This post is why I said "not on a chassis dyno."well maybe in usa its a difference of dyno thats why they get only 280 and maybe cos automatic gear, with manual people get 320 in stock
Generally, the chassis dyno correction factor is used to normalize to environmental variations from STD. 60degrees - 29.92baro and 0 percent humidity.The biggest problem with dyno numbers is that they can be modified to make the customer happy. (Chassis) Dynos measure the hp and torque at the wheels, unless you take your engine out and put it on an engine dyno. The chassis dyno will show around 15%-20% less than the engine dyno due to losses in the transmission, driveshaft, etc. That number can be lowered depending on modifications made. Most chassis dynos allow you to put a correction factor to account for these losses. The correction factors can be manually enterred, so a dyno operator can put in whatever percent he wants to make his customer happy. Most good dyno operators will not put in a correction factor and will just tell you what the hp and torque are at the wheels (which is essentially all that really matters). However most people want to see BIG numbers or want to compare their car to the factory numbers. So dyno operators have been using correction factors to make them happy. Everyone wants to say that their car has a big HP number, but all I care about is how much of the HP is actually getting put to use by being transferred from my tires to the road.
Generally that is correct, however it is entered in manually by the operator. He can put in whatever he wants. Some operators enter in an additonal correction factor to guesstimate the power at the engine. I had a friend of mine who has a dyno in his shop show me how he can change the factors and make any HP numbers he wants. Dynos are a great tool to determine the gains you get from doing mods, but to compare dynos from different people (especially when they are run on different dynos) without knowing all the details is almost pointless. Next time I go by my friend's shop I will have my new 335i dyno'd twice. The first time to get legit numbers, the second time to put in some crazy factors to see how high I can get the numbers. I will scan in the dyno sheets when I get back home. Then everyone can see that stock numbers are probably around 260HP at the wheels and that with a good dyno cheat the "stock" horsepower can be raised to well into the 300s, maybe even 400+.Generally, the chassis dyno correction factor is used to normalize to environmental variations from STD. 60degrees - 29.92baro and 0 percent humidity.