Petrol v Diesel in Alfa engines

I do not wish to generate a large and unending discussion but would
appreciate
confirmation of my own findings.

I have never owned a diesel car.

My 1999 Alfa 146 has 1.6 TS petrol engine and 89000 miles on the clock.
One of the really nice things with this car is that it will pull away
from 20 mph
in 5th gear so that once you are under way you can sail through
roundabouts
and some junctions without changing gear.

Today I had a test drive of 1.9 Diesel GT Blackline special edition.
Engine was a bit noisy to start with but acceleration was fine.
However it would not pull away from 20 mph in 5th gear and I
found myself changing gear on a familiar route much more frequently
than in my own Alfa.

I was always led to believe that diesel engines have masses of torque
at low revs but my experience proved to the contrary.
Do diesel cars need to be driven in a different way of which I am unaware ?

John Chapman

John Chapman > wrote:

> I do not wish to generate a large and unending discussion but would
> appreciate
> confirmation of my own findings.
>
> I have never owned a diesel car.
>
> My 1999 Alfa 146 has 1.6 TS petrol engine and 89000 miles on the clock.
> One of the really nice things with this car is that it will pull away
> from 20 mph
> in 5th gear so that once you are under way you can sail through
> roundabouts
> and some junctions without changing gear.
>
> Today I had a test drive of 1.9 Diesel GT Blackline special edition.
> Engine was a bit noisy to start with but acceleration was fine.
> However it would not pull away from 20 mph in 5th gear and I
> found myself changing gear on a familiar route much more frequently
> than in my own Alfa.
>
> I was always led to believe that diesel engines have masses of torque
> at low revs but my experience proved to the contrary.
> Do diesel cars need to be driven in a different way of which I am unaware ?

Chase the torque, not the power.

In terms of the 5th gear thing, it's because diesels run significantly
longer gearing than petrols.

--
SteveH 'You're not a real petrolhead unless you've owned an Alfa Romeo'
www.italiancar.co.uk - Honda VFR800 - Hongdou GY200 - Alfa 75 TSpark
Alfa 156 TSpark - B6 Passat 2.0TDI SE - COSOC KOTL
BOTAFOT #87 - BOTAFOF #18 - MRO # - UKRMSBC #7 - Apostle #2 - YTC #

On Sat, 29 Mar 2008 20:48:58 +0000, John Chapman >
wrote:

>My 1999 Alfa 146 has 1.6 TS petrol engine and 89000 miles on the clock.
>One of the really nice things with this car is that it will pull away
>from 20 mph in 5th gear

Good grief..*way* outside how you *should* be driving it!

> so that once you are under way you can sail through
>roundabouts
>and some junctions without changing gear.

Why do you have a manual car and not want to change gear?

>Today I had a test drive of 1.9 Diesel GT Blackline special edition.
>Engine was a bit noisy to start with but acceleration was fine.
>However it would not pull away from 20 mph in 5th gear

Correct..it isn't designed for that.

> and I
>found myself changing gear on a familiar route much more frequently
> than in my own Alfa.

Ouch..I can feel the engine hurting at this low-rev torture.

>I was always led to believe that diesel engines have masses of torque
>at low revs but my experience proved to the contrary.
>Do diesel cars need to be driven in a different way of which I am unaware ?

You should fix your lazy and unsafe driving technique. I was taught,
for safety, to always be in a gear that allows the car to accelerate
immediately and rapidly by just depressing the accelerator without the
need for a change down.

Diesels, these days, develop their maximum torque,typically, about
1700-1800rpm which is *much* lower than a non-turbo petrol. If you try
anything much below that (say 1200rpm), you will be off-turbo so the
engine will be significantly weaker. However, even at very very low
revs, the torquey diesel is magnificently resistant to stalling -
sometimes to the point of being violently jerky. It will shout and
scream at 5th gear 20mph attempts as that torque is being dissipated
in the engine bearings.

