So I just installed my scan gauge and took my car for a test drive. It pretty cool to be able to

see all the info like the temp after the intercooler and the supercharger inlet pressure (not

sure what it is telling me yet ) But I noticed the most boost it ever shows me getting is

about 7.5 PSI?!?!?!? And that’s only after I get into third around 4500 RPM. Other wise

its 6.5 PSI. The stock gauge showed a good 10 maybe 10.5 if it was cold out. For those of you

that have them have you noticed a difference in the PSI the stock gauge used to show you

compared to the Interceptor? I know I'm at 7000 feet but should I lose 5 PSI?? Losing just 2

seemed reasonable but 5? Seems like too much. Maybe it’s a good thing, once o take it down

to sea level it will be crazy fast . I lose about 21% of HP at 7000 Feet

 

you shouldn't loose any HP with your elevation. with a naturally aspirated car yes. but not forced induction. with a forced induction car. if your running 12 PSI then your running 12 times the outside air pressure. i think it's out side air pressure. hell i can't remember the name. but it runs 12 lbs over out side. so whether you are up at 20,000 FT or at sea level it makes no different on a forced induction car. you should always have the same HP rating and same level of boost.

 

True but unless you can make up for the lower PSI then you loose power. 12 PSI is not 12 times the

outside pressure its 12 pounds per square inch. If my car could make 12 PSI then i wouldn't loose

power. But it only makes 6.5 PSI. My air pressure here is much lower than sea level so i would have to

have a smaller pully are larger blower to make up for that loss.

 

at sea level the outside pressure is about 14.69 on a good day. At 7000 feet it is about 11.5 So even if i

make 12 PSI here there will still be a loss of power. I would have to make 15 PSI at this altitude to be

as fast as a stock one at sea level making 12 PSI. Right?? I think thats correct if anyone knows better

please inform me.

 

I cant scientifically explain it to you , but I guess it would compare to different air qualities , like where Im at . Their is a big difference in how my car acts and maximum boost acheived at various air quality levels . The difference between a humid 90* day and a cooler day with lower humidity is about 2 psi . Supercharged cars are suseptable as well to air quality . The worst air quality I have ever seen here at the track , when you do all the calculation ... worked out to the air being the equivelent of 2200 ft above sea level . That day my buddies 96 Supercharged Z28 would only make a max of 4 psi , it sees 6 usually . I could only imagine what elevation of 7000 ft would do , yikes !

 

this is incorrect. it does not affect turbo motors because turbos dump the extra psi out the wastegate. so altitude does not effect them until much later because untill your using all your psi and not dumping any out the wastegate your getting all the air you need. supercharging is diff. more like NA. yes you get a psi loss and a powerloss at altitude.

and 12 psi is most deffinetly not 12 times the atmosphere at sealevel...
that 14.7. if your running 14.7 psi of boost then you engine has about twice as much air a its NA equlivant. if our engines could take 12 times the psi of the atmosphere, we would be producing 12 times as much power... or about 1800hp.

 

that would be sweet