[AddyDaddy]

So in south Florida we're running about 90-95 degrees where heat index has been 95-100 degrees.

My new M550 is feeling slow, just did Dinan 2 or so weeks ago at 1500 miles but maybe it's just me thinking too much. But question is, I got the car April 29th and it was mid 70's out and it just felt a little quicker stock then it does now with Dinan and wondering how much the 30 degree difference and humidity does it make in our cars?

[modthispny]

i think a lot, especially turbo cars, and the humidity does not help either.

When we had a heat spell here a few weeks ago, my car felt like a dog. (relatively speaking).

[aus]

Cooler weather results in better cooling of the post turbo, pressurized intake air through your intercooler. The intercooler doesn't cool as well when it's hot outside.
.

[drjolokia]

Originally Posted by AddyDaddy

So in south Florida we're running about 90-95 degrees where heat index has been 95-100 degrees.

My new M550 is feeling slow, just did Dinan 2 or so weeks ago at 1500 miles but maybe it's just me thinking too much. But question is, I got the car April 29th and it was mid 70's out and it just felt a little quicker stock then it does now with Dinan and wondering how much the 30 degree difference and humidity does it make in our cars?

It's possible there's an issue with the Dinan tune.

Just to test, drive around with it in bypass. If it performs better, then you have an issue with the device.

There are several threads on these forums where owners describe a performance decrease after installing a Dinan tune. I believe each time the issue was resolved by putting the device in Bypass for a bit then turning it back on, or removing the tune all together and re-installing it.

😎

[AddyDaddy]

I tried taking Dinan out for a day. I think it's the 20+ increase in temp and humidity. Just wondering if anyone new a calculation for a correlation between heat/humidity and our engines(turbo'd) and difference at 60 degrees to 100 degrees

[mk1-fan]

Hot weather will make a huge difference. As said above, with added humidity it's even worse.

On all the turbo cars I have had, you could clearly feel a difference, especially mid day in summer.

Throttle response is also negatively affected.

[CLABRO]

There isn't a simple answer for your question as there are multiple variables affecting horsepower. Typically as air gets colder, it becomes more dense which gives you more oxygen within a smaller volume. The more oxygen available, the more power produced.

However, it's not all about temperature as you can have the same temperature and humidity in two different locations and the location that has a lower density altitude will produce more power (significantly more power in some cases- 15% or more).

Density altitude is calculated using your altitude, temperature, and humidity. Density altitude tells us how dense the air is compared to "normal" or standard elevation. And remember, the more dense the air, the more oxygen there is, and the more oxygen available will yield more horsepower.

A general rule of thumb (if you'd even call it that) is a 1-1.5% change in power for every 10 degrees. *This doesn't factor in humidity or elevation, but more people would probably know what the current temperature is where they are rather than what the humidity or elevation is.*

Lastly, for supercharged or turbo'd cars, they are even more susceptible to weather conditions and altitude than a NA car.

Only knowing the change of temperature from 60* to 100* and not knowing the altitude or humidity, I'd guess a loss of ~ 6-7% which would be ~ 27-32 horsepower on a stock M550 and even more on your car in particular given it has Dinan and other modifications.


EDIT: Here's a calculator that shows you the amount of horsepower available at any one time depending on weather conditions and elevation (you can change the temperature, barometric pressure, humidity, and altitude and in return it will show you the change in power).

http://www.csgnetwork.com/relhumhpcalc.html

**This is just a tool and real world circumstances are almost always different. This doesn't take into account superchargers or turbos- just the engine itself**

[530iDriver]

Not sure, but my 530i handled Orlando's heatwave this week like an absolute champ!

[530iDriver]

Originally Posted by AddyDaddy

So in south Florida we're running about 90-95 degrees where heat index has been 95-100 degrees.

My new M550 is feeling slow, just did Dinan 2 or so weeks ago at 1500 miles but maybe it's just me thinking too much. But question is, I got the car April 29th and it was mid 70's out and it just felt a little quicker stock then it does now with Dinan and wondering how much the 30 degree difference and humidity does it make in our cars?

Yes but also remember that we are at sea level so losses should still be minimal. Price we pay to live in a hot and humid swamp

[AddyDaddy]

Originally Posted by CLABRO

There isn't a simple answer for your question as there are multiple variables affecting horsepower. Typically as air gets colder, it becomes more dense which gives you more oxygen within a smaller volume. The more oxygen available, the more power produced.

However, it's not all about temperature as you can have the same temperature and humidity in two different locations and the location that has a lower density altitude will produce more power (significantly more power in some cases- 15% or more).

Density altitude is calculated using your altitude, temperature, and humidity. Density altitude tells us how dense the air is compared to "normal" or standard elevation. And remember, the more dense the air, the more oxygen there is, and the more oxygen available will yield more horsepower.

A general rule of thumb (if you'd even call it that) is a 1-1.5% change in power for every 10 degrees. *This doesn't factor in humidity or elevation, but more people would probably know what the current temperature is where they are rather than what the humidity or elevation is.*

Lastly, for supercharged or turbo'd cars, they are even more susceptible to weather conditions and altitude than a NA car.

Only knowing the change of temperature from 60* to 100* and not knowing the altitude or humidity, I'd guess a loss of ~ 6-7% which would be ~ 27-32 horsepower on a stock M550 and even more on your car in particular given it has Dinan and other modifications.


EDIT: Here's a calculator that shows you the amount of horsepower available at any one time depending on weather conditions and elevation (you can change the temperature, barometric pressure, humidity, and altitude and in return it will show you the change in power).

http://www.csgnetwork.com/relhumhpcalc.html

**This is just a tool and real world circumstances are almost always different. This doesn't take into account superchargers or turbos- just the engine itself**

Thanks
Yes
South Florida we're on sea level and 99% humidity
In all my cars, last 4 have been turbo'd BMWs, I only had my F10 M5 for 6/7 months before I said screw the up keep of $1500 a month plus loan payment and mods and leased this car. Meaning I had the M5 from December thru end of April- nice cooler low humidity months. Temp gauge hit I think 106 the other day driving on 95.

[jjscsix]

A few years back I was taking various Corvettes to the drag strip in the Houston area. I was pretty consistent. From winter temps of around 55-60 to a hot summer day - let’s say 90, it effected my trap speed by two MPH. A well respected Corvette performance shop at the time told me once that his uncorrected dyno runs in similar climates varied by as much as ten percent.

I would actually think turbo cars would be better because electronics can keep the boost in a narrower range, but that is just my guess. I really don’t know.