Flat-Four

Is it me, or are turbo diesels getting quicker?
I have a 310BHP V5 STI and struggle sometimes to pull away as fast as I think I should . Anyone else feel the same?

Chip Sengravy

BHP isn't everything you know

Tourque, talks

Flat-Four

It might just be me being paranoid as I've had it for ages now.

Hanslow

A lot of diesels easily pushing 200+ torque, so once rolling they are rather nippy. As Chip says, it's all about the torque.

CooperS

was driving my bro's 120d last week, pretty damned nippy with 163bhp :-O but can't beat a powerful petrol for fun :-)

Shark Man

Aye seeing BHP is just a multiple of actual torque and revs. (Horsepower = Torque x rpm / 5252 ).

Which is why a 200bhp@12000rpm engine can't pull the skin off a rice pudding. The dividing factor of 5252 will favour torqueless engines that can rev higher than 5252rpm, so high revving engines appear more powerful than they truely are.

In this example, the 200bhp@12000rpm engine has a pathetic 87.53lb/ft of torque....motorbike owners take note

J4CKO

iTrader: (1)

Thats the tyranny of fast cars, to have much of an advantage on the road you have to have way more power (and torque), I have a Grandad Saab 9-3 and it is enough to keep up with most mortal stuff, i.e. less than 250 bhp.

AndyC_772

iTrader: (2)

My 330d has over 300 lb.ft of torque despite 'only' 204 bhp - so it still pulls as hard as a scooby up until the 5000 rpm redline. Most of that torque is available from just 1500 rpm too.

Best of all, that car's only a couple of years old, and already the 3.0D engine in the new X3 develops nearly 300bhp. So, yes, diesels are getting quicker

J4CKO

iTrader: (1)

Like anything with a turbo, wind the boost up it will go faster.

Shark Man

No det with a diesel. Just wind up the boost ......

Although running 38psi on a Ford V8 diesel might be a "little" too much.....
http://www.pbase.com/wyk/image/34420906

Tam the bam

I have an old VW Passat 1.9 TDI which I use for work It's a P plate but can move it's **** when I put the throttle down, fair doos it wouldn't touch a scoob but it leaves most chav chariots standing plus I get over 700 miles to the tank, I love the old bugger even if the windows no longer work very well

Shark Man

About running too much boost: This was the link I was looking for (SIAL btw) :

http://ausrotary.dntinternet.com/for...a039545618fc42

diesel power

Shark Man

As for silly fast diesel truck vids...have a look here:

http://www.dieselinnovations.com/gal...ea8d276d4be1d6

The "snow White" ones are pretty quick

Here's one from the above lot doing a 12sec 1/4 : http://www.dieselinnovations.com/gal...ea8d276d4be1d6

zxr750Nick

http://nickjdavies.fotopic.net/p22840086.html

400Nm at 1800 rpm and 155PS

Pulls really well at 70mph in top....... suprises lots of fast stuff

Crap off the line, but good for 50 mpg.

Nick

Flat-Four

Diesel Schmeisel
They should still be no match for the Scoob power surely!
Paul.

Luminous

iTrader: (3)

Scoob power = only 2 litres and only 1 turbo
Turbo diesels = 3+ litres and 2 turbos

Scoob needs bigger engine

Bubba po

Luminous, you bender. Why don't you go in Muppets anymore?

LG John

I really get annoyed by these threads that always have claims such as - diesels are better because they have x torque followed by the counter of petrols are better because they have y bhp followed by someone pointing out that bhp is torque x rpm.

Torque at the wheels is all that matters ever. It's a measure of the turning force that reaches the axles and that is where it counts. My S2000 has faff all torque at the flywheel compared to a 330d but I'd bet my *** that if you take a spot measurement of torque at the wheels at 8500rpm in 1st gear it'll be more than the 330d can manage at any point and this is why it accelerates quicker.

Whether you drive a diesel or petrol is largely irrelevant as the key consideration is what the powerplant and gearing together acheive.

