Who needs a VR6 when youve got a TDI....

What engine in the world has the most torque? As fitted to 1km long oil tankers....

...bet you it's not high revving petrol engine!



Cheers,

Drew.

 

lmao!!

 

but then oil tankers dont really have to accelerate fast do they? Speedboats do and I'm pretty sure they are petrol powered.

 

can't you run a jet engine on diesel? or is that just what they put on those daft jet cars to make them beltch out smoke?

 

I think that most people here are missing the point, there is the gearbox involved to get the power to the wheels rather than looking simply at the pub figures of peak bhp / torque.

If a diesel engine can make decent torque to say 4,500rpm (you dont talk about rev limits on diesel engines) then the gearbox is going to have to have a lower gearing ratio in order for the diesel to reach the same max speed as a 6,500rpm petrol engine. If you can revolve the crank quicker then you can have a higher ratio of gearing (to increase torque) while still pulling the same speed as a crank revolving at the same speed.

I think that you should be factoring the gearbox and the ratio's into the equation as a diesel box will pull that initially impressive torque figure down a notch or two. The reason the Vtec engines are so good is that because they can pull massive rpm's the gearbox can be geared higher so upping the lower torque to the wheels.

With race cars the emphasis is on BHP, torque can be adjusted using the gearbox but BHP is what dictates your highest speed. The torque figure of an F1 car is going to be crap compared to the bhp figure but as they can rev to 18K then the gearing is going to give it enough torque.

As for the talk about everything being about power for acceleration then its blx. A diesel might make maximum power at 4K-5K rpm but the actual pull, seat of the pants feeling is from 2K - 4K rpm. With race cars the engines are tuned to produce max torque at almost the same point as peak power as the power band is so low, you get no torque for ages until the engine comes on cam very late in the rpm range and then you get peak torque and power at the same time.

Cheers,

Chris

 

Sorry but if that was the case there would be a hideous gap between 4th and 5th on the A3 which would make it a pretty useless drivers car, given that they both top out at the same speed.


Oh wait Audis are pretty hideous drivers car.



I see your point.

 

No, they will have different ratios. You'll just find the mk3 engine is working at a higher rpm when it hits maximum speed.

 

I think we've found the reason behind this argument.

Its management vs floor staff.

 

a rather fast deisel indeed

 

Diesel - Now fast but tarred with the same brush as Skoda - A "brand" image of old gits trying to skimp on fuel costs.
If any of you can just give up the sound, responsiveness and adjustability of a petrol then I'm afraid you don't have a ounce of petrol (yes PETROL) in your veins.
Why is the term PETROL head not diesel head?

 

Im sure plenty of farms are diesel heads =D

 

Still don't buy it I'm afraid. And by this logic, we will never be able to compare 0-60 times of diesel vs petrol as the diesels will apparently always have longer ratios (But surely wouldn't that reduce the amount of torque availible at the front wheels - the diesel's raison d'etre - as you always have to divide torque by gear ratio? Not entirely clear on this, but seems to make sense). Anyway the R32 driver above has hit the nail on the head as far as diesels go for me - for keen drivers, they will always be second best in terms of noise, adjustability and throttle response, and more importantly, in terms of outright power.

 

A lot more money is being put into diesel developement. Im no expert but all these new lean burn FSI etc etc engines are based on technology developed on the common rail diesels?

 

divide torque by gear ratio - i don't ever remember doing that.... especially as a gearbox is a torque multiplier.....

it's a bit of a narrow minded viewpoint isn't it - "they will always be second best in terms of noise, adjustability and throttle response, and more importantly, in terms of outright power" - maybe you could enlighten us with your crystal ball
i would estimate that over 75% of automotive research is being done on compression ignition engines. on average in Europe 40% and rising (over 50% in some countries) new cars purchased are Diesel. The specific power output of Diesel engines are rising to come on par with gasoline engines - look at the new sequential turbo 4 cylinder BMW Diesel about to be released.
As for noise, this is a subjective quality - good for one may be bad for another. If you're talking about NVH Diesel suffers at idle and low speeds especially in the transition between pilot and no-pilot injection phases; this is being addressed with 3rd generation common rail using rate shaping and multiple/split injections. If you're talking about subjective noise quality, well this can be dialled into the exhaust system to make whatever note you want - one reason it isn't so much at present is because the marketing branches of OEMs want differentiation between gasoline and Diesel engines. If you're talking about noise due to high engine speed, well i can envisage in the next 10 years that Diesel engine speeds will incease as combustion is controlled further and CR decreases.
Quite what you mean by adjustability is anyone's guess - the vast majority of modern cars are not meant to be human adjustable because this is where problems begin. those with any adjustment are very tightly controlled.
and as for throttle response, on the horizon (and work i am directly involved in) are turbochargers with both variable geometry turbines AND compressors resulting in minimal lag. combined with careful fuelling control the throttle response will be on a par with a gasoline engine.
I love gasoline engines but Diesel is going to become more and more prominent and there's nothing you or i can do to stop it, so just accept it. it's not down to preference, it's down to legislation and energy consumption/availability.

