in the same size as the G6 (that would be the Passat) would cost almost 50% more than the G
6. There is no way on Earth to get this price difference back on fuel savings during the car's lifespan. Another problem is that our climate is colder around here. With weeks of temperatures around -25 deg Celsius you may get into some problems.
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Superfly
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 12:24 am

Quoting Kay (Reply 11):
I must say this is surprising for someone who usually praises classic american V8 cars..

LOL! Big grin

Well petrol/gas engine econoboxes over here don't get milage that is significantly greater than a powerful V8. The diesels on the other hand does.
A petrol/gas powered econobox is a half-ass attempt at making a fuel efficient engine.
The only import I've ever owned was a 1980 Volkswagon Dasher diesel stationwagon. That car had excellent fuel economy.
If I were to ever buy a German car or a fuel efficient car, it would only be a diesel.

Now for fun cars to drive; meaning powerful, luxurious and stylish, I would only buy American!  yes 
Bring back the Concorde
 
andz
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 12:30 am

I am now 6 months into my first diesel car and I don't think I could go back to petrol. I have a BMW320d, 6 speed manual, and it really is "sheer driving pleasure".

My previous car was a 320i 2.2 litre 6 cylinder 5 speed manual and it was a good drive until you tried to tow something. The diesel is a joy at this task, it will run all day in 6th at 140km/h and deliver fuel economy that most petrol cars can only dream of. The only time you know this is a diesel car is when stopped at a light or when you go to the filling station.

So far my best fuel consumption was 938km on 62.4 litres: just over 15km/litre or 6.6 litres/100km. This was mostly town driving with a long open stretch of about 300km.
After Monday and Tuesday even the calendar says WTF...
 
pelican
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 12:37 am

Quoting Andz (Reply 14):
I have a BMW320d, 6 speed manual, and it really is "sheer driving pleasure".

The *20d of BMW is probably one of the best Diesel engines out there. It's really a pleasure to drive.

pelican
 
sky0000547
Posts: 257
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 12:43 am

Diesel cars are quick, very quick but that is only when you got going and the turbo spinning. I can't say they are smooth to drive. You either have power or no power and there is nothing in between. They do give you more miles for your money and could be very quick. Diesel engines tend to be more robust.

Petrol car are more refined and quieter. You don't get so much miles for your money though. But performance wise is much better than a diesel for a like for like capacity.
 
Kay
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 12:47 am

What does it for me in Diesel cars is the lack of high rpm. You're just getting started and the engine wants the next gear.

Otherwise, they pull real good. Alot of torque.

Kay
 
Superfly
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 12:53 am

Any of you guys in German familiar with the BMW 2.4liter turbo diesel?

Here in the United States, that engine was availible in the 1984-1985 Lincoln Continental and Mark VII.
I wouldn't mind getting the Continental diesel.

http://www.4wheelz.net/makes/images/lincoln/1984_lincoln_continental01_e14e_big.jpg
Bring back the Concorde
 
pelican
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:03 am

Quoting Superfly (Reply 18):
Any of you guys in German familiar with the BMW 2.4liter turbo diesel?



Quoting Superfly (Reply 18):
Here in the United States, that engine was availible in the 1984-1985 Lincoln Continental and Mark VII.

No, I'm neither into antiques nor one myself.  Wink

pelican
 
Superfly
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:13 am

1984 isn't old enough to be considered an antique.
Bring back the Concorde
 
pelican
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Joined: Mon Apr 05, 2004 9:51 pm

RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:17 am

Quoting Superfly (Reply 20):
1984 isn't old enough to be considered an antique.

What is it than? Junk? Sorry, I wasn't serious. Although the car wouldn't be much younger than me...

pelican
 
Kay
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:20 am

You must mean this:

Introduced in 1982, 2.4liter Diesel, and 86bhp.



We drooled over this 3 series for years, but sorry, only the 320i, 323i and 325i.

Kay
 
Superfly
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:29 am

Quoting Kay (Reply 22):
86bhp.

Only 86bhp?
YIKES!

That is not good for car that weights 1814 kilograms (4000 pounds)
I doubt the turbohcarger adds much.
Bring back the Concorde
 
andz
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:42 am

Quoting Superfly (Reply 23):
Only 86bhp?
YIKES!

That is not good for car that weights 1814 kilograms (4000 pounds)
I doubt the turbocharger adds much.