TopBanana

You're getting toward the point, but you haven't nailed it. It's about the area under the curve of a torque graph, specifically in the range used between gearchanges.

Dracoro

People who go on about torque often have overweight, lardy **** cars that can't pull a skin of a rice pudding without loads of the stuff. A light car (i.e. PROPER sports cars) doesn't need big torque numbers to go fast. Put it this way, many of these TD's produce MORE torque than a Formula 1 car.

Torque figures by themselves are the most irrelevant things on earth. It's all down to the torque AND the gearing AND the rev capabilities that indicate how much power a car has. Funnily enough, there's a measurement for this, it's called BHP To finally establish how fast the car can be (disregarding aerodynamics, tyres, suspension etc. will have relatively less effect), you need to know the weight of the car. The higher the weight, the higher the torque figures need to be.

Soooo banging on about big torque numbers is for fat-*****

kingofturds

iTrader: (1)

At the end of the day I may blow my chav chariot to pieces revving to 8000rpms, but at least I can 4000rpm and its all over for those oil burning trumped up tractors.

LG John

Yes but the area under the curve still looks at the torque from the powerplant in isolation unless you are measuring area under the torque at the wheels curve. This is actually easy to do as you just need any dyno given that they measure the force applied by the rubber and then extrapolate up to pub-fly figures It's a fair assumption on a standard car that the gearing will make best use of the available force for the purpose of that particular car.

It would be a real bonus if manufacturers started to quote bhp and torque at the wheels

rossi_classicwrx

Have to say the new diesels are really amazing cars! I currently have a classic wrx thats had a rebuilt engine and modded to about 350bhp, I test drove some newish diesel cars as I want to get a car thats cheaper to run for a few years and will be a better car for commuting in. I was really amazed at the performace of a lot of the cars and I am now expecting delivery of my 330d at the end of December. They are so quick for cars that are kicking out over 40mpg and even a couple of year old 330d bmw is a lot cheaper to insure than my impreza. I will be sad to see my impreza go but I can't wait to get the new car now!!

TopBanana

Rubbish. The only thing you can extrapolate from the peak power is the top speed.

TopBanana

Yes torque at the wheels.

Dracoro

Care to explain this comment?

People seem to think torque = acceleration and bhp shows top speed, this shows ignorance on the subject. All top speed is the vmax in top gear (the point where the power isn't enough to push the car through the air anymore). Acceleration is all about torque X revs X gearing. As stated bhp is pretty much this figure (the gearing isn't per se, the gearing is the 'multiplier', you need to see the power graph to see what best gearing to use to best make use of the power spread - the higher the revs that power is produced, the shorter gearing is needed, hence more gears. On this point, why we have golfs tdi's with 6 gears I don't know, it doesn't need 6 unless that power is really peaky)and how well that bhp is put down is down to weight, grip, aerodynamics etc.

lozgti

My wife's Skoda Fabia has the same torque as a Porsche Boxter.Fact.

I would however expect the porsche to cream our shopping car into oblivion

Vapid

........because they have an extremely narrow power band. Also the 6th ratio is perfect for cruising at 100mph and returning about 48mpg.

///\oo/\\\

Agreed

What you really need is a graph plotting torque at the wheels for each gear.

Your S2000 will be much lower geared than any diesel gear for gear and therefore the torque multiplying effect in all gears wth a ratio of less than 1:1will be much greater.

Hence it accelerates faster through the gears.

This is the key point that people keep missing when slagging off vtec hondas as gutless simply becase the peak torque figures at the flywheel are not that high.

LG John

See, spidey gets it

It's a key point though - you can't judge the accelerative abilities of any car without knowing how its geared. Bolt a 6 speed TDI gearbox onto the S2000 and it would be sh*t slow despite its willing little engine.

What I am loving is that the 535d and 335d are now quick enough in a straight-line to take the likes of my car down. If they can do that and still have that torquey mid-range grunt they must feel exceptionally potent to drive. Shame they are so bloody expensive just now!