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9K > Testarossa?

11K views 58 replies 16 participants last post by  Superaero 
#1 ·
The 5-speed Saab 9000 Aero will streak from 50 to 75 mph faster than a Ferrari Testarossa or a Porsche Carrera 4.
As far as I know, the Testarossa put down at least 380 HP.
The Carerra 4 had 282 HP in '98.

This can't be right, can it?
 
#2 ·
I think if it is true it is attributable to the other cars' high-revving engines compared to the 9k's power curve with its meatier low-end torque.

Keep in mind this is top gear acceleration they are talking about.
 
#3 ·
In gear accelerations can be a bit misleading in terms of outright performance, but more prevalent for normal day-to-day driving.
My other playthings (Reliant Scimitar SS1s) also came in an 8v 1800 Nissan (Sylvia) turbo engined-version. Even with a quoted 135bhp, they would give a better 30-50, 50-70 and (I think) 70-90 time than a Sierra Cosworth - they were both launched in 1986. The SS1 had lower gearing, plus a smaller turbo (T2 vs a T3) - hell, it didn't even have an intercooler as it only boosted to 6psi!
 
#5 ·
Top gear acceleration would put both cars in the top gear. Likely, not only would the top gear of the 9k be lower, but the 9k probably has more torque in low RPMs than both of those cars. These tests are really an issue of gearing and powerband, not overall power. A high revving car with tall gearing like the sports cars quoted won't do great in top gear at 50mph.

The stats would be different if each car were being tested in a gear that puts them in their "sweet spot," so to speak, for the speed range being tested.
 
#6 ·
Yes, I should have clarified that ^ was what I meant.
 
#11 ·
Saab only did it because Volvo or BMW tried saying it first... and saab said something like... "BMW [or volvo] Forgot to include Saab in their test panel, the 9k AERO has faster 50-70 acceleration than.. blah blah."

We were basically rubbing it in BMW or volvos face, i cant remember who.
 
#9 ·
I think it's a bit of a rubbish stat to be honest-what Testarossa driver would be doing 50 in top gear anyway? And I've gone and tested this in my Aero and to be honest the Saab isn't on song at all at that speed either-I'd do that overtaking move in 3rd...

It just lets them say that the Saab is 'quicker' than a 911 or a Testarossa I suppose, but fair enough.
 
#12 ·
I can believe this as i seem to remember that bbc's TOP GEAR ran a similar test only this time they pitted a saab 9-5 against the porsche 911.Again both cars are at 50 mph in top gear and floored,guess what? the 9-5 won!!! its for this reason that Jeremy Clarkson thinks all us saab drivers have a smug smile on our faces!!!:p:p
 
#13 · (Edited)
Also the TESTAROSSA is a heavy car, weighs a lot more more than a loaded 9-3 or 9-5, makes it's power at the high end, and is geared for ~180MPH in 5th I believe.

The stat that the 9-5 is faster than any 911Turbo/930(I believe it was the 911Turbo not just a Carrera),even a first gen 930 in 50-70MPH passing still surprises me.

R.S.
 
#14 ·
I don't think it is top gear. I think it might be third gear for the SAAB and whatever the appropriate gear is for the other makes. The important element is what torque is developed at what useable rpm for the speed range you are talking about. The manual shift SAAB Aero has 258 lb ft from 1,900 rpm to about 4,000 rpm. I doubt the Ferrari or the Porsche can match that and the Aero is not as heavy as either of those cars.

I know an Aero is mighty quick once you get rolling. the 0-60 number is misleading because the car bogs off the line or spins its tires from a standing start. From about 40 mph up to about 80 mph the thing is a rocket. I know I can hang with Porsches and Corvettes if I am already rolling, but you have to forget it if the liight just turned green and you are stuck with a standing start.

I also have a chipped Audi S4 with 350 lb ft of torque at low rpm and it is blindingly quick from 50 to 100 mph in any suitable gear, third is particularly quick but even in 6th gear the thing is also a rocket and quicker than my Aero even though it is 500 lbs (240 kg) heavier!

It is a mistake to compare a turbo car's standing start times to other normally aspirated makes and deduce that the turbo car is slower at higher speeds, just isn't so.
 
