quaz

We've seen several posts with incredible mph claims and 0-60 times lately.

My question is....what is the maximum mph attainable for the CLK body style given it's drag coefficient?

Surely....this body style cannot attain 180 mph?

Anyone have a clue? Ben ?



quaz

Mach430

I do not know the max speed that the CLK is capable of. With the right power, I would say over 200 mph.

quaz

REALLY ??? Over 200 mph???

Let's see as I surf the net...I see something that says that a "slippery" road car has a drag coefficient of .32....a "chunky" one would be over .38 .

By the measuring stick, the CLK is actually fairly "slippery"!!

I guess I look at my CLK...then at a Corvette say....and I just think "ok...the vette has got to be a heck of a lot more slippery". My CLK just seems too round and high compared to even a stock corvette.

Looks like a corvette C5 has a drag coefficient of .29 .

http://www.neosoft.com/~cbjetboy/c5specs.htm

NOW,

The top speed of an Aston Martin Vanquish is 187 mph, drag limited.

So how could a CLK...with any engine...do better than that? Keep in mind I'm nowhere NEAR knowledgeable on this...just did some random searches under "top speed drag limited" on yahoo.


quaz

Mach430

Kleemann pushed an E55K over 215 mph. I would think that the CLK has a much better drag coeffecient than the E. Renntech has a 7.4L CLK with a top speed of 220 mph.

quaz

If that is the case then the only thing that makes sense is that the "drag limited" really means "drag limited given the engine's horsepower".

Right?



quaz

Mach430

Both factors, as well as gearing, are very important in determining a car's top speed. Due to drag, there becomes a point where more HP is not as effective because the car is fighting too much resistance.

quaz

Makes sense.

Thanks Ben.

jswedberg

I think that when car magazines say "drag-limited" they mean that at top speed the engine still has a few more rpms available - it just doesn't have the horsepower to push the body any faster

"Rpm limited" would mean that the car might have gone faster, but the rpm limit on the engine would be exceeded (or the rev limiter kicked in).

MBs of course are electronically limited (usually ) so they only go what our revered Benz engineers say they can go.

Air resistance goes up as the cube of the speed, so doubling your horsepower should only give you about 26% speed increase ( 2 ^ 1/3) assuming no other constraints (tire friction, etc.)

Ahmed

The renntech CLK GTX can do a 0 to 60 mph in 3.8 seconds and hits a top speed of 220 mph!!

All that comes with a 375,000 dollar price tag!

rroberts

Basically, it starts with two opposed forces, HP and drag. Top speed is controlled by whether one has enough HP to overcome drag, and that includes enough at all intermediate speeds until top speed. This is where RPM and gearing come in. If you cannot overcome the drag at 135mph you are not going to make it to 155mph, even if that is peak on the HP/RPM curve.

My understanding, and here I am less certain of automotive standards, is that drag is expressed as a ratio or a relative value, and thus one needs the cross section of the particular object to determine the actual HP needed to overcome the drag on it. By example, my CLK55 and a 747 jet might have the same drag ratio, but a 747 obviously presents a greater cross-section and requires greater HP (force) to get the job done.

My CLK55 is good for 155, where the speed limiter cuts in (yes, I have tried that, and do not ask me to make an admission against interest and say were). According to European road tests, an unlimited CLK55 will do 179.5mph, but that is at red-line, and where the rpm limiter cuts in. With the rev limiter disabled, a rear-end gear ratio change, or tires with a different radius than stock, it might do more.

Frankly, IMHO, one needs very good road surface to do any better than 140mph in a stock CLK anyway.

Newbie

I've been up to 150 on decent roads in my de-restricted 430, and it still felt impressively solid and stable. Good roads definitely help though .

Ahmed

yup... i've been up to 250 kmh on normal freeway in a CLK320.

RPM idle at 5000

Lucas

The renntech CLK GTX can do a 0 to 60 mph in 3.8 seconds and hits a top speed of 220 mph!!


3,8 to 60, right



Did it ever occur to any body, that it's impossible to bring a 2 ton
CLK from 0 - 60 in 3,8 sec.

Any body which have tried a KLEEMANN CLK 55 K will know.

It's for sure not because there isn't power to do it, but simply a traction problem.

Mach430

Renntech has wider fenders on that car to allow more tire. Not to mention, I'm sure they were using slicks.

Ahmed

lucas!

dont insult my intelligence please!

use your internet connection for useful purposes and go to renntech site!

or would you like me to repeat?

goalie_k

Lucas - how about 4.0 as tested by Car and Driver from "only" 6 liters.

http://www.caranddriver.com/xp/Caran...enntech&page=2

Oh wait how about 0-60 in 3.7 seconds from the Renntech SLR7.4 that was in Car and Drivers 0-150-0 test???

Face it, these cars have a better way of getting the power to the road.