Dracoro

RIGHT! Let's sort some things out!

It's about weight and size. You can have a larger capacity engine with more torque. Or bung a turbo/super charger onto a given engine and get more torque but these mean extra weight. The other option is to expand the rev range and have the power up higher as a consequence. It'll feel different but thats a personal preference. I don't actually have a preference either way as long as it is done well. e.g. the scoob will give you a push in the back whereas the S2000 will just keep revving and revving. They both have similar performance though despite the torque difference. However the S2000 (I'm using this as an example, could be any similar type car, same goes for the scoob) doesn't need a turbocharger to get 240bhp whereas the scoobs engine isn't as highly developed so it needs a turbo to get 200+bhp. The S2000 is accused of not having much torque. Well compared to a larger capacity engine or turbo'd car I agree BUT not compared to any other n/a 2 litre engine AND it weighs less too. From a car designers perspective, they can design a fast car and keep weight and size of the engine down to improve weight distribution etc.

As a preference, I err towards the S2000 style as it's feels and sounds like a racing car. I also like the Scoob (to drive only mind ) as I also appreciate the surge of power but to me it's just that less involving and detached. (not a slate BTW, just my preference from driving both)

So for the Ferrari having little torque, don't forget that it'll weigh less and take less space (giving the the designers more flexibility to have beautiful bodies and able to put the engine anywhere (almost ) whether mid/rear/front and thus improve the weight distribution.

ALSO, another point. People say about where the power is and power bands. An s2000 feels powerful from 1/2 way up it's rev range (about 4.5k revs) a scoob is similar (i.e. 3krpm), A diesel (2.5krpm). So a drag from 2krpm comparing a TD to a vtec isn't really represntative as a diesel or scoob can't rev to 9000rpm (i.e. how much power does a diesel or scoob generate at 6/7/8/9000rpm? not much, especially given that they will struggle get to those rpm.

BTW, I'm using S2000, Scoobs, Diesels as EXAMPLES to please read as such. This isn't slating any method of power generation, just highlighting the differences.

[Edited by Dracoro - 4/3/2003 11:02:28 AM]

logiclee

Some good points..

Again here I'm only picking cars as examples not saying one way is better etc.

Exactly but its torque at the wheels. If 200lbft of torque is produced at 2000rpm to 4000rpm "Diesel" and second gear was geared at 10mph/1000rpm at 40mph you would have to change up into third gear. In a high revving vtech special that produced 200lbft at 6000rpm to 8000rpm and with the same gearing, weight and wind resistance the vtech would accelerate at the same rate between 60mph and 80mph as the diesel would between 20mph and 40mph.
Between 60mph and 80mph the example deisel would be in third or even fourth gear with the corresponding drop off of torque reaching the wheels. This is why torque x rpm =bhp and bhp is an indicator to how much work can be done.

Torque at higher revs lets you take advantage gearing. A UK scoob may have more lowdown grunt than a S2000 but in 5th gear the Scoob is geared at 24mph/1000rpm were as the Honda is geared nearer 16mph/1000rpm. At an 80mph 5th gear gear dash the scoob would be at 3300rpm and the S2000 at 5000rpm, so both would be ready for their work to begin.

The plus side for the turbo route is that the wave of torque is available at a more day to day driving range were as the S2000 is higher up so has to be sought after a little more. The Scoob is also a more relaxed cruiser.

The torque delivery of the UK turbo, however, could be descibed as being more peaky than the S2000 as 80% of the Scoobs torque is availble from around 3000 to around 5750rpm on the S2000 80% torque is available from around 3500rpm until 7500rpm, a 1250rpm wider band.

A better example of flat torque turbo charging is the Skoda vRS and other VAG cars that use the 150/180bhp unit. Maximum torque is availble from 1750rpm until 5500rpm so the 80% figure will be close to a 4000rpm band.

Lee



[Edited by logiclee - 4/3/2003 6:36:14 PM]

Deep Singh

Can someone please explain this to me without using long formulae which will hurt my head.The 355 and 360 both have about 270lbs/ft of torque and 350 and 400 BHP respectively.A Porker GT3 has 360 BHP but the same torque as a std 996 ie about 270ish.What does that all mean in the real world? When we modify our Jap cars we are obsessed by our torque figures as many say they are the real measure of the car.So why have these fast exotic cars got low torque figures and how(if at all) does this affect they way they deliver power?
NB,must point out I have never driven a 355/360 and drove a 993 for about 5 mins 4 years ago.

