Torque or Boost?!

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Torque or Boost?!

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I've been thinking about this for the past few days and just wanted to know what people thought.

I know that torque and bhp are different, in a way that torque is the power that you actually feel and bhp is just a number that your car has. (well thats what i've read in google anyway)

Now then when the car is on boost, is this also torque? Or is this just boost pulling you into your seat.

In other words, what I'm wanting to know is turbo boost the same thing/feeling as torque?

Or can anyone elaborate it more for me.

Cheers darlings

Mr Dan
 
Torque is "turning moment"
BHP is "rate of doing work"

The two are related and engine/drive design (size, ratios etc) is all about managing and optimising BOTH for a given application.

Imagine you have a very tight and very long threaded coach bolt/screw to screw 6 feet into the ground/wood within a given time period.

You could have a short spanner and have to pull hard on it, but the hand movement will be small for a 45 degree rotation.

Or you could have a long spanner and only have to pull gently on it, but the hand movement will be large for a 45 degree rotation.

Work Done/Power = Force * Distance Travelled

Short spanner requires high force and short distance
Long spanner requires low force and long distance

Torque gets you going and power keeps you going.

Generally the higher the RPM the lower the torque.

For a given mass of car or truck and trailer load, the design art is getting both the torque and power curves ideally matched together with correct gearbox gearings.

For good road performance cars you want a nice balance of torque and power distribution. For balls out racing, like F1, then you want/need high RPM to develop power (rate of doing work) but you will lose torque. But that is not so much of an issue as and F1 car weighs little so is easier to get going. A truck however is very difficult to get going so it needs starting & pulling ability, is not interested in rapid acceleration and still needs the power to keep to load moving.

Hope this adds a little extra info to your understanding.
 
Absolutely brilliant :D

Thanks alot for that S130. Really helpful :)

I actually made a slight error...forgive me

I said: Work Done/Power = Force * Distance Travelled

Not quite true

Work Done = Force * Distance Travelled
Power = Work Done / Time Taken

Sorry for that slip-up. Apart from that the basics are still basically true and hopefully described in way that most can understand.

There is no generic/magic power and bhp combination unless it is combined with the mass of the vehicle and the gearbox ratios.

To give and example

The Fiat Strada Abarth has 130BHP and 130 ft-lb (foot pounds) of torque and weighs 980kg. Lets round this up to a metric ton 1000kg or 2156lbs which is near enough 2400lbs or a UK ton. So a 130BHP/Ton car.

Official figures are 0 to 100kph in 7.9 seconds. 100kph = 62mph. 0 to 60mph is typically around 7.0 to 7.5 seconds. These are by no means staggering performance figures, however, point-to-point the 130TC is a very rapid and driveable car. Will never win a 0-60 dash and tops out at 122mph. But once rolling the 130 ft-lb torgue curve is almost flat over the entire rev range and this coupled with the fairly close ratio gearbox means the 22+ year old Strada Abarth is still able to keep pace with the more modern 160+BHP turbo charged Puntos/500 Abarths/others (Renault Clio Sports etc. etc.)

For most people (non track racers) performance and driveability is the key factor and this is achieved by a well balanced torque/power compromise. Some cars get it wrong and some get it right. This right/wrong judgement is market and driver judged.
 
They way I think of it is an engine with plenty of torque is like a body builder pulling you along with a piece of rope where as an engine with more BHP is more like an Olympic sprinter pulling you along. The sprinter accelerates faster but runs out of puff going up hills etc where as the body builder will keep on pulling.
 
They way I think of it is an engine with plenty of torque is like a body builder pulling you along with a piece of rope where as an engine with more BHP is more like an Olympic sprinter pulling you along. The sprinter accelerates faster but runs out of puff going up hills etc where as the body builder will keep on pulling.

Ahh very nice analogy. Puts it into perspective better for a simple minded person like myself :p

That reminds me of the thing I thought about 2 and 4 stroke engines in quads.. 2 stroke with better acceleration but 4 stroke has more grunt power
 
Some pretty comprehensive replies there. As s130 has pretty much stated, torque is the amount of work an engine can carry out and the power is the speed at which it can carry it out.

