FrankW

uh...C55's not 3600lbs....more like almost 3800lbs. The M3's probably still a little lighter.

RLx02

http://www.motortrend.com/roadtests/...ecs_price.html

Do a little bit of research, friend . A friend of mine with a e92 335i used to always say how heavy my car was blah blah blah until he found out his 6cyl coupe weighed more than my v8 sedan.

FrankW

curb weight is the weight with standard equipment and full tank of gas. the options on these cars added a lot of weight.

and the weight are given by MB headquarters which differs from the standard equipment for MBUSA.

different magazine also had listed different weight previously. for example, Road&Track has a category of Test Weight. If i remember correctly the C32 for their test weight was 170-180lbs more than what was listed as curb weight.

RLx02

Regardless if the test weight IS more (I just looked it up on C&D and its 3588 there), The test weight of the M3 is still going to weigh over a 100 pounds MORE than the C55. Bottom line: the e92 m3 is heavy.

e1000

Well yeah you can mod anything to make it faster. The guy in the M3 can slap on one of those ESS superchargers. Also, take a look at your timeslip in your sig compared to the time for the stock M3 I posted. Yes it might have a bad day but that's a lot of time and speed to make up.

Stock for stock, a E92 M3 is faster than a C55. PERIOD.

I just noticed you highlighted the low crank torque figure for the M3. Again, this number DOES NOT MATTER. Engine torque is multiplied by the gearbox. The resultant torque to the wheels is much much greater, and I can guarantee the M3 puts down more wheel torque than a C55. Quit lying to yourself.

moosejaw

Curb weight on a M3 is 3704 lbs.
C55 curb weight is 3605 lbs.

Curb Weight doesnt include a driver which explains the 180lbs.
So in terms of weight C55 < M3

e1000

Here you go:

C55:
Final Drive 3.06:1
1st Gear Ratio 3.59:1
2nd Gear Ratio 2.19:1
3rd Gear Ratio 1.41:1
4th Gear Ratio 1:1
5th Gear Ratio 0.83:1

E92 M3:
Final Drive 3.64:1
1st Gear Ratio 4.23:1
2nd Gear Ratio 2.53:1
3rd Gear Ratio 1.67:1
4th Gear Ratio 1.23:1
5th Gear Ratio 1.00:1
6th Gear Ratio 0.83:1


So in first gear it looks like:

C55: 376lb-ft * 3.59 * 3.06 = 4,130lb-ft to the wheels
M3: 296lb-ft * 4.23 * 3.64 = 4,557lb-ft to the wheels

Second Gear:

C55: 376lb-ft * 2.19 * 3.06 = 2519lb-ft to the wheels
M3: 296lb-ft * 2.53 * 3.64 = 2725lb-ft to the wheels

I could go on but the advantage is always there. Keep in mind the M3 not only produces more torque to the wheels, it does it until 8,400 rpm, giving it a significant advantage. Let it go, it's not a good race, from a dig, from a roll, in reverse, dosen't matter, just stop now.

loudandheard

So then if the c55 was geared the same as the e92 m3, then they would have the advantage?

Is it possible to change the gearing in our vehicles? Seems like gearing alone would yield much better power results than most of the mods that we put on our vehicles.

crazeazn

have no idea why this is an argument. unless you are heavy duty modded not even close.

TemjinX2

You can just upgrade the final drive ratio, which would be the same thing and its easier to do.

Usually in engines thats low displacement high rev's it tends to have shorter gears to make up for the lack of tq.

Higher displacement low revving engines then to have wider gears since they run out of revs quickly.

I wouldn't really mess with any of the individual gears since mercedes geared the car to be a good daily driver.

ABALONE

Horsepower is how fast you are going to get to the wall, torque is how far you can move the wall.

Torque has nothing to do with acceleration, it's all about horsepower and gearing. If you have a high torque at some RPM,that also means that your have a high HP number at that RPM and thats what keeps the car accelerating faster, not the torque.

New M3 will walk a stock C55 anyday any year!

TemjinX2

You do know how horsepower is calculated right?


HP = (RPM x Tq) /(5252)

If horsepower and gearing determine acceleration, and tq is a factor in determining horsepower. Then tq does matter in acceleration.

Its just generally easier to increase rpms then tq. Hence why the m3 has such a large hp rating for a 4.0L V8.

e1000

It wouldn't work that way, the shorter (numerically higher) you gear a car, the quicker it will have to upshift, and you'll eventually lose the race anyway. You will run out of RPM's. I was just pointing out how comparing flywheel torque figures of two cars is irresponsible.

e1000

That's a little slogan to try and help people understand the relationship between horsepower and torque, but it's not really accurate.

Horsepower is a measurement of WORK
Torque is a measurement of power.

Torque describes how much power an engine can exert. Horsepower describes how much power can be applied and also for how long. Although the C55 engine makes more torque at the flywheel, it cannot sustain that power for very long. The M3 engine is less powerfull, but can continue to make that power over a very long time. The key to this equation is that through gearing, we can compress, or spread that power out. Horsewpower is not multiplied by gearing.

As an oversimplification, Horsepower IS torque and gearing.

timdf

how come Formula 1 race engines are weak on torque but yet still produce incredible output powers and performance ?

I'll give you a clue just like e1000 has below.

