attaching brake ducts- just want to make sure

U

uncleben

New member
If I'm reading the GCR right- if I attach my brake duct hoses to an air dam, I can *only* make 3" holes in the air dam, correct? Can I not have a naca-style inlet scoop that the 3" hole attaches to? It sounds like if I attach the duct hoses to the stock bumper cover (in this case a 90 Civic Si hatchback) then I am free to have 5"x7" inlets for the brake duct hoses.

Is this correct?
 
Originally posted by uncleben:
If I'm reading the GCR right- if I attach my brake duct hoses to an air dam, I can *only* make 3" holes in the air dam, correct? Can I not have a naca-style inlet scoop that the 3" hole attaches to? It sounds like if I attach the duct hoses to the stock bumper cover (in this case a 90 Civic Si hatchback) then I am free to have 5"x7" inlets for the brake duct hoses.

Is this correct?
Click to expand...

Take a look at the pieces I have for the brake ducts. If you have fog light openings molded in the bumper cover you have a perfect mounting point for an adapter.
www.sbmsinc.com/race_shop.html
 
Tom thanks, I got your email response earlier as well, but it also did not answer my question. I don't want to be rude, but it is frustrating that I ask a fellow racer a question (one that I've already purchased goods from no less) and instead of answers, I am told about more of their products for sale. I don't have a lot of people to get advice from- I only know of 2 gentlemen in my area that even race, and they do not race SCCA ITA. So I rely on the help from people I meet online or purchase parts from who have "been there done that" and I hope for the best. I am very green and while everyone seems to pretty helpful, a lot seem to just want to sell me something. I'm not saying that about you, but there have been plenty like that. I also appreciate all your help and advice, and for trying to clear up the problem with your brake ducts not fitting on my car.

Regardless, as I've said, I do not have a CRX, nor do I have a CRX bumper with those fog light inlets, nor do I have the money to buy more parts. I told you we were making our own air dam. Thanks for recommending your air dam as well, but again, I do not have the funds.

I'm not trying to make a bad impression here-Tom is a great guy and has given me good advice. But at this point, I don't need more parts, I just need to make sure I'm reading the GCR right so I can continue with my plan. I know my cheap air dam idea might not be the best, but I'm not trying to win points championships, I'm just trying to have some fun, improve my car a little, and be legal.

Thanks and sorry for ranting- again, Tom is a great guy and has given me lots of good advice, I just need my question answered from fellow ITA racers.
 
Yes on both accounts.no air dam 5x7 inlet, air damn 3" holes. mike g.
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Thank you sir! I suppose I would be correct in assuming a straight 3" hole would probably not be as good at collecting the air as a nice big 5x7 naca inlet. Looks as though I will be making some holes in the stock bumper cover!
 
I don't have my GCR here at the office but if the question is big duct vs 3" hole, I'm not sure that it makes a ton of difference. The airflow is a function of the smallest cross-section of the path and the difference between the inlet and outlet pressures. I don't think that a duct that tapers to a 3" hose is going to flow much - or any - more than a 3" hole to a 3" duct would.

To clarify one point, a NACA profile duct (one of those distinctive holes that is pointy at one end and flat at the other) is intended for use in a surface that sees "laminar airflow" - that is, flow across that surface.

They suck air off at a right angle to the airflow, the intent being to do so with limited penalty in drag, so they really aren't beneficial (theoretically) in an airdam. It IS possible that the air is flowing across the front of the car to some extent but I don't know how much.

It MIGHT be that the potential inlet pressure is higher in some places on the front of your car than others. There might be some bleed off near the edge of the airdam, for example, or the lower portion of the nose migh see higher pressure than that up by the radiator opening. There's no easy way to know.

K
 
Kirk, as usual, makes valid points...a NACA duct is probably not the ideal item for your purpose.

As you are making your own airdam, I would suggest a careful reading of the rules. Does it specify the materials or shape of the air dam? I think there is reasonable freedom in design that you can take advantage of. Perhaps yuo can mold in a shape to your dam that a 3" tube attaches to that is more appropriate ?

