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I will be making trips from my home which is neear sea level to areas that are 1200ft above sea level will I encounter any issues at all? I would think not just making sure and at what point would it be safe to, I.E. 4000ft?
 

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well are you using baro compesnation?

if you are not, you should ;)
 
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No...you shouldn't be using baro compensation, baro compensation is for specific types of mass air flow. You will be using Speed density, or MAP based load correction. THat is what MAP does...Manifold Absolute Pressure. If your tune is done correctly, the car will run perfectly at anything less than 18,000'!
 

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edit:

wait

on second thought... MAP doesn't measure MASS. It measure pressure and you CAN have the same pressure for different mass. no need for baro comp during boost. But when off boost when VE changes as the engine changes in altitude? I am almost certain that braro comp is infact needed (except on the AEM where the boost comp table is used).
 
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figgie said:
edit:

wait

on second thought... MAP doesn't measure MASS. It measure pressure and you CAN have the same pressure for different mass. no need for baro comp during boost. But when off boost when VE changes as the engine changes in altitude? I am almost certain that braro comp is infact needed (except on the AEM where the boost comp table is used).
It wouldn't matter if he was N/A...as long as he is running speed density...doesn't need baro comp...the map automatically does it.
 

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Everytime you boost the baro changes. That's why we have boostcomp, etc. No baro changes, Map is just that manifold pressure, that means it's your pressure and since your running positive pressure you don't need baro. :)
 

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mike91t said:
Everytime you boost the baro changes. That's why we have boostcomp. No baro changes, Map is just that manifold pressure, that means it's your pressure and since your running positive pressure you don't need baro. :)
:hug:
 

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Jason S. said:
It wouldn't matter if he was N/A...as long as he is running speed density...doesn't need baro comp...the map automatically does it.
What do you mean it doesn't matter?

As altitude increases the air pump has ZERO choice but to have it's VE change accrodingly. So please explain how it doesn't matter? when Bernoullis principle does apply to this air pump.

mike91t said:
Everytime you boost the baro changes. That's why we have boostcomp, etc. No baro changes, Map is just that manifold pressure, that means it's your pressure and since your running positive pressure you don't need baro
It might not matter for the AEM (and that is the key word) as it uses some algorithm to reach that but AEM is the only one to that but the fact is that engine VE does change with Barometric and theirfore altitude changes. Just like changing the stock DP for an aftermarrket catless DP. Pressure is the same but the VE changes and as such the FUELING requirement changes!

So I want an explanation based on your opinion and mathematics. Bernoullis principles do apply here. And so do other gas laws.
 
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figgie said:
What do you mean it doesn't matter?

As altitude increases the air pump has ZERO choice but to have it's VE change accrodingly. So please explain how it doesn't matter? when Bernoullis principle does apply to this air pump.



It might not matter for the AEM (and that is the key word) as it uses some algorithm to reach that but AEM is the only one to that but the fact is that engine VE does change with Barometric and theirfore altitude changes. Just like changing the stock DP for an aftermarrket catless DP. Pressure is the same but the VE changes and as such the FUELING requirement changes!

So I want an explanation based on your opinion and mathematics. Bernoullis principles do apply here. And so do other gas laws.
Your completely missing the point. MAP corrects for BARO....by default. If the outside air pressure changes, the MAP sensor automatically changes because it KNOWS MANIFOLD ABSOLUTE PRESSURE. When the throttle is fully opened on an N/A engine, the pressure in the manifold equalizes with outside pressure, then if the engines volume requirements exceed that of the flow capability of any restriction in the intake tract, then you would get a depression in MAP. Regardless of what baro pressure is, map is the ONLY thing that matters.
 

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Jason S. said:
Your completely missing the point. MAP corrects for BARO....by default. If the outside air pressure changes, the MAP sensor automatically changes because it KNOWS MANIFOLD ABSOLUTE PRESSURE. When the throttle is fully opened on an N/A engine, the pressure in the manifold equalizes with outside pressure, then if the engines volume requirements exceed that of the flow capability of any restriction in the intake tract, then you would get a depression in MAP. Regardless of what baro pressure is, map is the ONLY thing that matters.

no i am not. Pressure stays the same in either case BUT backpressure in the exhaust changes with baro. Essentially less bpsi. If that is the case then the VE of the engine must change and that is independant of the MAP psi as that can be the same at diff elevations.
 
