How much impact does heat and humidity have on performance with turbochargers?
amazda6
I would say quiet a bit, at least that was my experince with the MSP. Turbo'd cars always seem to run faster/better in the cooler weather.
OK...just confirming my suspicions. Turns out it wasn't my imagination then. I'm still breaking her in at 600 miles and it's been too hot to really get any shots of cooler air to the intercooler, but I've still been glued to my seat once so far. It's also been 4+ years since I've driven a stick, so the driver could be the biggest problem here. :drive:
Definitely. Back in February-March when it was 45-55 degrees, after a drive the aluminum pipe between the IC and throttle body was cool to the touch. Now that it's 100-110+ everyday it's always very warm-scorching hot after a drive. Heck, even after being off for two days and sitting in the garage it's still warm just from ambient. I don't have hard numbers, but the car seemed to pull harder when it was cooler. She still goes like mad, but just not as potently as in cooler temps.
This is Vegas though and it's been unseasonably warm thus far even for Vegas, so this car takes about as much heat punishment as mother nature can dish out (short of Death Valley or something!).
This is Vegas though and it's been unseasonably warm thus far even for Vegas, so this car takes about as much heat punishment as mother nature can dish out (short of Death Valley or something!).
Humidity is better for it then dry air. Heat does make a difference, but in a dry heat vs humid heat comparison, the humid heat will make more power because you will not detonate as much in the humid heat.
When I lived in MD, my turbo'd MP3 made 226whp, whne I moved to AZ, it only made 205whp. I had to pull more timing when I moved here because of the dry heat. The altitude added to teh lower numbers, but it was more about the heat. I had to run less timing so I made less fuel.
The J&S safeguard lit up like a X-mas tree on the same tune I had from teh east coast, so it needed to be retuned for the dryer air.
When I lived in MD, my turbo'd MP3 made 226whp, whne I moved to AZ, it only made 205whp. I had to pull more timing when I moved here because of the dry heat. The altitude added to teh lower numbers, but it was more about the heat. I had to run less timing so I made less fuel.
The J&S safeguard lit up like a X-mas tree on the same tune I had from teh east coast, so it needed to be retuned for the dryer air.
I have to disagree with bigg tim.
You want...
1) Cool Air
2) Dry Air
3) Sea level Air
For maximum air density, and maximum potential power.
Anytime you add humidity to the air, you decrease the density of air.
Anytime you add heat to the air. you decrease the density of air.
Anytime you increase your altitude, you decrease the density of air.
Most people think more humidity is better because the air is "more dense". The air is heavier, but the weight is from the water, not from additional oxygen content. The more humid, and the more water in the air, the less overall density of the air itself.
Here's some basic rules of thumb.
1) For every 1000 ft increase in elevation, you decrease horsepower by 3-4%.
2) For every 7C increase in air temp, you lose roughly 1% horsepower. (As long as the cooling system is still sufficent...if the cooling system starts being overtaxed, this can leap upwards to 4-5%).
3) Humidity's effects is based on the ambient air temp. One example from forced induction performancing tuning is... "65% humidity + 95F ambient reduces the oxygen content to a similar level of 1000ft elevation". [Chapter 5, p 62-65)
So in other words, if you were 60F ambient, at sea level, with low humidity (40% or lower) as your baseline, and then you moved to 95F, 1000ft, and 65% humidity...
You'd be down nearly 12-15% in horsepower. Remember that's a %...so you're looking at roughly 25-30 whp loss....not taking into account the effect of heatsoak/cooling issues with the intercooler, or possible charge temp/detonation/retarding issues with the engine. This would just be the power loss due to the changes in air density...nothing else.
Btw information polled from...
Maximum Boost
http://www.amazon.com/gp/product/083760160...2504627?ie=UTF8
Forced Induction Performance Tuning
http://www.amazon.com/gp/product/185960691...ce&n=283155
You want...
1) Cool Air
2) Dry Air
3) Sea level Air
For maximum air density, and maximum potential power.
Anytime you add humidity to the air, you decrease the density of air.
Anytime you add heat to the air. you decrease the density of air.
Anytime you increase your altitude, you decrease the density of air.
Most people think more humidity is better because the air is "more dense". The air is heavier, but the weight is from the water, not from additional oxygen content. The more humid, and the more water in the air, the less overall density of the air itself.
Here's some basic rules of thumb.
1) For every 1000 ft increase in elevation, you decrease horsepower by 3-4%.
2) For every 7C increase in air temp, you lose roughly 1% horsepower. (As long as the cooling system is still sufficent...if the cooling system starts being overtaxed, this can leap upwards to 4-5%).