------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]
 
this got confusing so let me restate and see if anyone thinks i am wrong.
when there is no air dam you may cut 2 5"x7" holes in the stock front valance (the body below the front bumper)and connect 3" hoses.
when there is a air dam there is no limit to the size of the scoop in the air dam, but you must choke to a 3" hose and only a hole large enough for that is allowed in the stock front valance.

dick
 
Originally posted by uncleben:
Tom thanks, I got your email response earlier as well, but it also did not answer my question. I don't want to be rude, but it is frustrating that I ask a fellow racer a question (one that I've already purchased goods from no less) and instead of answers, I am told about more of their products for sale. I don't have a lot of people to get advice from- I only know of 2 gentlemen in my area that even race, and they do not race SCCA ITA. So I rely on the help from people I meet online or purchase parts from who have "been there done that" and I hope for the best. I am very green and while everyone seems to pretty helpful, a lot seem to just want to sell me something. I'm not saying that about you, but there have been plenty like that. I also appreciate all your help and advice, and for trying to clear up the problem with your brake ducts not fitting on my car.

Regardless, as I've said, I do not have a CRX, nor do I have a CRX bumper with those fog light inlets, nor do I have the money to buy more parts. I told you we were making our own air dam. Thanks for recommending your air dam as well, but again, I do not have the funds.

I'm not trying to make a bad impression here-Tom is a great guy and has given me good advice. But at this point, I don't need more parts, I just need to make sure I'm reading the GCR right so I can continue with my plan. I know my cheap air dam idea might not be the best, but I'm not trying to win points championships, I'm just trying to have some fun, improve my car a little, and be legal.

Thanks and sorry for ranting- again, Tom is a great guy and has given me lots of good advice, I just need my question answered from fellow ITA racers.
Click to expand...

Not trying to sell you anything, there are pictures there that you can look at for free. The point being is that a lot of money is being wasted by reinventing the wheel. If you don't have fog light openings, than you can't make them up. You can try and route some air from the spaces left in the radiator area, but it's a tight sqeeze.
 
Sorry Kirk- I didn't mean "naca" inlets, I guess that was the last thing I saw when I was looking at the different type of inlet ducts in my Pegasus catalog and said that. Sorry about the confusion. I mean the regular brake duct scoop type of inlets.

originally posted by dickita15:
when there is a air dam there is no limit to the size of the scoop in the air dam, but you must choke to a 3" hose and only a hole large enough for that is allowed in the stock front valance.
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I don't think so. I think you have that backwards. Here is the original text from the GCR:

Where an air dam/spoiler is used, two total openings may be cut in the front valance to allow the passage of up to a three (3) inch diameter duct leading to each front brake/rotor assembly.

Where no air dam/spoiler is used, two total openings of a maximum size five (5) inches by seven (7) inches maybe cut in the front valance so that brake ducts can be added with a three (3) inch diameter hose leading to each front brake/rotor assembly.

The problem with the way this is worded is that it says that with a air dam you can cut "openings" to allow 3" brake ducts. So why can't I cut a 4x6" opening to place a duct scoop in, providing only a 3" hole exits it to the brake tubing? The only reason I think you can't, is because it *specifically* says you can cut 5x7" openings into the stock valance, which to me would imply you can ONLY have 3" openings in the air dam. I don't know, it's a tricky subject. I guess the bottom line is, would anyone file protest if I had some scoops on my air dam feeding 3" hose??

Originally posted by Tom Blaney:
The point being is that a lot of money is being wasted by reinventing the wheel.
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As I told you before, there is not a "lot of money being wasted", in fact, there is no money being wasted. And if in the end I have the same thing everyone else has, then fine, but I got a chance to try other things and there is nothing wrong with that.

What we have done, because it was free and I don't have the money to buy an air dam right now, is to create our own from a spare bumper cover. We cut it in half lengthwise and are attaching the bottom half of it, upside down, to the stock bumper cover. It doesn't look like a traditional flat air dam, and I don't know anything about aero, so it could be total crap in that regard, but it's given us nice places to mount air ducts, and surely it's better then nothing. Maybe I'm completely wrong, and I'm not even sure if I will tell any difference. At this point, I more care about having functional brake cooling ducts then an air dam, and it's hard to get the ducts into the bumper with some of the stuff that is in there and in the way. This at least provides a place to mount them. *shrug* We'll see...

[This message has been edited by uncleben (edited June 23, 2004).]
 
ben says;
I don't think so. I think you have that backwards. Here is the original text from the GCR:

Where an air dam/spoiler is used, two total openings may be cut in the front valance to allow the passage of up to a three (3) inch diameter duct leading to each front brake/rotor assembly.

Where no air dam/spoiler is used, two total openings of a maximum size five (5) inches by seven (7) inches maybe cut in the front valance so that brake ducts can be added with a three (3) inch diameter hose leading to each front brake/rotor assembly.

