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Old 05-29-2010 | 02:11 AM
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bigdogkanicsar's Avatar
bigdogkanicsar
 
Joined: Dec 2007
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From: fresno, CA
Default RE: tuning help!

ORIGINAL: skrilla


ORIGINAL: bigdogkanicsar


ORIGINAL: skrilla


ORIGINAL: bigdogkanicsar

ORIGINAL: skrilla


ORIGINAL: bigdogkanicsar
i agree, humidity means moisture and when heated it creates a lean condition

It has been a while since I ran in very humid conditions, but I'm pretty sure that higher humidity requires the needles to be leaned some, so it in effect creates a rich condition, not lean
actually it's just the opposite. one of the first things i learned in basic engines was that water(moisture) when you spray it in the carb of automobile evaporates creating a lean condition. causing the combustion chamber temps to rise rapidly and break up carbon deposits in the engine. while that's automotive , there is no difference here. water when heated turns into a vapor(air) which causes a lean condition. therefore you need to richen the mixture to even out the addition of humidity(moisture+heat=air).

I'm talking about humidity, water already vaporized and in the air, not straight water. In the post you quoted above (by papy_yosh), he said the opposite of what you said, that the OP should lean the engine, hence the humidity creates a rich condition. You said you agree with him, but your statement contradicts what he said. I'm thinking if the air is full of moisture, then there is less oxygen available. When you decrease the amount of available oxygen in your intake charge, you need to compensate the fuel charge accordingly, which means less fuel, ie, leaner mixture. So, higher humidity creates a rich condition

As for spraying water in an intake, when it goes in and evaporates, it displaces oxygen, causing there to be less available oxygen, so less fuel is needed in the combustion chamber, so it pushes it in the rich direction. This is just my rationalization of it, don't claim to be an expert on the subject

Also, what do you mean by 'water when heated turns into a vapor (air)'? I know it turns into water vapor, something inflamable and useless in an engine, but 'air' implies simply that, air...oxygen, nitrogen, the stuff in the atmosphere.
yeah i didn't really read what he wrote, but noticed it afterward. i don't want to drag this out like the last time you and i started postin' on the same thread.

water turns to steam, and steam is indeed inflamable. however, when i attended auto tech, one of the first things my instructer showed us was a way to raise the combustion temp by spraying water into the carb, and i wouldn't have beleived it if i hadn't seen it for myself. it does indeed raise the temp and to watch the carbon coming out the exhaust made a believer out of me.

on another occasion i lived in virginia with 85% humidity and the only way i could keep my RS4 cool was to run it pretty rich to offset the high temp of the engine caused by humidity. the same car in cali some time later in a place where there was only 15% humidity i had to lean it out to get it to warm up.

so, 6 of one and half dozen of the other. now i have a buddy who lives in va. with a jato and he says he's got to richen it up on the days after it rains and a little leaner if it doesn't rain for a few days.
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Water injection does not raise combustion chamber temperatures, it lowers them. Here's a basic expalnation: http://en.wikipedia.org/wiki/Water_injection_(engines)
ok, you are right. how ever i did have to richen to keep it runnin i do remember that much. now it may have been that i was tryin to run in 115 degrees and 85% humidity and the fuel wouldn't burn. all i know is the engine was hot and i ran it richer to cool it off, this was twelve years ago. to be honest i pretty much listen to the engine to hear what it's doin' and go from there. so, you're right i had it backwards.