#15 ·
For some reason I remember reading this from a car magazine article or press release or similar article, and that they specifically stated it was top-gear acceleration. I may be thinking of a different comparison though.

In any case, the fact is that 5th gear in a 9k (I have a CSE but the idea is the same) is a very viable passing gear on the freeway, and this fact makes everyday driving a lot easier.

I'd much rather be shoved backwards by a turbo-induced torque wall, than auto tranny kickdown :cheesy:
 
#16 ·
It was a print ad from 1993 for the Aero, i have a copy somewhere, kept it because it was a white 9k Aero and I have one, don't have it to hand so can't post here.

Big torque at low revs make a car far easier to drive, and very quick in many real world driving situations. Technology has moved on, now out on the autobahn when the traffic clears the BMW with 500 ft/lbs torque or VW chipped turbo fuel oil burner vanishes rapidly ahead in a cloud of fillthy soot, and it is not until the big hp of my Aero kicks in above 100mph that it is possible to reel them in and pass them.
 
#17 ·
These days 225 hp is not "big" horsepower. Is your Aero modified?

In any event, only torque can accelerate your car. Horsepower determines what the final speed will be after applying that torque. Torque is essentially Force and acceleration is determined by the formula F/mass = a(cceleration) more usually expressed as F = ma.

Power involves the time element required to produce a speed number which is d/t=v(elocity) (with a vector) or simply speed if the vector is not relevant (although there is always a vector in reality).

So, power will never tell you how quick a car is, only how fast it might be. Torque is the number that tells you how quick that car is.

Also, because the torque is converted to linear force at the contact patch the inertia of the rotating forces is important. Diesels have more inertia to overcome and the fuel burns more slowly than does petrol (gasoline). Torque for torque a gasoline engine will out accelerate a diesel.
 
#18 ·
In any event, only torque can accelerate your car. Horsepower determines what the final speed will be after applying that torque. Torque is essentially Force and acceleration is determined by the formula F/mass = a(cceleration) more usually expressed as F = ma.
Torque and horsepower are inseparable when motion is involved. You can never have one without the other. Horsepower does not determine speed.

So, power will never tell you how quick a car is, only how fast it might be. Torque is the number that tells you how quick that car is.
???

Again, horsepower and torque are inseparable. If you give me a car's torque curve, I can give you its horsepower curve and vice versa. What's important is not just the peak hp/tq, but the shape of the curve. A Honda S2000 and Ford Mustang will hang with each other despite the fact that the Mustang has more peak torque.

Also, because the torque is converted to linear force at the contact patch the inertia of the rotating forces is important. Diesels have more inertia to overcome and the fuel burns more slowly than does petrol (gasoline). Torque for torque a gasoline engine will out accelerate a diesel.
That's only because gassers tend to rev higher. Why would diesels have more inertia to overcome? This would depend mostly on the vehicle's curb weight.

I don't think you really understand what torque is.
 
#19 ·
From what I understand torque is the more basic force which is generated by force of the piston on the arm of crank. Horsepower is that torque over the rpm band or something like that. That's why a lot of trucks have small hp but hell of a lot of torque, because they are low in rpm. At least that's the way I always understood it.

As far as the dyno graphs are concerned, you want the integration of those graphs, the area under the curve, not the peak power. That's why getting 200 hp at from 7000-7200 rpm is worse then having 180 hp 3000-6000 rpm.

Klim
 
#22 · (Edited)
And if you really are an engineer you will know that power is work over time, not force. Of course torque and power are related, and directly so, but technically only the torque can accelerate the car. This is why turbo diesels with relatively anemic power figures (restrained by rpm and the slower burning of diesel fuel) will accelerate so quickly compared to petrol cars with the same bhp but much lower torque.

With respect, I believe you are confusing the effects of gearing on acceleration with some link to horsepower. Horespower has nothing to do with it, except of course as it is proportional to torque.

Finally, the numbers we are discussing are peak horsepower and peak torque. My point was that peak power will not tell you anything useful about performance except that it will give a good indication of how fast a car will eventually go. To assess how quickly it will accelerate you need to know the torque the engine produces and over what rpm range. I agree that one could calculate the horsepower the engine develops at any of those points on the rev range but that would tell you no more about acceleration than the torque figure would, for obvious reasons.

