stephens

jkrutch with respect your example was meaningless and irrelevant. My Ducati has only 80lbft of torque, but accelerates quicker than the E55, what does this prove? I don't see where your torque fixation comment comes from, the only interest here is in real performance numbers.

jkrutch

My "torque fixation" comment is based on what I have read on here over and over again. Go back to the 1st page of this thread...you'll understand. I 150% agree with you....the numbers are what matters. I think you might have missed my point. I could care less how much torque or HP a car has. With regards to performance, the numbers are what count, not the specs.

AMG Fan

I've driven both too. While the 996 is a bit faster machine, it must be driven perfect to beat the E55. While you might be a great driver, most people are not and will not shift appropriately. I'll step on the gas of my E55 & beat probably 85% of the Turbo drivers out there.

Vic55

This is just like what I used to say to M5 owners who told me they were faster than my W210 E55.

BlownV8

"My point here is that everyone is fixated only on torque."

OK guys, listen up! This is why people keep referring to torque instead of horsepower and why it is so critical to acceleration. However, gearing is also very important too.

Horsepower = (torque)(rpm)/5252 Not debatable!


From Car Craft:

Engines don’t make horsepower; they convert fuel into torque. Torque is the twisting force imparted to the crank flange and then transmitted to the transmission and the rest of the drivetrain. To some degree torque is the grunt that gets things moving, and horsepower is the force that keeps things moving. An engine is most efficient at its torque peak, wherever that happens to occur. Below the torque peak, engines generally have more than enough time to fill the cylinders; above the torque peak, they don’t have enough time to completely fill the cylinders. This is generally beneficial in that it lets engines produce most of the desirable grunt work (torque) at lower engine speeds, which means reduced wear-and-tear and better fuel economy. The ability to extend an engine’s speed-range allows it to stretch that torque curve out farther, provided that the high-speed efficiency is there to make horsepower.

Power is torque multiplied by engine speed to produce a measurement of the engine's ability to do work over a given period of time. The story of its origin is well known, but worth repeating, briefly. In the 18th century, steam engine inventor James Watt sought a way to equate the work his steam engine could perform to the number of horses required to perform the same task. Watt performed simple tests with a horse as it operated a gear-driven mine pump by pulling a lever connected to the pump. He determined that the horse was capable of traveling 181 feet per minute with 180 pounds of pulling force. This multiplied out to 32,580 lbs-ft per minute, which Watt rounded off to 33,000 lbs-ft per minute. Divided by 60 seconds, this yields 550 lbs-ft per second, which became the standard for 1 horsepower. Thus, horsepower is a measure of force in pounds against a distance in feet for a time period of one minute. By substituting an arbitrary lever length for the crankshaft stroke, you can calculate the distance traveled around the crank axis in one minute multiplied by engine speed (rpm) and known torque to arrive at the formula for horsepower:

Because torque and rpm are divided by 5252, torque and horsepower are always equal at 5252 rpm. If you solve the equation at 5252 rpm, the rpm value cancels out, leaving horsepower equal to torque. If you plot torque and horsepower curves on a graph, the lines will always cross at 5250 rpm (rounded off). If they don't, the curve is undoubtedly bogus.

Torque is the static measurement of how much work an engine does, while power is a measure of how fast the work is being done. Since horsepower is calculated from torque, what we are all seeking is the greatest-possible torque value over the broadest-possible rpm range. Horsepower will follow suit, and it will fall in the engine speed range dictated by the many factors that affect the torque curve.

Increased displacement is the easiest way to achieve increased torque. Very large cylinders and a long stroke offer the greatest cylinder volume and overall piston area for the fuel charge to push against the crankshaft or lever, if you will. Stationary industrial engines that produce tremendous amounts of torque are typically quite large. The mass and bulk of one of these engines makes extremely large displacement engines impractical for use in cars.

Hence, we are limited to displacement values that are easily packaged within the confines of your typical automobile engine compartment. The practical limit is between 400-500 cubic inches for most large automobile engines. Big-block engines in this range deliver tremendous torque, and they are easier on parts for the same amount of power output. Car crafters have stretched displacement out as far as 800 cubic inches with highly modified cylinder blocks and crankshaft strokes, but these engines are not practical or economical for general high-performance applications.