Also, on a naturally aspirated engine, power and torque are simply mathematical equations of each other. If I could remember how much you multiplied (or divided) one to get the other I'd let you know.

Generally speaking, 8 valve engines produced more torque but less power than a 16 valve motor and diesel engines produced more torque than an 8 valve petrol engine. Electronics though have changed everything, allowing, among other things, for 16 valve motors to be far more tractable than they used to be.

Long stroke engines also tend to produce more torque than short stroke motors and those with a short stroke produce more power than their long stroke cousins.

When pulling a heavy weight, torque is more important than power, which is why diesels which are higher in torque are used to power trucks. This is highlighted if you compare the relevant figures from both types of engines.

A 6 litre N/A petrol engine will probably produce 400bhp and about 425 lb/ft of torque. A turbo diesel of the same capacity will generate only 280 bhp but over 650 lb/ft of torque. When you get up to truck engines of 10 - 13 litres you could be talking of 400 - 500 bhp and 1500 lb/ft of torque. But, with the aforementioned clever electronics, the 12 litre Volvo truck engine produces 440 bhp but in marine specification in the kind of motor yacht you might buy after winning the lottery it can put out 775 bhp.

If you look at the specs of your car, you will find that on a petrol version, max power would be produced at about 6,000 revs whereas max torque will probably be around 2,000 to 4,000 rpm.
 
Was really having a bad hair day yesterday. :bang:

1000kg = 2204.6lbs which is nearly 2240lbs which is a UK ton.

Time for a holiday.
Alternatively, 1 ton = 1,016 kgs.

I'm trying to remember, is a UK ton what used to be referred to as a "long ton"?
 
Check this out: 2010 Audi A8, the DIESEL is faster.

Audi A8 FSI Quattro Executive

Petrol | 4.2ltr V8 | 366 bhp | 445 Nm | 5.5s (62mph) | 155mph (limited) | 1835 kg

Audi A8 TDI Quattro Executive

Diesel | 4.2ltr V8 | 345 bhp | 800 Nm | 5.3s (62mph) | 155mph (limited) | 1995 kg

The Diesel is HEAVIER and has LESS bhp yet is quicker to 62mph. But just look at that torque difference.

Can't think of another car where the diesel is faster ???
 
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Look at the torque difference. And the TDI is turbo'd which completely alters the power delivery. The petrol will be quicker to 100mph and beyond due to the power curve IMO.

It's interesting because the reviews say the TDI is the quicker car, but the FSI is smoother and a tad nicer to drive.

I'd have the TDI purely for that epic torque figure. Twice the torque of an M5!
 
Excellently explained by S130, personally i only found out the difference the other month from this http://www.carkeys.co.uk/features/technical/636.asp

it uses a hammer analogy which is pretty appropiate for me! :D

Interesting to hear the specs of the Strada 130 Abarth, actually has the same amount of torque as a tipo 16v! though the tipo produces it at 5000 rather than the 3600 of the strada. but also the tipo has a fairly flat torque curve which lends itself to easy driving charecteristics. it produces at least 115ft-lb from 2500-6000rpm. and peak power is acheived at 6250rpm. miss mine already :(

Strada engine is more of a hooligan though, no balance belts or constricting emissions rgulations. also strada weighs a fair bit less. must be a right hoot!
 
Sure is a "right hoot"

Every time I take her out and gently "press the pedal to the metal" I end up rasing the driving style/attitude and use more agressive "pedal to the metal".

Without even trying I exit the car with my right leg quivering/shaking. No I'm not a wimp. I've been in cars with 500BHP+ at the wheels (e.g. Metro 6R4, Cosworth/Sierra/Maserati special out dragging Dodge Vipers and others) and none of these seemed to get my right leg shaking.

There is some magical combination that cars, like the Strada Abarth, seem to get absolutely right. A blend of handling, performance, noise, feel and feedback etc., that just tick all the right human response boxes. The Strada is not unique in this and there will be others who say that their car has the same effect.

Sadly, IMHO, modern sports cars do not seem to elicite the same earthly response/feeling/feedback that many of these older 70s to 80s cars (all makes) do.
 
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