LG John

If a car seems to have lower torque than you'd expect for the power output then it means only one thing - That the torque is made higher up the rev range. If I recall power it torque multiplied by rpm. Therefore, torquey oil burners have great low down grunt and feel, as they make lots of torque at low rpm but because of this they don't make a massive amount of power. A vtec honda on the other hand would take a pasting from an average oil burner in a drag from 2000rpm but once it makes it more humble torque figure way round at 6000-9000rpm the multiplication factor gives big power which is why vtec's would come back and thrash it (if reved).

For tuning purposes you have to think what you want the car to do and then try do develop the correct amount of torque in the right place accordingly. If you want effortless driving then get lots of it low down. If you want a screamer then work on moving it up the rev range. If you want it all get a Cerbera

chrisp

SB is quite right taking the 355 is produces its max torque at 6000rpm and max power at 8250. In comparison my scoob produce max torque at 4200rpm and max power at 6600rpm. The relationship from bhp to torque is

BHP=Torque(lbs/ft)*RPM / 5252

The Ferrari with 268lb/ft at 6000rpm would have 306bhp
The Ferrari with 375bhp at 8250rpm would have 238lb/ft

You will always get a good torque figure from a turbo engine but a bigger NA engine will give you roll on power. That Ferrair engine suggests to me that it loves revs.

Take an average F1 car say 800bhp @ 18,000 rpm it would have 233lb/ft torque @ 18,000 rpm.

Deep Singh

ok time to show my stupidity.Does that mean that the Ferrari etc will not pull well from low down and will only feel alive when having its **** revved off?

chrisp

Without all the power/torque graph its difficult to tell. These engines run trick variable valve timings to give low end torque. The Honda VTEC (variable valve and lift elctronic control, I think makes the car behave differently at low and high revs, attempting to get the best of both worlds.

It the engine spins well then it shouldnt be a problem. The Ferrari is quite a big capacity and multivalve so it should rev very easily, you would probably want to give it plenty of revs anyway .

logiclee

Just to give you some idea on how good they are getting with variable valve timeing the new Mazda engine doesn't produce maximum torque until 4500rpm and maximum power is at 6500rpm, however 90% of torque is available from 1750rpm.

The Civic Type R has 80% torque available from 2500rpm.

The latest VVT systems are far from being no bottom end rev only motors.

It would be nice to see a torque graph for a F360 though.

Lee

MooseRacer

To add to that list, the Integra Type R - which is anything upto 7yrs old - revs to nearly 9000rpm and produces 90% of it's torque at 3000rpm.

mik

Hopefully THIS will help

Mycroft

BHP = MPH that is all...

Torque determines everything else... that is why 9000rpm sounds cool but is in fact just a mask for 'failings' in the envelope... you need more gears the less torquey and the more revvy the motor.

There is an interesting thread on here about a Modena... where 'somebody' explains how an auto that weighs more and has only just the same power can give the said 'Prancing Donkey' a bloody hard time... all because of torque...

logiclee

Mycroft,

As technology increases with flatter torque curves this is no longer the case. If you had a light car which had 150ftlb of torque availabe from 2000rpm till 8000rpm perhaps a 3 speed gearbox would do.

Take a turbo engine that only boosted between 3000 and 6000 rpm and you would need more gears to stay in the torque zone.

VAG and Saabs petrol turbo engines are better in this respect as they have virtualy flat torque "curves" from 1750rpm to 5500rpm.

A TDi with torque from only 1750rpm to 3750rpm is desparate for a six speed box.

Lee

Deep Singh

Ah ha,the mighty Mycroft appears again.No offence mate,but would not be seen dead in a Soarer no matter what.Call me a snob if you like.......

Old_Fart

Another ghost from threads past....and an olive branch.
If you want to look at the real difference between BHP and torque (as in real world) take a look at 0-100mph as compared to 0-60.
Something like a Subaru STI (with AWD and low down torque) is very quick to 30mph, and to 60 will be just about as 'quick'. However look at the 0-100 and you see the Rari/Porsche pull away as the high revs and BHP start to tell(the Scoob is suffering from it's drivetrain losses by now).
They are both going to need more revs than you may be used to after the scoobs fat lowdown torque, but that just adds to the driving experience IMHO. You are going to want to rev them anyway for the noise.
In 'the real world' you will probably find the cars aren't as quick point to point down you favourite B road as 0-100 doesn't mean as much there, and the lack of low-down torque means you will be caught outside of the powerband more often than you would in a Subaru/turbo'd nutter-car.
One thing that suprised me recently was the Evo magazine Fast Club test where a 'base' Carrera2 was quicker than the STI8PPP (which was itself quicker than the current M3) around one of Bedfords longer circuits. The car is just so sorted chassis-wise, the inverse snobbery around this BBS had effected me too I guess, it shouldn't really have come as a suprise how able the Porker really is around a circuit. I'd certainly have had a GT3 (last one, the new ones spoiler is just too ugly (LOL@me the scooby owner saying that) if it wasn't for those pesky kids I have to lug around. Lucky for me I still feel the 22 is as much 'fun' as any porker I've driven..and I'm no badge snob.
The real limiting factor of these cars is your own awareness of chucking £70K+ of car around the lanes(and the width of the 355)...a small off can be very expensive! (Saying that a rear bumper on a Boxster is about a third of the price of a 22B bumper LOL)
Good luck, and if you want advice about sourcing one on the continent you could do alot worse than get in touch with Ian Litchfield (got a banner ad on here) who has done alot of european car importing.
Chuck

