Some questions for the more serious tech guys/racers.

[Carnivalride]

I know yesterday during my testing I had great conditions, water was good and air quality had to be great, definitely better than when the boat drags are around here. So here are my questions:
At 1363Â’ above sea level how will these temperatures and humidityÂ’s compare to the lower three (my typical race conditions). What is the air density or altitude equivalents for these numbers? How much power loss in percentage or ET loss etc?
67 degrees 26% humidity
67 degrees 22% humidity
65 degrees 27% humidity
90 degrees 60% humidity
95 degrees 50% humidity
100 degrees 35% humidity
Is there a site where a can look this stuff up for myself in the future?
Thanks,
Loren

[GofastRacer]

Try this site!..
Calculator! (http://wahiduddin.net/calc/calc_da.htm)

[steelcomp]

I know yesterday during my testing I had great conditions, water was good and air quality had to be great, definitely better than when the boat drags are around here. So here are my questions:
At 1363Â’ above sea level how will these temperatures and humidityÂ’s compare to the lower three (my typical race conditions). What is the air density or altitude equivalents for these numbers? How much power loss in percentage or ET loss etc?
67 degrees 26% humidity
67 degrees 22% humidity
65 degrees 27% humidity
90 degrees 60% humidity
95 degrees 50% humidity
100 degrees 35% humidity
Is there a site where a can look this stuff up for myself in the future?
Thanks,
Loren
How did the performance differ?

[Carnivalride]

How did the performance differ?
This was the 4th time on the water for this combination. Engine, rocker, hardware placement all different. Trying to get a good idea how it will run next year.

[Carnivalride]

Try this site!..
Calculator! (http://wahiduddin.net/calc/calc_da.htm)
Thanks Art! :)
If I was using it right I was right around 2000'-2100' all afternoon during my testing. I know at some of the races I've heard them complain about 3500'-4000' altitude density's. So I wonder how this relates to performance, some of my car buddies swear 5/10th on their ET's? Is it really that bad? :confused: :confused:

[Fiat48]

I know yesterday during my testing I had great conditions, water was good and air quality had to be great, definitely better than when the boat drags are around here. So here are my questions:
At 1363Â’ above sea level how will these temperatures and humidityÂ’s compare to the lower three (my typical race conditions). What is the air density or altitude equivalents for these numbers? How much power loss in percentage or ET loss etc?
67 degrees 26% humidity
67 degrees 22% humidity
65 degrees 27% humidity
90 degrees 60% humidity
95 degrees 50% humidity
100 degrees 35% humidity
Is there a site where a can look this stuff up for myself in the future?
Thanks,
Loren
Temperature is the most important factor and humidity has the least effect on corrected altitude.
2360 feet corrected
2335 feet corrected
2227 feet corrected
4460 feet corrected
4753 feet corrected
4911 feet corrected
To be accurate you need an altimeter. The altimeter changes all the time and will not stay at a static 1363 feet where you were at. Generally the air going away makes the altimeter rise. But not always.
Still the above gives you an idea of the air going away.
How to relate this to performance drop is tough. Less air/less power. Blown alcohol wise I would be bumping the blower (depends on the setup and the blower) about 2% to run the same et at 2300 feet as I would 4400 ft. When it got near the 4911 feet....I'd probably be in another 2% on the pulley. Depends on the motor.
Here's some calcs based on running a drag car.
2360 feet corrected baseline
7.50 seconds base e.t.
Now running at 2335 feet
Et now is 7.498
2360 feet corrected baseline
7.50 seconds base e.t.
Now running 4911 feet
Et now is 7.729
Best I can do.

[Fiat48]

Thanks Art! :)
If I was using it right I was right around 2000'-2100' all afternoon during my testing. I know at some of the races I've heard them complain about 3500'-4000' altitude density's. So I wonder how this relates to performance, some of my car buddies swear 5/10th on their ET's? Is it really that bad? :confused: :confused:
The air can clobber you a couple tenths and not correcting the fuel mixture for the less air can clobber you some more. Why it is all about the tune up.

[Carnivalride]

Temperature is the most important factor and humidity has the least effect on corrected altitude.
2360 feet corrected
2335 feet corrected
2227 feet corrected
4460 feet corrected
4753 feet corrected
4911 feet corrected
To be accurate you need an altimeter. The altimeter changes all the time and will not stay at a static 1363 feet where you were at. Generally the air going away makes the altimeter rise. But not always.
Still the above gives you an idea of the air going away.
How to relate this to performance drop is tough. Less air/less power. Blown alcohol wise I would be bumping the blower (depends on the setup and the blower) about 2% to run the same et at 2300 feet as I would 4400 ft. When it got near the 4911 feet....I'd probably be in another 2% on the pulley. Depends on the motor.
Here's some calcs based on running a drag car.
2360 feet corrected baseline
7.50 seconds base e.t.
Now running at 2335 feet
Et now is 7.498
2360 feet corrected baseline
7.50 seconds base e.t.
Now running 4911 feet
Et now is 7.729
Best I can do.
Thanks,
That was kind of what I was looking for. I know the boat was running better Sunday than it will be next summer at the races. I was just trying to get an idea how much? I realize being naturally aspirated it will have to be jetted down as the air gets worse or it will run even slower but I was just trying get an idea of how much power it will cost me. It looks like it may be on a borderline in the brackets, only competitive with good air and not real competitive with bad air. :(

[Carnivalride]

The air can clobber you a couple tenths and not correcting the fuel mixture for the less air can clobber you some more. Why it is all about the tune up.
So you think worst senerio probably about 3/10ths max if tuned right and 2/10ths most likely? :idea:
Thanks Bob

[Fiat48]

Not what I think but what the calcs show. And that being for a drag car having less drag than a boat. Just trying to give you and idea on air. The better air pump (engine/cylinder heads) you have the less you get clobbered. Running blown motors for so long and being adjustable for altitude, I'll have to see if I can dig up any old records of how the air clobbered my unblown deals. I do remember the injected altered on gas would pick up 1/2 second by driving from my corrected altitude (about 6500 ft) to Sacto raceway which would average about 2200 ft corrected.
I think all the old pro gas flat records are gone but I'll check.

[Carnivalride]

Not what I think but what the calcs show. And that being for a drag car having less drag than a boat. Just trying to give you and idea on air. The better air pump (engine/cylinder heads) you have the less you get clobbered. Running blown motors for so long and being adjustable for altitude, I'll have to see if I can dig up any old records of how the air clobbered my unblown deals. I do remember the injected altered on gas would pick up 1/2 second by driving from my corrected altitude (about 6500 ft) to Sacto raceway which would average about 2200 ft corrected.
I think all the old pro gas flat records are gone but I'll check.
That would be great if you could come up with some boat comparisons.

[Fiat48]

No good on the PGF records. The associations were changing the lights and approach areas back then and I have et's from 7.75 to 9 seconds. All over the map.
Put a blower on it and bump it 2% when you need a .10. LOL. Best I can tell ya.
But you might get hold of Voodocanoe and those oregon guys who bounce around elevations in their travels. They are a great group and they may have some info of how bad the air gets em.

[ECeptor]

Loren,
Get the SAE test procedure (SAE J???) for engines that includes how to correct for atmospheric conditions from either Jason or Aaron.
I don't have a copy...