how much does cool air affect performance
Le Mans Master
Joined: Jan 2009
Posts: 5,423
Likes: 43
From: Daytona Beach/ Atlanta---- Good Ol' Florida Boy/ Georgia
Depends on the tune. I believe most safe tuners don't allow the car to add timing for cooler air so you start losing power around 75* IAT.
That being said cooler air is more dense so you make more boost and make more power that way. I've seen my PD blower car fluctuate from 15.8-17.4lbs which could be about 20-40hp.
That being said cooler air is more dense so you make more boost and make more power that way. I've seen my PD blower car fluctuate from 15.8-17.4lbs which could be about 20-40hp.
Team Owner
Joined: Nov 2007
Posts: 24,035
Likes: 2,342
From: Gilbert AZ
Depends on tune, meth, etc. Could be a 200hp difference or basically none. Go dyno it and find out.
My car makes the same power if it is 70 or 110 out. Doesn't pull timing until 140, and meth keep sit below that, so it doesn't care really about outside temps as far as power goes.
My car makes the same power if it is 70 or 110 out. Doesn't pull timing until 140, and meth keep sit below that, so it doesn't care really about outside temps as far as power goes.
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Race Director
Joined: May 2004
Posts: 16,667
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From: Raleigh, NC
St. Jude Donor '15
The "Density" part of "speed density" comes from knowing the temperature of the air. Lower temp = higher density, which means the computer knows there is more oxygen, so it adds more fuel accordingly
Higher temps, lower density, less oxygen-->less fuel needed
PV=nRT basically
So.. it should work itself out. Does it perfectly every time? Hell if I know.. it's close on mine but not perfect. Mine goes slightly lean at higher IAT's, slightly rich at lower IAT's. I've just richened it up a few % and left it alone. Air temps fluctuate too much here for me to feel like constantly tweaking it
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
Outside air temps really don't matter. The temp of the air going into your motor is what does matter. Intake air temps. If it's 60 degrees outside and you're not moving much (sitting in line at the dragstrip), the intake air temps may be WAY over outside air temps. That temp is what influences your power output more than outside air temps.
Drifting
Joined: Jun 2009
Posts: 1,730
Likes: 93
From: St. Petersburg Florida
Outside air temps really don't matter. The temp of the air going into your motor is what does matter. Intake air temps. If it's 60 degrees outside and you're not moving much (sitting in line at the dragstrip), the intake air temps may be WAY over outside air temps. That temp is what influences your power output more than outside air temps.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
With 60 OAT's (outside air temps), you can see intake air temps WAY below that using meth. Sit in line at the drag strip, with no meth, and you may may see 120+ degree IAT's. Big power difference between the two with the same tune and the same 60 degree outside air temps.
Drifting
Joined: Jun 2009
Posts: 1,730
Likes: 93
From: St. Petersburg Florida
With 60 OAT's (outside air temps), you can see intake air temps WAY below that using meth. Sit in line at the drag strip, with no meth, and you may may see 120+ degree IAT's. Big power difference between the two with the same tune and the same 60 degree outside air temps.
My iats drop instantly as soon as I start moving, even on the dyno with almost 100* temps and extreme humidity
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
1-2 tenths from 90* down to 60*....assuming the humidity and baro pressure is the same.
You really need to compare density altitude from day to day, that will average all of the weather characteristics and tally them up for you for an easy comparison.
This isn't even talking about additional boost/timing etc etc.... This is just basic NA engine gains, which should easily be matched by a FI engine combo.
You really need to compare density altitude from day to day, that will average all of the weather characteristics and tally them up for you for an easy comparison.
This isn't even talking about additional boost/timing etc etc.... This is just basic NA engine gains, which should easily be matched by a FI engine combo.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
My point was that 40 degree or 110 degree OAT's....the only thing that matters is what kind of intake air temps the motor actually sees. Whether that's influenced by OAT's, air flow, position of earth in relation to Mars, or meth. Doesn't matter.
Drifting
Joined: Jun 2009
Posts: 1,730
Likes: 93
From: St. Petersburg Florida
You said "Outside air temps really don't matter." which isn't true because OATs have a huge impact on IAT, is what I was saying.
