Has anyone dyno'd their SL55 or know where I can find a dynograph of an SL55? I'm curious to see what the torque and horsepower curves look like.

-Joe-

there was a dyno-test on a german magazine called "MOT". the results were only 489hp but 750nm torque (instead of 700nm).

How accurate are the tests and what criteria do tey use?

Hmm...anyone have that issue of MOT? I'd like to see what the power curves look like.

If there are any SL55 owners in New Jersey or New York that'd be interested in dynoing their car, I'm more than willing to pay for the dyno session and gas

-Joe-

issanni I live in NJ and I am getting a SL55 late January early Febuary if by then u still care about dyno let me know where and how.

Oh, of course I'd still be interested There's a race shop in Hackensack called Bullish racing, they have a nice setup there to dyno. And yes, I'll pay for the dyno runs which are $50 each and gas

-Joe-

What you need is a little box which is available in the UK called a Road Dyno. This hooks up to the ignition and monitors the ignition timing during a series of acceleration runs. You then download the data into a PC for analysis.

By measuring the time between ignition pulses and with knowledge of the car's weight and gear ratios, you can measure both speed, acceleration, torque and power. A friend has one and I've seen the results of it running with his E-type.

Best news is that this little box costs about $150 including software. You can use it on as many cars and as many runs as you like.

The only issue is that the SL doesn't have HT leads, so I'm checking with the manufacturer how it can be used.

For more info, check out "Road Dyno" on Google

That sounds similiar to the Gtech, except I don't think the Gtech actually physically attaches to your car, it just has a sensor to measure accerlation and other lateral forces to compute the horsepower, torque, etc. But I'm not sure about their accuracy.

Both methods work, in each case you're trying to measure acceleration against speed and from that, using conversion factors like the car's weight, the size of the tyres & the gear ratios, plot torque and power against engine speed.

Seems to me that measuring time is easier and more accurate than measuring acceleration from an analog sensor like an accelerometer but how the results compare with a static dyno, I do not know but I think they would be good enough for me and (as you long-suffering forum members will know), I'm on the geekish side of normal.

The attraction of something like the road-dyno is that the measurements take seconds so the results can be repeated whenever I like, so I can monitor the peformance as the car ages, understand the differences between cold and hot days, different fuels. My friend's results show up clearly the differences of using regular 95 octane gas and premium 98 octance on his E-Type.

Once they confirm I can hook up to the SL55, I'm buying one and will post the results here.

I think that compared with a static dyno an instrument like road-dyno adds an important element of uncertainty: aerodynamic drag. Because of drag, measured horsepower will be reduced the faster you go.

You're certainly correct that only part of the power of the engine goes in propelling the car. There's drag, rolling resistance, driveline losses and the anciliaries to consider - the supercharger along consumes up to 91 bhp. It just depends on where you choose to measure the power. The SL55 engine is producing much more than 600 bhp but some of that immediately goes on driving the anciliaries. A static dyno measures the power with no drag and some rolling resistance. The road-dyno or equivalent gives you the bottom line power available to drive the car net of all losses.

I'm not so interested in confirming my car meets the magic 500 bhp figure, more in being able to evaluate objectively the effect of different fuels, temperature and so on. People in Denver will also be interested in seeing how the altitude saps the power of the normally aspirated engine by reducing the charge density.

The road-dyno figures will be lower than a static dyno because of the drag and you can factor it in if you know the Cd and frontal area - not exact, but a first order correction.

found this foto on the "AMG Owners Club" homepage, maybe there are information about the dyno-run



http://amg-owners-club.com

mmm.. nice!!