3) Humidity's effects is based on the ambient air temp. One example from forced induction performancing tuning is... "65% humidity + 95F ambient reduces the oxygen content to a similar level of 1000ft elevation". [Chapter 5, p 62-65)
So in other words, if you were 60F ambient, at sea level, with low humidity (40% or lower) as your baseline, and then you moved to 95F, 1000ft, and 65% humidity...
You'd be down nearly 12-15% in horsepower. Remember that's a %...so you're looking at roughly 25-30 whp loss....not taking into account the effect of heatsoak/cooling issues with the intercooler, or possible charge temp/detonation/retarding issues with the engine. This would just be the power loss due to the changes in air density...nothing else.
Btw information polled from...
Maximum Boost
http://www.amazon.com/gp/product/083760160...2504627?ie=UTF8
Forced Induction Performance Tuning
http://www.amazon.com/gp/product/185960691...ce&n=283155
That's why the best drag racing conditions are considered mine shaft conditions.
You tune for corrected altitude. Basically you extrapolate corrected atlitude with humidity, dew point, AMB temp, altitude, barometric pressure, etc.
Mine shaft is good, Hot humid Florida summer bad.
You tune for corrected altitude. Basically you extrapolate corrected atlitude with humidity, dew point, AMB temp, altitude, barometric pressure, etc.
Mine shaft is good, Hot humid Florida summer bad.
Here are the SAE Standards.
Inlet Air Pressure 0.986 Atmosphere (Same as 4000 ft elevation)
Inlet Air Temp 25C (77F)
Humidity 50%
Engine is also warmed up with a 10 minute drive @ around 60mph prior to testing.
http://forum.mazda6tech.com/viewtopic.php?...t=dyno+variance
Inlet Air Pressure 0.986 Atmosphere (Same as 4000 ft elevation)
Inlet Air Temp 25C (77F)
Humidity 50%
Engine is also warmed up with a 10 minute drive @ around 60mph prior to testing.
http://forum.mazda6tech.com/viewtopic.php?...t=dyno+variance
Not exactly true, unless you are mining under a body of water or in/around a water table, mines are relatively dry and cool. Old mines are now being used for document storage due to their naturally cool temps with low humidity.
In any case a cool dry environment is the ideal atmosphere in which to produce the most HP available.
http://wahiduddin.net/calc/calc_hp_abs.htm
This is nice way to see how humidity and manifold air temp effect power on a turbo engine.
Set air temp to 77F, pressure to 29.24, and rel humidity to zero as a start for basic SAE conditions to rate oem's engine hp. Rel hp should be 100%.
Do not change absolute pressure (not for turbos)
Note how rel humidy has little effect at cold temps, where it can not hold much water vapor. But at 100F ambient, 100% humidity can drop power.
Leave at zero humidity to see how manifold temps (130+) can drop power, vs lower winter temps (short bursts on hi-way with high short-term IC efficency can give brief charge temps near ambient, thanks to thermal mass if IC ... ie cold soak).
This is nice way to see how humidity and manifold air temp effect power on a turbo engine.
Set air temp to 77F, pressure to 29.24, and rel humidity to zero as a start for basic SAE conditions to rate oem's engine hp. Rel hp should be 100%.
Do not change absolute pressure (not for turbos)
Note how rel humidy has little effect at cold temps, where it can not hold much water vapor. But at 100F ambient, 100% humidity can drop power.
Leave at zero humidity to see how manifold temps (130+) can drop power, vs lower winter temps (short bursts on hi-way with high short-term IC efficency can give brief charge temps near ambient, thanks to thermal mass if IC ... ie cold soak).
I'm not big on numbers and scientific stuff. I was saying what I have seen in real world results I personally have had. I dyno'd in NJ at 98 degree's in june, I think, and made 226whp. I moved to AZ and dyno'd in the early spring when it was around 90 + degree's and only made 205whp. The altitude is higher but enough to loose 20hp? THere was no heat soak at the time of these numbers, a lazer temp gauge on the TB pipe showed almost 100% efficiency of the intercooler.
Also when I moved here in the summer, I had to remove 7 degree's of timing to keep the car from detonating. I was told that the dry air is what caused my detonation, not the altitude. I could be wrong, but these are results I have experienced. I have all the dyno files to back it up, I know dyno's can vary, but the car even felt weaker when I moved here.
Also when I moved here in the summer, I had to remove 7 degree's of timing to keep the car from detonating. I was told that the dry air is what caused my detonation, not the altitude. I could be wrong, but these are results I have experienced. I have all the dyno files to back it up, I know dyno's can vary, but the car even felt weaker when I moved here.
Tim,
Two different dyno's will usually show variances of up to 30 whp, depending on what type of dyno, how the car is strapped down, ambient conditions...etc etc.
