Air breather loves sea level

[llis]

For a holiday visit, my E92 M3 is loving the thick air of sea level! This is a different experience altogether. Throw in some 100 octane and wow!

Just wanted to share that, from someone normally a mile high (or higher).

[double eagle]

Yep, sure makes a difference. But it's still a quick car at 8500'.

[jmrinvt]

Originally Posted by llis

Throw in some 100 octane and wow!

I'm with you on the air... the octane not so much.

[dimabimmer]

I am at sea level and not looking forward driving up the mountans... I did it with my 335i and it was weak in higher altitude... turboes didn't help. I was always wondering how is it up in altitude for M3 NA Engine? Is the difference very noticable?

[skierman64]

Welcome to sea level and the designed horsepower.

Must be nice having 15-20% more horsepower than you're used to having.

[CSanto]

I find the motor responds very well to cooler temperatures as well. The M3 loves the fall air. Also, the AC easily sucks up 15% of the cars power.

I also feel a huge difference when driving alone, it's exhilarating, but with my 225lb brother in the car it feels bogged down.

[skierman64]

Originally Posted by HREM3

I find the motor responds very well to cooler temperatures as well. The M3 loves the fall air. Also, the AC easily sucks up 15% of the cars power.

I also feel a huge difference when driving alone, it's exhilarating, but with my 225lb brother in the car it feels bogged down.

I wish the AC didn't come on automatically when I hit the auto button. It should be a seperate thought to turn on the AC compressor IMHO. My AC is usually turned off anytime it's below 80 degrees.

I really doubt that the AC saps 60 hp. It would be a lot more noticable if it did. I'd bet the AC only uses 10-20 hp. I've heard many times that using the AC is actually more efficient than running with your windows down at highway speeds. This is due to the drag created with the windows down uses more hp than the AC does.

[KJM3]

Summer density altitude is pretty bad here, around 4000' or so. Been in the 40s and 50s the last few days and I've been enjoying it, only problem is the roads get cold so the DSC goes through a workout.

Most modern cars shut off the A/C compressor at high RPM or over 75% throttle so thats not an issue if you are on it hard.

[dnvrdrvr]

Did the same thing back in May... amazing isn't it?

[The Woo]

Haven't got my car yet (still on order since 10/17). But I live at the sea level (California, bay area). Perfect driving weather all year round. Never too hot or too cold. Can't wait...

[dexx]

doubt the 100 octane did anything... It would be nice to know for sure but those kind of hackers don't own BMW's.. I run 93 all year at sea level. I wouldn't have bought the car if I lived at altitude, too slow, needs turbo's..

[jmrinvt]

Originally Posted by dexx

doubt the 100 octane did anything... It would be nice to know for sure but those kind of hackers don't own BMW's.. I run 93 all year at sea level. I wouldn't have bought the car if I lived at altitude, too slow, needs turbo's..

Higher octane just means that you can compress the fuel more before it ignites. The engine ignites the fuel at a set point regardless how high a octane level you are using. The problem occurs if you use an octane rating that is too low for your compression ratio and the fuel ignites before it is supposed to... THIS IS BAD!

Higher octane does not equal more horsepower... yet higher horsepower often means higher octane.

[dexx]

Originally Posted by jmrinvt

Higher octane just means that you can compress the fuel more before it ignites. The engine ignites the fuel at a set point regardless how high a octane level you are using. The problem occurs if you use an octane rating that is too low for your compression ratio and the fuel ignites before it is supposed to... THIS IS BAD!

Higher octane does not equal more horsepower... yet higher horsepower often means higher octane.

Uhhhh yeah... notice I used the word hacker.

Someone would need to get a datalog from the ECU of dynamic timing advance, and further more understand how the dynamic timing maps work. If the ECU runs the same advance as with the lower octane, the additional octane is entirely wasted. I'm sure at 12:1 with MPFI it could allow closer to MBT timing, but its unlikely the factory maps/software will do it.

Translation in english: probably doesn't do shieeet.

[llis]

Originally Posted by dexx

doubt the 100 octane did anything... It would be nice to know for sure but those kind of hackers don't own BMW's.. I run 93 all year at sea level. I wouldn't have bought the car if I lived at altitude, too slow, needs turbo's..

I notice a difference.

But if a little altitude convinces you to skip the M3, that would be your loss. Had a 335 for 3 years. There is no comparison.

[saeedg48]

Haha sounds like fun

[mfeltiii]

Higher whp numbers using higher octane fuel are consistantly seen on the dyno database.

[jmrinvt]

Originally Posted by mfeltiii

Higher whp numbers using higher octane fuel are consistantly seen on the dyno database.

Rather than get into a big discussion on the chemistry of fuel, I will simply say, we will have to agree to disagree on higher octane producing more horsepower.

[llis]

Originally Posted by jmrinvt

Rather than get into a big discussion on the chemistry of fuel, I will simply say, we will have to agree to disagree on higher octane producing more horsepower.

Speaking only from feel, not math and hypotheticals about what BMW has tuned for, the biggest difference is in the lower RPMs. It's like there's more torque. The sound is different, too. Perhaps after a certain point, there are diminishing returns. But nobody is going to convince me that the M3 performs optimally on 91 octane.

[cmk227]

Originally Posted by The Woo

Haven't got my car yet (still on order since 10/17). But I live at the sea level (California, bay area). Perfect driving weather all year round. Never too hot or too cold. Can't wait...

I get mine back in about a week... You will love it...

[008]

Turbos work better in higher altitude.

Higher octane actually has less power per gallon than lower octane but it allows the computer to advance the timing further making the stroke cycle more efficient. Most modern performance car ECUs can advance timing some for octane higher than 93 so you will most likely see an increase of output using 100 octance but there are diminishing returns at some point. Is it 94 or 104? Testing or someone intimate with the coding is the only way to find out.

[mpardun]

not to steal any thunder from Frontier Airlines. But there is not much of a comparison between the two.

Having only had my e90 M3 for a day (still on the east coast)...can't wait to get it up at elevation to see for myself.

Originally Posted by llis

I notice a difference.

But if a little altitude convinces you to skip the M3, that would be your loss. Had a 335 for 3 years. There is no comparison.

[dexx]

Originally Posted by mfeltiii

Higher whp numbers using higher octane fuel are consistantly seen on the dyno database.

O RLY? http://www.m3post.com/forums/showthread.php?p=5539480

Note: I do not condone the anaylsis contained, but just the plot of the same car being dyno'd back to back with race fuel.

I repeat: doesn't doooo shieeeeeet. More advanced timing has to be run to use better fuel, unless someone can prove that it is - it isn't. Is there even an interface for datalogging in this car?

If the car is modded, that's a different story. ECU's probably pulling back timing in the normal case using feedback from the knock sensors, i.e. you've installed an exhaust system. But the car will knock all the time... You really do have to be a computer engineer, part scientist, and part hacker to properly modify these cars