Having my 211 put on the chasis dynomometer next week. What should i be careful of? Can this cause damage?

David

 

Vadim told me they just tested the cars by turning off the ESP. There will be warning lights for ESP and brakes that will come on and they will reset themselves after driving 30 minutes or so afterwards.

 

What gear will give me the most accurate readings? They recommend a gear with a 1:1 drive ratio which is fourth gear I believe.

David

 

On an automatic you need to use 3rd gear in manual shift mode. Start the run at about 3k rpm so it won't downshift.

 

Hope you guys are goin to post the results of those dynos. Please do.

 

Has anyone on the board dyno'd the S55, SL55 or CL55?? I bet my results will be EXACTLY the same for the W211! Who is Mercedes trying to kid? It is the same engine regardless of exhaust, intake or any other variable. The mechanics of the engine would have to change rather drastically to lose 6% of the engines power. 470hp is enough, but I beleive my car closer to 500hp! I have owned some lightweight powerful cars and my E55 (when "hooked up") has proven to be an absolute acceleration rush. There is almost nothing like it.


How do I post my results of the dyno test?

DG

 

The only other thing that I have read here on the boards concerning dynos and the E55 is turn off the ESP and possibly unplugging the wheel speed sensor. The computer senses the great difference in speed between the front and rear wheels and stops the dyno run before redline. I know that there have been successful pulls as I have seen some sheet from an SL55 posted on MBautowerks website before and after the Renntech mods. The URL is http://www.mbautowerks.com. Maybe you can e-mail them direct to get the proper technique so you don't waste your time at your local dyno. Hope this helps.

 

What ratio is 3rd? On my E55 (W210) 4th gear was 1.00 so that's what we used. You want to use the gear that's as close to 1.00 without going under.

-m

 

Fourth gear is too fast on the W211 for most dyno's. I think the car will hit the speedlimiter in fourth if you have not had the V-max limiter removed.

 

has software to calculate the torque curve based on rear wheel speed.It doesn't care what gear you're in...that's why the dyno has a pickup going under the hood to grab an rpm signal.In a lot of cars,3rd gear is tall enough to make the time-in-gear duration enough for an accurate reading.Having to be in a gear a w/1:1 ratio is a myth.
Remember-a dynamometer only needs rpm and torque to work.

 

You are assuming all dynos have that capability, and they don't. The Dynapack does not have an RPM input, rather it needs the gear ratios input manually to figure out what wheel speed equals what rpm.

-m

 

Doesn't matter where the RPM info comes from,as long as it is accurate.The point I'm trying to make is that gearing alone does not affect engine output...or dyno results.

 

LYSHOLM

Am very much interested in seeing your dyno results next
week as I'm sure others are as well.

The topic of the stock HP rating for the W211 E55 has been
discussed many times before on this board and hopefully you
can help put the "mystery" to bed.

The calculations for the E55 at a curb weight of 4,087LBS(confirmed at the MBUSA web site) with a 1/4 mile trap speed of 116.4MPH (2004 R&T Annual Road Test) works out to 503HP at the rear wheels. If we add a driver at 180LBS (total of 4,267LBS)
that would be 525HP at the rear wheels. R&T lists the "test weight" for the E55 at an even 4,300LBS (=530RWHP).
Measured 116+ 1/4 traps have been confirmed by others too.

We're talking rear wheel HP here and not even at the flywheel!

Can anyone confirm what 530RWHP would approximately be at the flywheel?

Looking forward to those dyno results

 

How would adding a driver, thus more weight add more rwhp? Splain that to me please. I would be very surprised to know that figure of 540 was rwhp and not crank. I would take the 540 crank in a New York minute. I am debating with myself about putting a personalized plate on the E55 that reads...469HOSS....I think that is low but I want to be as accurate as possible....maybe 493HOSS? I too await some credible dyno results and more than one car. I have a Vette that has a trap speed of 119 and change, but only dyno of 385 rwhp. You can't just use trap speed to interpolate accurate power in terms of a number.

 

to remain accurate, you can always do 516HOSS

 

Firstly, calculators that use trap speed only are notoriuosly inaccuracte, secondly most of the formulas give you crank, not rear wheel horsepower. According to most HP calculators based on 1/4 mile performance the W211 makes around 530hp at the crank.hp
calculator

Lastly, the W211 weight of 4087lbs includes 90% full fuel tank, luggage and driver. This is an EC based standard weight spec for manufacturers.

 

quote:
--------------------------------------------------------------------------------
Originally posted by imthduke
How would adding a driver, thus more weight add more rwhp? Splain that to me please. I would be very surprised to know that figure of 540 was rwhp and not crank. I would take the 540 crank in a New York minute. I am debating with myself about putting a personalized plate on the E55 that reads...469HOSS....I think that is low but I want to be as accurate as possible....maybe 493HOSS? I too await some credible dyno results and more than one car. I have a Vette that has a trap speed of 119 and change, but only dyno of 385 rwhp. You can't just use trap speed to interpolate accurate power in terms of a number.
--------------------------------------------------------------------------------

That adding more weight (i.e. driver) to the base curb weight of a
vehicle means that HP rating goes up with the heavier example when speed attained remains constant (116.4MPH) and the specified distance remains constant (1,320FT-1/4 mile).

Your Vette has a trap speed of 119 but what is the total weight
including a driver? With a 119 trap and 385 RWHP your Vette is going to be quite a bit lighter than the W211 and yes you can't just use trap speed to interpolate acurate power unless you have the weight.

Which brings up Stephens point that trap speed or elapsed time calculators are notoriously inaccurate because there is too much
possible err on weight inputs. Some think that the elapsed time calculators are more accurate but again it uses weight in the calculations (BTW the elapsed time calculations using 4,087LBS and 12.4sec are 424 RWHP and 508 at flywheel -seems more realistic and closer to Stephens trap calculations as well) .

The most accurate way to get HP ratings is definitely on the dyno.
But lets say Lysholm posts his dyno number next week and it's 425 RWHP. Then the debate is going to start on how much power is lost through all the drivetrain components (estimates on this could be anywhere from 10% to 22% but who knows for sure) and thus what is the "true" number at the flywheel?
The only truly accurate flywheel HP figure would be to take the engine out of the car and dyno it that way...any volunteers

 

arguing over HP@the flywheel,why don't we all just stick to what the chassis dyno sees?...After all,it's what connects to the pavement that counts.I'm only interested in the torque curve.
As to calculating HP with trapspeed and total vehicle weight,the results are fairly accurate.Innacuracies will creep in when trying to crunch numbers for different cars.
It's best use is to compare changes made to the same vehicle-if your ET slows but the trap speed goes up,you're making more power.

 

Agree totally on both points. I use both myself to correlate the effectivness of modifications.