hp lose with 100% humidity
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hp lose with 100% humidity

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    Senior Member Skydog's Avatar
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    Thumbs up hp lose with 100% humidity

    Hey guys on these blowen mountain motors making 1100-1200hp do they lose like 50-80 hp? When temp gets high 90s and humidity goes to 90-100%
    Ty

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    gn7
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    Quote Originally Posted by Skydog View Post
    Hey guys on these blowen mountain motors making 1100-1200hp do they lose like 50-80 hp? When temp gets high 90s and humidity goes to 90-100%
    Ty
    using a quick and nasty calc, going from 60* and 0% humidity, to 100* and 100% humidity at the location, a 1000HP loses about 142 HP.



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    Quote Originally Posted by gn7 View Post
    using a quick and nasty calc, going from 60* and 0% humidity, to 100* and 100% humidity at the location, a 1000HP loses about 142 HP.
    I believe it.i was down 200rpms from 12 to 5 yesterday.started making test passes at noon at 6700 and by 5 i was runnin rich and down 200rpms. same tracked off 800ft etc. air turned to shit was even hard to breathe it was so heavy.

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    Senior Member Skydog's Avatar
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    Ty guys yup I sure could feel it. Lol

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    Quote Originally Posted by Skydog View Post
    Hey guys on these blowen mountain motors making 1100-1200hp do they lose like 50-80 hp? When temp gets high 90s and humidity goes to 90-100%
    Ty
    doesn't lose any power. but when temp and humidity drop, you can gain some. depends how you look at it.

    very very seldom you'll ever see 100* and 100%. if it's been hot, sun shining and a monsoon moves rapidly in, it could be close for a short while. but the temps are going to start dropping. in the worst conditions I've seen, it's usually a little cooler in the morning with humidity a t70-80% (maybe 75-80*). as temps rise, humidity will drop a few percent. you get in conditions where it's 100-105 or 6, and humidity is in the 50-70% range, it's pretty bad.

    but I go back to what I said. how much it might drop depends on where you started, where you ran before. everything is generally compared to standard air and temp, but it's very seldom anyone runs in those conditions. also, a huge ci engine shouldn't be as sensitive to change as a smaller ci engine...

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    gn7
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    Quote Originally Posted by bp298 View Post
    doesn't lose any power. but when temp and humidity drop, you can gain some. depends how you look at it.

    very very seldom you'll ever see 100* and 100%. if it's been hot, sun shining and a monsoon moves rapidly in, it could be close for a short while. but the temps are going to start dropping. in the worst conditions I've seen, it's usually a little cooler in the morning with humidity a t70-80% (maybe 75-80*). as temps rise, humidity will drop a few percent. you get in conditions where it's 100-105 or 6, and humidity is in the 50-70% range, it's pretty bad.

    but I go back to what I said. how much it might drop depends on where you started, where you ran before. everything is generally compared to standard air and temp, but it's very seldom anyone runs in those conditions. also, a huge ci engine shouldn't be as sensitive to change as a smaller ci engine...
    I used that example as an extreme condition. Like BP said, you are likely to never encounter those conditions. It would be virtually 100 degree fog. Closest thing you will probably ever encounter would be a sauna.
    Also as BP said, that would be from a SAE standard HP conditions, to virtually unseen conditions. Pretty bad case.
    Your odds are only slightly better of ever running in the opposite conditions of 60 degrees and 0% humidity. So anytime you are running your boat you are almost always down power from the SAE standard, or "corrected" HP from your dyno testing.

    What you felt wasn't a near a 14% lose of power and more like 5-8% from conditions you NORMALLY run in



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    some years back I dyno'd an engine at 85*, a couple weeks later had it at the river on a 115* day and high humidity it ran a bit sluggish called my dyno guy and told him the conditions he calculated we were off about 7% from the dyno day. the 30* was worth about 50hp

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    to put it in simpler terms " when the weather goes away" the air goes away and with that so does the tune.

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    Quote Originally Posted by Sleeper CP View Post
    some years back I dyno'd an engine at 85*, a couple weeks later had it at the river on a 115* day and high humidity it ran a bit sluggish called my dyno guy and told him the conditions he calculated we were off about 7% from the dyno day. the 30* was worth about 50hp
    what would you consider high humidity??? in 7 years of living here (next to the lake), I've never seen 115 AND high humidity. except for a short period when monsoons are beginning to roll in and the temp hasn't dropped yet. and nobody should be on the water when the monsoon starts.
    you need to visit the Midwest when it's between 105-110, with humidity between 50-60%. just to get a taste...

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    I dyno year round in North East Texas and generally race within 500 miles of here. Our early Spring and late Fall to winter weather averages close to STP, which indicates very small changes from the observed power to the corrected power. Extreme good air days I see a correction down in power from observed power to corrected power. And then from the Spring-Fall STP days to summer air we see from the measured or observed power to corrected power a correction up. The changes from the Spring-Late Fall to the hot days of summer for us is generally in the 5% to 7% range.

    Now this past weekend we raced at the US Nationals. A great event to say the least, but Indy was experiencing some crazy weather. In some areas they were recording record heat days. But it was the humidity or water grains in the air that was giving us a run for the money. It is difficult to burn Nitro with extreme water! On 9-31 for example the heat was not extreme but it varied from 70 degrees to 96 degrees and the humidity was from 46% to 90% with the average right at 70% for the day.

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    Quote Originally Posted by Gearhead View Post
    I dyno year round in North East Texas and generally race within 500 miles of here. Our early Spring and late Fall to winter weather averages close to STP, which indicates very small changes from the observed power to the corrected power. Extreme good air days I see a correction down in power from observed power to corrected power. And then from the Spring-Fall STP days to summer air we see from the measured or observed power to corrected power a correction up. The changes from the Spring-Late Fall to the hot days of summer for us is generally in the 5% to 7% range.

    Now this past weekend we raced at the US Nationals. A great event to say the least, but Indy was experiencing some crazy weather. In some areas they were recording record heat days. But it was the humidity or water grains in the air that was giving us a run for the money. It is difficult to burn Nitro with extreme water! On 9-31 for example the heat was not extreme but it varied from 70 degrees to 96 degrees and the humidity was from 46% to 90% with the average right at 70% for the day.
    the worst I've been in was the first wheatland race in july a couple years ago. temps were over 100 all weekend, with humidity dropping to 60% or so in the afternoon. I've raced in chowchilla when it was 119, and it was nothing like that wheatland race. taking a shower at the wheatland campground just didn't matter - you couldn't dry off. I've always liked it when it was up there like that...
    I guess, while you were at indy, people at wheatland were experiencing similar conditions.

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    I feel noticeable loss when temp climbs above 110 and humidity is high. I know we both run Whipple 5/8.3 litre blowers and I have been told that they are more sensitive to high heat/humidity index vs quad rotor setups. I notice it the most in the low/mid range. Upper RPM does not seem to be affected as that much.

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