jnmunsey

I thought it was no secret the 335i has a LOT more horsepower than 300... I am turned off by the reported lack of LSD. That alone has kept me from considering the car..

DropTopGal

From BMW website:
Weight
Unladen 3571 [3582] lbs

Weight distribution, front/rear 51.2/48.8 [51.4/48.6] %

Engine
Liter/type/valves per cylinder Turbocharged 3.0/inline 6/4

Bore/Stroke 3.31/3.53 inch

Nominal output/rpm 300/5800 hp

Maximum torque/rpm 300/1400-5000 lb-ft

Compression Ratio 10.2 :1

Fuel Grade Unleaded premium

Transmission
Gear ratios - I/II 4.06/2.40 [4.17/2.34] :1

Gear ratios - III/IV 1.58/1.19 [1.52/1.14] :1

Gear ratios - V/VI/R 1.00/0.87/3.68 [0.87/0.69/3.40] :1

Final drive ratio 3.08 [3.46] :1

Performance
Drag coefficient 0.30 Cd

Top speed 1 130/150 mph

Acceleration 0-60 mph 2 5.3 [5.5] sec


I'm sure if the 335i had more HP, BMW would say it simply for the purpose of sales and not to find themselves in the same false advertising situation that Mazda had with the RX8 when it came out. Now, if you ask a BMW diehard type, the 335i has an extra 30hp but BMW just doesn't say.... yah, right! Also, the G37 will rev to higher RPM and have a wider torque curve, thus not having to shift a gear early as the 335i does, thus a possible faster 0-60 time. This is how the S2000 marginalized the 350Z 0-60 time.

KAHBOOM

iTrader: (4)

Actually the 060 calculator is a relative comaprison. Of course there are many other factors to consider. However when you place the Sedan's power/weight in the boxes it is pretty close. So you may keep in mind that the 3.7 will likely have similar characteristics in it's torque curve to the 3.5. Thus it looks like max/ stock 0-60 will be right at 5 seconds (perhaps 4.9)

As regards the MT/Auto-If the coupe follows suit to the Sedan, there was only a difference of 2 HP to the wheels at peak on a dyno for the Sedan between the AT and MT. The AT will come with a high-stall torque converter just the same as the Sedan. Thus I suspect that 0-60 will be identical in MT vs AT but the MT will probably have a slightly better quarter mile (1 to 2 tenths difference) because of gearing. If I remember the specs correctly, third gear and fourth is the biggest difference between AT and MT. First and Second gear are nearly identical.

FAST1

I'm sure if the 335i had more HP, BMW would say it simply for the purpose of sales and not to find themselves in the same false advertising situation that Mazda had with the RX8 when it came out. Now, if you ask a BMW diehard type, the 335i has an extra 30hp but BMW just doesn't say.... yah, right!

I have yet to see any manufacturer get into trouble because they understated a car's HP. It would be a hillarious scene where some guy would be yelling at a salesman because he was told that his car had 300 HP and he tested the engine on a dynanometer and the dam thing puts out 340 HP or he was told that the car would run 0/60 in 5.3 and he keeps on getting 4.8s.

So how do you account for the fact that a 300 HP 335, which weighs about the same as a 295 HP G35, runs a 0/60 in 5.0 whereas a G35 runs a 0/60 in 5.9. Since 0/60 times vary, I pulled both of the preceeding times from the same source: Road & Track. The truth is that BMW wanted to show a HP differance between their M3 and 335. Since there is about a $15K differance in price between the two cars, BMW didn't want to show them with a similar HP output.

DropTopGal

Correct me if I'm wrong, but under SAE, every engine must be "certified" which entails having an independant SAE person verify the engine at time of testing. There was a report about this on TV recently and it showed the process. Thus, the engine output should be as stated.

I often wondered why the hp vs weight ratio varies in performance from car to car. It must have to do with gearing and power loss in the drivetrain. I've noticed that certain makes such as Hyndai can make an engine with equal or more hp than their target (Toyota or Honda), but their cars simply don't perform as well in the times. Things that make you go "hummmm".

RBull

iTrader: (1)

Correct, but that doesn't stop a manufacturer from under rating their car. No matter what you believe its well documented through many dynos the 335 is underated by about 10%. A similiar thing happened with the G sedan in '03 and '04. They were rated at 260 hp and the coupe at 280. It's well accepted it was the same motor but Infiniti underated the sedan proabably for marketing reasons.

I think one key difference with performance amongst similiar specced engines of different manufacturers is the peak ratings. Everyone talks about peak hp and torque. Those are not as important as the levels at low range and throughout the band. That may explain more the differences even more than the gearing or parasitic drivetrain losses between brands.

FAST1

The most egrigious example of a auto manufacturer understating an engine's HP was GM with its '69 ZL1 Vette. My boss was one of the few fortuante owners of that car, and I'm certain that it could compete with any high peformance car today in a drag race. GM laughingly rated the HP of that car at 435 HP in order to make it more affordable to insure. My boss put on a pair slicks and went to Capital Raceway, and ran three consecutive 1/4s in the 11.2 - 11.4 range. I believe that Motor Trend listed the car at a tad under 11 secs in their magazine. Not bad for a car with 1960s technology.