That's the thing about diesel engines, the power is less relevant than the torque. My 320d weighing 1415kg makes 115kW but 330Nm torque and this is what gives it the edge over the petrol equivalent (320i, 110kW, 200Nm).

Acceleration (0-100km/h) and top speed are similar for both, although the acceleration of the diesel from 80 to 120km/h is 2 seconds better than the petrol. Add the better fuel consumption and the reduced emissions of the diesel and there isn't much point in buying the petrol version.
After Monday and Tuesday even the calendar says WTF...
 
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ManuCH
Crew
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:49 am

I'm a petrol engine fan when considering "small" engines (less than 3 liters or so). What I really dislike is the diesel engine noise of smaller engines. For example, Volkswagen/Audi's 2.0 liter diesel sounds like a heavy truck, and I prefer not owning a car which sounds like that. OTOH the 3.0 liter by the same manufacturer is a completely different issue and I'd probably prefer it when compared to the Volkswagen/Audi 3.2 petrol engine.

Just an interesting story for those who are mechanically illiterate, like myself: we were on vacation with friends in Davos, Switzerland, for a week. During the night temperatures were often around -25°C. Guess what - our friend's diesel froze, and he had to have his car towed to a garage to un-freeze his diesel, empty the tank and fill in new diesel. Not fun.  Smile

-Manuel
Never trust a statistic you didn't fake yourself
 
Superfly
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:51 am

Andz:
Very true but the gas version of the Continenetal was a 5.0 V8 that put out 170hp and eventualy 220hp a few years later.
I guess the whole point of a diesel Continental was to have stylish & roomy car that got good fuel economy.
Bring back the Concorde
 
Dougloid
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 1:53 am

I don't mean to rain on anyone's parade but I'm a skeptic.

I don't like things that smell bad and are noisy, whether they get great mileage or not. Diesel fuel costs about 25 per cent more than mogas here which wipes out any economic advantage that might accrue. They belong in tractors and large trucks. You all are welcome to them.

On the other hand, the last time I moved cross country was in 1993 and I drove a brand new IHC turbodiesel from Los Angeles to Iowa. It was a 28 footer full to the shit line pulling a Voyager on a trailer, and it got 6 mpg running a steady 55-60 mph. Which was pretty good considering. But it still smelled bad.

 yuck   yuck   yuck 
If you believe in coincidence, you haven't looked close enough-Joe Leaphorn
 
Superfly
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 2:00 am

I guess I am an odd-ball.
I like the smell and knocking sound of a diesel engine.
Bring back the Concorde
 
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WildcatYXU
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 2:12 am

Quoting ManuCH (Reply 25):
Guess what - our friend's diesel froze, and he had to have his car towed to a garage to un-freeze his diesel, empty the tank and fill in new diesel. Not fun. Smile

Well, we had two weeks of similar temperatures in Toronto in early 2004, my former boss was driving his wife's car for the whole 2 weeks, because his E 300 CDi wouldn't start...
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aloges
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 4:08 am

Diesel all the way for me. I've driven far more Diesel cars and kms than petrol cars in the four-and-a-bit years I've got my licence. Most importantly, there are the family's two VW Passat TDIs: one from 1994 with 90 hp, sold in 2002 and replaced with a 130 hp TDI.

The difference between the old and the new one was immense, it's a joy to drive now. Of course, 130 hp is not a world of power, but who needs that anyway? It's fast enough to comfortably pass cars on roads with distant oncoming traffic, it's fast enough to stay in the fast lane of the Autobahn for a long time and not bother anyone and it's economical enough to be a charm at the filling station.

As for fuel economy, I once got 6.9 l per 100 km out of it, with three people and some luggage in it, lots of speeding up and slowing down, the a/c set to "econ" and no extra attention paid to economic driving. Not bad. As for the smell - well, there wasn't a filter available when the car was bought, so you can see soot coming out of the exhaust at times. But once the engine is warm, you don't smell anything much.

Everyone, please don't compare diesel engines from the 70s or 80s with the TDIs, CDIs and so on of today. It just doesn't make sense. Someone said the revolve slower than petrol engines. While that is true, the Passat TDI I mentioned can comfortably be revved up to 4000 rpm. I sometimes do it when entering the Autobahn, when I want to speed up from 50 to 90 within the merging lane. Otherwise, I do care about fuel economy.  Wink
Don't cry because it's over, smile because it happened.
 
