kevinmalec

I noticed since the weather has dropped significantly in the mornings, the Mustang feels a lot quicker and is pulling a lot harder as well. During the hot summer season here in GA, my car sometimes ran like dog....

What is the general rule of thumb when it comes to HP gain with cooler weather?

Is it like a 1% gain in hp for every 10 degrees cooler it is?

jpplaw

Yep. Not sure if they change seasonal gas formulas in GA, but that would also have an effect.

High Humidity levels really mess with these cars too.

Another old rule of thumb is dropping 100 pounds is equivalent to gaining 10hp

kevinmalec

Thanks for chiming in! I am not sure if they change gas formulas here in GA either. However, I do notice on hot humid days, I feel like I am down to 3 cylinders. LOL

mighted1987

I cant say what are the hp gain but lemme tell you i usually read 8 lbs on boost gauge but with this cold temp it alway boosting at 10lbs, if this car could push same in hot weather this would be awrsome

MadStang40

Well Kevin, I'd have to suspect so. Research 'work' in a thermodynamics book and you'll see that efficiency is directly related to system temperature and environment temperature. Or if you look at a heat transfer book, hot components in cooler atmospheres (relatively speaking) transfer heat to the surrounding environment (called a 'heat sink') a little quicker due to the increased temperature gradient of a hot car and a cold environment, compared to a hot car and 80 degree temps. Humidity also plays a huge role in this as humidity retards the rate of heat transfer between two bodies and thus negatively effects engine efficiency. Sorry for the lesson, I just loved thermodynamics class and am happy that I finally stumbled upon a real world application on accident haha.

As for the gasoline blend, however, I don't have a clue. That's chemical engineering and I'm for the most part in the dark there haha.

kevinmalec

Impressive. Thanks for the scientific educational point of view! ;-)

kevinmalec

Nice! Giddy up!

siggyfreud

Cooler air = Denser air! More air, more fuel to compensate, more power! It's the same reason why people run intercoolers or have ice packs sitting on their intake before 1/4 mile runs .

Lifter583

True...colder air contracts so there are more oxygen molecules per cubic foot of air...so the more O2... the more fuel can be added...

moosestang

Besides cooler air being denser, your ecm will pull some timing with a hotter air intake temp. Timing = power. I don't think colder air will affect the amount of fuel being delivered at WOT, you'll probably run a little leaner, but it will at part throttle, that's why you generally get worse mpg in the winter.