Splitter question
10-26-2009, 10:54 AM
#1
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Splitter question
One of the winter projects for my car is to add a splitter and canards.
I am wondering on the splitter how much difference in downforce I would get between
A) Splitter under nose with air dam below splitter
and
B) Traditional splitter as low as possible
My thoughts are that A should be more tolerant in terms of trailer loading, surface irregularities etc.
Anyone have any thoughts on what I give up with A?
I have no clue yet on what I want to do for canards. The rule says that total surface area can be no more than 172.8" square inches. Any thoughts/experience on 1 versus 2 per side? Angle of attack?
I am wondering on the splitter how much difference in downforce I would get between
A) Splitter under nose with air dam below splitter
and
B) Traditional splitter as low as possible
My thoughts are that A should be more tolerant in terms of trailer loading, surface irregularities etc.
Anyone have any thoughts on what I give up with A?
I have no clue yet on what I want to do for canards. The rule says that total surface area can be no more than 172.8" square inches. Any thoughts/experience on 1 versus 2 per side? Angle of attack?
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10-26-2009, 11:10 AM
#2
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B or nothing else. Its not very hard to make these quick release with 4-bolts from under the car. The lower you get it, the more it works...and they work really well when done right.
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10-26-2009, 11:36 AM
#3
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Is the effect from blocking more air under the car with the lower splitter or is there some weird ground effect of a flat plane that I don't understand?
The ones that I have seen the lowest, typically have a small raised section on the center or the leading edge to let some air under, what is that for?
Does the pressure being exerted on the top of the splitter from the high pressure wave in front of the car add to the down force?
The ones that I have seen the lowest, typically have a small raised section on the center or the leading edge to let some air under, what is that for?
Does the pressure being exerted on the top of the splitter from the high pressure wave in front of the car add to the down force?
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10-26-2009, 12:02 PM
#5
I realize this is a BMW and not a miata, but the principle remains the same.
how splitters work
how splitters work
I am about to add one below my R-pack lip. Put it as low as you dare. You are basically stacking high pressure air on top of the lip, pushing it down since (if it's low enough) the air below the lip is at a lower pressure.
Added benefit is reducing the amount of air that gets under the car, generally reducing lift. Your airdam is doing some of this already...the lip will improve it.
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10-26-2009, 12:22 PM
#6
no, it doesn't add downforce like a wing does in the rear. it makes negative lift, (less lift) which equals "net" downforce.
don't worry about the center.
when i added an air dam, only thing i noticed was my car was slower on long straights, i imagine it was due to increased drag. maybe i made it too low.
i just run the splitter now. only reason i made the air dam was because i put qa1 springs in and didn't have the nb tophats yet. so the car was almost stock height and i was going to a big track with high speed straights. i know from spec miata's that dropping the car an inch or more (compared to stock)picks up 2-3mph on long straights.
don't worry about the center.
when i added an air dam, only thing i noticed was my car was slower on long straights, i imagine it was due to increased drag. maybe i made it too low.
i just run the splitter now. only reason i made the air dam was because i put qa1 springs in and didn't have the nb tophats yet. so the car was almost stock height and i was going to a big track with high speed straights. i know from spec miata's that dropping the car an inch or more (compared to stock)picks up 2-3mph on long straights.
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10-26-2009, 12:30 PM
#8
You should have noticed the car being quicker in the turns- something you're turbo can't help with. We put that ISC splitter (design is rules limited) on an ITA Miata and saw exit speeds rise nearly 5mph - from a typical 90mph exit. The straight top speed was the same- my guess due to a higher exit speed from the preceding turn.
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10-26-2009, 01:00 PM
#9
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so I can run two that 86.4" or four that are 43.2" or some combination that adds up to 172.8"
It is an autocross car, so I am not as concerned about drag as a track car.
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10-26-2009, 01:07 PM
#10
Just an uneducated (or only halfway through edumecation) guess...one large canard should be better.
You will be putting more of that surface area away from the body of the car and the slower moving boundary layer. The more surface you have outside of the boundary layer the more force they will provide.
I'm guessing they are going on the front corners...where flow is still laminar...so this is important.
It will also make adjusting angle of attack quicker and easier.
You will be putting more of that surface area away from the body of the car and the slower moving boundary layer. The more surface you have outside of the boundary layer the more force they will provide.
I'm guessing they are going on the front corners...where flow is still laminar...so this is important.
It will also make adjusting angle of attack quicker and easier.
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10-26-2009, 01:14 PM
#11
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all the splitter does is help isolate the volume inside the airdam, and hopefully allow some vacuum to build in there, so I dont really see why would would wnat the airdam under the splitter. I suppose it woild give you more volume to build vac in, but you would still end up wanting a splitter under that airdam too...
hmmm, double splitters
hmmm, double splitters
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10-26-2009, 01:57 PM
#12
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One name, Bernoulli. You want stagnant (high-pressure) air above the splitter, and flowing (low-pressure) air underneath the splitter; The resulting pressure differential creates the down force.
Therefore B is the way to go. If you put the dam below the splitter a-la A, it will slow the airflow under the splitter, cause a pressure rise, and thus not work as well.
Therefore B is the way to go. If you put the dam below the splitter a-la A, it will slow the airflow under the splitter, cause a pressure rise, and thus not work as well.
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10-26-2009, 03:54 PM
#19
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The air dam on the c6 is different than the previous years. The reason they overheat without it is due to high pressure behind the heat exchangers created by removing this. People can't seem to grasp the concept that opening a hole for the radiator doesn't make more air go through it.
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