After owning the car for a few months, my boss took his car to a Speed Shop to have it dyno tuned, and they got it up to 590 HP with just a few minor mods.

DropTopGal

In the 60s I can see how a company can understate hp, but in todays litigious environment, I would presume that the auto makers would put to market as advertised. Also, is SAE mandatory for auto makers? If so, then there shouldn't be much deviation from the posted numbers.

Don't get me wrong, tell us that a given product puts out ie. 330hp and really is 350hp, great! As long as it doesn't go the other way...ie. Mazda RX8 issue.

BTW... this is a great forum!

FAST1

but in todays litigious environment, I would presume that the auto makers would put to market as advertised.

But you can understate a car's HP without lying. If I advertise that car A produces 300 HP at 6800 RPM and list that info in all my advertising, can someone sue me because the same car produces 330 HP at 7300 RPM? It's not always in the best interests of the auto manufacturer to list the maximum HP output of a car. On the other hand under no circumstances can they inflate the HP output.

DarkG

its gonna hit 4.9!!


hopefully

DropTopGal

I'm not an attorney, but deliberate or negligent changes in the product could warrant a case. Regardless if the hp is increased or decreased. False advertsing and misleading by the seller ---> case.

Use another product or service to compare. You come to me for,ohhh, say... penile enlargement. I market to you that you'll gain an additional 2 inches length and 1 inch girth. You IMMEDIATELY sign up and I put my Columbia NY Med talent to work. Surgery done, gauze comes off and oh no!...results reveal only 1/2 inch gain in lenth and 1/4 inch girth. You sue, I settle out of court. Why settle? Because I didn't hold up my advertised end of the bargain and alleviate the teeny weeny syndrome. Now, say I was feeling funky during the surgery and gave you an additional 8 inches in length and 5 inches in girth. Your sex life is now non-existant because you are TO HUGE. You sue and again, I settle out of court because I didn't uphold my end of the advertised bargain. Reality is, you don't sue over the "accidental" increase in length and girth because you think bigger is better. Just like hp with cars.
Of course, I would be smart and have you sign a consent that would include the variance in size. I don't see any manufacturer stating that hp varies from car to car.

Yes, going out on a limb here... playing with this a bit. Hope the analogy gets a smile out of you guys.

muscarel

I have no idea where you got that from, but let's test your theory....

A honda s2000 has a pathetic peak torque. The torque curve at the wheels is something like 115 lb-ft at 3,000 rpm-6,000 rpm, and 135 lb-ft at from 6,000 rpm to redline. According to the quote above, if I nail the gas at 3,000 rpm, I would feel the same level of acceleration than if I nail the gas at 6,000 rpm. Similarly, if I nail the gas at 6,100 rpm, I would feel the same level of acceleration as if I nailed it at 8,000 rpm. Now, anyone who has ever driven this vehicle (I have) knows that the car accelerates at a greater rate as rpm's rise, with the greatest acceleraiton near redline. In addiiton, the difference is HUGE as you get higher. At 3,000 rpm, the car has almost no acceleration. At 8,000 rpm, things get fun.

Another example for you:

Motorcyles. Take a look at this article that shows a dyno curve for a motorcyle:

http://www.motorcyclistonline.com/ro...mpression.html

Torque is FLAT. Once again, if you've ever been on a motorcyle, you will notice how the bike accelerates at a faster pace at much higher rpm's than down low. That's because HORSEPOWER is increasing as rpms rise. The torque is not rising.

Last but not least (in metric, but you get the idea - FYI 274 NM is equal to 200 lb-ft of torque, "PS" is almost equivalent to our horsepower):

Formula One currently uses four-stroke V8, naturally-aspirated reciprocating engines. They typically produce 300 horsepower per litre of displacement, far higher than most internal combustion engines. For comparison, the naturally-aspirated piston engine production car with the most specific power is the Honda S2000 engine with 92kW (125PS) per litre.

Formula 1 engines derive their power through their ability to operate at a very high rotational speeds, up to 20,000 revolutions per minute (rpm). This contrasts with road car engines of a similar size which operate safely at typically less than 7,000 RPM. However, the torque (turning power at a given speed) of a Formula 1 engine is not much higher than a conventional petrol engine. For example, the 2.4 litre toyota engine producing 544 kw (740 PS) at 19000 RPM, outputs 274 N.m thus a 14,3 bar mean effective pressure. This is comparable with the 14,3bar maximum MEP of the 2003 BMW E46 M3 CSL, the best production car in this respect, although the F1 torque value is perhaps higher at a lower rotational speed.

