Here is how much heat affects performance in the RX8
06-27-2004, 12:12 PM
#52
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Originally posted by O.R.A.
all else being equal. Hotter air IS less dense than cooler air.
A hot day has LESS barometric pressure than a cold day. Just like a high altitude place has less barometric pressure than a low altitude place. So, if the day is hotter today than 6 months ago, the air is less dense than 6 months ago.
all else being equal. Hotter air IS less dense than cooler air.
A hot day has LESS barometric pressure than a cold day. Just like a high altitude place has less barometric pressure than a low altitude place. So, if the day is hotter today than 6 months ago, the air is less dense than 6 months ago.
April 27
Temp: 54
Humidity: 27
Bara: 29.04
June 23
Temp 104 / 107
Humidity: 100
Bara: 30.83 / 31.04
The barometric pressure at 52 to 55 degrees warmer day was higher, yet the air was denser (at least according to the best measurement we have available with these statistics – the barometer reading and humidity) on June 23.
Ah but wait. I cannot say that the barometer measure has a direct correlation to density of the immediate surrounding air anymore than you can say heat does. Air has the capacity to carry other particles. Most importantly to the survival of life on earth, it carries moisture.
So, let us draw a very simple analogy to cause you pain. Let us say our body skins were equal and we carried nothing but water. Now imagine each body equals 1000 feet. You are on the bottom of the stack of bodies, and you are 27 percent full of water. You are now under pressure from all the bodies above you, each having their own percentage of water they carry. Now, if I poke a hole in your body, the speed at which the air and water will squirt out of you will be relative to the amount of pressure (weight) that you were forced to support. This is effectively what is available for injection into your engine.
What I have been injecting into this thread is that pressure, the barometric measurement, has far more impact than the other two measurements. I would put the humidity has the number two influencer for performance.
As you can see, the quote A hot day has LESS barometric pressure than a cold day is an over simplification, though is true under equal conditions. But, the conditions were not equal, as the humidity clearly illuminates.
06-28-2004, 03:14 PM
#53
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OK, I just want to say... I ended up lining up against one of these SRT-4's Friday night at the strip. I was supposed to run a BMW, but something happened. This car had Mopar stickers all over it. He got the best of me and I felt pretty bad until I parked next to him after the race. I walked over by the fence, took a glance at the neon, then the '8. Nothing was left on my face but a smile. A Neon is just an economical family car... I can put a 302 in my ranger, but that doesn't make it a Classy Sports Car. Auto-X Anyone?
06-30-2004, 08:03 AM
#54
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If I were to guess. High temp air being thin and less dense starves the engine for air lowering the hp a bit. Instant controlling of the air fuel ratio clearly helped but nothing is better than cool dry air for performance.
06-30-2004, 08:10 AM
#56
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Originally posted by Zeltar
Density is the mass per unit volume of a substance. In this case, air. You say all else being equal. But all else is not equal in these two tests. I again lead you to consider Humidity. Air has more mass when saturated with moisture at 100% (I still question this number) vs. 27%. Here were the important numbers:
April 27
Temp: 54
Humidity: 27
Bara: 29.04
June 23
Temp 104 / 107
Humidity: 100
Bara: 30.83 / 31.04
The barometric pressure at 52 to 55 degrees warmer day was higher, yet the air was denser (at least according to the best measurement we have available with these statistics – the barometer reading and humidity) on June 23.
Ah but wait. I cannot say that the barometer measure has a direct correlation to density of the immediate surrounding air anymore than you can say heat does. Air has the capacity to carry other particles. Most importantly to the survival of life on earth, it carries moisture.
So, let us draw a very simple analogy to cause you pain. Let us say our body skins were equal and we carried nothing but water. Now imagine each body equals 1000 feet. You are on the bottom of the stack of bodies, and you are 27 percent full of water. You are now under pressure from all the bodies above you, each having their own percentage of water they carry. Now, if I poke a hole in your body, the speed at which the air and water will squirt out of you will be relative to the amount of pressure (weight) that you were forced to support. This is effectively what is available for injection into your engine.
What I have been injecting into this thread is that pressure, the barometric measurement, has far more impact than the other two measurements. I would put the humidity has the number two influencer for performance.
hmmmm ...... have you heard of the https://www.rx8club.com/showthread.p...light=cryogenic at all>?
As you can see, the quote A hot day has LESS barometric pressure than a cold day is an over simplification, though is true under equal conditions. But, the conditions were not equal, as the humidity clearly illuminates.
Density is the mass per unit volume of a substance. In this case, air. You say all else being equal. But all else is not equal in these two tests. I again lead you to consider Humidity. Air has more mass when saturated with moisture at 100% (I still question this number) vs. 27%. Here were the important numbers:
April 27
Temp: 54
Humidity: 27
Bara: 29.04
June 23
Temp 104 / 107
Humidity: 100
Bara: 30.83 / 31.04
The barometric pressure at 52 to 55 degrees warmer day was higher, yet the air was denser (at least according to the best measurement we have available with these statistics – the barometer reading and humidity) on June 23.
Ah but wait. I cannot say that the barometer measure has a direct correlation to density of the immediate surrounding air anymore than you can say heat does. Air has the capacity to carry other particles. Most importantly to the survival of life on earth, it carries moisture.
So, let us draw a very simple analogy to cause you pain. Let us say our body skins were equal and we carried nothing but water. Now imagine each body equals 1000 feet. You are on the bottom of the stack of bodies, and you are 27 percent full of water. You are now under pressure from all the bodies above you, each having their own percentage of water they carry. Now, if I poke a hole in your body, the speed at which the air and water will squirt out of you will be relative to the amount of pressure (weight) that you were forced to support. This is effectively what is available for injection into your engine.
What I have been injecting into this thread is that pressure, the barometric measurement, has far more impact than the other two measurements. I would put the humidity has the number two influencer for performance.
hmmmm ...... have you heard of the https://www.rx8club.com/showthread.p...light=cryogenic at all>?
As you can see, the quote A hot day has LESS barometric pressure than a cold day is an over simplification, though is true under equal conditions. But, the conditions were not equal, as the humidity clearly illuminates.
07-26-2004, 12:34 PM
#57
Ride Naked!
Has anyone looked at water injection? The turbo people use it to cool the intake charge and prevent timing pull due to knock. Check out the link.
http://www.racetep.com/wik.html#nah20
http://www.racetep.com/wik.html#nah20
07-26-2004, 12:48 PM
#58
I like cheese!
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Originally Posted by Dark8
Has anyone looked at water injection? The turbo people use it to cool the intake charge and prevent timing pull due to knock. Check out the link.
http://www.racetep.com/wik.html#nah20
http://www.racetep.com/wik.html#nah20
You should start a new topic on WI. There are pros and cons to a setup like WI, but more importantly WI is not for curing high ambient temps, and WI is highly debatable.
Thanks!
07-26-2004, 01:11 PM
#59
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Here's a thread I started about a month ago on water injection 
.
https://www.rx8club.com/series-i-tech-garage-22/water-injection-13b-msp-32449/
.https://www.rx8club.com/series-i-tech-garage-22/water-injection-13b-msp-32449/
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