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Discussion Starter · #1 ·
OK guys and gals - this morning here up in the North Pennines, it was minus 9.7C with a barometric pressue of 1033mb at 8.00am. Out of curiosity I wondered what kind of power gains this very cold, dense air would give me compared to standard conditions (often quoted when you have a dyno run, typically 20C [293Kelvin] and 1000mb). Using the ideal gas law equation PV = nRT and rearranging to get n (number of oxygen molecules or amount of oxygen per cylinder charge) is proportional to P/T (because V and R are constant) we get:

P/T = 1033/1000 divided by 263.3/293 = 1.149 - ie 14.9% more power than on a summer's day where the temperature is 20C and pressure is 1000mb.

Now, given that my car makes a tad over 260bhp under standard conditions, this equates to roughly 260bhp x 1.149 = 298.8bhp in these very cold conditions. Not bad for a 2L normally aspirated car :D Gotta love that lovely Siberian air :cool:
 

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OK guys and gals - this morning here up in the North Pennines, it was minus 9.7C with a barometric pressue of 1033mb at 8.00am. Out of curiosity I wondered what kind of power gains this very cold, dense air would give me compared to standard conditions (often quoted when you have a dyno run, typically 20C [293Kelvin] and 1000mb). Using the ideal gas law equation PV = nRT and rearranging to get n (number of oxygen molecules or amount of oxygen per cylinder charge) is proportional to P/T (because V and R are constant) we get:

P/T = 1033/1000 divided by 263.3/293 = 1.149 - ie 14.9% more power than on a summer's day where the temperature is 20C and pressure is 1000mb.

Now, given that my car makes a tad over 260bhp under standard conditions, this equates to roughly 260bhp x 1.149 = 298.8bhp in these very cold conditions. Not bad for a 2L normally aspirated car :D Gotta love that lovely Siberian air :cool:
I think you need to factor in humidity too, like the SAE correction factor.
 

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Yes, he need that factor for sure...there is also more denser air and much more resistance than in summer. It is little more power, but not much as I understand....anyway for me is better summer in all wievs....higher MPG and less clothes....hehe
 

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Discussion Starter · #5 ·
Yes of course, things like humidity and more resistance to air flow will play a minor role in reducing the amount of power gained in these conditions. However, I'd be very surprised if most people didn't see at least 10-12% more power - soemthing you'd normally pay £thousands for with NA tuning :)
 

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