Diesel - low power?

If diesel is so much more efficient (no spark) - why aren't they kicking ass?
Why is a diesel torque peak so narrow?
Why is a diesel rpm limit so low?
Anyone any ideas?

diesel peak torque is generally wider than petrol, hence why they give a 'relaxed' driving style.

diesel engines cant rev as high because the cylendar pressures are so high - as a result of this it is very hard to get a reaonsably priced diesel engine to rev much about 6krpm, just like it waswith petrol engines 20 years ago.

>If diesel is so much more efficient (no spark) - why aren't
>they kicking ass?
>Why is a diesel torque peak so narrow?
>Why is a diesel rpm limit so low?
>Anyone any ideas?

They DO kick ass!

As already mentioned, they actually have a very large torque range. The low rpm limit isn't really a problem, since you have most of the max torque available almost from idle. The reason why the rpm limit is generally lower than petrols is due to the inherent design of diesel engines requiring the components to be stronger, therefore having more mass.

Adam.

>If diesel is so much more efficient (no spark) - why aren't
>they kicking ass?
>Why is a diesel torque peak so narrow?
>Why is a diesel rpm limit so low?
>Anyone any ideas?

Driven a D5 yet?

My own D5 is certainly faster than the 2.4T engine models, and in most real world scenarios it is faster than the T5 too. I did a direct comparison of power plots between a tuned V70 T5 phase 2, and a tuned D5. Up until 70 mph, the D5 will pretty much always have the edge, and you have to be driving the T5 at 4000 rpm or higher in order to even stand a chance of keeping up.

The only reason why the D5 has a slower 0-60 than the T5 is due to the fact that the T5 can reach 60 in 2nd gear, whereas the D5 cannot and so it wastes time on a 3rd gear change. Apart from that, give me a D5 any day!!!

Oh, and look at the BMW 535D - 272 bhp out of the box. And it can be tuned to 340 bhp. That *WILL* kick ass.

Adam.

>Oh, and look at the BMW 535D - 272 bhp out of the box. And it
>can be tuned to 340 bhp. That *WILL* kick ass.


the most impressive thing about that engine is it can pull the mammothly heavy 5 series to 60 in ~6 seconds, yet still does 35mpg.. i'd love to see what it could do in a mini :)

[cootuk]

if you are talking about diesels from a few years ago then lots did have loads of turbo lag and were very lethargic. The manufacturers have taken people's gripes on-board and reduced the turbo lag...my bosses Mondeo TDCi pulls like a train.

Been in a d5 but haven't driven it.

Read that about the new 535 alright - two turbos etc - and it's why I posted the thread. Couldn't understand why its taken so long for diesel to 'catch up'.

Guess it'll be intersting when the Japs develop this for the mass market esp now Honda are making diesel blocks. I guess we could see diesel boy racers soon!

How heavy are the blcoks anyway - an avg bloke is 80kg - is there that much in the block.

And please excuse my ignorance. I really just couldn't understand why something like that 535 has taken so long with all the devleopment that's been thrown at diesel. Is the fuel difficult to pump or atomise or something? Or are manufacturers holding back?

Thanks for the info.

Ken

[Dan F]

>Is the fuel difficult to pump or atomise or something?

Hi Ken.

Funny you should say that, because at the compression pressures present in a diesel engine, you need a very high pressure fuel pump and the fuel IS very hard to atomise I believe.

Regards,
Dan.

>>Is the fuel difficult to pump or atomise or something?
>
>Hi Ken.
>
>Funny you should say that, because at the compression
>pressures present in a diesel engine, you need a very high
>pressure fuel pump and the fuel IS very hard to atomise I
>believe.
>
>Regards,
>Dan.

Yes indeed, it is harder to atomise. The fuel is more dense which also gives rise to certain limitations because there is only so much you can flow.

As with anything, technology moves forward at a fair rate of knots, which is why diesels have rapidly caught up. Getting more power from a petrol engine is relatively easy, but with diesel a bit more ingenuity is required, hence why it takes longer to develop.

Adam.