One assumes that the manufacturer of any car for which perfomance is of interest has got the gearing correct to exploit the torque curve.

Ironically, my point is proved by the performance of the 9000 which has ample torque available over a wide rpm range and accelerates much more quickly than its peak horsepower would lead you to believe, were you unaware of the massive torque available from as low as 1,900 rpm. This petrol turbo technology is also what got the modern turbo diesel technology going, just as direct injection has crossed back from diesel to petrol with similar benefits to peak torque and improved torque curves in petrol engines both blown and unblown.

One speaks of torque curves for acceleration and horsepower curves for attained speeds..
 
#27 ·
... power is work over time...
...and if you've ever run a Dynamometer, you'll remember that it only measures Torque. The Operator then applies a calculation (also subject to silly arguments) which gives Torque over Time. That's the Horsepower number you sell to whomever is paying the bill.
 
#23 ·
Ok - here's the simpler rules I think work: This is for flat out driving only.​

1) BHP can be considered the 'energy' more energy = faster. Not much else matters tbh.​

2) With the correct gearing torque is not meaningful - BHP always wins.​

3) Up to about 100mph, bhp to weight ratio always wins.​

4) After that, bhp vs aerodynamics almost always wins - especially for top speed.​

Find me a car (same-ish weight) that is beaten by lower bhp, but higher torque in something like 0-100mph.​

Yes - in daily driving a torquey engine is quick, but BHP always wins in the end! Proven nicely by the b0llocks saab advert. The porsche and ferrari are miles faster cars... Maybe they can do a 'fastest in reverse' test - just as useless.​
 
#24 ·
This is not my idea. Colin Campbell, an automotive engineer, who also taught automotive engineering I believe, says this in his excellent book: The Sports Car, its design and performance. In Chapter 12 he sets out this formula and claims it is reasonably accurate as a predictor of acceleration: t 0-60 =(2W/T) to the power of 0.6. This means that acceleration is proportional to twice the vehicle weight divided by the torque and then taken to the power of 0.6 (which is a root function I believe though I am no mathematician.)

bhp has nothing to do with acceleration, except as it is proportional to torque. The old fashioned "power to weight" ratio still used by many is actually shorthand for torque to weight. Incidentally, the power to weight ratio is quite poor at predicting acceleration.

As for examples try a Jaguar XF 4.2 V8 against the newer version of the same car, the Jaguar XF 3.0 DS twin turbo diesel. The gasoline V8 develops 300 hp but only 310 lb ft of torque. The diesel develops 271 hp but a stupendous 443 lb ft of torque. The cars are otherwise effectively identical. The diesel is about 5% quicker to 60.

Another example is the BMW 330d which develops only 241 hp but 383 lb ft of torque and is about 5% quicker to 60 than the BMW 330i M Sport with 258 hp but only 221 lb ft of torque. The diesel is actually nearly 200 lbs heavier but still noticably quicker.

Now diesels are generally slower than gasoline engines due to higher internal inertia inside the engine and slower burning fuel. the usable rev range is much less than equivalent gasoline engines but they are still quicker where the torque is significantly higher.

The real test is to compare two similar cars like the Subaru WRX STI equipped with different displacement engines in different markets, at one point the Subie was equipped with a 2.0 in Europe and a 2.5 liter in North America. Our WRX STI was quicker even though the European car had more horsepower.

If you want to compare two cars check out the torque to weight ratio and all other things being equal the higher torque car will be quicker. Trouble is, all other things are hardly ever equal (usually the gearing is different) which makes it harder to see this pattern, but it is there and it is real.



bhp tells you how fast a given car will go relative to the same car with a less powerful engine. Weight actually has very little to do with top speed except as weight tends to increase rolling resistance
 
#26 · (Edited)
And if you really are an engineer you will know that power is work over time, not force. Of course torque and power are related, and directly so, but technically only the torque can accelerate the car. This is why turbo diesels with relatively anemic power figures (restrained by rpm and the slower burning of diesel fuel) will accelerate so quickly compared to petrol cars with the same bhp but much lower torque.
Again, torque and horsepower are inseparable. Average horsepower will tell you a lot more about how fast a car is than any other figure because torque is included in the horsepower calculation.

bhp has nothing to do with acceleration, except as it is proportional to torque.
So then it has everything to do with acceleration, because horsepower is nothing more than torque weighted with RPM. Horsepower is a measure of power, directly convertible to Watts, BTU's and other measures of energy. Torque is NOT a measure of energy, thus any performance calculation that depends solely on torque is taking other things for granted. Torque can exist where no work is being done, horsepower cannot.