Dougloid
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 4:18 am

Quoting Aloges (Reply 30):
Otherwise, I do care about fuel economy.

Compare to me the price of mogas to diesel fuel in your neck of the woods. Are they the same, or different? By how much?
If you believe in coincidence, you haven't looked close enough-Joe Leaphorn
 
sky0000547
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 4:31 am

Quoting Andz (Reply 24):
That's the thing about diesel engines, the power is less relevant than the torque. My 320d weighing 1415kg makes 115kW but 330Nm torque and this is what gives it the edge over the petrol equivalent (320i, 110kW, 200Nm).

No it doesn't. A diesel is never as fast as a petrol car. You are comparing a TURBO diesel with a NON-TURBO petrol even though they both have a 2L engine. If you want to compare then compare like for like (e.g TURBO Diesel vs TURBO Petrol)!

This is the reason why people think diesel is so quick is because they have a TURBO.....if you take that away they are as good as a tractor.
 
aloges
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 4:54 am

Quoting Dougloid (Reply 31):
Compare to me the price of mogas to diesel fuel in your neck of the woods. Are they the same, or different? By how much?

 rotfl  I knew living right next to a filling station might come in handy some day. The view out my window reveals:



Benzin is standard, Super is premium, all prices in EUR cents per litre

Quoting Sky0000547 (Reply 32):
You are comparing a TURBO diesel with a NON-TURBO petrol

In other words, he's comparing the norm with the norm. How many people buy non-turbo Diesel engines and how many people buy turbo petrol engines?  Wink
Don't cry because it's over, smile because it happened.
 
andz
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 4:59 am

Quoting Sky0000547 (Reply 32):
No it doesn't. A diesel is never as fast as a petrol car. You are comparing a TURBO diesel with a NON-TURBO petrol even though they both have a 2L engine. If you want to compare then compare like for like (e.g TURBO Diesel vs TURBO Petrol)!

I compared two similar cars in my price bracket and picked the one that would do the job better. The fact that one has a turbo is immaterial.

Quoting Aloges (Reply 33):
In other words, he's comparing the norm with the norm

Correct.
After Monday and Tuesday even the calendar says WTF...
 
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WildcatYXU
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 5:00 am

Holy cow! Two bucks (CDN) for a liter of gas? That's insane...
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cosec59
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 5:04 am

Quoting WildcatYXU (Reply 35):
Holy cow! Two bucks (CDN) for a liter of gas? That's insane...

That's cheap. Try buying fuel in the UK  Sad
Rules are for the obedience of fools but for the guidance of wise men
 
sky0000547
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RE: Diesel Or Petrol Cars?

Fri Dec 15, 2006 6:00 am

Quoting Andz (Reply 34):
I compared two similar cars in my price bracket and picked the one that would do the job better. The fact that one has a turbo is immaterial.

You were not comparing similar price bracket cars but against your 2L turbo diesel vs a 2L NASP petrol. But anyway with similar capacity a turbo diesel win hands down have better performance and better economy.

[Edited 2006-12-14 22:03:37]
 
andz
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RE: Diesel Or Petrol Cars?

Mon Dec 18, 2006 2:34 pm

Quoting Sky0000547 (Reply 37):
You were not comparing similar price bracket cars

I said "in my price bracket". In this country the 320d is $41,880 and the 320i is $38,010 which is pretty close anyway. Even the 323i is cheaper than the 320d but it can't get close to the torque.

Yesterday I drove from Johannesburg to Cape Town, two of us in the car pulling a trailer with a 180kg motorcycle on it. I did the 1,480km trip in exactly 13 hours, which is an average speed of 113km/h including stops. On the road I had the cruise control set at 140km/h and the car didn't even feel the trailer, never varying off the speed no matter what the incline. I filled up twice along the route, the last time only 150km from our destination.

Petrol? what's that? LOL
After Monday and Tuesday even the calendar says WTF...
 
N243NW
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RE: Diesel Or Petrol Cars?

Mon Dec 18, 2006 3:28 pm

Quoting Superfly (Reply 28):
I guess I am an odd-ball.
I like the smell and knocking sound of a diesel engine.

You're not alone, Superfly. I'm also an odd-ball.