tt

 

Yes, they have much smaller ratio's from engine to wheels, this is because of the huge amount of torque supplied it doesn't need to be "Upped" as much as it is in petrol cars.

Both diesels and petrol cars of similar Bhp will have similar Torque at the wheels due to the gearbox transfering it all. This is why diesels don't need to rev as high, and have "longer" gear ratios. They can make more use of the avilible torque with out having to generate it by having large ratios

Indeed, totally true, FSI technology is an adaptation of the "direct injection" that has been used in diesels since the "TDI" badge appeared, its not "Turbo diesel injection" its "Turbo direct injection"

I agree with you all until you go for the balls argument of "in terms of outright power"

We've proven during this that "in terms of outright power" the engines are pritty much IDENTICAL at the moment. Otherwise there would be ZERO diesel engines in the VW Cup (there are currently 3) Obviously if they were not on par due to their 'lack' of "outright power" then they wouldn't bother, since there is now way they could even compete (which they are doing)

Next?

 

Christ, trendytramp knows his stuff


/me bows down to trendytramp

 

/trendy tramp knights you for your Diesel knowledge

"Arise Sir Rippsy"

tt

 

ROFL =D

Since im now your knight, you must bless me with more knowledge!

Please do explain the following

Whats an "NVH" diesel, whats the "pilot/no-pilot" phases during the injection? "Rate shaping"?
Edited by: Rippsy

 

It's interesting that you bring FSI engines into the argument, they've almost been universally criticised for being gutless and rough out of their power band - hardly the finest specimens of petrol engines availible. More econmoical yes, but nicer to drive? Far from it. In fact, I remember evo recommending you buy the diesel version of the new Golf because the FSI unit was so poor. VW had to do something tho, their earlier petrol engines were even worse (apart from the performance versions of course - the 2.0 16v, V5 and VR6).

You question adjustability. You also prove your lack of understanding of the keen driver's needs when you do this. Adjustability has nothing to do with the engine - it is to do with the handling of the car. A good chassis will allow you to adjust your cornering line by adjusting the throttle opening accordingly. However to do this you need a highly responsive, preferably Naturally Aspirated engine, which responds to variations in throttle instantly. It's why purists will shy away from forced induction, due to the throttle lag this induces. And it's not something you could ever hope to do in a diesel. A point made pretty moot by the nose-heavy handling all but the best diesels (i.e. those with a blue propellor on the front) demonstrate - this will also need to get fixed before petrolheads embrace the dirty black stuff.

Rippsy, if diesels are so suitable for racing, why are there only 3 on the grid? Surely with all the money savings for these largely amatuer racing teams diesel power would bring, they'd all be at it? It's still a racing novelty - Oh look how fast we can make a diesel go. And like all novelties, it quickly gets rendered unimportant by all those petrol teams going "Oh look how much faster we can get a petrol car to go". Oh and terms of outright power, diesel and Petrol are still nowhere near each other. A quick scan of The Knowledge at the back of evo throws up the most powerful diesel engine availible at 313bhp (the VW Toe-rag V10 TDI - anyone else find that a pathetic power output for a 5 litre V10?). The most powerful petrol engine is currently at 680bhp (the hideous looking Edonis). Remember this is also about to go up, with the 800bhp+ Koenigsegg CC8R and the 990bhp Bugatti Veyron. That's over 500bhp short, and what's more, the petrol motors have more torque aswell. So explain to me, how are diesels getting anywhere close?

 

BHP mean f**k all. Once and for all!!!