In *ordinary* (i.e. not blasting about) use, the only difference
between a diesel and a petrol is (in broad terms) that the diesel
works between 1800 and 3800rpm whereas a petrol will work in
2500-3500rpm or slightly higher in each case. I've always maintained
that, due to gearing ratios, the apparent power band width of petrol
and diesel cars is similar. For example, the difference in revs
between gears in a petrol car can be 1500-2000rpm. Also, the diesel
will not rev as highly as a high-revving petrol.

As for why your car does 20mph pull-aways in 5th gear, I suspect it
has so little torque at those revs that it simply hasn't got the
output to make any complaints obvious but I wouldn't want to drive any
car like that.

--
Z
Scotland
Alfa Romeo 156 2.4JTD Veloce Leather
'Oil' be seeing you..
(Email without 'Alfa' in subject will be auto-deleted..sorry!)

John Chapman wrote:

> My 1999 Alfa 146 has 1.6 TS petrol engine and 89000 miles on the clock.
> One of the really nice things with this car is that it will pull away
> from 20 mph
> in 5th gear so that once you are under way you can sail through
> roundabouts
> and some junctions without changing gear.

This is the complete opposite of most diesel vs petrol views especially
with Alfas!

Alfa petrols are traditionally high revving engines requiring lots of
gear changing to enjoy. The modern TS engines have a bit more torque low
down but nothing to compare with a modern turbo diesel.

The general view from petrol heads like me is that Italian cars are
*meant* to rev, hence I find diesels at odds with that. The alternative
view is that times have changed and high torque diesels are just as
quick and a more relaxed drive with economy. It comes down to preference.

As Zathras says you must be off turbo in the diesel and as Steve says
the gearing is different as diesels have a lower and more limited rev
range so the gearing is higher.

Try accelerating hard in 5th in the diesel at say 40mph and you would
need to change down a couple of gears in a petrol to achieve the same.

The issue most have going from a sporty petrol to a sporty diesel is the
opposite, they will find they run out of steam just when the petrol is
starting to fly because they are in the wrong rev band. Which is why it
doesn't always feel sporty as less is more with the diesel.

Cheers
Tony

On Sun, 30 Mar 2008 10:37:52 GMT, Tony R
> wrote:

>The issue most have going from a sporty petrol to a sporty diesel is the
>opposite, they will find they run out of steam just when the petrol is
>starting to fly because they are in the wrong rev band. Which is why it
>doesn't always feel sporty as less is more with the diesel.

That depends on your definition of *sporty* in terms of the engine.
For example, I think of my diesel as having a similar character to a
large capacity V8 (old-style American, say) as opposed to a smaller
capacity (perhaps) Italian V12. I don't see how that V8 must be less
*sporty* just because it has lower maximum revs.

Also, because the Diesel (well mine anyway) delivers it's performance
in such a relaxed and effortless manner, in a limited zone, reminds me
more of a supercar than any petrol car I've owned.

--
Z
Scotland
Alfa Romeo 156 2.4JTD Veloce Leather
'Oil' be seeing you..
(Email without 'Alfa' in subject will be auto-deleted..sorry!)

Zathras wrote:
> On Sun, 30 Mar 2008 10:37:52 GMT, Tony R
> > wrote:
>
>> The issue most have going from a sporty petrol to a sporty diesel is the
>> opposite, they will find they run out of steam just when the petrol is
>> starting to fly because they are in the wrong rev band. Which is why it
>> doesn't always feel sporty as less is more with the diesel.
>
> That depends on your definition of *sporty* in terms of the engine.
> For example, I think of my diesel as having a similar character to a
> large capacity V8 (old-style American, say) as opposed to a smaller
> capacity (perhaps) Italian V12. I don't see how that V8 must be less
> *sporty* just because it has lower maximum revs.

It is just a state of mind. Muscle cars have their own character but
doesn't conjure up a sporty style of driving in my view whilst muscle
car lovers hate silly little screaming engines...