From what I understand, the real obstacle holding back diesel sales in the U.S. is the fuel itself, which is poorly refined and more polluting compared to the diesel in Europe. Feel free to correct me if I'm mistaken.

If diesels become more eco-friendly and still can come up with good fuel efficiency numbers by the time I'm in the market for my next car, I may well consider one.

-N243NW Big grin

[Edited 2006-12-18 07:29:38]
B-52s don't take off. They scare the ground away.
 
captaingomes
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RE: Diesel Or Petrol Cars?

Mon Dec 18, 2006 3:40 pm

How's this for a diesel? http://www.youtube.com/watch?v=IfcP8HaFhYw&mode=related&search=

Slow and unrefined eh?  Wink
"it's kind of like an Airbus, it's an engineering marvel, but there's no sense of passion" -- J. Clarkson re: Coxster
 
aerobalance
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RE: Diesel Or Petrol Cars?

Mon Dec 18, 2006 11:08 pm

Right hand drive Diesel Grand Voyagers are the tits, Right 'birdie!  Wink
"Sing a song, play guitar, make it snappy..."
 
TheSonntag
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RE: Diesel Or Petrol Cars?

Mon Dec 18, 2006 11:24 pm

Try driving on the German Autobahn 2 from Dortmund to Berlin, and you will see how big Diesel BMWs, Mercedes and Audi dominate the left lane.

The average Diesel for the BMW 3 series, Mercedes C-Class, VW Passat and so on does around 200-230 km/h (125 to 135 MPH) today as Vmax, thats usually enough, and even at speeds around 100 MPH, which is a fair average for this route, you have a fuel consumption of around 8 litres/100km.

The Diesel engine mentioned above from the 80s has NOTHING to do with modern Diesel engines. In 1990, Audi introduced the first TDI, a Diesel engine with direct injection. This was the first time that Diesel cars had lots of power. In the 80s, Diesel engines were fuel efficient but boring, as they had no power. The introduction of the direct injection Diesel engines led to even lower fuel consumption while having more power.

It is certainly true that a Diesel has less power than a comparable gasoline-powered car, but since many Diesel have between 130 to 170 HP in the middle class today, that is more than enough power.

The cool thing is when you push down the speeder at 110mph, the cars still accelerate extremely fast.

There is nothing more convenient than a big Diesel on the Autobahn  Wink
 
trvyyz
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RE: Diesel Or Petrol Cars?

Mon Dec 18, 2006 11:35 pm

Quoting TheSonntag (Reply 42):
The Diesel engine mentioned above from the 80s has NOTHING to do with modern Diesel engines. In 1990, Audi introduced the first TDI, a Diesel engine with direct injection.

I thought all diesel engines were direct injection even the old ones, I am not a mechanical engineer, so I'm not sure.

From what I remember (studied a long time ago), Diesel engines(basic) work on compression ignition ie, diesel is sprayed by nozzles in to the cylinder and ignites due to the compression.
While the petrol engine worked on spark ignition, that is a mixture of air and fuel is sucked into the cylinder through the intake valve and a spark ignites the fuel (carburetted engine). Now you have a the multi injectors for petrol with IC controls etc.Technologies have improved vastly over the years.

[Edited 2006-12-18 15:45:24]
 
TheSonntag
Posts: 4306
Joined: Wed Jun 15, 2005 7:23 pm

RE: Diesel Or Petrol Cars?

Mon Dec 18, 2006 11:41 pm

Quoting TRVYYZ (Reply 43):

Not quite. Until the 1990s, there were no injection pumps available which could produce a pressure high enough to inject directly into the cylinder. Instead, the fuel was injected into a chamber connected to the cylinder, the "Vorkammer" (Mercedes) or "Wirbelkammer" (Volkswagen).

In order to get an optimal usage of the fuel, the Diesel fuel must be injected in as small parts as possible so that it can spread optimally. This was only possible for small car engines since the 90s.
 
trvyyz
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Joined: Thu Oct 21, 2004 9:19 am

RE: Diesel Or Petrol Cars?

Mon Dec 18, 2006 11:49 pm

Quoting TheSonntag (Reply 44):

Thanks. I understand now, before it was fuel injection but not direct.
 
JJJ
Posts: 2249
Joined: Wed May 31, 2006 5:12 pm

RE: Diesel Or Petrol Cars?