If you want to compare two cars check out the torque to weight ratio and all other things being equal the higher torque car will be quicker. Trouble is, all other things are hardly ever equal (usually the gearing is different) which makes it harder to see this pattern, but it is there and it is real.
Jetta TDI: 236 lb/ft torque, 140 horsepower
Honda S2000: 153 lb/ft torque, 237 horsepower

Guess which one is faster by a sh!t ton?

Your torque metric sucks. What good is it to say, "if all other things are equal" when they never are? It's like saying using my pinky finger is a good way to measure things against each other if they're already the same in inches. It's stupid.

By the way, the reason the Saab walks away from the Ferrari and Porsche is because it generates more horsepower at 50mph, in top gear, than the other two.

Instead of spouting off theory, do some research about what torque is.
 
#28 ·
For a dyno to produce a torque figure, it needs to know the RPM/MPH figure of the current gear (this includes things like tire outer diameter), or it simply needs to know at what RPM you let off the gas.

An Aero can put down several thousand lb/ft of torque at the front axles in first gear. You can trade speed for torque, but horsepower remains.

A dyno knows how much horsepower is being expended on its rollers without any information, but in order to make a proper plot it needs to know gear ratios or what the redline was.

Depending on what gear you're in, you can have between 400 and 2400 lb/ft of torque at the front axles, but in every gear you'll put down about the same horsepower. I can roll up to a dyno, not say a word to the operator, give a WOT run in any gear I please, and he'll know how much horsepower I put down. What he won't know is how much torque my engine produced.
 
#34 ·
I can roll up to a dyno, not say a word to the operator, give a WOT run in any gear I please...
So you're not familiar with Engine Dynamometers. Do you think your engine produces different Horsepower in different gears?

Horsepower encompasses RPM and Torque.
One Horsepower is how much water a horse can pull out of a mine in England in an hour. How do they figure that? How many RPMs does a horse have? How does the Hour part fit in?
 
#29 ·
...and if you've ever run a Dynamometer, you'll remember that it only measures Torque. The Operator then applies a calculation (also subject to silly arguments) which gives Torque over Time. That's the Horsepower number you sell to whomever is paying the bill.
The calculation is Torque x RPM / 5252 = HP. It's not subject to any silliness. Time is not a variable here. Notice that the torque and horsepower lines on EVERY dyno chart intersect at 5,252 RPM? That's no accident.
 
#30 ·
I find this to be a strange argument. HP= (torque*rpm)/5252, right? They are completely interconnected. The engine primarily produces torque, if it is not rotating. If the engine starts rotating then the measurement of length of time is included. BOTH can be used to figure out the engine's performance, you just have to be consistent. Torque measures the force which engine can produce if it is not rotating, let's say you are holding it. The more force the engine can produce the better performance it will give then a similar engine which produces less torque BUT HAS SAME REDLINE!!! This is the crucial point of all of these examples, the rpms are different. S2000 redlines way higher then a TDI. Honda F1 motor redlines way higher then cummins diesel. However, if you have two engines with same redlines and one produces on average more torque then the other, this engine will necesseraly outperform the other!

But really I think this all besides the point and has to do with an inefficiency. Comparing cars/engines based on peak numbers is flat out stupid. It is the area under the curve which is important, or if you want to be more mathematical about it it is the average value of a function, which is an integral with limits set to be 0 and redline. Torque without rpm is nothing as is hp. To properly compare two engines performance, you have to compare the average number of torque or hp over the rpm range as just described. Doing this will show that hp and torque really give you the same result, because in both cases you will be taking into the consideration the other, because they are interdependent. It is because of an inherent inefficiency of the way we compare cars such arguments of torque vs hp arise. It would be a mute question if averages would be used.

Klim
 
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