[Edited by Old_Fart - 3/31/2003 8:10:23 AM]

Deep Singh

Chuck, olive branch accepted(LOL).
This is the bit I d'ont understand.You say that I might(in Pork/Fer) find myself out of the powerband more often than in a turbo'd car(if in wrong gear etc).Should'nt that be less of a problem in a large capacity na car rather than a small capacity turbo charged car? There will always be some degree of turbo lag.
ps I've already test driven one of Ians cars! D'ont want to bother him again until I can actually make up my mind what car I want.Maybe a Por/Fer would make me look to much like a Banker(LOL)

Old_Fart

The engines are tuned to develop alot of horsepower high up the revs, this in turn means the torque is developed higher up, and it's far more 'peaky' ie your ecutek'd scoob probably has a tabletop shaped torque curve, 280ishlbft from 3300 to 6000 rpm or so. The na cars will make their peak at 6000ish(I guess?)
It s the torque that turns the wheels...do you have a UK sti? If so remember how gutless it was below 4k revs before the remap? And how once remapped every gear felt like the one below? Ie it pulled from 3k revs in 3rd like it used to in 2nd? Thats where the low down torque is paying divedends, if you drove everywhere with 5k revs before and after you'd hardly have noticed a difference.
Certainly throttle response will be better with a nice big NA than a 2L scoob turbo, but whereas the scoob suffers from lag the NA 'suffers' from needing to get the revs up.
Once you've got used to it though you'll just keep the revs up and won't find it any hardship. I never have less than 3.5k dialled into the scoob, you'll find you never have less than 4.5k in the porker/rari. I've found that I drive other cars too lazily after relying on the 22's fat torque curve..really have to concentrate and rev ither cars.
All this talk has rekindled my interest and I'm off to get a drive in a 308/328GTS...I want to be Magnum PI
C

DavidBrown

I had a F355 last summer, which had 380bhp, but pathetic torque 268 lb/ft -- being normally aspirated, you didn't get a kick in the back that you do with Turbo cars. That aside, it still felt slow, having to wind the rev counter all the way round to 8250rpm.

I swapped that for a 996 GT2, which has 457bhp (not that much more than the F355s 380bhp), but a whopping 454 lb/ft of torque.. that extra ~190 lb/ft makes an amazing difference, pulling strongly through all gears. (near-zero lag helps)

So long as you have a wide enough rev band to exploit the torque.

See if you can get yerself a 993 GT2.

Deep Singh

Chuck,yes I get it.As for my Scoob having 280lbs/ft of torque its been dynoed before further tweaks at 295!(LOL).I could defo see you as a Magnum type ie bushy moustache,tight shorts.....!
David,if only I could afford a £100k+ car mate!

brickboy

The other way of looking at it is "you drive on torque, you race on BHP".

Torque measures the amount of shove available to get you accelerating. You can do this the turbo way -- large torque output and flattish torque curve, means instant push at most rpm & road speeds. So the car is usually geared a bit higher.

Or the Honda / Ferrari way: lower & peakier torque, with lower gearing.

Think of it this way: my Passat PD130 will outdrag a 360 Modena from 50-70mph in 4th or 5th gear. But it won't from 120 - 140
'cos you don't buy a Ferrari to do 70 in 5th gear.

Mycroft

Answer this...

Output per Ltr.
Now we all hear about cars that put out 100hp per ltr it is an achievement and the Manufacturers have every right to 'crow' about it.
Go back 30 years to F1 in 1972/3 the cars ran 3ltr motors and kicked out 400hp on average jump back to today and we have 3ltr motors producing 800hp how can this be you ask?

Well would anyone care to explain this apparent 100%improvement in just 30 years, what happened?