Typically muscle cars rely on exactly that for performance and typically
(but not exclusively) do not handle particularly well on the twisty
stuff. Hence my view on what are sporty cars.

> Also, because the Diesel (well mine anyway) delivers it's performance
> in such a relaxed and effortless manner, in a limited zone, reminds me
> more of a supercar than any petrol car I've owned.

Again I would think grand tourer not supercar. Supercars aren't relaxed
and effortless in my view though I know what you mean when you think
back to the kind of effortless performance that used to be the province
of prestige luxury and very thirsty cars of the past.

Cheers
Tony

On Mon, 31 Mar 2008 18:05:17 GMT, Tony R
> wrote:

>Zathras wrote:
>> On Sun, 30 Mar 2008 10:37:52 GMT, Tony R
>> > wrote:

>> Also, because the Diesel (well mine anyway) delivers it's performance
>> in such a relaxed and effortless manner, in a limited zone, reminds me
>> more of a supercar than any petrol car I've owned.
>
>Again I would think grand tourer not supercar. Supercars aren't relaxed
>and effortless in my view though I know what you mean when you think
>back to the kind of effortless performance that used to be the province
>of prestige luxury and very thirsty cars of the past.

I've more experience of supercars than GTs so that's why I made that
comparison.

--
Z
Scotland
Alfa Romeo 156 2.4JTD Veloce Leather
'Oil' be seeing you..
(Email without 'Alfa' in subject will be auto-deleted..sorry!)

"Tony R" > wrote in message
k...
> Zathras wrote:
>> On Sun, 30 Mar 2008 10:37:52 GMT, Tony R
>> > wrote:
>>
>>> The issue most have going from a sporty petrol to a sporty diesel is the
>>> opposite, they will find they run out of steam just when the petrol is
>>> starting to fly because they are in the wrong rev band. Which is why it
>>> doesn't always feel sporty as less is more with the diesel.
>>
>> That depends on your definition of *sporty* in terms of the engine.
>> For example, I think of my diesel as having a similar character to a
>> large capacity V8 (old-style American, say) as opposed to a smaller
>> capacity (perhaps) Italian V12. I don't see how that V8 must be less
>> *sporty* just because it has lower maximum revs.
>
> It is just a state of mind. Muscle cars have their own character but
> doesn't conjure up a sporty style of driving in my view whilst muscle car
> lovers hate silly little screaming engines...
>
> Typically muscle cars rely on exactly that for performance and typically
> (but not exclusively) do not handle particularly well on the twisty stuff.
> Hence my view on what are sporty cars.
>
>> Also, because the Diesel (well mine anyway) delivers it's performance
>> in such a relaxed and effortless manner, in a limited zone, reminds me
>> more of a supercar than any petrol car I've owned.
>
> Again I would think grand tourer not supercar. Supercars aren't relaxed
> and effortless in my view though I know what you mean when you think back
> to the kind of effortless performance that used to be the province of
> prestige luxury and very thirsty cars of the past.

I think the OPs experience from test-driving the diesel left him with the
same view as I have of diesels - they are far from efforless and relaxing to
drive...

Petrol engines are much more forgiving with regard to gears and speed -
whilst it might not be good for the engine, a petrol engine will pull at a
much lower speed in a given gear than a diesel, meaning less need to change
gear, leading to a smoother, more relaxed drive. In a diesel, if you are not
in the right gear for the road speed, the drive is choppy, sluggish, smokey
and noisy. Also in a diesel, the power band is so short that just as the
power band actually kicks in properly, thanks solely to the turbo, it is
time to change gear again! One of the regulars here (Catman or Zathras I
think) said that their diesel will pull from 30-90 in a single gear. This
was supposed to prove their superiority over petrols, but my 2.0JTS petrol
will pull happilly from about 15-90ish in 3rd and 25-137 in 5th gear, so am
still not convinced!

I have said this before in this group and my experience of diesels is
limited and probably old, so my opinion is perhaps dated, but I can only
comment on what I have seen.