This leaves us searching for ways to increase torque in smaller engines by increasing efficiency through the manipulation of mechanical components, gas dynamics and thermodynamics (to increase and harness cylinder pressure). There are many ways to do this, but most involve some sort of tradeoff somewhere in the power curve. To a great degree, we are forced to build engines for greater efficiency within a chosen engine speed range. Some combinations will function very well at low speeds, others will be strong in the mid-range, and still others will only run hard at a high rpm. The key is selecting the combination of components that will stretch and fatten the torque curve (improve efficiency) as much as possible in the driving range we prefer. Our saving grace is the relatively forgiving nature of internal combustion engines wherein torque dissipates gradually as engine speed increases. As long as the induction system can carry the airflow demand created by the cylinders at high engine speeds, the torque curve will remain broad. This allows engine speed and horsepower to carry the engine farther in the rpm range before the net effect of induction restrictions at high engine speeds chokes off efficiency.

Kens-E55

Maybe the most impressive part is that our E-55's are being used in the same breath as the Porsche Turbo's!!!!! I don't hear that being said about ANY OTHER 4 door sedans!! Thank you Porsche owners for the comparo. BTW - R&Track tested 25 cars this month

E55 ------------------- 0-60 in 4.2 // 1/4 mi - 12.39 @ 117

Porsche Turbo ------ 0-60 in 4.3 // 1/4 mi - 12.4 @ 116

As you can see - the cars are a dead heat. - If we can solve the E55 traction issue ie: bigger contact patch, softer rubber, then who knows how quick our E-55's will be. As far as the M5, There is no way it will have the Tq to get "out of the gate" the way the E55 does. Once underway from 30mph and higher, I'm sure the comparo's will be close.

Just my .02

Note: If I remember correctly, the TTurbo Porsche was a few tenth's quicker - still a close race!

:p

AMG Fan

Which month of Road & Track is article from?

Pierre32///AMG

yes you are right, nevertheless, as mjc123 said and I agree, when you tune a Turbo....byebye.

For the same money that you can get a RENNtech pulley & ECU you can get a Stage II Turbo (440 rwhp & 445 wrtq) that makes 0-100 on 8 sg flat, and 0-125 (0-200km) in 12.4 sg., and not even mention the handling. I love the E55 and if I would not have the ML55 for sure, it would be the car that I am driving today .

Kens-E55

To AMG Fan,

The mag is on the newstands this month. The actual comparo's were done earlier in the year - this is simply the re-creation of the articles.

As far as the M5 - "Too Much Pork, Not Enough Torq"

stephens

Put into perspective, that is a good time for a stock E55 and a poor time for the 996TT.
Last months (I think) R&T had the 0-100-0 test. 996TT was 0-100mph in low 8.8sec, the E55 was tested at 9.8 sec (a slow time for the E55). Even considering the E55 more typically posts a 9.3-9.4sec time this is still 0.5 sec slower than the 996TT and at 100mph 0.5sec is a lot of road.
The E55 will eat a tiptronic (which I think uses the same tranny as the E55 BTW) 996TT for lunch, but a well driven manual is another story up untill about 100mph, where the better aerodynamics and power of the E55 take over.

EDWARD CONROY

Looks like the M5 will at best be about as fast, and probably not even. This is what all the fuss has been about, the anticipation??? Let me see if I've got this right. You get a car that handles better, but doesn't look as good inside or out, has a more complicated electronics system, and that you have to wind out like a screaming meemie to achieve its potential. No thanks. Man, there are going to be some sad M5 owners if E55's end up kicking their butts out on the freeways. Especially any that might unfortunately meet up with the likes of Dr. Chill and T-bone.

jkrutch

Maybe I should get a Cummins diesel Dodge Ram...it must be faster...it has 600ft/lbs torque. You still don't get it.

