Glad you were able to get it installed and hope you are enjoying the extra power along with it! I guess I am glad the install for the new JB4's are a bit easier then. I still have to remove mine on a regular basis for dealer visits

Moving to the Fort Collins/Evans/Greeley area in a few days for work. If anyone is local then just shoot me a text @ 318 497 3250.

I'll just throw myself in this here thread for now. Always up for a beer in the springs area!

Doing Bandimere this coming Saturday. First tuner weekend of the year. Be nice to have another 35 there.

Unfortunately I cannot make it this weekend, but I am going to try the weekend after. Post up your results!

i am in denver as well I love the n54:)

New member in Denver looking for thoughts on upgrades that are seamless with high altitude. Thoughts? I posted a thread earlier asking the same.

Hi from an ex-Castle Rock resident.

DCI's will give your struggling turbos a little breathing room. The JB4 works swimingly for me

Thanks! I figured the DCI's would be good...if for nothing else than freer flowing air would allow the turbos to work less hard. What have been your experiences with the JB4? Is that your only mod? What map have you found to be the smoothest?

I have dci's and JB4. Map 5 works but I think I get more boost from map 1. It is a dream to use.

I will be doing meth injection when I get back from deployment and from what I have researched the WW kit will vaporize int he lines at our altitude. Trunk mount kit is necessary for it.

Thanks! Good luck with the meth upgrade. And since it sounds like you're in the military...thanks for what you do for all of us!

I haven't noticed having to do anything different with any of my tunes so far. The WW kit seems like it may take some extra consideration as mentioned. My car has the JB4, BMW performance exhaust, AR ********* DP, ER charge pipe, and AFE intake. I have not noticed any rough running issues even for longer distances. I run map 1 & 2 regularly and have tried 5(dynamic). I used 3 after buying some race gas and again had no issues. The temps do go up slightly with more boost. The car may breath easier with the new intake however I never noticed any issues with my old stock box with a K&N either. Honestly I think it just sounds better. Hope this helps

I realize this thread is quite old - just wanted to say hello as a fellow Coloradan!

Does anyone have dyno's from sea level vs. up in Colorado at high altitude? I've been interested to see the kind of power loss an n54 has compared to a typical N/A engine.

My guess is at a Mile High (I'm in Boulder, CO) our n54's will see ~10% power loss compared to almost 20% for a N/A engine.

Standard Air Pressure (sea level): 14.7 PSI @ 59 degrees F, In Hg 29.9
Air Pressure @ 5500 ft: 12.01 PSI @ 40 degrees F, In Hg 24.9

What would the PSI be at 5500 ft @ 59 degrees F? I'm trying to figure out how much temperature affects air pressure vs. how much altitude affects air pressure.

Anyways, lets assume our stock turbo's are running @ 8 PSI of boost.
Sea level: 14.7 PSI + 8 PSI = 22.7 PSI
5500 ft: 12 PSI + 8 PSI = 20 PSI
2.7 / 22.7 = 11.89% loss of power @ 5500 ft and 19 degrees cooler

Now, lets assume we're running 17 PSI w/ a tune:
14.7 PSI + 17 PSI = 31.7 PSI
12.0 PSI + 17 PSI = 29.0 PSI
2.7 / 31.7 = 8.52% power loss @ 5500 ft and 19 degrees cooler
**Notice the more boost (PSI) you run at high altitude the lower percentage power loss you see! N/A engines are simply doomed at high altitude.

And finally a N/A car:
Sea level: 14.7 PSI
5500 ft: 12.0 PSI
2.7 / 14.7 = 18.36% power loss

Now what would happen if I ran my car on a day where its 10 degrees F? As cold air is denser air pressure would go up a few ticks - maybe in the range of 12.2 to 12.4 @ 5500ft? Does anyone know the exact equation to figure this out?

I'll be at sea level with my 335i the rest of summer, so I'm hoping to get a baseline dyno here in Houston w/ hot temperatures & high humidity then dyno again in Boulder on a nice cool day for a comparison.

Zach,

One thing that is a benefit of having a turbo at high altitude is that there is less loss of power. The computer can compensate and allow the turbo to boost higher. So at sea level their's 8 psi boost. But at altitude there's about 10 psi boost. So you're generally running the same power in a completely stick vehicle.

Hate to state the obvious but if you're looking for pressure density equations, I'm sure you can google them and find the exact equation that will factor altitude, temp, and humidity. Humidity is a detractor from performance as well as temp and altitude, so in CO, that's one thing we have working for us.

I'd say up here one of the bigger considerations is the intercooler. You need a highly efficient intercooler to run higher boost up here. Since the IC struggles because their is less air to run over the cooling fins. The higher the boost, the more apparent the heat soak will be, especially with initial torque when no air is passing through the IC.

Anyway, that's something I've learned and while upgrading is fun, the variables are far more than you expect. Be careful not to overboost up here. The heat soak is more apparent, the gas can't keep up because our octane is lower, and if you go for a drive in the mountains you go from 5500 to 10000 feet or higher very quickly. If your cooling system and fuel can't support it, you're going to create a problem.

Hope some of that info helps!

Zach,

Hi, I live in Boulder too although I'm in China at the moment and not checking in very often. I don't have time to completely think through your equations, but it looks like you are thinking correctly in the case of an old school wastegate controller that always runs the same relative boost level if the turbos can generate it.

However, as the next poster talked a bit about, our boost isn't constant. Our ECU is actually trying to hit a load target, which means more boost will be run at our elevation to hit that load if possible. Other than being laggier, in theory we should run close to the same power level here as at sea level when running near stock power levels.

And yes, up here an intercooler is an even bigger deal than it is at sea level. The turbos are making more heat and the specific heat capacity of the cooling air is lower.

Im in CO!!!!!

just sold my evo x for a 335i!

I wish that were true and the reasoning is spot on. The thing is there is definitely some degree of power loss - at least 10% on a stock 335i and ~5% on a FBO 335i.

Stock 1/4 mile times at sea level are in the 13.4-13.6 range. 1/4 mile times at 6000 ft altitude are closer to 13.9-14.1.
Though the increased lag would lead to slightly slower times there must be some degree of power loss as laggier turbo's alone won't add .5 seconds to the 1/4 mile. Actually, after installing my JB4 I noticed a reduction in turbo lag despite running higher boost. So I doubt running ~2.5PSI higher boost will reduce 1/4 miles by .5s from just turbo lag.

If anyone can find some 1/4 mile slips of a bone stock 335i running low to mid 13's at 5000+ ft altitude I will be convinced. Until then I plan on dyno'ing here and then again when I arrive in Boulder, CO which is ~5400 ft elevation.

Carl isn't just saying its the increased lag, his last sentence mentions the increased heat (and decrease ability of the dry air to be cooled) due to the turbos running at the edge of their efficiency curve at high altitudes. Higher boost pressures also lead to decreased volumetric efficiency due to increased backpressure from the turbos spinning faster...so it's not just additional boost, but the engine management trying to hit a load target that is more difficult to achieve due to a number of factors that lead to the lower power.

BMW could design the turbo with enough headroom so that the power here would be identical to the power at sea level, but this would be an inefficient design for the majority of users who are mostly below 1000'...keeping the wastegates open more, increased lag at sea level, etc. that it just wouldn't make sense to do. So they designed a turbo system with enough headroom that it isn't completely down on power at altitude compared to an NA car.

Oh **** there are some Bimmer folks in Colorado. Colorado Springs here!

Here in the Parker area myself.

What are you guys dynoing at with tunes?