Classic G/C air dam

[racergeo]

   O.K. I'm trying to help a friend build a air dam on the front of a 78 Firebird in the classic category. It seems clear to me that it is allowed in the classic G/C class. The confusion comes from the fellows building it who claim a tech person said it couldn't be mounted straight down from the front most part of the bumper. They have built it under the leading edge and the front leading edge creates a lip where the air would actually hit it and cause lift. It seems to me that the statement in the rule book "so long as no point of the air dam projects more than 1/4 inch forward of the original contour of the LEADING EDGE of the front bumper when viewed from ABOVE.) Emphasis mine to be an A HOLE.....makes it seem  clear. I think the Hot Rod Camaro is that way and many others. The rule book does warn not to block the grill. The leading edge is what I understand to be the front most part of the bumper. Please help.     George

[will6er]

I don't think you can block off the air inlets below the bumper.
At least that is how I interpreted the rule.

Will Willis #6302

[jacksoni]

Although Keith Turk's So Al special/Hot Rod Special ran more often in /Alt I think it ran GC some as well. Is Camaro but similar vintage and the air dam was legal-AFAIK:

http://www.hotrod.com/articles/bonneville-national/

Also:  http://www.hotrod.com/articles/car-aerodynamics/#113-0703-01-s-chevy-camaro-aerodynamics-front-view

[thundersalt]

" I think it ran GC some as well. Is Camaro but similar vintage and the air dam was legal-AFAIK:"



no it was not

[Dynoroom]

***

[jacksoni]

" I think it ran GC some as well. Is Camaro but similar vintage and the air dam was legal-AFAIK:"



no it was not

Ok. Rules for air dams are same regardless of class. What is not legal?

[racergeo]

   When you call a supplier and ask for a grill they want to sell you the plastic honey comb item that fills the space above the bumper on a 78 Firebird. A lot of cars have openings for air that do not have a grill in them. They are usually under the bumper. In The so called air dam they built,it still covers the air inlets below the bumper but does not take advantage of the rule that allows the dam to be at the leading edge.

[racergeo]

   I just looked at my 2009 rule book and the car pictured in the gas coupe category has no grill and is closer to the ground in front then the air dam I'm proposing. It is a mid 80's Trans Am and this of course explains why 4 of them have gone over 300. I am not in any way trying to bend the rules, only apply them to my advantage as you would expect. In those cars the air for cooling the radiator comes under the front of the car. I probable should have made this under rule questions.

[thundersalt]

" I think it ran GC some as well. Is Camaro but similar vintage and the air dam was legal-AFAIK:"



no it was not

Ok. Rules for air dams are same regardless of class. What is not legal?

The rules have changed slightly since 2008....DF/KT camaro  as shown in your pics is not legal for gas coupe... 4.cc.1 (last sentence) "Bodies cannot be cut away to accommodate air dams or splitters"   5.D.3 gas coupe 2017 book page 85 7th paragraph '
".....not permitted.....blocked off grills......."


Ask me how I know......I got my $100 back from DW

[jacksoni]

OK. I understand about the cutting body thing. Also the blocked grille which of course is an /Alt modification. I showed the pictures to represent the mounting of the air dam (not those other features) with respect to the bumper which was the original question. Sorry if have been misleading.

[thundersalt]

The cool thing now is you can slam it right  to the front of the bumper. Back then nothing could be past the edge including the thickness of your material

[SPARKY]

even if the grill opening does not pass air you cannot cover it!

[will6er]

In Gas Coupe, The opening has to pass air. It cannot be blocked.

Will Willis
#6302

[thundersalt]

I think this is what Sparky is referring to:   using a 1978 camaro as an example, the lower grill is cosmetic only but in gas coupe it can not be blocked or covered

[racergeo]

  Should going into Alt. class with the grill blocked, a proper full air dam and rear spoiler result in more then an 5 mph increase?