so my brother is going to have his 2002 camaro Z/28 with a huron speed on 3 performance 78/75mm turbo with no a/c delete kit..his running a 3 bar map sensor and been tuning with hp tuners, now in colorado the air is thinner due to the elevation and his buddy said that he adjust for the kpa so his boost gauge says is he running 11 psi but with adjustments he is running 9 psi of boost..

so like brother's do i went with a ECS kit got my car tuned professionally made 562 rwhp and 519 rwtq at 9 psi of boost...but one thing i am confused on is with the air adjustments like brother say's is, does that mean i am only running 7 psi of boost then???

he says with his turbo kit he will be making 630rwhp and tq is unknow...

and he says that he will smoke my vette, i am just curious as to what everything things would happen if we were to go the the local 1/4 mile track and let open them up???

 

The air density should not change boost pressure, the turbo will have to work harder to achieve the same boost pressure. So the car may not make as much power on 11 psi at high altitude than it would on the same boost at a lower altitude. That is the way I understand it, someone correct me if I'm wrong!
However if he really is only running 9# I find it hard to believe he's making 630 to the wheels, that seems awful high to me.

 

correct - boost is a representation of pressure ratios. air at sea level is denser than air in the mountains, so dense air at a specific pressure will move more molecules through the engine than thin air at that same pressure. a turbo should build to the same boost because it's controlled by a valve that operates at a set pressure.

a supercharger, however, moves at a specific speed in relation to the crank, so it will spin at a set rate and only move as much air as it can take in. thinner intake air will result in less pressure being built inside.
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the best example i can think of is like taking an empty bag, some mulch, & some sand. the bag is your engine, the mulch is mountain air, and the sand is sea-level air. boost will be represented by weight.

with a turbo, you say "i need 10lb in my bag". at sea level, you get to use sand and quickly reach your goal. in the mountains, you can only use mulch & burn more energy with the extra scooping it takes to get 10lb worth in the bag. you still moved the same weight, but you're more tired from the extra work it took to get there.

now with a supercharger, you take the bag and say "i'll put 10 scoops of whatever into it." with sand, you end up putting 10lb in the bag, but when you scoop the mulch, you only end up with 7lb.