LBZ: Altitude

[LBZ]

Does anyone know what the specific number is for at what altitude medium starts? I'm looking at the main injection correction multypliers and saying WTF to myself alot right now.

 

[LBZ]

Nobody knows?

 

[JoshH]

Look at table B0202

 

[LBZ]

Thx Josh, but that's not what I am looking for.

I want to know what altitude medium starts and ends? B0202 only says sea, med and high. I want to see 0, 3000, 5000 or something.

 

[JoshH]

It's based off of barometric pressure not altitude. That table is the multipliers for what baro pressures change from high, med, and low altitude. That is the only info you will find, but it is what you're looking for. At 13.9 psi and above you are completely running on the low altitude tables. When it drops below that you are beginning to transition to med. altitude tables. At 12 psi you are completely on med. altitude tables, and when it drops below that you are starting to transition to high altitude tables. Once it reaches 8.5 psi and lower, you are fully on high altitude tables.

Here's a table that might help you relate it to altitude, but pressures aren't constant at a given altitude. They will change with weather. http://www.sablesys.com/baro-altitude.html

 

[LBZ]

Cool I understand it now Josh.

Thanks

 

[JoshH]

You're welcome

 

[LBZ]

It turns out that I run right between the medium and sea level pressures at 90 kpa on the average today. So now I know what the multyplier it's running off of. I wonder what happens if you just set all the multypliers to 1?

 

[JoshH]

You would need to set it so that when you add across (horizontally) the mulitplier adds up to 1. So, if you look at the 13.0 psi table, you would want 0 in the high and medium altitude column and 1 in the low (sea level) column.

The only problem you might have is with boost tables. If you set it so it is always running off the low altitude table, it will be trying to build more boost than you really want. Say you are at an altitude that has a barometric pressure of 11.5 psi. If you are running off the low altitude table, you will be trying to build 3 more psi than you really want.