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-   -   Boost #'s... what does you gauges show? (http://www.focusfanatics.com/forum/showthread.php?t=299762)

shineboy 10-13-2012 02:34 PM

Boost #'s... what does you gauges show?
 
Boost gauge is 0 to 25 with at what I would guess are: 0, 6.25, 12.5, 18.75 and 25 lbs. Those red number are a guess but seems right.

Mine is right below the 18.75 line. Owners manual supplement says it's SAE HP numbers are at 19.5lbs and up to 21lbs can be achieved depending on atmosphere conditions and gas.

Curious what others are seeing??????

Alan_L 10-15-2012 05:27 PM

I don't have an ST but I have a Solstice GXP that is turbo charged and hast the same system as the ST. Basically depending on altitude (and other factors) the car will have more boost at higher elevation and less at lower elevation. The ecu detirmines the amount of boost needed to make the rated power (252 for the ST) and adjusts accordingly.

shineboy 10-15-2012 06:15 PM

Quote:

Originally Posted by Alan_L (Post 4406843)
I don't have an ST but I have a Solstice GXP that is turbo charged and hast the same system as the ST. Basically depending on altitude (and other factors) the car will have more boost at higher elevation and less at lower elevation. The ecu detirmines the amount of boost needed to make the rated power (252 for the ST) and adjusts accordingly.

Speed density thing?

Alan_L 10-15-2012 08:22 PM

Quote:

Originally Posted by shineboy (Post 4406950)
Speed density thing?

Well if it is like my GXP (which has a 2.0 turbo direct injection like the ST) it it a pretty complex calculation having to do with air density, charge temps, amount of fuel used, fuel octane etc and then based on that it can electronically open the waste gate at the desired boost to achieve the advertised power level. Now I don't know if the ST has it but the GM DI turbos actually have a learn down feature. So basically of you put an intake and exhaust the car will detect the increased air flow and turn down the boost to get back to stock levels. It was pretty funny but when I got my car I did an intake and exhaust and before the mods it did 235 horsepower at the wheels and after it did the exact same (I'm now over the 400 mark, just have to tune it for new mods). But again this is a GM vs Ford car so I don't know if the ST has learn down but I am 95% sure the boost levels are based on the same procedure.

For a quick reference when I bought my GXP at sea level I was at 16 psi and when I got it home (Albuquerque 5000 feet ASL) it was at 21 psi. Take the ST for a romp in the mountains and the psi will go up to compensate.

shineboy 10-16-2012 06:57 PM

Quote:

Originally Posted by Alan_L (Post 4407145)
Well if it is like my GXP (which has a 2.0 turbo direct injection like the ST) it it a pretty complex calculation having to do with air density, charge temps, amount of fuel used, fuel octane etc and then based on that it can electronically open the waste gate at the desired boost to achieve the advertised power level. Now I don't know if the ST has it but the GM DI turbos actually have a learn down feature. So basically of you put an intake and exhaust the car will detect the increased air flow and turn down the boost to get back to stock levels. It was pretty funny but when I got my car I did an intake and exhaust and before the mods it did 235 horsepower at the wheels and after it did the exact same (I'm now over the 400 mark, just have to tune it for new mods). But again this is a GM vs Ford car so I don't know if the ST has learn down but I am 95% sure the boost levels are based on the same procedure.

For a quick reference when I bought my GXP at sea level I was at 16 psi and when I got it home (Albuquerque 5000 feet ASL) it was at 21 psi. Take the ST for a romp in the mountains and the psi will go up to compensate.

Mountains is an interesting idea.... 4 hour trip one way for me, need to convince the wife

but I do know I am about 400' above sea level here

BLRich1 10-16-2012 07:16 PM

I'd be curious to see what an aftermarket gauge reads in comparison.

shineboy 10-16-2012 08:32 PM

Quote:

Originally Posted by BLRich1 (Post 4409008)
I'd be curious to see what an aftermarket gauge reads in comparison.

me too part of the reason I posted this....

No one has put any numbers, etimates?

What you seeing on your gauge?

I have a aeroforce gauge but it is only good to 1 atm or 14.7lbs


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