vegastrashed

Let's try to schedule a group dyno day for March 17th. Anyone else care to join?

JetBlack

I will be up in San Jose on March 14th to 16th and can possibly stay an extra day. I am debating if I will drive the 550 or fly....

Vegas - I know Dinan is not the answer to all, but they do have the BEST dyno setup for REALWORLD numbers since MOST dyno shops cannot reproduce 80mph wind speeds. Since most of us drive at 80mph or faster don't you want to know what those actual numbers are at regular speeds?
When you get your car dynoed at Dyno Spot and your car is pulling 100mph but only receiving air like it was traveling 30mph you will have skewed figures.

EFC - The numbers technically are not exaggerated but the power that the engine actually makes at 80mph.

You guys should really read the white paper before questioning dyno techniques from one shop to the next. I read it twice.

JetBlack

Here is one paragraph out of the white paper.

By far the most significant criticism I have for many dyno facilities is the use of fans that are simply too small for the job at hand. The fan size is so significant that we employ a very large unit that was actually designed for ventilation systems installed in high rise buildings! This powerful fan produces 38,000 cfm of air flow @ 75 MPH, which is still less than the 150 MPH air that a modern BMW might see at redline in 5th gear, but it certainly provides a closer to real-world scenario than the more common fans I have seen used in dyno facilities. It should be noted that 5th gear is used for our dyno testing because it is one to one, meaning that the input and output shafts are connected, reducing power losses and transmission wear. I have seen many examples of dyno facilities where low flow fans obtained from the local hardware store are employed, and even situations where there was no fan at all. A minimum of 15,000 cfm and preferably 40,000 cfm of air flow is required for proper heat exchanging. This type of fan will produce a 40-80 mph air discharge velocity.

EuroCarFan

Thanks for the info Jet. The concept certainly makes logical sense.

Also by no means am I criticizing any dyno shops...just asking questions to get more knowledge. I have no technical skills to judge anyone on this issue.

JetBlack

Just an idea
I can ask if we can visit Dinan's dyno shop that day after your runs are complete and he can answer all of your questions. I will only approach Steve if there are enough individuals to meet there also.

EuroCarFan

That would be cool but are they opened on Saturdays?

JetBlack

No they are not open on Saturdays that is why I will only ask Steve Dinan to meet us there if there are enough people.

vegastrashed

Even if the dyno shop where I will be getting a dyno is not absolutely correct, at least I will I have a baseline which to use if I decide to do any engine mods while I'm in the Bay Area.

my530i

Mr. J.
You should get your car dyno'd at the same place before and after the mod.

cobradav

There have been many definitions for the term over the years since James Watt first coined the term in 1782. The following metrics have been widely used:

Mechanical horsepower ? 0.74569987158227022 kW (33,000 ft?lbs per minute)
Metric horsepower ? 0.73549875 kW


Metric horsepower
Metric horsepower began in Germany in the 19th century and became popular across Europe and Asia. The various units used to indicate this definition ("PS", "CV", "pk", and "ch") all translate to "horse power" in English, so it is common to see these values referred to as "horsepower" or "hp" in the press releases or media coverage of the German, French, Italian, and Japanese automobile companies. Companies of the United Kingdom often intermix metric horsepower and mechanical horsepower depending on the origin of the engine in question.

Metric horsepower, as a rule, is defined as 0.73549875 kW, or roughly 98.6% of mechanical horsepower. This was a minor issue in the days when measurement systems varied widely and engines produced less power, but has become a major sticking point today. Exotic cars from Europe like the McLaren F1 and Bugatti Veyron are often quoted using the wrong definition, and their power output is sometimes even converted twice because of confusion over whether the original "horsepower" number was metric or mechanical.

367 * 98.6% = 361.862 plus some emissions differences and or fuel used in testing accounts for the rest of the difference.