Outside temperature and performance.

[monmart]

Coming from an E39 and now owning my F10 for about a week now (lovin' it)... I remember the E39 had a dramatic performance decreasing when outside temperatures go past 90º+. There was a difference in power when running on cooler days or late evening after the sun goes down.

Have you guys noticed the same with the F10?

Just recently we've been seeing near 95º days down here in Southern Florida and I took my F10 out and could feel it wasn't pulling as hard (was expected)

So my question is, do these cars thrive on cooler air? And is there anything we can do to provide a cooler intake to the engine to assist for warmer climates? Maybe a mod perhaps.

[94jedi]

Originally Posted by monmart

Coming from an E39 and now owning my F10 for about a week now (lovin' it)... I remember the E39 had a dramatic performance decreasing when outside temperatures go past 90º+. There was a difference in power when running on cooler days or late evening after the sun goes down.

Have you guys noticed the same with the F10?

Just recently we've been seeing near 95º days down here in Southern Florida and I took my F10 out and could feel it wasn't pulling as hard (was expected)

So my question is, do these cars thrive on cooler air? And is there anything we can do to provide a cooler intake to the engine to assist for warmer climates? Maybe a mod perhaps.

Naturally aspirated cars are less affected by ambient temps but still affected. Forced induction cars like ours are even more so affected. What happens is that if the IAT's get too hot (repeated runs or a hot day), the ecu pulls timing causing the car to lose power. I'm assuming most folks here go the meth route to cooler intake temps, i.e. less timing pull. Nitrous (n2o) is another option but you don't see that much in Forced Induct. applications. Obviously external charge coolers (intercoolers) etc. help, but at some point most of them heat soak as well.

[Craze]

Big difference on nights with cool air! Feels 50-100hp more!

[induc916]

Add meth.

[monmart]

Originally Posted by induc916

Add meth.

Ok, can you explain a bit what you mean by "meth". I'm still kinda new here. You mean put methanol in the tank or something?

[monmart]

Originally Posted by Craze

Big difference on nights with cool air! Feels 50-100hp more!

Yes same here. Definitely a 100hp jump.

[94jedi]

Originally Posted by monmart

Ok, can you explain a bit what you mean by "meth". I'm still kinda new here. You mean put methanol in the tank or something?

[QUOTE=monmart;24945500]

Originally Posted by induc916

Add meth.

Yes methanol injection system.

[RPiM5]

Yes. Density Altitude or rather the pressure altitude corrected for non-standard temperature, affects all engines from piston engines to jet engines. Although turboprop engines are the least affected by DA, in terms of power performance at lower altitudes anyway. The piston engines in our cars are especially bad the higher your IAT's (Intake Air Temperatures) are. Cold outside air temps are great for engines because cold air is packed with lots of O2 molecules and the more molecules you can pack into a cylinder the more combustion you can get with a set amount of fuel delivery.

Engineers in WWII were the ones to pioneer solutions to get piston engines to produce more power. It wasn't so much of a problem for WWII fighter planes to produce power due to high outside air temps, but the main problem back in those days was how to produce more power when flying at high altitudes because like hot air, when you fly at high altitudes the air is more more thin and there are not as many air molecules above 20,000ft. So engineers designed turbochargers and superchargers as a way to pack more air molecules into aircraft piston engines at higher altitudes in order to get more performance.

The Germans in WWII took things a step further and invented something new called Water/Methanol Injection. They figured out that if you introduced water or methanol(which has better cooling properties than water) into the intake of a piston engine, it would supercool the air going into the cylinder intake. Cooling that air makes that air more dense and thus more molecules to burn and thus more power for a given altitude or Outside Air Temperature (OAT).

In terms of performance for our cars, turbo cars will always perform more efficiently for all DA's and OAT's than Naturally Aspirated Engines, because that's what turbochargers were designed for. However, turbo engines will also suffer from more heat soak than NA engines because turbos get very hot and that hot air usually makes it way back into engine in some way and may affect engine performance too. Our engines built today aren't really built to maximize thermal efficiency.

For our S63tu turbo engines, the general rule of thumb is that for every 10 degrees F change in your IAT, your power will be affected by 25-30hp.

In the Winter in San Diego, I experienced IAT's as low as 60 degrees F and so it produced power at a certain level at those temps. In Southern Florida in the Summer, you will be at around 130 degrees IAT, and using 30hp as a reference and with 130 minus 60 degrees equals an IAT difference of 70 degrees. That means an M5 with an IAT of 130 degrees will make about 210 horsepower less than an M5 with 60 degree IAT's. Add Water/Meth Injection to this formula and using a 50/50 mix, I can usually reduce my IAT's by 10 or 20 degrees, which equates to about 30-60hp increase in performance.

Also consider the ECU programming by BMW M. I always laugh at people who dyno a newly released BMW and "discover" that their new M8 Competition is making 100hp than what is rated by the factory. One factor is that their dyno is not accurate, but that's a rabbit hole I don't want to go down, but the other factor is the DA on the day that they dyno their new M8 Competition. Again, you could dyno that same M8 Competition in the Winter in San Diego and again in Miami, FL in the middle of July, and get two vastly different dyno readings. Also, BMW usually claims that the 617hp that an M8 Competition would make is the minimum power it would make in any Density Altitude, even in Denver Colorado on a hot day. So the power it would make would actually be a bit more in much better conditions such as in San Diego at Sea Level on a cool day. Also consider this food for thought, why don't we ever see videos of IND taking their cars down to Miami for a dyno session in July whenever they get their hands on a new BMW M car?? Lol! Get it?

So to answer your question, yes your M5 is making less power in SoFlo in the summer. But also remember, that even though your M5 is quite a bit down on power, so is every body else's car. Your still gonna be making more power than that Lamborghini Huracan next to you at the stop light in those sweltering hot conditions in Florida especially as his engine is NA.

Hopes this helps. I was also bored, but feel free to ask any questions. Lol!

[RHM5Y]

Thanks for an explanitation that i was able to follow and understand. Always thought the E39 M5 felt greater in the cool air, now i understand why.

[BeachM5nster]

the m5 loves 55°F weather

[94jedi]

Originally Posted by BeachM5nster

the m5 loves 55°F weather

True but tires don't lol. It's a trade off; a delicate balance between power and traction.

[BeachM5nster]

Originally Posted by 94jedi

True but tires don't lol. It's a trade off; a delicate balance between power and traction.

nah. they can still get warm at 55°.. i was mostly just running with the 5 theme.. but i think sunny and 55°F is perfect hauling ass weather. we do have good asphalt here though