Also.. don't try to equate humid air w/water being sprayed on the IC because I know thats where you probably will go after my post.. the humidity is already in the air and is therefore innefective where the water sprayed on the intercooler evaporates and takes heat with it.

 

Yep. More oxygen is more power.

Everyone runs slower in the humidity. Anyone who doesn't believe that hasn't spent enough time around the tracks in the Mid-Atlantic.

 

bishi,

Humidity is the enemy of performance.

Want proof? Turn off the SAE correction factor on any dyno and run the car on a humid day and then on a less humid day with the same temperature. The low humidity makes more power. This has always been true. You can tune all you want, but if you optimize the car in a less humid situation, it will make more power. Go to any dyno in the country, look at cars with lots of runs, and verify this fact for yourself.

 

I live in the middle for FLA (I know, you're from S. FLA) and you're wrong. Did you have your evo in FLA? I have a lot of freinds that go to the track with me in their evos and you can watch the timeslips go higher with the humidity. To a degree some humidity I'm sure helps, but anything as oppressive as the humidity here (70 - 95%) can only kill compustion.

It's obvious that you're adminent about your stance here, so I don't want to start a flame war. Yes, my car was tuned (Dynoflash) for the humidity; as much as possible. But even Al insists you get the best tune at night when the humidity drops a little and so do temps. I too lived in AZ and I know what you are saying, but to make a blanket statement like "humidy is good for performance" is rediculous.

I personally can't wait till the humidity and temps drop around here; I really wanna get some 12's down on the 1/4.

Thanks for you input though.

 

Bishi,

When I used water injection, I was under the impression that:
1. water does not compress, thus I would realize a gain in compression.
2. when the water went through phase change in the combustion chamber it would carry away more heat and prevent knock.

This differs from high humidity in that water vapor compresses and does not absorb as much heat as a phase change does.

Mayhem,

You are right, but humid air does hold more heat than dry air, not comparable to liquid water though.

 

Heat robs power.
Humidity robs power.
Heat + Humidity turns a 12-second car into a 14-second car.

Summertime in Florida = Heat + Humidity = VERY BAD!

Dry, 40-50 degree days in the fall and winter in Florida = VERY GOOD!

 

i was runnin 13.7 @99 in 40% relative humidity..

last nite i was runnin 14.1 @98 in 100% relative humidity...

same deal for the guy w/ the SRT-4 last nite... he 2 was runnin like ****....

the more humid means less oxygen... the less oxygen the less power.....

 

Humidity is bad actually. Water is denser then oxygen,... so what humidity does is take way the amount of oxygen in fuel/air mixture. Alot of the time it really just lowers your octane rating.

 

Typically, temperatures are higher when there's high humidity. Maybe this theory holds out on a cold, rainy winter day, but no way in the summer.

 

guys give it up, if you tune for humidity you will get more power, but since you don't tune for humidity you loose power when it is humid. Bishi is right and so are you.

 

Oh are you saying he is right based on the fact that your knowledge on this subject is so weak you don't know who to beleive and it's hurting your brain so much that we should all just give it up? no way. there's right and there's wrong. if you settle for wrong you have worse problems than air density. complacency kills.

it's the same principle as altitude. the higher up you are the less dense the air is. there is less oxygen per part of air. it's harder for us to breathe and it's harder for the car to breathe. you can tune to compensate but you will never make the same power at altitude or humidity as you will at sea level or less humidity. the effective altitude changes based on humidity (and temp). more humidity is the same as being at a higher altitude.

this BS theory is the same as saying that it is better to have a restrictive intake so less oxygen gets to the motor. oxygen is the only thing that burns in the air the motor ingests and if there is less air it is no different than just plain having less oxygen. we open up intakes so more air carrying the needed oxygen can get in. we open up the exhaust so the motor can get rid of the used air to make way for more good air sooner. it's so basic.

this is so bunk it's ridiculous.

 

find me a place with air that has a perfect level of humidity all the time and that will make some sense, though very little because it still doesn't take into account the completely different thermodynamic fluid flow of humid air as opposed to dry air as the droppletts of water hit the compressor wheel... *shrug* I'm just telling you from an engineering perspective... negative ghostrider...

 

the colder the air the more dense the air is. humidity is very bad. in chicago you can tell the difference night and day with humidiy.

 

hey all your personal experience means squat. do a little research on the topic.

 

I see your point Bishi.. Theoretically your correct, but tuning for a specific humidity and temperature would put people at a disadvantage once it dries out.. This would promote knock since you got all aggressive while the weather was helping. Unless they have something to tune on the fly, they would risk engine damage tuning to the specific weather of the day.. Hence again why tuners tend to tune "safely" to cover there butts. (i.e. someone in AZ was tuned at 75 degrees and 20% humidity, then went to Florida in 99 degrees and 90% humidity).

Terry S