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figgie said:
no i am not. Pressure stays the same in either case BUT backpressure in the exhaust changes with baro. Essentially less bpsi. If that is the case then the VE of the engine must change and that is independant of the MAP psi as that can be the same at diff elevations.
Exhaust backpressure from baro doesn't change enough to make ANY measureable difference in V.E. You might see a 3psi change (less b.p.) going from sea level to 7k feet. You can see more backpressure by retarding the ignition timing 5 degrees.

You DO NOT RUN BARO CORRECTION ON MAP BASED SYSTEMS.....PERIOD!
 

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Ok

was waiting for a reply from GEMs. You know they make the AEM EMS and got back the answer I was expecting

GEMS ECU UK said:
Thank you for your enquiry. We've always fitted baro compensation to our ECUs (many have an internal sensor). Although many people don't use the feature as they operate close to sea level all the time, anyone who does change alitiude regularly will find baro compensation very important.

Best regards,

GEMS
Straight from the horses mouth.
 
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figgie said:
Ok

was waiting for a reply from GEMs. You know they make the AEM EMS and got back the answer I was expecting



Straight from the horses mouth.
First of all Gems doesn't make the AEM EMS. The core software is liscensed from them. Second of all you clearly didn't tell them you were running a speed density system. 3rd of all, just becuase they make ecu's....does in NO WAY mean they know how to tune! Sooo....Figgie.....you go ahead and use baro correction, and when you blow up your engine at altitude, make sure and post your ignorance for all of us here to enjoy!:)
 

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Jason S. said:
First of all Gems doesn't make the AEM EMS. The core software is liscensed from them. Second of all you clearly didn't tell them you were running a speed density system. 3rd of all, just becuase they make ecu's....does in NO WAY mean they know how to tune! Sooo....Figgie.....you go ahead and use baro correction, and when you blow up your engine at altitude, make sure and post your ignorance for all of us here to enjoy!:)

actually I did ask them about MAP based system as their ecus don't have MAF or AFM input. BUT I do really appreciate the guess none the less.

As for Core software....

you might want to send them an email

http://www.gems.co.uk/ems/standard_aem15.html

GEMs co UK said:
GEMS has developed a powerful ECU with AEM Power Inc.
How intresting. Developed a powerful ECU NOT Developed the software that runs the ecu.... how intresting indeed.

wow GEMS must be ignorant than I initially thought to post such a fallacy!
 
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figgie said:
actually I did ask them about MAP based system as their ecus don't have MAF or AFM input. BUT I do really appreciate the guess none the less.


<-- will continue to use Baro comp on MAP based system. Unlike most lemmings/sheeple. I HAVE done my research ;)

/case is closed
Very good! Make sure and post when you blow it up.... Or you might want to actually ask someone who knows....say in COLORADO! Where they are constantly driving from 2k feet to 8k feet.

Either way...post when you blow it up.
 

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Jason S. said:
Very good! Make sure and post when you blow it up.... Or you might want to actually ask someone who knows....say in COLORADO! Where they are constantly driving from 2k feet to 8k feet.

Either way...post when you blow it up.

I have.

no issues with popping motor.

as a matter of fact.

5000 ft alt at 850 mb - 860 mb. and goes to sea level constantly (Colorado is not the only place at 5000 ft above sea level). And runs rich at sea level. But you already knew that.
 
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figgie said:
I have.

no issues with popping motor.

as a matter of fact.

5000 ft alt at 850 mb - 860 mb. and goes to sea level constantly (Colorado is not the only place at 5000 ft above sea level). And runs rich at sea level. But you already knew that.
That's becuase you have baro turned on....If your 'Theory' was correct....it would run leaner...not richer.... More air pressure at sea level, requires MORE FUEL.... less air pressure requires LESS fuel.... Thank you for proving my point, albeit through ignorance.
 

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Jason S. said:
That's becuase you have baro turned on....If your 'Theory' was correct....it would run leaner...not richer.... More air pressure at sea level, requires MORE FUEL.... less air pressure requires LESS fuel.... Thank you for proving my point, albeit through ignorance.
actually nope, baro comp was never on ;)

but nice ASSUMPTION. thankfully ASSUMING makes and ass out of you and ONLY you as it does not effect me and way, shape or form.!!

Though I appreciate the straw grabs at you futile attempt to discredit what I have said but failed miserably at it.
 

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PS. here is a clue

between sea level and 5000 feet there is roughly 16 kpa difference. Unlike your "theory", that is a significant amount of back pressure, enough to change VE.
 
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