cliokhunt said:
Morning Dan..
I know what torque is, do you?:rasp:
Morning, I'm getting slightly tired of this stuff now because it just goes around and around, but I'll respond out of courtesy to your question, and also try to avoid rehashing a tired debate. This post will most likely be quite long
Yes I do know what torque is, because I studied HND motor vehicle engineering. As has already been said, it's a twisting force ie. in this context, the twisting force available at the crank. Imagine a 100lb weight on the end of a 1ft long bar attached to the crank, and that is generating 100lbf/ft of torque into the transmission, where some will be lost through general transmission losses, and some would effectively be increased by lower ratios than 1:1 (Diesels tend to have higher ratios to accommodate their lower rev band, so the gearing advantage is less than it would be with ratios more suited to a petrol engine). With little power, the engine can generate that torque but not necessarily very quickly, so in that application it would be ideal for something slow and lumbering that has to carry/tow heavy loads. However, if the engine also generates lot's of power, it can do the same work but much quicker. The relationship between the two is really a bit more involved than that, but that's basically the principle as I understand it.
The nuts and bolts of it are that the smaller and lighter the application, the less important torque becomes. Simply because there is less work to do. It can use high revving power to do it's work very quickly, the best example being a motorbike. Of course, more of each is always better though.
A focus ST has a lot more torque than a Clio 182, and similar power/weight, yet it's no faster to 60mph, probably hardly even to 100mph. It will be quicker in-gear of course, where the torque comes into play. If it's giant torque advantage doesn't actually provide much performance advantage over a small engined NA car, how is a diesel that revs to 4k rpm going to fair?
If we're still debating
literally petrol vs. diesel - then like for like, in the same car, any given displacement and cylinder layout, natural or forced induction, remap for remap, the petrol engined car will always pwn the diesel hardcore. Also the petrol will sound better, and generally be more involving. The only conclusion I can draw is that diesel is better for fuel economy. Remember this paragraph is fuel vs. fuel, not car vs. car
You have mentioned before that a "remapped" 330D or some such, can beat a Ferrari 360 down the strip? Which car would you rather be in? Incidentally, how much does it cost to tune these super diesel saloons to such states of tune, and do they retain warranty? I ask because I wouldn't want to be invalidating my warranty on a very expensive brand new car just so I could keep up with smaller engined petrols and change gear at 4k rpm. Better to just buy the petrol in the first place and have more fun for less cost, financially and dynamically.
Ultimately, the diesel technology is getting better all the time, but then so is petrol is it not? When the fossil fuel age is drawing to a close, and a handful of wealthy petrol heads still own classic drivers cars, do you think they're going to be petrol hatchbacks and track cars or super cars, or do you think they're going to be BMW diesel saloons with a copy of Torque Bi-Monthly in the glove box? Who knows? By then, diesel engine technology may have advanced so much that the cars they are in are actually rewarding to drive? . In response to that point, I know you will ask if I've ever driven a 330D. The answer is no and nor do I wish to. I like my engines to rev. Period. However that's getting onto personal choice again, which is probably a good place to end this lengthy geek-fest of a post. Thanks for reading
PS. Someone did mention in some thread ages ago, that petrol will run out before diesel, did they not? I had to laugh at that one, as the though the oil rigs pump Optimax straight out of the North Sea floor :rasp: