Awhile back, I remember someone posting that their MCS seemed to be getting faster and more responsive as more and more miles racked up.

I vaguely remember something in the discussion about driving hard after the break-in period because the ECU would adapt to the driving style, as this was thought to be a possible explanation for the increased responsiveness of the engine.

After reading about the possibility of putting the intercooler in the deep freeze with some type of evaporative gas (nitrous, CO2) for increased horsepower, it jogged my memory of the above, and my thought was that the increase may not be from the ECU adapting, but mainly an increase in horsepower due to the colder temps of winter and the cold air going into the intercooler. Most people who would be in a position to notice any increase over time would have likely taken delivery of their MCS in the summer.

Thoughts?

Any ideas as to what horsepower difference one would see with 32 degrees F (0 C) as opposed to 80 degrees F (27 C)?

Also, would this have any bearing on current horsepower enhancing modification test results, or are those done in climate controlled areas?

See ya,
JS

 

Interesting question. Would love one of the Gurus to give a shot at this one.

 

By no means am I a guru, but I have actually heard a blurb on the radio somewhere a couple years ago that your suspicion is a reality. The cooler ambient air temperature does indeed help - just not sure how much. I'll leave that kind of answer up to the gurus.

 

Where's Randy when you need him.

 

The cooler air helps, since cold air is more dense than warm. Unfortunately current generation ECU's do not "learn" at Wide Open Throttle (WOT). ECU's change fuel trim in response to oxygen sensor readings at part throttle operation only. When you mash your foot to the floor, the ECU goes into "open loop" which ignores the O2 and derives fueling requirements from calculations extrapolated from various sensors and a lookup table. This is why your ECU must be re-programmed to take advantage of new modifications to get the most power from them. While this thought of "learning" is a common mis-conception, I usually sum it up by pointing out that if your ECU "learned" then we wouldn't be begging a vendor to come up with ECU upgrades taylored to specific bolt ons, preferably documented via wideband O2 readings and dyno results.

_________________

 

Now that's a full-on guru answer! Thanks!

 

>>Now that's a full-on guru answer! Thanks!

No Guru, but thanks anyway! I have much to learn...

 

The Cooper S seems especially sensitive to ambient temperature. Hot weather >90 degrees absolutely kills performance with my car. Cold weather does just the opposite.

Not only cold air but "thick" air is important too. I envy those who live at sea level because your MCS's are a bit quicker than mine.

This senario is common with all cars but more significant with the MCS due to it's greater reliance on air for power (supercharger). Also, the small cramped engine compartment with the intercooler sitting on top of all the heat doesn't help.

As the engine breaks in things do get smoother and power delivery seems better.

Probably a combo of some of the factors you mentioned with temperature being the greatest variable of the bunch. :smile:

 

Lets put it this way:

If your a manufacturer and you want to test an exhaust... do it at the Dead sea during the coldest blizzard of the year.

These are the results that are published

 

Daron,

Great answer! We are currently working on a "plug and play" ECU system. This would account for the mods you have done specifically.

The car does "get faster" with more miles. The fuel and timing curves do adapt on the newset ECUs, which is why people are talking about the driving style. You can look at them when you pull the data.

As for horsepower with more dense air, I know there is a formula - I'll hunt for it. There were two different ones based on whether it was a turbine or a recipricating engine.

As for dyno runs, when I have done testing on the dyno, you have a base run the same day, so the numbers are accurate. You can also correct for non-standard atmosphere, but that's not as accurate as just doing another base run.

Randy

 

Also, dry air is better than humid air.

 

>>Also, dry air is better than humid air.

Well, I might as well have a Cooper, since I live in the south where its 90 degrees from late May until September and about the same number in humidity level.

See ya,
JS

 

No you still need the S. I live in Fla and the S on its worst day will smoke a non S even if it was its best day. The $3000 is well worth it.

 

>>Also, dry air is better than humid air.

That may not be the best generalization to make. Dry air is better for the air going through the intake. In, lets say, a liter of humid, foggy, air some of that litre will be taken up by water. When you're trying to get air into your cylinders, this strikes me as a bad thing.

However, water has a much much higher specific heat than air, so cool, wet air flowing over your intercooler keeps your engine running nice and cool. The extreme example would be running a garden hose over your intercooler. That's pretty darn humid. It'd keep the engine niiice and cold. But you wouldn't want to feed that through your air intake. There's probably a forumula out there somewhere for the "optimal" humidity.

 

Personal Experience

In Atlanta when it's in the 30F the MCS is fast.

When I travel down to Tampa FL 85F I can definatley notice a decrease in the performance and a sluggishness that I don't feel in the cold.

 

I work at 5am and everyone knows it's coldest in the early morning. I can DEFINITELY tell a difference between 30* in the morning and 50*+ in the afternoon on my way home. There's a noticeable kick in the morning that isn't present in the afternoon. I'd say about a 5-10hp at the wheels between 30* and 50*.

And here's a great calculator for figuring out differences:

Realtive HP Calculator

According to this calculator, at the present barometric conditions here in Portland tonight, the difference between 45* and 90* is about 10% engine power. That's HUGE!

R