The thread I posted earlier has links showing how dyno's can vary by a massive amount.
http://forum.mazda6tech.com/about3300.html
As mentioned before, this type of information is listed in some of the books I've posted repeatedly. Here they are again if you're interested in obtaining information that isn't randomly scattered throughout the internet.
Maximum Boost
http://www.amazon.com/gp/product/083760160...2504627?ie=UTF8
Forced Induction Performance Tuning
http://www.amazon.com/gp/product/185960691...ce&n=283155
Two different dyno's will usually show variances of up to 30 whp, depending on what type of dyno, how the car is strapped down, ambient conditions...etc etc.
The thread I posted earlier has links showing how dyno's can vary by a massive amount.
http://forum.mazda6tech.com/about3300.html
The only way to get 100% efficency on an intercooler is if its actively cooled by temps lower then ambient. ie boat racing, where the intercooler is submerged in the water. Laser temps are not sufficent enough to get accurate charge temp readings, you need a sensor imbedded in the airstream for temp data.
As mentioned before, this type of information is listed in some of the books I've posted repeatedly. Here they are again if you're interested in obtaining information that isn't randomly scattered throughout the internet.
Maximum Boost
http://www.amazon.com/gp/product/083760160...2504627?ie=UTF8
Forced Induction Performance Tuning
http://www.amazon.com/gp/product/185960691...ce&n=283155
Both dyno's where Dynojet 248c AWD dyno's. I used 94 octane in both places and 8psi with no other changes. The altitude here in Phoenix is about 1000 feet higher then it was in NJ. Why did I have to remove 7 degree's of timing when I came here to keep it from detonating? Is it just the altitude difference? I thought it was a combo of the altitude and the humidity difference.
You keep skipping all the threads I gave you to read over...including the one where a 350Z shows a massive difference in horsepower, just going from dyno to dyno on the same day.
http://forum.mazda6tech.com/about3300.html
You can't really compare two dyno's...especially dynojets, which can show almost a 10 whp difference just from what OS you run the software in!!!
I've seen and heard about the variances before. They both where running the latest SW, I forget now, but that was one of the things I asked when I went to the one here.
So forgetting about the dyno's, why did I have to pull 7 degree's of timing when I came here? I'm not trying to argue, I see that you know your stuff, I'm just trying to find answers now. If the dry air here is better then the humidity back east, then that works for me. I have always been pissed that I thought I would not make as much power here as I would back east, but if that's wrong, then I'm happy with that!
So forgetting about the dyno's, why did I have to pull 7 degree's of timing when I came here? I'm not trying to argue, I see that you know your stuff, I'm just trying to find answers now. If the dry air here is better then the humidity back east, then that works for me. I have always been pissed that I thought I would not make as much power here as I would back east, but if that's wrong, then I'm happy with that!
It's possible there are other issues effecting your vehicle besides just the ambient weather conditions.
I mean I guess you could look at it this way...
If the dry air is more dense, then you're going to get more oxygen then before. If you don't adjust your air/fuel ratios to compensate, you will be running a slightly leaner fuel mixture, which would increase your chances of detonation.
Did you ever compare your A/F's between the two dyno's? Were they the same? Or did they vary?
Don't forget changes in humidty/temp also effect the effectiveness of your overall charge/cooling system. How were the EGT's between the two locations?
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I mean I guess you could look at it this way...
If the dry air is more dense, then you're going to get more oxygen then before. If you don't adjust your air/fuel ratios to compensate, you will be running a slightly leaner fuel mixture, which would increase your chances of detonation.
Did you ever compare your A/F's between the two dyno's? Were they the same? Or did they vary?
Don't forget changes in humidty/temp also effect the effectiveness of your overall charge/cooling system. How were the EGT's between the two locations?
You said you pulled timing because of detonating problems. That means you could reasonably presume you are running a lower quality (octane) gas in AZ.
As stated over and over, altitude and humidty are two factors in tuning a motor, not the only ones.
You obviously lost HP from a combination of the fact that dyno's are almost useless when comparing one to another, altitude, and probably more importantly gas. Although the adjusted altitude figure would probably end up similar considering the relative low humidity in AZ vs the summer N.E.
In anycase, this is starting to feel like beating a dead horse.
As stated over and over, altitude and humidty are two factors in tuning a motor, not the only ones.
You obviously lost HP from a combination of the fact that dyno's are almost useless when comparing one to another, altitude, and probably more importantly gas. Although the adjusted altitude figure would probably end up similar considering the relative low humidity in AZ vs the summer N.E.
In anycase, this is starting to feel like beating a dead horse.
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