according to http://www.convert-me.com/en/convert/pressure
1 Atmosphere = 14.69595 PSI
being that the unit of Atmosphere is based on STP (standard temp and pressure)
that would mean that sealevel is about 14psi
I'm not sure of the air pressure at 6000' but lets say its 9psi

so in an 11:1 engine at sea level at TDC the air is at a pressure of 161.65545psi
then at 6000' it would be 99psi
so to bring the car to be even with sea level via a supercharger you should need about 5psi of boost and need to acount for the fact that as the air is less dense that the same pully size would make less boost than at sea level

now a super charged car at say 11psi with 11:1 (ya a bit crazy) would have pressure of 282.65545psi at sea level

at 6000' (assuming its 9psi) you'd have 220psi tdc

 

Can you substantiate that please? I've never heard of that until now and certainly never read it in any manufacturer's documentation or brochures.

 

Derf00 is making it up. my 2007 GT was made for CA (windowsticker) order was cancelled then shipped to MT, no change in the PCM or tuning on it. modern fuel injection doesn't require any changes in tuning. old carberuated engines did need to be tuned for the elevation though. many cars driving from Phoenix to flagstaff used to die once they got up in the mountains back in the day.

 

I was just making up numbers but if you want to get techincal your math and how you look at it is completely wrong look here: https://mustangforums.com/forum/stre...lping-you.html


The true correction for FI depends on how much boost you are making. The 1/2 correction factor is accurate if you are making 14.7psi of boost, below that and you should get more correction and above you get less.

I'll use a NA car, one making 14.7psi boost and my Buick as an example making 21psi of boost.

Say that we have a day with a DA of 6000' (pretty common on a summer day in Acton). That equates to 11.78psi of air pressure. Percent loss is going to be absolute pressure up here divided by absolute pressure at sealevel

14.7psi / 14.7psi = 1 (sealevel has no power loss so no correction)
11.78psi / 14.7psi = 80.1% NA (19.9% less power for the NA car))
(11.78psi + 14.7psi) / (14.7psi + 14.7psi) = 90.07% (9.93% less power or 50% correction for 14.7psi boost)
(11.78psi + 21psi) / (14.7psi + 21psi) = 91.82% (8.18% less power or 41% correction for 21psi)

What about a 40psi dsm...
(11.78psi + 40psi) / (14.7psi + 40psi) = 94.66% (5.34% less power or 27% correction for 40psi)

How about a low boost supercharger, my GTO had 5.5psi
(11.78psi + 5.5psi) / (14.7psi + 5.5psi) = 85.55% (14.45% less power or 73% correction for 5.5psi)

and people are running 15psi on the stock 11:1 coyote engine, so not too crazy.

 

Makes sense to me. We had a 3 car caravan. I was leading, followed by my friend's Nissan Juke Turbo, and another friend's 4 cyl Equinox trailing.

The Juke held up pretty well. My friend hardly noticed any power dropoff. The guy with the Equinox told me his little 4 cyl was having a hard time passing cars up the mountain.

 

We ended up renting a cabin on the Heavenly side past Al Tahoe Blvd off of Pioneer Tr. We spent most of our time at Fallen Leaf Lake and Pope Beach.

Zephyr Cove = very nice. It was our first choice, but we booked late and there were little options there by then.

 

I drove my 4.6 3v car at over 10,000 feet here in MT. Beartooth/Cook City pass. The car was an absolute DOG at low rpms. That was with a brenspeed tune on there.

Altitude sucks.