cobalt123
Platinum Member
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---------- Post added at 01:26 AM ---------- Previous post was at 01:21 AM ----------
these are just an example of some parts needed to turbocharge your vehicle they also give a good idea as to what is happening to the engine under forced induction. note that these are generic parts not GM specific
NOw for some GM specifics The SS/TC borg werner twin scroll k04 turbo
Using (P1 + P2) / P2 = Pressure Ratio
P1 = Desired boost pressure in psi
P2 = ambient atmospheric pressure (14.7psi)
Our engines are almost 122 CID, so at 100% VE our engines should flow close to 220 CFM. Assuming 80% VE this means approx 176 CFM at 6,250 RPM, which is approx 12 lbs/min at that rpm
Quick calculations (it takes several calculations to calculate a single data point on that map) show our 260hp to be at about the 0.12 mark on the X axis. I believe the X axis is Kg/s, so you can convert to lb/min if you want to by multiplying the numbers by 7. (7 is not the exact number to convert, but it will get you very very close and is easy to remember)
This also assumes many variables that are not listed here such as air temperature, altitude (assuming 14.7 psia for sea level), etc. The chart shows the calculation used to achieve nredV using 183.5, which means they are using 83.5% VE for their calculations.
Using assumed variables, and assuming that this chart is the correct one (lots of assumption there), that would seem to indicate that at the very outside edge of the efficiency island is around 22 psig before the compressor will surge - this lines up with both the overboost protection in the computer and what some tuners have run into already. 21 is about the max safe boost level on the stock K04 (which is what Hahn's tuner sets the boost to, so this lines up as well)
All this is now public info.
http://media.gm.com/us/powertrain/en/product_services/2008/08car.htm
Engine power curve:
http://media.gm.com/us/powertrain/e...ry/Ecotec/2008 LNF/2008_20L_LNF_Cobalt SS.pdf
Engine Spec Sheet:
http://media.gm.com/us/powertrain/en/product_services/2008/Spec Sheet/Ecotec/08_LNF.xls
Engine Information:
http://media.gm.com/us/powertrain/en/product_services/2008/Whats New/Ecotec/08_LNF.doc
Trans Spec Sheet:
http://media.gm.com/us/powertrain/e...eet/Transmissions/2008 Manuals/08_GME_MU3.xls
Transmission Info:
http://media.gm.com/us/powertrain/e...smissions/2008 Manual Transmission/08_MU3.doc[
---------- Post added at 01:26 AM ---------- Previous post was at 01:21 AM ----------
these are just an example of some parts needed to turbocharge your vehicle they also give a good idea as to what is happening to the engine under forced induction. note that these are generic parts not GM specific
NOw for some GM specifics The SS/TC borg werner twin scroll k04 turbo
Using (P1 + P2) / P2 = Pressure Ratio
P1 = Desired boost pressure in psi
P2 = ambient atmospheric pressure (14.7psi)
Our engines are almost 122 CID, so at 100% VE our engines should flow close to 220 CFM. Assuming 80% VE this means approx 176 CFM at 6,250 RPM, which is approx 12 lbs/min at that rpm
Quick calculations (it takes several calculations to calculate a single data point on that map) show our 260hp to be at about the 0.12 mark on the X axis. I believe the X axis is Kg/s, so you can convert to lb/min if you want to by multiplying the numbers by 7. (7 is not the exact number to convert, but it will get you very very close and is easy to remember)
This also assumes many variables that are not listed here such as air temperature, altitude (assuming 14.7 psia for sea level), etc. The chart shows the calculation used to achieve nredV using 183.5, which means they are using 83.5% VE for their calculations.
Using assumed variables, and assuming that this chart is the correct one (lots of assumption there), that would seem to indicate that at the very outside edge of the efficiency island is around 22 psig before the compressor will surge - this lines up with both the overboost protection in the computer and what some tuners have run into already. 21 is about the max safe boost level on the stock K04 (which is what Hahn's tuner sets the boost to, so this lines up as well)
All this is now public info.
http://media.gm.com/us/powertrain/en/product_services/2008/08car.htm
Engine power curve:
http://media.gm.com/us/powertrain/e...ry/Ecotec/2008 LNF/2008_20L_LNF_Cobalt SS.pdf
Engine Spec Sheet:
http://media.gm.com/us/powertrain/en/product_services/2008/Spec Sheet/Ecotec/08_LNF.xls
Engine Information:
http://media.gm.com/us/powertrain/en/product_services/2008/Whats New/Ecotec/08_LNF.doc
Trans Spec Sheet:
http://media.gm.com/us/powertrain/e...eet/Transmissions/2008 Manuals/08_GME_MU3.xls
Transmission Info:
http://media.gm.com/us/powertrain/e...smissions/2008 Manual Transmission/08_MU3.doc[
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