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Official "Pure" 91 octane evo thread

Old Jul 22, 2018, 11:07 AM
  #256  
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Those numbers are nice. I need to get me some S2s
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Old Aug 8, 2018, 09:38 AM
  #257  
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Hey Guys I figure I can share my recent results now that I am on 91oct (Shell V-Power) and I am currently in Albuquerque, NM which is about 5300ft above sea level. One log is in 3rd and the second is in 4th. I will need to adjust my boost in 4th since I dont want it to spike above 26psi. This was more of a test hit to see how it looked.

I read a thread on here stating that for 5K ft altitude we can use 24.9 in barometric pressure so I used that in the SAE correction setting. If accurate, this altitude is definitely robbing me of power

Without SAE correction


with SAE selected and Barometric pressure set to 24.9


Let me know what you guys think
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Old Aug 8, 2018, 12:25 PM
  #258  
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Does elevation affect power for boosted cars, seeing how you're getting the same psi as you would at sea level?
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Last edited by kaj; Aug 8, 2018 at 03:11 PM.
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Old Aug 8, 2018, 01:24 PM
  #259  
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Originally Posted by kaj View Post
Does elevation affect power for boosted cars, seeing how you're getting the same psi as you would at ground level?
​​​​​
Hey Jason. I think you mean "Sea Level" vs "Ground Level". Our friend in Albuquerque is certainly at ground level as well

Most notes shows a 3% loss per 1000ft change in elevation. So a rough estimate of running at 5000ft would be a 15% loss (maybe our turbo cars reduce that 3% margin a bit?)

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Old Aug 8, 2018, 03:15 PM
  #260  
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Originally Posted by MinusPrevious View Post
Hey Jason. I think you mean "Sea Level" vs "Ground Level". Our friend in Albuquerque is certainly at ground level as well

Most notes shows a 3% loss per 1000ft change in elevation. So a rough estimate of running at 5000ft would be a 15% loss (maybe our turbo cars reduce that 3% margin a bit?)

Fixed. I hate posting from my phone.

3% isn't much and makes sense for an N/A car, seeing how it's limited to sucking air at the density avail. But our cars compress the air to a certain psi, no matter how thin or thick the air is. I could see the turbo having to work 3% harder, though.
I'm just thinking out loud and could be 100% off
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Old Aug 8, 2018, 03:55 PM
  #261  
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On higher altitude things are not only affected by the composition of the atmospheric air, the lower percentage of oxygen, and the lower density, all which make the air move at a lower speed and in regards to combustion engines either internal or external, not being able to burn as much fuel as in lower altitude, but it is also down to the specific setup of a car or bike. On a turbocharged setup, i.e the 4g63t, it depends on the volumetric efficiency of the engine and the turbocharger used. The smaller the turbocharger the more effort it will need to put in to reach intented boost threshold, thus the more it will heat up the compressed air and thus even less oxygen will enter the combustion chamber. So loses could vary from 2-3% to 6-7% and even higher if there is a lake around and elevated water (hydrogen) particles exist in the air composition taking the place of oxygen ones.






Marios

Last edited by Evo8cy; Aug 8, 2018 at 04:02 PM. Reason: typo
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Old Aug 8, 2018, 06:04 PM
  #262  
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This is all new to me since I have always been at sea level until now. Comparing what my wastegate duty cycle is set to now which is spiking to 26psi in 3rd at sea level it would have made about 29psi. I have also made sure to adjust the formula in evoscan to account for the altitude so hopefully the boost numbers are accurate. I do want to take the car to a dyno and see what happens. But I guess for now I am happy the car feels ok and no knock on 91oct.
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