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Discussion Starter #1
Just a short post about my drive on quite roads this evening. I'd forgotten
how much a turbocharged engine loves the cold air,more oxygen, more power.
My only concern, and this is one for the experts on the forum. What percentage increase in torque does a tuned engine get to, over a safe tune, when the oxygen levels are high,due to the colder denser air?
Probably only applies to the guys who are pushing their torque levels, and are concerned about their rods.
 

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You also notice it a lot on tuned NA engines, my B16B always felt a lot better the closer to freezing the air was.
 

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Hmm, it could be a problem on tuned GTRs with OEM injectors then...
My IDC is at 96%, temperature was ca 12-14°C when I was logging...
Coudl I have a problem when temperature will be 0°C or even less...?
I am rarely driving this car at this cold weather, but still, just want to be sure...
 

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Discussion Starter #7
Hmm, it could be a problem on tuned GTRs with OEM injectors then...
My IDC is at 96%, temperature was ca 12-14°C when I was logging...
Coudl I have a problem when temperature will be 0°C or even less...?
I am rarely driving this car at this cold weather, but still, just want to be sure...
Thats why I asked if any expert could look at my post. From my limited knowledge, if you are running near the max on standard injectors when there is more oxygene, you may well need bigger injectors, as the ecu will get ask for more fuel to compensate. Please correct me if I'am wrong.
The bigger issue is, if your on the limit on torque, another 20/30 hp might put the rods in peril.
 

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I'm neither a tuner nor a mapper so I cannot answer that part. However, it's not just air temperature that affects this; altitude and humidity do as well. Unless the ECU can measure this and alter parameters accordingly, they will not be adjusted on the fly so I wouldn't worry too much unless the map is right on the jagged edge.

As a bit of fun, here are a couple of links that can help you see the difference in air density as temperature, altitude and humidity are affected:

Air Density Calculator

Online Conversion - Temperature Conversion

As an example, where I live at a temperature of 32 degreesF, at an elevation of +183ft, and with the current relative humidity of 86%, the air density here is ~0.0796 lbm/ft3. If I adjust the temperature down to about 5degreesF (-15degreesC) and humidity up to 100%, I get a reading of 0.0843 lbm/ft3, an increase in density of ~6% (and they are pretty low temperatures for here). However, if I used the original temperature and humidity values, if I went 'downhill' by 1613ft, I would get the same air density just by alterations in topography.
 

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IMO you are correct, a reason why a safe tune is essential (leave a little in the tank so to speak) Cold weather will ask a little more from your engine and tune peramiters...Get it checked :)
kk
 

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IMO you are correct, a reason why a safe tune is essential (leave a little in the tank so to speak) Cold weather will ask a little more from your engine and tune peramiters...Get it checked :)
kk
on a side note:
i remember seeing a graph during my efi101 course aaaages ago - it showed a curve of a car making power.. then at the pinnacle the curve started dipping down again. The point of knock came after the pinnacle of the curve... so the old adage of tune till it knocks then retard back would actually put the car on the pinnacle of the power curve. The argument was that the car could very easily slip into that curve downslide where knock can occur just by temperature conditions (such as very cold icy air weather which turbo cars love as the OP stated). So the guy doing the course (Ben Strader for anyone whose read his books) said its not worth tuning to that point for what is effectively a very small power increase. Better to tune the car to just before the pinnacle of power and as you say above 'save a little in the tank' :)

Dunno if that makes sense.. alot easier to explain with a graph and i'm sure its not the only condition to consider but i found it quite enlightening that the car generally 'loses' power when detonation and knock occurs... my understanding is that its always been at the point of peak power where things are unsafe and thats why you need to back off.

ant mcgrath
meandering musings #35468684.21
 

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I cant wait till it snows again :D
 

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Discussion Starter #12
on a side note:
i remember seeing a graph during my efi101 course aaaages ago - it showed a curve of a car making power.. then at the pinnacle the curve started dipping down again. The point of knock came after the pinnacle of the curve... so the old adage of tune till it knocks then retard back would actually put the car on the pinnacle of the power curve. The argument was that the car could very easily slip into that curve downslide where knock can occur just by temperature conditions (such as very cold icy air weather which turbo cars love as the OP stated). So the guy doing the course (Ben Strader for anyone whose read his books) said its not worth tuning to that point for what is effectively a very small power increase. Better to tune the car to just before the pinnacle of power and as you say above 'save a little in the tank' :)

Dunno if that makes sense.. alot easier to explain with a graph and i'm sure its not the only condition to consider but i found it quite enlightening that the car generally 'loses' power when detonation and knock occurs... my understanding is that its always been at the point of peak power where things are unsafe and thats why you need to back off.

ant mcgrath
meandering musings #35468684.21
Thanks for that. We would have to assume that the tuners/mappers we have used have left a little leeway, which I'am sure they have.
 
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