Ben
this says that when using a air dam you can only cut holes in THE STOCK VALANCE large enough for the hoses. it does not say you can not cut larger hole in the air dam. if you have an air dam which you have scoops in there is no need for larger holes in the STOCK VALANCE. the only problem at all with this wording is if you have the 5x7s in your stock valance and change to an air dam it means you have to replace your stock valance with a piece with smaller holes. the adding of the air dam woud make the 5x7 holes in your stock valance illegal
dick
 
The wording is clear. Yeah right.
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Actually, the way I read it, the only text that limits the size of any opening is when NO airdam/spoiler is used. Then the opening may not exceed 5x7". Otherwise the only size limitation mentioned is the hose, which must be 3" diamter max.

The size of the hole has nothing to do with the size of the hose (reread the rule). If I had an airdam, I could legally cut a 12" diameter hole in the valance to pass the hose through the way the rule is written. Now, I wouldn't do that because a) the rule could be changed and I could be left SOL, and B) one could conceivably protest that such a large opening served another illegal function such as providing additional cooling and then it's up to the SOM and COA.

The person who stated there is no limitation to the size of the opening in the airdam or even the valance to pass the hose through is quite correct per the letter of the law.

This is a rule that should probably be rewritten to clean out the mud.


------------------
George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com
 
***Where an air dam/spoiler is used, two total openings may be cut in the front valance to allow the passage of up to a three "(3) inch diameter duct" leading to each front brake/rotor assembly.***

This portition of the rule is written poorly IMHJ.
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When I go to the parts house & ask for a pair of "3 inch duct diameter duct" they will hand me two plastic items that require two 5 x 7 inch holes be cut in the air dam/spoiler that match the opening size of the two "3 inch diameter duct". Then I connect "3 diameter duct hose" that travels from the "3 inch diameter duct" to the brake rotor.

***Where no air dam/spoiler is used, two total openings of a maximum size five (5) inches by seven (7) inches maybe cut in the front valance so that brake ducts can be added with a three (3) inch diameter hose leading to each front brake/rotor assembly.***

This portition of the rule is written correct IMHJ.
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If the first portition of the rule allows two 3 inch diameter holes ONLY then it's ADVANTAGE to person who has a front valance. I don't beleive that's what the rules writters mean.

Have Fun
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David
 
uncleben,

If the search function on this site worked better, you would no doubt at least one thread from me asking the exact same question. Indeed, I have gone around in circles with my ducting as a result of the wording of the rules and I think I have found a happy ending. As I mentioned in my IM to you, I read the rules as dickita15 and some others do. If you do NOT use an airdam, you can cut a specified 5x7 opening to allow for your ducting. If you DO use an airdam, the openings can be designed however you please as long as they fit within the other rules for airdam construction and the hose is 3". The reason this finally made sense to me is the variability in airdam construction allowed by the rules. If I make an airdam out of flat aluminum and I attach two plastic bumper ducts to it that are 3.5" x 9" in size to attach to my 3" hose, who's to say that the bumper ducts aren't an integral part of the airdam itself? I believe this is why there is no restriction to the openings in the airdam, because it can be designed as you please as long as it's legal according to the other set rules (lower lip not below the wheel edge, etc.). Does that make more sense? This helped me understand it anyway, right or wrong.

------------------
'88 CRX Si - ITA/PS2/H4 #4: Handles like it's on jack stands
'98 ITR #0231 - DS autocrosser: Handles like I sold it
'02 Jeep Grand Cherokee - daily driver/tow vehicle: Handles like a jumping castle
 
Thanks all- I think I know what I'm going to do now.
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One last question- have any of you ever been protested based on your air dam or choice of brake duct locations?
 
I will bet the answer is no to the protest question......as a matter of fact, I bet the answer would still be "no" for 96% of us if the question were reworded to exclude the airdam and duct aspect....


So I thought they were saying that IF you have an airdam, you got to cut (only) 3" diameter holes in your stock valence, but if you use your stock valace AS your airdam, you get to cut a 5" x 7" hole for the scoopy thing...

Which seemed clear to me, but I must be missing something cuz' I'm not feeling confused!

------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]
 
Originally posted by lateapex911:
So I thought they were saying that IF you have an airdam, you got to cut (only) 3" diameter holes in your stock valence, but if you use your stock valace AS your airdam, you get to cut a 5" x 7" hole for the scoopy thing...

Which seemed clear to me, but I must be missing something cuz' I'm not feeling confused!
Click to expand...

Jake, please reread the rule and provide reference that limits the hole in the valance to 3" if you are running an airdam. You can't because it's not there. The only 3" reference is to the size of the hose.


------------------
George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com
 
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