It's to do with the engine RPM and gearing and thus torque TO THE WHEELS.

Absolute engine torque needs to be matched to the inertial load for optimum performance - maybe that's why we don't try to set off in 3rd gear :-)

For some reason most people are focused on engine torque and are oblivious to the effects of gearing....

kindafast

That was very interesting.

RLx02

My timeslip in my sig was when I put down 315hp was with just a tune and removed secondaries and bald 19" tires, not when I put down 337hp I do not have a time slip AFTER my header, new tune, new 18" tires and wheels. And obviously a m3 can slap on a supercharger and make his car faster. I'm not arguing that. Did I ever say that the c55 is faster stock or a mildly modded one is faster than a mildly modded m3? No. Please reread my posts before you try to come up with a rebuttal.


I highlighted THE WHEEL TORQUE FIGURE, NOT THE TORQUE AT THE CRANK. Now I don't want to insult your intelligence because I believe, that you believe you know what you're talking about except that you MISREAD my posts. However, I'm talking about WHEEL HORSEPOWER, NOT CRANK. I put down 345 ft/pounds of torque TO THE GROUND. A very healthy e92 m3 puts down 250 ft/pounds of torque TO THE GROUND. I wasn't comparing my crank torque figures to the m3's crank torque figures. Please take that into consideration before you go off into thinking that I don't know the slightest about how to calculate horsepower from torque.

Forgive me for over using the bold tag, but I fear you will just take another cursory glance and not understand any part of my post without me having to point out simple facts in bold.

RLx02

Actually, you're wrong. As temjinx pointed out, Horsepower is Torque over Time, or how much torque an engine can produce throughout the RPM band. Gear ratios have nothing to do with how well a car puts down power at the ground because you dyno at a 1:1 ratio. Have you ever put your car on a dyno before? You don't dyno from 1st gear or the last. The gearbox comes into play when seeing how EFFICIENT it is. An e92 m3 loses about 15-17% power through the drive train, which is YES, MORE EFFICIENT than a c32 or a c55 since we factory in a 18% loss.

Now when we are talking about acceleration, gear ratios definitely come into play. BMW's are usually geared lower whereas MB's are geared higher for autobahn cruising. This makes it easier for bimmers to get lower 1/4 mile times and races starting from ~60mph. Above 100 though they tend to lose steam and thats when we start walking away.

because they redline at up to 19,000RPMS. But when you multiply their low torque number over time...it adds up.

e1000

Quite simply, you're wrong. Torque figures for an engine are all measured at the crank. Torque is multiplied through the gearbox, however horsepower is not. I don't think you're grasping this concept. Think about it for a second, 250lb-ft or even 345lb-ft, would never be able to accelerate a 3500lb mass from 0-60 in under 6 seconds.

RLx02

Actually I'm not. Why are you trying to change your stance all of a sudden? You were quoted that the m3 puts down more WHEEL torque than a c55.

I just proved you wrong in my other post.

Now, are you talking about acceleration or power? I can agree that acceleration is greatly dependent on gearing and torque but putting power to the ground is completely different.

e1000

Cars are dyno'd at a 1:1 gear ratio because it is just that, a straight 1:1 gear ratio, that allows the dynomometer to give the most accurate results of an engine's performance.

Here's some reading for you since I can't seem to get it through your thick skull.

http://www.car-videos.net/articles/h...wer_torque.asp
http://www.maelabs.ucsd.edu/mae_guid...Ad/mech_ad.htm
http://www.team-integra.net/forum/di...g+Common+Topic
http://www.modified.com/editors/tech...las/index.html
http://www.absoluteastronomy.com/topics/Gear_ratio
http://eurowerks.org/showthread.php?t=18937

e1000

And I'm telling you, you're wrong, manufacturers state flywheel horsepower and flywheel torque. lol.

e1000

There's so much wrong with this post, I don't even know where to begin. Why don't you try to lookup actual WHEEL torque figures. Go ahead, plug it into google. You can't take the flywheel torque figures, take the drivetrain loss, and then get wheel torque like you can horsepower, it just dosen't work that way.

Here's yet another hint.

http://www.calcenstein.com/calc/0773.php

RLx02

Wow, its like arguing with a 4 year old. Why are you trying digress from the fact that you were proven wrong on how much torque an m3 puts to the ground? Why are you even bringing up the fact that manufacturers state flywheel/crank hp and torque? Do I have to quote your incorrect statement again?

If we're going to quote that, then lets bring flywheel power for my c55 and a stock e92 m3.

my c55: 410hp and 425 ft/pounds of torque OR 337hp and 345 ft/pounds of torque
stock e92 m3: 414hp and 295 ft/pounds of torque OR 340hp and 250 ft/pounds of torque

Again and again I'm proving you wrong against your own statements. Why do you even bring up links that just reiterate my points that I showed to you?

e1000

Keep dreaming buddy. Horsepower can be caluclated the way you're doing, but you're completely leaving out gearing with respect to torque. Until you understand the concept of gearing, torque multiplication and resultant force, you'll never get why some cars have higher horsepower with low torque ratings and some cars have low horsepower and high torque ratings and how they compare to each other on the track. I still stand by my statement that an E92 M3 puts down more torque to the wheels than a C55, even a lightly modded one. I've done the math up above, if you can't understand it, I'm sorry.