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Adjusting for altitude?

Old Mar 13, 2019, 08:06 PM
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Adjusting for altitude?

I have plans to buy an Evo VIII. It is pretty heavily but tastefully modified. Currently tuned on e85 for 6500 foot altitude. I have a long drive if I'm bringing it back personally and where I live, the altitude is 315 feet.

Are there any suggested precautions?
Am I better to pay the $800 to transport?

Should I stay out of boost and watch my afr so that it doesnt get to lean?

I've never owned an Evo. I do currently own a modified SRT4 and have had experience with forced induction vehicles for a few years now.

Thanks for any inpuy
Old Mar 14, 2019, 05:29 PM
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is it a maf car or speed density.?
Old Mar 14, 2019, 05:57 PM
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If SD, you can try it. It should cruise okay. Not the end of the world. May be a bit lean when you come down. Closed-loop cruising shouldn't be much of a problem. I used to drive my Hondas up and down mountain roads all the time.
If MAF, then it's all good to go.
Old Mar 14, 2019, 06:46 PM
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Depending on how the boost control was tuned you may experience overboosting at low altitude as air is denser at lower altitudes. Fueling should adjust perfectly fine, your trims will take care of that(unless it's tuned open loop fueling).
Just don't give it full beans until you know how the car will behave. It won't be the end of the world, though - you should have an overboost cutoff set.
Old Mar 14, 2019, 08:13 PM
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Depends on the tune/set up.

best thing to do IMO is start data logging at the new lower elevation. First check/log low rpm/load ranges ONLY working your way up the RPM range/into boost as you confirm the engine is still running exactly as it should be/was before at the old elevation. (you would need to send your logs to your tuner to double check this for you unless your familiar with reviewing and comparing log files.)
Old Mar 14, 2019, 08:49 PM
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Note: I was assuming you were going to pretty much keep it in vacuum. If SD, I wouldn't boost it. Actually...I wouldn't until you have the tune checked anyway. Who knows what's going on in that ECU.

Again, assuming you knew to keep the car in vacuum (which I'm sure you do).

Last edited by kaj; Mar 14, 2019 at 09:01 PM.
Old Mar 14, 2019, 10:45 PM
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Its tuned on speed density. I'm not very knowledgeable in data logs. I wont be driving it in boost(hopefully) until I get it retuned back home. If I do indeed take the plunge, I have the contact information on the shop that built/tuned it. I'll most likely sit down with them for a couple hours going over details.

Biggest problem at this point will be getting a retune to 93 from e85 since there isn't many e85 sites along the drive back. Otherwise I could just have it transported. The $800 to transport seems more appealing at the moment.

Thank you for the input.
Old Mar 14, 2019, 10:56 PM
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It would definitely be easier. Jay @ BoostedTuning or Gary @ BsinsTuned can get you a base map to get home, though. Much cheaper than $800


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