I moved to a place that is in the low 4000ft level and of course I am feeling the power drain that is associated with it. I went down south last weekend and in the California valley, this thing opened up and was just the nasty little beast. When I came back, it ran the same as before I left.

Now the question is, is there a way to tune the cars for high altitude operation like other cars can be? If so how? Will an aftermarket chip help?


please help... I want my power back!!! or at least some of it...

Good question. My guess is that there's not much to be done.

Mine was fine at 4k, but entering Yosemite at 10k was the only time since buying this car that I floored the gas and it still slowed down. I had to keep it in mid-high 3rd, 2nd on hills. Then I got to Modesto or so and it had more power than ever before :confused.

There is not much that you can do other than forced induction. The problem is air density and every 1000ft rise in altitude is a 3% loss of horsepower.

Formula:

hp loss = elevation x 0.03 x hp

Agreed, forced induction would be a sure (but expensive) solution. An aftermarket performance chip will help if you're still running the stock chip. I live at 5500 ft & have never had a chance to see what mine can really do. It would be a treat to take it down to sea level & light it up. I put a chip in my wife's m50 e36 & it made a pleasant difference, but it's still slack in the bottom end, either due to altitude or the nature of the m50 motor, but it pulls strong once I get it into the upper revs.

Well, a chip will adjust the fuel map, which "unbuckles" some hp, but you cant do anything without more oxygen. You think the M50 is anemic on the low revs, the S38 is a dog and at a similar altitude as you, a chip doesnt help much.

The nice part of operating at a higher altitude is using a lower octane fuel has no adverse effect upon the engine.

see Fuel Injected cars already compensate for all the factors....unlike a carb'd car, which has to be tuned for the weather/altitude factors.

basically, try to get cold air as its more dense, to you having colder air entering the car is of a lot more importance than to ppl at sea level

Is there a reason that going from 10k to more or less sea level, in ~3 hours, would make the car more powerful for an hour or so?

Adjusting of trims? Don't know how applicable it is to the bosche DME,but in most cars short term fuel trims can cause temporary gains or losses in power

I love going home to MS, sea level, nice humidity, moderate temps, and 93 octane... the m50 performs far better there than up here.

I just wonder if there's a way to have that gain be on full-time. Isn't that what chips are supposed to do?

nope. chips are supposed to modify the base maps to more aggressive settings.

I'm betting you were just a hair leaner than normal after descending from altitude.

Surely there's a way to tune something to extract that extra power all the time, not just when having descended from altitude.

dood, the reason u're getting extra power at lower altitute is that there are more oxygen molecules per cubic foot than before, more oxygen equals computer adding more fuel = more power.

basically, all a chip does is alter the fuel maps slightly and advance your timing. the timing is where all that increased power usually comes from...

lean = power. fat = no power... unless you are using the fuel to cool the charge and stave off detonation. Usually not the case in N/a engines.

Up until detonation begins, the leaner you can get the more power. 12.2:1 will make more power than 11.9:1. on most ECU the short term trims are usually a 10% range. I'm sure the chip tuners can tell us what range they are... (how I wish someone would finally hack the ECU and make it like DSMlink... a standalone tuning solution on a plug in chip inside the factory ecu)

I agree with you that most of the chip gains are probably from a global timing bump with a midrange cell lean down.

If it were merely more o2 molecules per cylinder event = more fuel molecules he wouldn't have lost the gain after an hour or so.

BTW This is why guys with 850 cfm carbs on their 350s are nutty. more fuel doesn't = more power

dood, the reason u're getting extra power at lower altitute is that there are more oxygen molecules per cubic foot than before, more oxygen equals computer adding more fuel = more power.

I know that. The question is why it was more powerful after being at high altitudes, than it was before it got to them in the first place.

The following figures are made up but indicative (all with an EAT chip, and at least 300 miles of settling in):
SE Florida prior to 26.8.2007 - 220bhp
Yosemite east entrance, 26.8.2007 - 12bhp (felt like it, anyway...)
Shortly after leaving Yosemite, heading west - 220bhp
From Stockton/Modesto to SF, 26.8.2007 - 240bhp
The 3-5 times I've driven in SF since then - 220bhp.

It was shoving me into the seat quite nicely even in 4th, and 2nd made my neck sore after a while, if I didn't use the headrest.

And the sound...:drool: