Understanding the new splitter rule(s)

The way that it is currently enforced is that ;Any air control that fits in the body shadow is legal . That includes dive planes, spiltters etc. The issue that we have is that the air dam rule was written before the rest came along.
Maybe the rule should just state "air control" instead of "air dam". Or the GCR should add the rest to the air dam description.
 
blamkin86":2331rcbs said:
From the glossary:

Air Dam – An air control device at the lower front of a car, intended to
divert some of the air which would normally pass under the car when the
car is in motion.
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I don't see any wording in the new rule that allows a splitter. I do see splitter-specific rules in the Touring category.

I think you could argue that a splitter's purpose is greater than diverting some of the air under the car - that is, a splitter is intended to add downforce that would not be there were it not present, and there were only an air dam.

Not trying to be difficult here- but this rule (now rules) really need some more thought; especially is splitters are supposed to be legal.
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I agree completely with this assesment. An air dam and splitter are 2 different items. One blocks air and doesn't really control where it spills to. The other acts to build up air pressure and use it to create downforce.

I wouldn't run a splitter unless it was explicitly added to the rules.
 
I have a horizontal panel (splitter) attached to the bottom of my bumper with a short vertical air dam attached within the shadow of the bumper profile. I believe the horizontal panel/splitter meets the definition of an intermediate panel between the bumper and the air dam. I have run this for at least six years and have never been challenged as to its legality. Maybe if I start going faster it will become and issue. :think: :lol:
 
"The opening in the spoiler/air-dam must be symmetrically aligned in both planes of the grille."
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Can someone help me understand which planes the rule is referring to? Does it mean the opening must be centered between top and bottom planes? Or does it mean that the opening in the air-dam must match the slope of the grille (symmetry with the surface planes of the grille).

Paul
 
Rule:

"The height of the opening must be equal to or greater than the distance measured perpendicularly
to the ground between the lowest and highest point of the portion of the grille that would
otherwise be covered. The opening in the spoiler/air-dam must be symmetrically aligned in both
planes of the grille."


Height and width of grill measured in a perpendicular plane to the ground.

Symmetrically aligned in both planes of the grill is that the new opening shall not be offset vertically or horizontally to the OEM grille opening.
 
blamkin86":17as7tcf said:
Ah I see, you're saying even a flat spoiler creates downforce, so a splitter that creates even more downforce must also be legal.

I still don't see why it isn't mentioned. Maybe folks think it doesn't have to be. I just don't trust some steward somewhere to be as level headed.

If the rule in fact used the word splitter, I Wouldn't have to hope some jackass doesn't understand aero.
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Well I didn't actually make the implied "therefore" statement. I just pointed out that generating downforce is not really a great differentiator between air dam and splitter.
 
dhrmx5":1mbzw2dj said:
I agree completely with this assesment. An air dam and splitter are 2 different items. One blocks air and doesn't really control where it spills to. The other acts to build up air pressure and use it to create downforce.

I wouldn't run a splitter unless it was explicitly added to the rules.
Click to expand...

The issue is when you try to legislate the definition between the two. You could make a very black and white definition that requires the air dam be purely vertical, because I don't see how you could possibly enforce the "intent" of any non-vertical surfaces. However then you will make what a lot of people use - optional OEM, or aftermarket air dams, which have a more complex shape than a simple vertical wall would, illegal.

DSC03052.jpg
(not my image)
 
I submit the air dam pictured should be legal by anyone's definition. I think that's the intent.

My suggestion would be to fix the glossary definition for either Air dam or spoiler. If the GCR definition of Air Dam or Spoiler sufficiently describe a splitter, I'll eat my hat.


Short of that... Pretty simple to just add the phrase "The Spoiler/Air dam may be of any shape (including those that increase downforce) provided it meets all the other parts of this rule."
 
chois":1n8azqpn said:
dhrmx5":1n8azqpn said:
I agree completely with this assesment. An air dam and splitter are 2 different items. One blocks air and doesn't really control where it spills to. The other acts to build up air pressure and use it to create downforce.

I wouldn't run a splitter unless it was explicitly added to the rules.
Click to expand...

The issue is when you try to legislate the definition between the two. You could make a very black and white definition that requires the air dam be purely vertical, because I don't see how you could possibly enforce the "intent" of any non-vertical surfaces. However then you will make what a lot of people use - optional OEM, or aftermarket air dams, which have a more complex shape than a simple vertical wall would, illegal.

DSC03052.jpg
(not my image)
Click to expand...

I agree that there is a problem with defining it. My heartburn derives from the fact that my del sol can't run a splitter as the airdam barely meets the silhouette rule. No way can I add a splitter. On the other hand, a Miata can run a 4" wide splitter or an air dam and 2" splitter and be within the rules.

If the rule explicitly allowed a 2" max splitter (horizontal surface) with any airdam (vertical/slanted surface) having to be within the silhouette of the car every chassis could get some downforce.
 
I wrote a letter asking for 1/2 in past the shadow for the fasteners and was refused. Just a letter changing the wording from "air dam" to "any air control" must be inside the shadow. Solves the problem of the rule. But not your Honda- they are too fast already.
Lots of current prod cars have a set back air dam and pretty big splitter.
 
So did everyone miss the second part, which was also in the latest Fastracks?

