Billy T.

So in 40 degree warmer weather you trapped over 2 mph faster? Sorry you are disappointed with your dyno results, but there is no doubt that your car is making quite a bit more power than it was before.

You will always be faster in cooler, drier air. The fact that you were faster in worse conditions speaks well to the extra power you are making. And for you non drag racing types, "faster" always refers to trap speed and "quicker" always refers to e.t.

Drag racing isn't as simple as the guys that don't do it like to make it out to be.

mnmike

And EuroCarFan is making good points as well. Just because some magazines got certain times says absolutely nothing.

Drag racing is a very exact science and many variables will change the outcome.
1) Temperature and humidity have a huge impact on the power your car is making and how much traction you may get off the line. This alone on a 14 second car could result in +/-.2 seconds.
2) The track itself will show a variance as well. Some tracks are at higher altitude which means less O2 for your engine which means less power. Additionally, some tracks are known as being sticky or slippery - even at the same track the right lane vs. the left lane can change your numbers. The track can impact your time similarily to the temperature.
3) The drivers in those magazines are professionals, period. If John Force (a drag racing legend and expert) put your car through the 1/4 mile, he would consistently roast your times.
4) The car itself can vary in power. Believe it or not there is some variance from car to car. Some cars could be known as a "factory freak" meaning the motor is actually producing X more HP than what it's suppose to. And the opposite can occur as well - not to mention a car which needs an oil change, spark plugs, has X miles etc. etc. will be affected.

The point of all this is that the only way to really see a difference is to take the exact same car before and after mods, driven by the exact same driver to the exact same track (perferably on a similar temperature day at the same time during the day). And even then, we're still just humans and our own results may vary. The pro's are the best not because they're fast, but because they are consistent.

By modifying any and all of these variables - i.e. C&D pro on a 60 degree track in NorCal vs. Average Joe on a 90 degree day in Denver with his own car and you get quite different results.

zen68

This is the thread from member grogan545 regarding how weather affects performance.

https://5series.net/forums/index.php?showtopic=50946

I have postponed the post-Dinan dyno until the weather gets cooler since my pre-Dinan dyno was done at 50 degree/15% humidity back in April.

kcleung

I havent read all the posts in this thread but havent seen in the last few post wind speed and direction taken into consideration?

e6t

what about driver weight fluctuation and amount of fuel on board?

EuroCarFan

What about the alignment of the planets and your horoscope sign?

Alfonze

Again i'll ask, why the hell does anyone change the throttle body on a valvetronic engine, it cannot give any gain if it is not used? Might be that i dont understand the valvetronic idea correctly, but if i read for example wikipedia: Wiki Link it states clearly: However, the throttle plate is not removed, but rather defaults to a fully open position once the engine is running. So it seems like a totally useless mod, because it cant give you any gain. Or maybe it has a larger area once fully open?