Consequently, high power is obtained in making the engines turn faster, a goal sought ever since research into performance engines began. The configuration of naturally aspirated engines has not been greatly modified since the Cosworth DFV, and their mean effective pressure stayed around 14 bars.[1] Until the 1980s, the metal valve springs limited revoltions to about 12,000 per minute, but since the 1990s they have been replaced by pressurised air, allowing up to 20,000 rpm.


Can we end this debate now?

FAST1

I'm not an attorney, but deliberate or negligent changes in the product could warrant a case. Regardless if the hp is increased or decreased. False advertsing and misleading by the seller ---> case.

I believe that you have to suffer a loss of some kind before you can sue for damages. If I advertise that my product has a certain level of performance, and in fact it exceeds what I advertised, what's your loss? That would be like going to a fast food restaurant and asking for a 10 oz beverage, and then suing them because you can prove that they always gave you 11 ozs.

Anyway if your statement is true, BMW is in serious trouble because the HP for their 335 is about 10% understated.

FAST1

Originally Posted by FAST1
The point that I've been traking to make is that I like to focus on a car's torque and as others have pointed out, the torque curve, since I'm interested in a car's acceleration or its ability to push me back in my seat. This is an excerpt from a technical treatise by Bruce Augustein:

First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.

In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.



I have no idea where you got that from, but let's test your theory....

A honda s2000 has a pathetic peak torque. The torque curve at the wheels is something like 115 lb-ft at 3,000 rpm-6,000 rpm, and 135 lb-ft at from 6,000 rpm to redline. According to the quote above, if I nail the gas at 3,000 rpm, I would feel the same level of acceleration than if I nail the gas at 6,000 rpm. Similarly, if I nail the gas at 6,100 rpm, I would feel the same level of acceleration as if I nailed it at 8,000 rpm. Now, anyone who has ever driven this vehicle (I have) knows that the car accelerates at a greater rate as rpm's rise, with the greatest acceleraiton near redline. In addiiton, the difference is HUGE as you get higher. At 3,000 rpm, the car has almost no acceleration. At 8,000 rpm, things get fun.

Another example for you:

Motorcyles. Take a look at this article that shows a dyno curve for a motorcyle:

http://www.motorcyclistonline.com/ro...mpression.html

Torque is FLAT. Once again, if you've ever been on a motorcyle, you will notice how the bike accelerates at a faster pace at much higher rpm's than down low. That's because HORSEPOWER is increasing as rpms rise. The torque is not rising.

Last but not least (in metric, but you get the idea - FYI 274 NM is equal to 200 lb-ft of torque, "PS" is almost equivalent to our horsepower):

Formula One currently uses four-stroke V8, naturally-aspirated reciprocating engines. They typically produce 300 horsepower per litre of displacement, far higher than most internal combustion engines. For comparison, the naturally-aspirated piston engine production car with the most specific power is the Honda S2000 engine with 92kW (125PS) per litre.

Formula 1 engines derive their power through their ability to operate at a very high rotational speeds, up to 20,000 revolutions per minute (rpm). This contrasts with road car engines of a similar size which operate safely at typically less than 7,000 RPM. However, the torque (turning power at a given speed) of a Formula 1 engine is not much higher than a conventional petrol engine. For example, the 2.4 litre toyota engine producing 544 kw (740 PS) at 19000 RPM, outputs 274 N.m thus a 14,3 bar mean effective pressure. This is comparable with the 14,3bar maximum MEP of the 2003 BMW E46 M3 CSL, the best production car in this respect, although the F1 torque value is perhaps higher at a lower rotational speed.

Consequently, high power is obtained in making the engines turn faster, a goal sought ever since research into performance engines began. The configuration of naturally aspirated engines has not been greatly modified since the Cosworth DFV, and their mean effective pressure stayed around 14 bars.[1] Until the 1980s, the metal valve springs limited revoltions to about 12,000 per minute, but since the 1990s they have been replaced by pressurised air, allowing up to 20,000 rpm.


Can we end this debate now?

There is no debate. There are just some who understand torque and many others like yourself who are clueless. Please do a little research before you post blatant inaccuracies. Your first example about an S2000 proves the point about torque, not refutes it. Why does a S2000 feel so sluggish at 3000 RPM and takes off at around 6000 RPM? It's bacause the S2000 doesn't hit its maximum torque until 6800 RPM.

Please invest the money and attend any reputable High Performance Driving School, and they will teach you all about torque in the first hour of class room instuction.

muscarel

Fast1,

The torque curve on a s2000 goes up only 20 lb-ft between 3,000 and 8,000 rpm. I hope you don't believe the sensation you get at redline is because of the 20 lb-ft extra available. In addition, the torque curve is FLAT (+/- 1-2 lb-ft) from 6,000 to redline. Do you think an s2000 feels the same at 6,000 than it does at redline.

You are obviously the one that doesn't understand how power is created, and the science behind all this. Did you not have anything to say about the motorcylcle example? How about the F1 car? Could you imagine how much less an F1 team could spend if they only knew as much as you do about torque? You should enlighten them as well as you have myself.