THE NEW M5 MIGHT BE QUICKER TO 60, 100, ETC. EVEN WITH MUCH LESS TORQUE! THAT IS MY POINT! TORQUE IS ONLY ONE FACTOR AND CERTAINLY NOT THE MOST IMPORTANT. There are things such as rear-end gearing, transmission grearing, ltd slip differential, tires, suspension, chassis, drag coefficient and more. All of these figure into performance.

The lbs/hp for the 996TT and E55 are as follows:
996TT (HP & TQ) 8.19 lbs
E55 (HP) 8.74
E55 (Torque) 7.94

The E55 has a superior tq/lb ratio, yet it is slower due to the other factors mentioned above.

Am I the only one who is aware of this??????

Kens-E55

I think most of us get it! The biggest reason the Porshe's are slightly quicker is less weight and shorter gearing - period!

If I gear the E55 - the same as the Porshe's, I'd bet the E55 will walk away everytime!

jkrutch

No it wouldn't...it can't get traction as it is with the tall gearing...shorter gearing would make it worse, not better. It needs less weight and more grip....

jkrutch

I agree with you, but I believe the R&T 0-100-0 was an X50 996TT. It is a tenth or two quicker than the non-X50. The 0-60 of 4.3 for the Porsche is by far the worst I have ever seen. The avg. is just under 4.0 seconds. My first 996TT was a tip....what a piece of crap! I had that car for 2 months and dumped it for a 6 speed.

stephens

jkrutch
You are right, however consider the following.
A good 996TT 0-6 time is 3.9sec, a good E55 0-60 time is 4.3sec.
Over the standing 1/4 996TT 12.0, E55 12.4
Now there are faster times recorded for both, but these are equal to the best published testing numbers.
If you fit an LSD to the E55 you will remove the 0-60 advantage of the 996TT and you will find also the 1/4 mile one too. So expalin how the E55 can equal the 996TT perfromance numbers when the traction advantage of the 4WD is removed?

What you have failed to consider in your argument is that performance is not about peak horsepower, it is the area under the power curve as a function of the gearing.
With its almost flat torque curve from 1900rpm to over 5000rpm (torque is just a function of HP at RPM remember) The SC V8 motor has probably the best such area for a motor with comparable peak power.
It isn't an International award winning perfromance motor for nothing.

jkrutch

STEPHENS...you actually demonstrated my point perfectly....The traction advantage is exactly what I was referring to. It is one of the many points of my argument. That is why I think the M5 will be as quick if not quicker despite the torque disadvantage. Thanks!

stephens

Time will tell, but the numbers don't bode well.
As I have stated on countless occaisions, the 575M Ferrari has better numbers than the M5, being lighter with more HP and torque and 100kg less weight, yet is equal to or slower than the E55.

jkrutch

Agreed....Time will tell.

BenzoAMGpower

W211 E55 = 516lb ft tq
V10 M5 = 369lb ft tq

V10 M5 is OWNED

~courtesy of W211 E55

stephens

jkrutch
I see your point about the torque issue.

My analysis is not about torque numbers. It is about the shape of the HP curve.
I look forward to my first opportunity to test my theory against a real M5!

Bilal

Stephens with all due respect, when you talk about E55 numbers and beating M5s, lets just say your E55 is not exactly "stock"


Near 600bhp!

MelsE55

Remember F=ma or acceleration=F/a where F=the driving force at the contact patch, or patches.

Also, as elluded to before, the torque coming from the engine is not the torque delivered to the rear wheels. It might be multiplied by the torque converter (in the case of an automatic transmission), then by the transmission gear ratios, then by a transfer case (in the case of 4wd), then by the differentials. This torque is then "converted" to a tractive force (f=t/r) based on the radius of the drive wheel. Lots of variables to consider given the different types of vehicles discussed here.

Also, just as a point of discussion, isn't the MB driveline limited slip because of the ESR function of the ESP system? I have always considered it an external, electronically controlled limited slip drive system.

In the end, let us not be too caught up in the details as we are a blessed bunch to be driving the vehicles that we are.

Kain

Why the hell do most people here think numbers are everything??

jkrutch

Because they don't know anything about cars. The only numbers that count are the performance numbers. They need to learn that power without traction is essentially useless...etc.......