regor60

yes, once again establishing lack of correlation between IQ and willingness to spend money...

stevebez

Wierd ....

These guys got a "drive train loss" of 5% in power and 8% in torque... 446rwhp and 476 rwt for CLS55. This removes the drive train loss from the tyres... I assume there is definately some lost in heat and traction of the rubber on the rollers....

So If I work back from these numbers and assume an 18% DT loss then these cars are in fact making 504hp and 523torque at the flywheel... which is in line on torque and more in HP ...

see here ...

http://www.rri.se/popup/performanceg...p?ChartsID=152

ChicagoX

Probably a Dynapack unit. Their PAU (power absorbtion unit) bolts right to the hub, eliminating the tire/roller interface and associated drivetrain losses. Strap-down techniques aren't affecting the numbers this way either.

stevebez

Yup so this tells me car produces more power than spec ... ?

But there are a bunch of cars in their database that are in same delta ball park as the 55K they tested.

I think it is a pointless exercise trying to estimate crank HP ... its only usefull if u can put the engine on a test bed ...

RWHP is the only "reliable" comparison metric we can use... we have to assume trannies are close enuf to be irrelevant to the end result.

We still have the dyno variances to consider too - and the ambients humidity pressure...

Shheeez sometimes I wonder if its at all worth it to do a dyno !!!!

Cylinder Head

iTrader: (1)

Wouldn't do that if I were you, I read an article about the M113's programming that specifically stated that AMG programmed it to run rich as an "artificial coolant", literally dumping in more fuel to keep the engine from heatsoaking. The more you learn about the engine the more you'll realize its a heat pig and any mods done should be done in accordance with "cooling mods" like intake spacers, headers/exhaust (extra backpressure and heat was needed to light off the cats for emissions requirements), and an upgraded intercooler pump.

Heisenberg

Anyone ever run their MB rich enough to get afterburners with full throttle ?

Grumpy666

Instead of calling someone stupid because you don't understand what they're saying, why don't you ask for clarification? His statements are, in fact, correct. Which value to use is a function of the reference point. Think about this:

Three is 50% larger than two, but two is 33% smaller than three.

When quantitizing the difference between crank HP and wheel HP, the difference is larger when compared to WHP (23%) than it is compared to CHP (18.5%). IOW, 23% of wheel HP is equal to 18.5% of crank HP (in this example).

On a dyno, correction values of 22-25% are valid for an automatic transmission car, since the correction is applied to the measured wheel HP. This is equivalent to an 18-20% loss at the crank.

Now you don't have to spend money on a calculator.

lbE55

I was looking at this as a concept for an "afterburner," but decided against it:

http://www.ebaumsworld.com/2006/07/buttrocket.html

2K6E55

Congrats on a healthy BEAST.