I clearly prefer petrol, but its all personal preference and probably most
importantly - driving style!

In alt.autos.alfa-romeo,
GT > wrote:

<first post after a long absence, and I might revert to lurking only >

> I think the OPs experience from test-driving the diesel left him with the
> same view as I have of diesels - they are far from efforless and relaxing to
> drive...
>
> Petrol engines are much more forgiving with regard to gears and speed -
> whilst it might not be good for the engine, a petrol engine will pull at a
> much lower speed in a given gear than a diesel, meaning less need to change
> gear, leading to a smoother, more relaxed drive. In a diesel, if you are not
> in the right gear for the road speed, the drive is choppy, sluggish, smokey
> and noisy. Also in a diesel, the power band is so short that just as the
> power band actually kicks in properly,

You must be talking about a "turbo-diesel", not "diesel"

> thanks solely to the turbo, it is

Ah, you are. :-)

> time to change gear again! One of the regulars here (Catman or Zathras I
> think) said that their diesel will pull from 30-90 in a single gear. This
> was supposed to prove their superiority over petrols, but my 2.0JTS petrol
> will pull happilly from about 15-90ish in 3rd and 25-137 in 5th gear, so am
> still not convinced!
>
> I have said this before in this group and my experience of diesels is
> limited and probably old, so my opinion is perhaps dated, but I can only
> comment on what I have seen.

I guess your diesel experience may be too young, or alfa only. ;-) (Did
alfa use any non-turbo diesels?)

I have owned 2 diesels without turbo in de past (golf and visa, yuck),
both would "pull" from 800-5000 rpm IIRC. Both where relaxing to drive,
very relaxing I might add as they did not just lack power in the low
revs, they lacked power over the entire range.


--
Stef (remove caps, dashes and .invalid from e-mail address to reply by mail)

They'll never get caught.
They're on a mission from God.

"Stef" > wrote in message
...
> In alt.autos.alfa-romeo,
> GT > wrote:
>
> <first post after a long absence, and I might revert to lurking only >
>
>> I think the OPs experience from test-driving the diesel left him with the
>> same view as I have of diesels - they are far from efforless and relaxing
>> to
>> drive...
>>
>> Petrol engines are much more forgiving with regard to gears and speed -
>> whilst it might not be good for the engine, a petrol engine will pull at
>> a
>> much lower speed in a given gear than a diesel, meaning less need to
>> change
>> gear, leading to a smoother, more relaxed drive. In a diesel, if you are
>> not
>> in the right gear for the road speed, the drive is choppy, sluggish,
>> smokey
>> and noisy. Also in a diesel, the power band is so short that just as the
>> power band actually kicks in properly,
>
> You must be talking about a "turbo-diesel", not "diesel"
>
>> thanks solely to the turbo, it is
>
> Ah, you are. :-)
>
>> time to change gear again! One of the regulars here (Catman or Zathras I
>> think) said that their diesel will pull from 30-90 in a single gear. This
>> was supposed to prove their superiority over petrols, but my 2.0JTS
>> petrol
>> will pull happilly from about 15-90ish in 3rd and 25-137 in 5th gear, so
>> am
>> still not convinced!
>>
>> I have said this before in this group and my experience of diesels is
>> limited and probably old, so my opinion is perhaps dated, but I can only
>> comment on what I have seen.
>
> I guess your diesel experience may be too young, or alfa only. ;-) (Did
> alfa use any non-turbo diesels?)
>
> I have owned 2 diesels without turbo in de past (golf and visa, yuck),
> both would "pull" from 800-5000 rpm IIRC. Both where relaxing to drive,
> very relaxing I might add as they did not just lack power in the low
> revs, they lacked power over the entire range.

lol - very nice!
My experiences are 'M' reg Citroen Zantia 1.9td (still going, but passed
elsewhere in the family) and a recent 2006ish Alfa 147 entry level diesel
(courtesy car). I did say my opinion is probably dated!