15% more power for free - thanks to Russian high

[Lunar Tick]

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 Gotta love that lovely Siberian air

[pulpmelon_r]

Originally Posted by Lunar Tick

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 Gotta love that lovely Siberian air

I think you need to factor in humidity too, like the SAE correction factor.

[xxDIABLOxx]

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

[robbo51]

Putting the powerdown on cold tarmac will cancel that power gain out anyway

[Lunar Tick]

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

[Lunar Tick]

Originally Posted by robbo51

Putting the powerdown on cold tarmac will cancel that power gain out anyway

Mate - you seriously need to change your tyres

[Alsone]

Makes little difference as everyone else gains the same power also!

[Lunar Tick]

Of course - however it's much more fun everyone driving around in high-powered cars than in low-powered ones

[robbo51]

Originally Posted by Lunar Tick

Mate - you seriously need to change your tyres

I already have
Both or cars have Winter tyres fitted....Mate

[culasse]

With this kind of freezing weather my car is going like a raped ape, especially since I currrently have some 102 Aral Ultimate fuel in my tank and a map with agressive ignition curves in my flashpro.

I also made a 3rd gear WOT test a few days ago:

http://www.civinfo.com/forum/modific...plot-pics.html