Clarify Air Dam Height Rule & Undertray Allowance In GCR section 9.1.5.E.9.a.9., make the following changes:
"A front spoiler/air-dam can be fitted to the front of the car.
A. The spoiler/air-dam shall not protrude beyond the overall outline of the body when viewed from above, perpendicular to the ground, or aft of the forward most part of the front fender wheel opening.
B. The spoiler/air-dam can be mounted to the body, chassis and/or frame and may extend no higher than four (4) inches above the horizontal centerline of the front wheel hubs. An intermediate mounting device may be used in locations where the front body-work is above the four inch maximum.
C. The spoiler/air-dam shall have no support or reinforcement extending aft of the forward most part of the front fender wheel opening.
D. If the spoiler/air-dam covers any portion of the stock grille, an opening must be created in the spoiler/air-dam. The width of the opening must be equal to or greater than the widest horizontal measurement of the portion of the grille that would otherwise be covered. The height of the opening must be equal to or greater than the distance measured perpendicularly to the ground between the lowest and highest point of the portion of the grille that would otherwise be covered. The opening in the spoiler/air-dam must be symmetrically aligned in both planes of the grille.
E. Openings in the spoiler/air-dam are permitted for the purpose of ducting air to the brakes, radiator and/or oil coolers. Openings can be cut in the front valance to allow the passage of up to a three (3) inch diameter round duct hose leading to each front brake. These openings can
serve no other purpose.”
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Add a new 9.1.5.E.9.a.10., and re-number the following paragraphs:
“An undertray may be added. The undertray may close out the area from the leading edge of the bodywork (including the spoiler/air-dam) back to the forward most part of the front fender wheel opening."
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Both "Air Dam" and "Undertray" are defined in the GCR glossary. If anyone decides they're going to torture these rules, that person better be able to defend their design to a tech steward (or their competition) within those definitions and these rules.
 
Yes Kevin, we actually posted the definition of air dam from the GCR, if you look back a page.

So, a splitter is now legal a long as we call it an undertray, and said undertray doesn't go beyond the vehicle silhouette. Got it.
 
So does the " vehicle silhouette" extend out to the shadow of a front bumper if a person chooses to run with one? Sure could get that "under tray " ledge pretty far forward on some cars !
 
rydermike":3f4qhiz9 said:
So does the " vehicle silhouette" extend out to the shadow of a front bumper if a person chooses to run with one? Sure could get that "under tray " ledge pretty far forward on some cars !
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Mike, "Silhouette" was my word - the rule Kevin points to is worded slightly differently.

I do think the intent is exactly what you're saying there, but YMMV.
 
On my Integra it's possible for an undertray to extend ~3" out from an airdam and still be within the vertical silhouette, if the air-dam is attached to the bottom lip of the OEM bumper cover. The alternative design is to bring the air-dam out to the vertical silhouette and go down from there, which confines the under-tray to being completely behind it (i.e. no "splitter"), but also makes the air-dam taller and does a better/easier job of cleaning up the front-end. I've built examples of both, have tried both, and picked the design that works the best for me. Now, if the "splitter" could be extended out front of the vertical profile of the car, and work in conjunction with an air-dam that's placed exactly at the vertical profile of the car, allowing for much better control/force of air over the top of the car (a la the ST rules), which one I chose might be a different story.

blamkin86":98m2kg78 said:
Yes Kevin, we actually posted the definition of air dam from the GCR, if you look back a page.

So, a splitter is now legal a long as we call it an undertray, and said undertray doesn't go beyond the vehicle silhouette. Got it.
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I know it was. The presented new wording was incomplete, resulting in much of the discussion in this thread, hence my post. I'd also venture to say that a majority of current Prod racers would say that a undertray/splitter was already legal before this new wording was added (see Brian Linn's post earlier in this thread), although I can certainly understand the counter argument to that. So because of that, all this newly created line does is make it very explicit and attempts to resolve a "grey area", which is really the only purpose to any of this.
 
When reasonable people can disagree on the legality of something, it's on the board to clear up the wording. I really hate how some rules seem to have a secret group of people who know it's OK, like the seam welding thing a few years ago. "Sure, I've never been protested," doesn't cut it - especially for those who don't have friends "on the inside."

So, job well done on this one.

There's still two issues here to resolve, but we'll tackle those another day.
 
Hypothetically if Prod just adopted the front valence treatment of another group, like GT or STU (just made the allowable splitter blades shorter, how would this detrimentally affect prod?

From the GT regs

12. A spoiler may be fitted to the front of the car. It shall not
protrude beyond the overall outline of the car as viewed from
above except as follows:
• GT2: a front splitter may extend up to 3 inches.
• GT3: a front splitter may extend up to 2 inches.
• GTLite: a front splitter may extend up to 2 inches.
In all classes, the spoiler shall not extend aft of the forward
most part of the front fender opening (cutout), and shall not
be mounted more than four (4) inches above the horizontal
centerline of the front wheel hubs. The spoiler shall not cover
the normal grill opening at the front of the car. An intermediate
mounting device may be used on cars whose front bodywork
is above the four (4) inch minimum. Openings are permitted
for the purpose of ducting air to the brakes, radiator, airbox
and/or oil cooler(s); equal openings may be placed in the
standard lower front panel directly behind openings placed
in the spoiler. When bumpers are retained, the spoiler and
bumper shall appear to be two separate parts. Spoiler “pans”
are only permitted forward of the leading edge of the front
wheel openings and shall be flat and follow, but not exceed,
the line of the front fender/spoiler bottom.
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Seems fairly simple compared to the Prod rules. Shorten the splitter length to balance performance in accordance with each specific class philosophy. STU is a bit more complicated, but the wording is pretty straight forward.
 
The GT rules looks the easiest to enforce and allows every car to have access to the aero advantage of the splitter.

Makes perfect sense.
 
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