John STI 8

For that matter, 20 years ago, 1.5 litre F1 engines were kicking out 1200+bhp. They were slightly boosted though.

I suppose the primary reason for the performance leap would be the reduction in reciprocating mass (with radical geometry) combined with electronic control that has allowed engines to operate at far higher speeds (19,000rpm vs 10,000rpm). So although a current 3ltr V10 develops similar torque to a 70's 3ltr, that torque is developed at a much higher speed. J

Mycroft

You are right, the old '72 3ltr V8 DFV hit its peak at 7900rpm and produced just 395hp.
The modern V10 Ford equivalent produces 770hp at 16500rpm.

Now look at it this way, this means the '72 car produced 16.7hp per 1000rpm per 1000cc, the latest car with better fuel and and all that tech produces 15.6hp per 1000rpm per 1000cc.

These are both 'peak' values.

MooseRacer

I've come back to this a bit late.....

The VTEC vs Turbo characteristic debate is a common, if unfair, one.

Modern iVTEC engines have a spread of torque that is as good as, if not better than, a lot of Turbo engines - The CTR is a good example with 90% torque available from 3000 to 8500rpm. CTR torque is amongst the very highest for a n/a 2ltr.

A lot of people complain that in a VTEC engined car you have to sit at 6000rpm to have any meaningful 'go' available. Whilst this is not strictly true, in reality once the driver is used to having around 3000 extra revs readily available it is no different from sitting at 3500rpm in a Turbo'd car.


If you want a more balanced comparison then compare a supercharged Vtec with a Turbo and the Turbo will loose on all counts.

Mycroft

Except the added 3000rpm is wearing to both the engine/drivetrain and driver alike.

VTEC is a great 'novelty' and needed to get through the emissions controls.. but almost any turbo'd motor is far superior for real world use... try driving that S2000 across Europe... a screaming frenzy that leaves both driver and passengers frazzled.

The same journey in a well sorted Turbo'd motor will be completed quicker and the last third finished with a driver suffering less fatigue and therefore we are all safer.

brickboy

On the BHP / litre debate, once again it's all down to torque x rpm. The big, big difference is really the use of pneumatic valve operation. This gives positive opening AND closure of the valves, enabling reliable high rpm performance.

The F1 motors of 20 years ago, with conventional sprung valves, simply couldn't rev to the figures they manage today because of the risk of valve bounce ... this is where the valve is closed by the spring but bounces open again when it hits the seat because of the speed it's travelling at. Apart from the mechanical wear & tear, it plays havoc with gas flow.

milkytadpole

Mycroft, you're current cosworth figures are a little low, I think you'll find that peak power is well in excess of 800bhp at 18,500rpm.

Don't really agree with the power per liter per 1000rpm argument, it's pretty irrelevant. Current F1 engines are build to produce max power for a single race, DFV's were expected to last.

Brickboy, good point, I'd forgotten about the pneumatic valve springs.j

[Edited by milkytadpole - 4/4/2003 12:12:23 PM]

Mycroft

Agree with what???

I put it in to illustrate how things have improved in only one way...

What is there to disagree with?

It is plain fact... 2 explosions in the time of 1 previously does (nearly) produce twice the power...

What bit do you have a problem 'agreeing' with...?

[Edited by Mycroft - 4/4/2003 3:44:14 PM]

Mycroft

The figures are Fords own... but if you know better...

MooseRacer

Whats that about emissions? Apart from complete rubbish?

A little unfair to use an S2000 as an example of European cruising but there we go.

And you are also wrong to state that more revs mean more drivetrain wear, that'll be why Honda's are so reliable then?

I get the slight impression you're not to keen on VTEC's - that's your perogative, depending on application/purpose etc then both Turbos and VTECs have their advantages.

At the end of the day, comparing FI with NA is a mismatch. Like I said - get a supercharger and have the best of both worlds.

Mycroft

Emissions... you know a lot about noxious emissions I'm sure

Compare a 240hp 2ltr VTEC against a 240hp 2ltr Turbo and the VTEC wins on the emissions front... that is what I refer to, VTEC needed to 'make up for' turbos when turbos no longer conform to Emissions regs.

Not rubbish, just not too obvious to the average Joe... OK Joe?

Unfair?, what's unfair? Would you never want to go to Monaco in the S2000, it's a nice idea, but a dreadful prospect...

All engine parts will be under greater strain as the revs rise... face it...

I am a great fan of VT Valvetrains but I am a greater fan of Turbos... and having both as in the Soarer gives ridiculously good results with no extended rev range just even greater mid-range talk.

Superchargers are good and I hope that we can look forward to lots of suped cars in the near future...