Morbid Intentions

so fellow S/S'er... I was bored tonight and figured some equations and broke down just exactly how to figure out how much more an N/A car suffers @ elevation as opposed to a FI car of the same caliber

alright, this is what I have concluded... if you guys find a flaw in my math, please, say something and correct it, like I said, I was bored and this is a one night sitting deal with windows notepad lol

turbocharged/supercharged elevation equation... simple steps

#1

figure out your TOTAL PSI @ sea level
(atmospheric pressure + boost pressure = TOTAL PSI)


#2

Figure out your CORRECTED PSI for your elevation and add it to your boost pressure

(2,000ft = -1.1PSI)


#3

Divide TOTAL sea level PSI into CORRECTED PSI

#4

your final product will be a percentage... you need to minus this percentage from 100% and this is your total percentage of BHP lost at given elevation through a forced induction application


#5
now that you have your percentage of power lost through your turbocharged application you need to find out what a N/A car would lose at the same BHP

so take your total PSI @ elevation and divide it into atmospheric pressure (considering there is no boost pressure)

#6
this percentage again, you need to minus from 100% and this is your total percentage of BHP lost at given elevation through a N/A application


now that you have percentages lost from both N/A and F/I application... now you have to figure out the difference in your given BHP between the two

this is how much of a help your forced induction is helping you at your elevation compared to other N/A cars

#7
TEST CAR

bone stock 2003 SVT cobra @ 6,000ft

stock PSI = 8PSI

#8
BREAKDOWN

14.7PSI + 8PSI = 22.7PSI

21.7 TOTAL PSI @ sea level for terminator

now factor in elevation

so...

14.7PSI - 3.3PSI = 11.4PSI

@ 6,000ft atmospheric pressure is 11.4PSI


now that we have corrected atmospheric pressure.... let's do the math

a terminator loses 14% of it's power @ 6,000ft... 15% of it's power is 59BHP, making a terminator into a 331BHP car @ 6,000ft


now let's equate for a naturally aspirated car for comparison to see just how much it's supercharger is helping it at elevation

math time...


seeing as a naturally aspirated engine with the same power output makes 304BHP and the terminator actually makes 331BHP @ 6,000ft we can conclude that 8PSI of boost pressure is helping the terminator make 27BHP @ 6,000ft... a small margin... but as boost pressure and elevation increases, so does this figure

ZeroIngold

So the only real advantage for FI is when above sea level what about below sea level?

Morbid Intentions

83gtragtop

Oh man.

Stone629

Hehehe.... whats this world coming too, lol.

mac10chap

ZeroInGold scores again!!!

However, one advantage to below sea level....no need for an air to water intercooler

On a different note, interesting break down you have there morbid.

drhoward

Real men who live in high elevations use nitrous!









(Then blow their head gaskets out)



But seriously, my car picked up 110 rwhp before the head gasket blew out, that was with a basline tune before he had a chance to screw with it

Stkjock

Nice write up Brian.....

Howard well with NO2 you have air in a bottle... not quite the same

Mishri

turbo or nitrous seems to be the best way to go at high elevation... I'm still not bored enough to make the chart I was talking about making with different elevations/boost levels and losses for each.. sorry guys hehe I can give you people that find that sort of stuff fun the formula/math to do it though

this site has some info on air density: http://www.2-stroke-porting.com/altiden.htm

TRBOPWR

Not to nit-pick or anything, but 14.7 - 3.3 = 11.4, not 11.7.