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Discussion Starter #1
Does outside temp effect boost ? I took my car for spin this morning after a month of not driving it and hittin almost 16 lbs ? Would this effect the tune ? Or is my gauge just broke lol
 

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Cooler weather does effect the boost. Cooler air is thinner so makes it easier to compress. This giving you more boost. That's why it will run stronger in cooler weather.
 

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a.k.a. Racecougar
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Cooler weather does effect the boost. Cooler air is thinner so makes it easier to compress. This giving you more boost. That's why it will run stronger in cooler weather.
That isn't entirely correct. Yes, you will see an increase in boost in cold weather, however it's due to the increased density of the cooler air.


Would this effect the tune ?
If the tune, fuel system, or MAF can't handle the denser air, yes, it can certainly cause problems.
 

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Discussion Starter #4
I mean like it seems to be running strong , no hiccups or nothin
I usally dont drive in winter
 

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Mine seemed to have a big more give n go as well!
 

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a.k.a. Racecougar
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I mean like it seems to be running strong , no hiccups or nothin
I usally dont drive in winter
It's all a matter of head room. The MAF needs enough head room so that it doesn't max out. The fuel system needs enough head room to prevent going lean up top. The tune needs to have additional range mostly in the MAF transfer function and borderline knock tables to ensure both adequate fuel and adequate ignition retard at higher loads than were seen when the car was actually tuned (there's far more to it than this).

Keep an eye on your wideband and an ear open for any sign of detonation. If you have a good tune, enough MAF, and an adequate fuel system, you'll be fine.
 

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Discussion Starter #7
I dont know about the tune besides is at 13 degree timein but I do have dual styker 340s and a pamas hpx maf hopefully they should hang in there but like i said I usally dont drive it , I got bored , hopped in it and punch it then I seen the boost hit 16 , I was like holy ****
 

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How much boost do you usually hit? I was tuned on a 60 degree day, made 11psi at 6000rpm. In this 30 degree weather it'll see 13psi at 6000rpm. 1-3psi at most in cooler air. Not like 5-6psi that's to much. Might be the gauge
 

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Discussion Starter #9
I usally hit 12 lbs and was tuned on a 80 degree day
 

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what was the temp today? i could see that if it was in the 30's. Im sure someone has an equation to where we could figure it out lol
 

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Discussion Starter #11
Ya 30s im in upstate ny
 

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Sweet! I can tell
 

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a.k.a. Racecougar
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what was the temp today? i could see that if it was in the 30's. Im sure someone has an equation to where we could figure it out lol
There's more to density altitude (which is what it really comes down to) than just temperature. There are a number of good DA calcs out there. Wallaceracing.com and Dragtimes.com both have decent ones.

Cooler weather equals more power in boosted cars. Cold air is more dense.
It isn't just boosted cars. NA engines pick up power as the DA drops as well.
 

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Sheriff Metal Face
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There's more to density altitude (which is what it really comes down to) than just temperature. There are a number of good DA calcs out there. Wallaceracing.com and Dragtimes.com both have decent ones.



It isn't just boosted cars. NA engines pick up power as the DA drops as well.
More noticeably with boosted cars was my point, as this thread is about FI not NA.


Sent from my iPhone using AutoGuide.com App
 

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At sea level and 25% humidity. Units in Metric, because **** you!

0° 1.288 kg/m3
10° 1.241 kg/m3
20° 1.198 kg/m3
30° 1.156 kg/m3

what was the temp today? i could see that if it was in the 30's. Im sure someone has an equation to where we could figure it out lol
MATH LESSON BELOW!!! ITS LONG AND HARD <---- just like zip..

*******************************************

Air Density Calculations:

To begin to understand the calculation of air density, consider the ideal gas law:

(1) P*V = n*Rg*T

where: P = pressure
V = volume
n = number of moles
Rg = universal gas constant
T = temperature


Density is simply the mass of the molecules of the ideal gas in a certain volume, which may be mathematically expressed as:

(2) D = m / V

where: D = density
m = mass
V = volume

Note that:

m = n * M

where: m = mass
n = number of moles
M = molar mass

And define a specific gas constant for the gas under consideration:

R = Rg / M

where R = specific gas constant
Rg = universal gas constant
M = molar mass

Then, by combining the previous equations, the expression for the density becomes:

(3)

where: D = density, kg/m3
P = pressure, Pascals ( multiply mb by 100 to get Pascals)
R = specific gas constant , J/(kg*degK) = 287.05 for dry air
T = temperature, deg K = deg C + 273.15
 

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The car will pull harder in cold weather, but i have never seen an increase in boost. I drive my car year round. My tires will break loose in cold weather before the gauge will hit full boost. Whether summer or winter i have never seen the gauge go past 9 psi.
 

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That seems like a rather dramatic increase in boost for just a temperature change and I would question the accuracy. If you have any logs prior to this event and take new logs it would be interesting to compare side by side to determine if the system is indeed attempting to compensate for an increase of if it is merely and indication issue.
 

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Yeah I really don't think it would go up that much. I do see 2psi more now that it's cold. Some of it could be from the tighter belt. But, I usually see 1-2psi more in cold weather.

4/5psi is unrealistic
 

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Discussion Starter #20
Ya it could b just the gauge from not operating for awhile and bein cold , I was more hopin it was gauge due to tuning issues of that much boost , I'm gonna take it for another spin today and see what happens
 
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