On Sat, 29 Mar 2008 20:48:58 +0000, John Chapman <jchapman@[EMAIL PROTECTED]
>
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!)
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