Tue Dec 19, 2006 12:06 am

Quoting ManuCH (Reply 25):
Just an interesting story for those who are mechanically illiterate, like myself: we were on vacation with friends in Davos, Switzerland, for a week. During the night temperatures were often around -25°C. Guess what - our friend's diesel froze, and he had to have his car towed to a garage to un-freeze his diesel, empty the tank and fill in new diesel.

In Russia they put some paraffin in diesel fuel because of this.

Quoting Kay (Reply 17):
What does it for me in Diesel cars is the lack of high rpm. You're just getting started and the engine wants the next gear.

That's not a big difference if you're driving an auto car, . However, if you want to drive sporty you need a good petrol engine. Preferably turbocharged, of course Big grin

Quoting WildcatYXU (Reply 12):
Apparently GM has much better diesel engines now that some 6 years ago.

Of course, GM is using Fiat designed JTD engines that are some of the best around.
 
Dougloid
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RE: Diesel Or Petrol Cars?

Tue Dec 19, 2006 12:18 am

Quoting TheSonntag (Reply 44):
Quoting TRVYYZ (Reply 43):


Not quite. Until the 1990s, there were no injection pumps available which could produce a pressure high enough to inject directly into the cylinder. Instead, the fuel was injected into a chamber connected to the cylinder, the "Vorkammer" (Mercedes) or "Wirbelkammer" (Volkswagen).

In order to get an optimal usage of the fuel, the Diesel fuel must be injected in as small parts as possible so that it can spread optimally. This was only possible for small car engines since the 90s.

Well, I pulled out my copy of "Diesel and Other Internal Combustion Engines" by Howard E. Degler which was published in 1938. Quite a number of the engines described therein were direct injection diesels. They were sometimes called 'solid injection' diesels. The early diesels used blast injection-a substantial compressor was utilized to provide enough high pressure air to assist in complete combustion of the fuel, which was injected at relatively low pressure.

Firms such as MAN (Maschinenfabrik Augsburg-Nurnberg) did much development work in prechamber design as did Sir Harry Ricardo, all in the 1920s. A Ricardo based prechamber diesel made by the Waukesha Motor Company is shown on page 156 and described in detail. Prechambers were developed to promote more complete combustion and assist in cold weather starting.

The Robert Bosch company is more responsible than any other for progress in diesel fuel injection. We're still relying on the seminal work of this company, as well as the work that Ricardo undertook in developing combustion chamber design.
If you believe in coincidence, you haven't looked close enough-Joe Leaphorn
 
andz
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RE: Diesel Or Petrol Cars?

Tue Dec 19, 2006 1:01 am

Quoting N243NW (Reply 39):
If diesels become more eco-friendly

According to BMW's specs, the Diesel versions are already more eco-friendly than the petrol engines. Some examples of CO2 emissions (g/km):
320i: 178
323i: 203
320d: 153
330i: 210
330d: 174

In countries where the excise duty on cars is based on their emissions it is no wonder Diesel is becoming so popular.
After Monday and Tuesday even the calendar says WTF...
 
TheSonntag
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RE: Diesel Or Petrol Cars?

Tue Dec 19, 2006 2:37 am

Quoting Dougloid (Reply 47):

Indeed, direct injection Diesels were not necessarily an invention of Audi, the technology was used for bigger Diesel engines much earlier already.

The problem was that you needed extremely small high-tech parts for getting the injection holes small enough for the cumbustion rooms like the ones found in small car engines. Trucks had direct injection systems much earlier.

For cars, the Diesel development was boosted by a few companies only. Bosch did a major part in this development by developing high pressure pumps and injection systems.

The first real direct injection Diesel was a Fiat Croma in the late 80s, but this was not really satisfying yet. Shortly after, Audi presented its 2,5 litre, 110 HP TDI, the first really good Diesel engine, which also was powerful for that time.

Today, it is possible to get the same amount of power out of Diesel engines as out of gasoline engines. Some problems remain, however. Diesel cars have higher emissions of NOx, and they exhaust small solid particules. These problems will be solved, though, with filters and new exhaust cleaning technology.

I would prefer the Diesel, if I could choose. If you need more power, try the new Audi Q7 V12 TDI, with 500 hp (I hate SUVs, but that is certainly a BIG engine  Wink )

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